core.c 214.8 KB
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/*
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 *  kernel/sched/core.c
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 *
 *  Kernel scheduler and related syscalls
 *
 *  Copyright (C) 1991-2002  Linus Torvalds
 *
 *  1996-12-23  Modified by Dave Grothe to fix bugs in semaphores and
 *		make semaphores SMP safe
 *  1998-11-19	Implemented schedule_timeout() and related stuff
 *		by Andrea Arcangeli
 *  2002-01-04	New ultra-scalable O(1) scheduler by Ingo Molnar:
 *		hybrid priority-list and round-robin design with
 *		an array-switch method of distributing timeslices
 *		and per-CPU runqueues.  Cleanups and useful suggestions
 *		by Davide Libenzi, preemptible kernel bits by Robert Love.
 *  2003-09-03	Interactivity tuning by Con Kolivas.
 *  2004-04-02	Scheduler domains code by Nick Piggin
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 *  2007-04-15  Work begun on replacing all interactivity tuning with a
 *              fair scheduling design by Con Kolivas.
 *  2007-05-05  Load balancing (smp-nice) and other improvements
 *              by Peter Williams
 *  2007-05-06  Interactivity improvements to CFS by Mike Galbraith
 *  2007-07-01  Group scheduling enhancements by Srivatsa Vaddagiri
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 *  2007-11-29  RT balancing improvements by Steven Rostedt, Gregory Haskins,
 *              Thomas Gleixner, Mike Kravetz
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 */

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#include <linux/kasan.h>
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#include <linux/mm.h>
#include <linux/module.h>
#include <linux/nmi.h>
#include <linux/init.h>
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#include <linux/uaccess.h>
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#include <linux/highmem.h>
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#include <linux/mmu_context.h>
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#include <linux/interrupt.h>
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#include <linux/capability.h>
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#include <linux/completion.h>
#include <linux/kernel_stat.h>
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#include <linux/debug_locks.h>
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#include <linux/perf_event.h>
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#include <linux/security.h>
#include <linux/notifier.h>
#include <linux/profile.h>
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#include <linux/freezer.h>
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#include <linux/vmalloc.h>
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#include <linux/blkdev.h>
#include <linux/delay.h>
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#include <linux/pid_namespace.h>
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#include <linux/smp.h>
#include <linux/threads.h>
#include <linux/timer.h>
#include <linux/rcupdate.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/percpu.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/sysctl.h>
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#include <linux/syscalls.h>
#include <linux/times.h>
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#include <linux/tsacct_kern.h>
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#include <linux/kprobes.h>
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#include <linux/delayacct.h>
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#include <linux/unistd.h>
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#include <linux/pagemap.h>
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#include <linux/hrtimer.h>
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#include <linux/tick.h>
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#include <linux/ctype.h>
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#include <linux/ftrace.h>
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#include <linux/slab.h>
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#include <linux/init_task.h>
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#include <linux/context_tracking.h>
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#include <linux/compiler.h>
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#include <linux/frame.h>
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#include <linux/prefetch.h>
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#include <asm/switch_to.h>
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#include <asm/tlb.h>
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#include <asm/irq_regs.h>
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#include <asm/mutex.h>
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#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#endif
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#include "sched.h"
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#include "../workqueue_internal.h"
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#include "../smpboot.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/sched.h>
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DEFINE_MUTEX(sched_domains_mutex);
DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
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static void update_rq_clock_task(struct rq *rq, s64 delta);
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void update_rq_clock(struct rq *rq)
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{
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	s64 delta;
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	lockdep_assert_held(&rq->lock);

	if (rq->clock_skip_update & RQCF_ACT_SKIP)
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		return;
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	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
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	if (delta < 0)
		return;
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	rq->clock += delta;
	update_rq_clock_task(rq, delta);
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}

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/*
 * Debugging: various feature bits
 */
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#define SCHED_FEAT(name, enabled)	\
	(1UL << __SCHED_FEAT_##name) * enabled |

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const_debug unsigned int sysctl_sched_features =
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#include "features.h"
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	0;

#undef SCHED_FEAT

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/*
 * Number of tasks to iterate in a single balance run.
 * Limited because this is done with IRQs disabled.
 */
const_debug unsigned int sysctl_sched_nr_migrate = 32;

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/*
 * period over which we average the RT time consumption, measured
 * in ms.
 *
 * default: 1s
 */
const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;

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/*
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 * period over which we measure -rt task cpu usage in us.
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 * default: 1s
 */
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unsigned int sysctl_sched_rt_period = 1000000;
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__read_mostly int scheduler_running;
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/*
 * part of the period that we allow rt tasks to run in us.
 * default: 0.95s
 */
int sysctl_sched_rt_runtime = 950000;
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/* cpus with isolated domains */
cpumask_var_t cpu_isolated_map;

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/*
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 * this_rq_lock - lock this runqueue and disable interrupts.
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 */
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static struct rq *this_rq_lock(void)
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	__acquires(rq->lock)
{
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	struct rq *rq;
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	local_irq_disable();
	rq = this_rq();
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	raw_spin_lock(&rq->lock);
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	return rq;
}

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/*
 * __task_rq_lock - lock the rq @p resides on.
 */
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struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
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	__acquires(rq->lock)
{
	struct rq *rq;

	lockdep_assert_held(&p->pi_lock);

	for (;;) {
		rq = task_rq(p);
		raw_spin_lock(&rq->lock);
		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
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			rf->cookie = lockdep_pin_lock(&rq->lock);
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			return rq;
		}
		raw_spin_unlock(&rq->lock);

		while (unlikely(task_on_rq_migrating(p)))
			cpu_relax();
	}
}

/*
 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
 */
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struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
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	__acquires(p->pi_lock)
	__acquires(rq->lock)
{
	struct rq *rq;

	for (;;) {
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		raw_spin_lock_irqsave(&p->pi_lock, rf->flags);
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		rq = task_rq(p);
		raw_spin_lock(&rq->lock);
		/*
		 *	move_queued_task()		task_rq_lock()
		 *
		 *	ACQUIRE (rq->lock)
		 *	[S] ->on_rq = MIGRATING		[L] rq = task_rq()
		 *	WMB (__set_task_cpu())		ACQUIRE (rq->lock);
		 *	[S] ->cpu = new_cpu		[L] task_rq()
		 *					[L] ->on_rq
		 *	RELEASE (rq->lock)
		 *
		 * If we observe the old cpu in task_rq_lock, the acquire of
		 * the old rq->lock will fully serialize against the stores.
		 *
		 * If we observe the new cpu in task_rq_lock, the acquire will
		 * pair with the WMB to ensure we must then also see migrating.
		 */
		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
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			rf->cookie = lockdep_pin_lock(&rq->lock);
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			return rq;
		}
		raw_spin_unlock(&rq->lock);
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		raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
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		while (unlikely(task_on_rq_migrating(p)))
			cpu_relax();
	}
}

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#ifdef CONFIG_SCHED_HRTICK
/*
 * Use HR-timers to deliver accurate preemption points.
 */

static void hrtick_clear(struct rq *rq)
{
	if (hrtimer_active(&rq->hrtick_timer))
		hrtimer_cancel(&rq->hrtick_timer);
}

/*
 * High-resolution timer tick.
 * Runs from hardirq context with interrupts disabled.
 */
static enum hrtimer_restart hrtick(struct hrtimer *timer)
{
	struct rq *rq = container_of(timer, struct rq, hrtick_timer);

	WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());

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	raw_spin_lock(&rq->lock);
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	update_rq_clock(rq);
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	rq->curr->sched_class->task_tick(rq, rq->curr, 1);
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	raw_spin_unlock(&rq->lock);
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	return HRTIMER_NORESTART;
}

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#ifdef CONFIG_SMP
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static void __hrtick_restart(struct rq *rq)
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{
	struct hrtimer *timer = &rq->hrtick_timer;

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	hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
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}

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/*
 * called from hardirq (IPI) context
 */
static void __hrtick_start(void *arg)
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{
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	struct rq *rq = arg;
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	raw_spin_lock(&rq->lock);
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	__hrtick_restart(rq);
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	rq->hrtick_csd_pending = 0;
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	raw_spin_unlock(&rq->lock);
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}

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/*
 * Called to set the hrtick timer state.
 *
 * called with rq->lock held and irqs disabled
 */
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void hrtick_start(struct rq *rq, u64 delay)
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{
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	struct hrtimer *timer = &rq->hrtick_timer;
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	ktime_t time;
	s64 delta;

	/*
	 * Don't schedule slices shorter than 10000ns, that just
	 * doesn't make sense and can cause timer DoS.
	 */
	delta = max_t(s64, delay, 10000LL);
	time = ktime_add_ns(timer->base->get_time(), delta);
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	hrtimer_set_expires(timer, time);
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	if (rq == this_rq()) {
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		__hrtick_restart(rq);
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	} else if (!rq->hrtick_csd_pending) {
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		smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
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		rq->hrtick_csd_pending = 1;
	}
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}

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#else
/*
 * Called to set the hrtick timer state.
 *
 * called with rq->lock held and irqs disabled
 */
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void hrtick_start(struct rq *rq, u64 delay)
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{
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	/*
	 * Don't schedule slices shorter than 10000ns, that just
	 * doesn't make sense. Rely on vruntime for fairness.
	 */
	delay = max_t(u64, delay, 10000LL);
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	hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
		      HRTIMER_MODE_REL_PINNED);
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}
#endif /* CONFIG_SMP */
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static void init_rq_hrtick(struct rq *rq)
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{
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#ifdef CONFIG_SMP
	rq->hrtick_csd_pending = 0;
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	rq->hrtick_csd.flags = 0;
	rq->hrtick_csd.func = __hrtick_start;
	rq->hrtick_csd.info = rq;
#endif
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	hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	rq->hrtick_timer.function = hrtick;
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}
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#else	/* CONFIG_SCHED_HRTICK */
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static inline void hrtick_clear(struct rq *rq)
{
}

static inline void init_rq_hrtick(struct rq *rq)
{
}
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#endif	/* CONFIG_SCHED_HRTICK */
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/*
 * cmpxchg based fetch_or, macro so it works for different integer types
 */
#define fetch_or(ptr, mask)						\
	({								\
		typeof(ptr) _ptr = (ptr);				\
		typeof(mask) _mask = (mask);				\
		typeof(*_ptr) _old, _val = *_ptr;			\
									\
		for (;;) {						\
			_old = cmpxchg(_ptr, _val, _val | _mask);	\
			if (_old == _val)				\
				break;					\
			_val = _old;					\
		}							\
	_old;								\
})

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#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
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/*
 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
 * this avoids any races wrt polling state changes and thereby avoids
 * spurious IPIs.
 */
static bool set_nr_and_not_polling(struct task_struct *p)
{
	struct thread_info *ti = task_thread_info(p);
	return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
}
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/*
 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
 *
 * If this returns true, then the idle task promises to call
 * sched_ttwu_pending() and reschedule soon.
 */
static bool set_nr_if_polling(struct task_struct *p)
{
	struct thread_info *ti = task_thread_info(p);
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	typeof(ti->flags) old, val = READ_ONCE(ti->flags);
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	for (;;) {
		if (!(val & _TIF_POLLING_NRFLAG))
			return false;
		if (val & _TIF_NEED_RESCHED)
			return true;
		old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
		if (old == val)
			break;
		val = old;
	}
	return true;
}

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#else
static bool set_nr_and_not_polling(struct task_struct *p)
{
	set_tsk_need_resched(p);
	return true;
}
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#ifdef CONFIG_SMP
static bool set_nr_if_polling(struct task_struct *p)
{
	return false;
}
#endif
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#endif

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void wake_q_add(struct wake_q_head *head, struct task_struct *task)
{
	struct wake_q_node *node = &task->wake_q;

	/*
	 * Atomically grab the task, if ->wake_q is !nil already it means
	 * its already queued (either by us or someone else) and will get the
	 * wakeup due to that.
	 *
	 * This cmpxchg() implies a full barrier, which pairs with the write
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	 * barrier implied by the wakeup in wake_up_q().
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	 */
	if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL))
		return;

	get_task_struct(task);

	/*
	 * The head is context local, there can be no concurrency.
	 */
	*head->lastp = node;
	head->lastp = &node->next;
}

void wake_up_q(struct wake_q_head *head)
{
	struct wake_q_node *node = head->first;

	while (node != WAKE_Q_TAIL) {
		struct task_struct *task;

		task = container_of(node, struct task_struct, wake_q);
		BUG_ON(!task);
		/* task can safely be re-inserted now */
		node = node->next;
		task->wake_q.next = NULL;

		/*
		 * wake_up_process() implies a wmb() to pair with the queueing
		 * in wake_q_add() so as not to miss wakeups.
		 */
		wake_up_process(task);
		put_task_struct(task);
	}
}

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/*
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 * resched_curr - mark rq's current task 'to be rescheduled now'.
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 *
 * On UP this means the setting of the need_resched flag, on SMP it
 * might also involve a cross-CPU call to trigger the scheduler on
 * the target CPU.
 */
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void resched_curr(struct rq *rq)
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{
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	struct task_struct *curr = rq->curr;
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	int cpu;

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	lockdep_assert_held(&rq->lock);
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	if (test_tsk_need_resched(curr))
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		return;

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	cpu = cpu_of(rq);
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	if (cpu == smp_processor_id()) {
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		set_tsk_need_resched(curr);
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		set_preempt_need_resched();
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		return;
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	}
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	if (set_nr_and_not_polling(curr))
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		smp_send_reschedule(cpu);
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	else
		trace_sched_wake_idle_without_ipi(cpu);
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}

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void resched_cpu(int cpu)
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{
	struct rq *rq = cpu_rq(cpu);
	unsigned long flags;

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	if (!raw_spin_trylock_irqsave(&rq->lock, flags))
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		return;
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	resched_curr(rq);
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	raw_spin_unlock_irqrestore(&rq->lock, flags);
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}
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#ifdef CONFIG_SMP
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#ifdef CONFIG_NO_HZ_COMMON
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/*
 * In the semi idle case, use the nearest busy cpu for migrating timers
 * from an idle cpu.  This is good for power-savings.
 *
 * We don't do similar optimization for completely idle system, as
 * selecting an idle cpu will add more delays to the timers than intended
 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
 */
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int get_nohz_timer_target(void)
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{
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	int i, cpu = smp_processor_id();
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	struct sched_domain *sd;

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	if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
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		return cpu;

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	rcu_read_lock();
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	for_each_domain(cpu, sd) {
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		for_each_cpu(i, sched_domain_span(sd)) {
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			if (cpu == i)
				continue;

			if (!idle_cpu(i) && is_housekeeping_cpu(i)) {
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				cpu = i;
				goto unlock;
			}
		}
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	}
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	if (!is_housekeeping_cpu(cpu))
		cpu = housekeeping_any_cpu();
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unlock:
	rcu_read_unlock();
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	return cpu;
}
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/*
 * When add_timer_on() enqueues a timer into the timer wheel of an
 * idle CPU then this timer might expire before the next timer event
 * which is scheduled to wake up that CPU. In case of a completely
 * idle system the next event might even be infinite time into the
 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
 * leaves the inner idle loop so the newly added timer is taken into
 * account when the CPU goes back to idle and evaluates the timer
 * wheel for the next timer event.
 */
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static void wake_up_idle_cpu(int cpu)
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{
	struct rq *rq = cpu_rq(cpu);

	if (cpu == smp_processor_id())
		return;

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	if (set_nr_and_not_polling(rq->idle))
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		smp_send_reschedule(cpu);
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	else
		trace_sched_wake_idle_without_ipi(cpu);
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}

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static bool wake_up_full_nohz_cpu(int cpu)
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{
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	/*
	 * We just need the target to call irq_exit() and re-evaluate
	 * the next tick. The nohz full kick at least implies that.
	 * If needed we can still optimize that later with an
	 * empty IRQ.
	 */
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	if (tick_nohz_full_cpu(cpu)) {
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		if (cpu != smp_processor_id() ||
		    tick_nohz_tick_stopped())
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			tick_nohz_full_kick_cpu(cpu);
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		return true;
	}

	return false;
}

void wake_up_nohz_cpu(int cpu)
{
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	if (!wake_up_full_nohz_cpu(cpu))
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		wake_up_idle_cpu(cpu);
}

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static inline bool got_nohz_idle_kick(void)
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{
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	int cpu = smp_processor_id();
603 604 605 606 607 608 609 610 611 612 613 614 615

	if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
		return false;

	if (idle_cpu(cpu) && !need_resched())
		return true;

	/*
	 * We can't run Idle Load Balance on this CPU for this time so we
	 * cancel it and clear NOHZ_BALANCE_KICK
	 */
	clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
	return false;
616 617
}

618
#else /* CONFIG_NO_HZ_COMMON */
619

620
static inline bool got_nohz_idle_kick(void)
P
Peter Zijlstra 已提交
621
{
622
	return false;
P
Peter Zijlstra 已提交
623 624
}

625
#endif /* CONFIG_NO_HZ_COMMON */
626

627
#ifdef CONFIG_NO_HZ_FULL
628
bool sched_can_stop_tick(struct rq *rq)
629
{
630 631 632 633 634 635
	int fifo_nr_running;

	/* Deadline tasks, even if single, need the tick */
	if (rq->dl.dl_nr_running)
		return false;

636
	/*
637 638
	 * If there are more than one RR tasks, we need the tick to effect the
	 * actual RR behaviour.
639
	 */
640 641 642 643 644
	if (rq->rt.rr_nr_running) {
		if (rq->rt.rr_nr_running == 1)
			return true;
		else
			return false;
645 646
	}

647 648 649 650 651 652 653 654 655 656 657 658 659 660
	/*
	 * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
	 * forced preemption between FIFO tasks.
	 */
	fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
	if (fifo_nr_running)
		return true;

	/*
	 * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
	 * if there's more than one we need the tick for involuntary
	 * preemption.
	 */
	if (rq->nr_running > 1)
661
		return false;
662

663
	return true;
664 665
}
#endif /* CONFIG_NO_HZ_FULL */
666

667
void sched_avg_update(struct rq *rq)
668
{
669 670
	s64 period = sched_avg_period();

671
	while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
672 673 674 675 676 677
		/*
		 * Inline assembly required to prevent the compiler
		 * optimising this loop into a divmod call.
		 * See __iter_div_u64_rem() for another example of this.
		 */
		asm("" : "+rm" (rq->age_stamp));
678 679 680
		rq->age_stamp += period;
		rq->rt_avg /= 2;
	}
681 682
}

683
#endif /* CONFIG_SMP */
684

685 686
#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
			(defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
687
/*
688 689 690 691
 * Iterate task_group tree rooted at *from, calling @down when first entering a
 * node and @up when leaving it for the final time.
 *
 * Caller must hold rcu_lock or sufficient equivalent.
692
 */
693
int walk_tg_tree_from(struct task_group *from,
694
			     tg_visitor down, tg_visitor up, void *data)
695 696
{
	struct task_group *parent, *child;
P
Peter Zijlstra 已提交
697
	int ret;
698

699 700
	parent = from;

701
down:
P
Peter Zijlstra 已提交
702 703
	ret = (*down)(parent, data);
	if (ret)
704
		goto out;
705 706 707 708 709 710 711
	list_for_each_entry_rcu(child, &parent->children, siblings) {
		parent = child;
		goto down;

up:
		continue;
	}
P
Peter Zijlstra 已提交
712
	ret = (*up)(parent, data);
713 714
	if (ret || parent == from)
		goto out;
715 716 717 718 719

	child = parent;
	parent = parent->parent;
	if (parent)
		goto up;
720
out:
P
Peter Zijlstra 已提交
721
	return ret;
722 723
}

724
int tg_nop(struct task_group *tg, void *data)
P
Peter Zijlstra 已提交
725
{
726
	return 0;
P
Peter Zijlstra 已提交
727
}
728 729
#endif

730 731
static void set_load_weight(struct task_struct *p)
{
N
Nikhil Rao 已提交
732 733 734
	int prio = p->static_prio - MAX_RT_PRIO;
	struct load_weight *load = &p->se.load;

I
Ingo Molnar 已提交
735 736 737
	/*
	 * SCHED_IDLE tasks get minimal weight:
	 */
738
	if (idle_policy(p->policy)) {
739
		load->weight = scale_load(WEIGHT_IDLEPRIO);
N
Nikhil Rao 已提交
740
		load->inv_weight = WMULT_IDLEPRIO;
I
Ingo Molnar 已提交
741 742
		return;
	}
743

744 745
	load->weight = scale_load(sched_prio_to_weight[prio]);
	load->inv_weight = sched_prio_to_wmult[prio];
746 747
}

748
static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
749
{
750
	update_rq_clock(rq);
751 752
	if (!(flags & ENQUEUE_RESTORE))
		sched_info_queued(rq, p);
753
	p->sched_class->enqueue_task(rq, p, flags);
754 755
}

756
static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
757
{
758
	update_rq_clock(rq);
759 760
	if (!(flags & DEQUEUE_SAVE))
		sched_info_dequeued(rq, p);
761
	p->sched_class->dequeue_task(rq, p, flags);
762 763
}

764
void activate_task(struct rq *rq, struct task_struct *p, int flags)
765 766 767 768
{
	if (task_contributes_to_load(p))
		rq->nr_uninterruptible--;

769
	enqueue_task(rq, p, flags);
770 771
}

772
void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
773 774 775 776
{
	if (task_contributes_to_load(p))
		rq->nr_uninterruptible++;

777
	dequeue_task(rq, p, flags);
778 779
}

780
static void update_rq_clock_task(struct rq *rq, s64 delta)
781
{
782 783 784 785 786 787 788 789
/*
 * In theory, the compile should just see 0 here, and optimize out the call
 * to sched_rt_avg_update. But I don't trust it...
 */
#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
	s64 steal = 0, irq_delta = 0;
#endif
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
790
	irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811

	/*
	 * Since irq_time is only updated on {soft,}irq_exit, we might run into
	 * this case when a previous update_rq_clock() happened inside a
	 * {soft,}irq region.
	 *
	 * When this happens, we stop ->clock_task and only update the
	 * prev_irq_time stamp to account for the part that fit, so that a next
	 * update will consume the rest. This ensures ->clock_task is
	 * monotonic.
	 *
	 * It does however cause some slight miss-attribution of {soft,}irq
	 * time, a more accurate solution would be to update the irq_time using
	 * the current rq->clock timestamp, except that would require using
	 * atomic ops.
	 */
	if (irq_delta > delta)
		irq_delta = delta;

	rq->prev_irq_time += irq_delta;
	delta -= irq_delta;
812 813
#endif
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
814
	if (static_key_false((&paravirt_steal_rq_enabled))) {
815 816 817 818 819 820 821 822 823 824 825
		steal = paravirt_steal_clock(cpu_of(rq));
		steal -= rq->prev_steal_time_rq;

		if (unlikely(steal > delta))
			steal = delta;

		rq->prev_steal_time_rq += steal;
		delta -= steal;
	}
#endif

826 827
	rq->clock_task += delta;

828
#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
829
	if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
830 831
		sched_rt_avg_update(rq, irq_delta + steal);
#endif
832 833
}

834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863
void sched_set_stop_task(int cpu, struct task_struct *stop)
{
	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
	struct task_struct *old_stop = cpu_rq(cpu)->stop;

	if (stop) {
		/*
		 * Make it appear like a SCHED_FIFO task, its something
		 * userspace knows about and won't get confused about.
		 *
		 * Also, it will make PI more or less work without too
		 * much confusion -- but then, stop work should not
		 * rely on PI working anyway.
		 */
		sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);

		stop->sched_class = &stop_sched_class;
	}

	cpu_rq(cpu)->stop = stop;

	if (old_stop) {
		/*
		 * Reset it back to a normal scheduling class so that
		 * it can die in pieces.
		 */
		old_stop->sched_class = &rt_sched_class;
	}
}

864
/*
I
Ingo Molnar 已提交
865
 * __normal_prio - return the priority that is based on the static prio
866 867 868
 */
static inline int __normal_prio(struct task_struct *p)
{
I
Ingo Molnar 已提交
869
	return p->static_prio;
870 871
}

872 873 874 875 876 877 878
/*
 * Calculate the expected normal priority: i.e. priority
 * without taking RT-inheritance into account. Might be
 * boosted by interactivity modifiers. Changes upon fork,
 * setprio syscalls, and whenever the interactivity
 * estimator recalculates.
 */
879
static inline int normal_prio(struct task_struct *p)
880 881 882
{
	int prio;

883 884 885
	if (task_has_dl_policy(p))
		prio = MAX_DL_PRIO-1;
	else if (task_has_rt_policy(p))
886 887 888 889 890 891 892 893 894 895 896 897 898
		prio = MAX_RT_PRIO-1 - p->rt_priority;
	else
		prio = __normal_prio(p);
	return prio;
}

/*
 * Calculate the current priority, i.e. the priority
 * taken into account by the scheduler. This value might
 * be boosted by RT tasks, or might be boosted by
 * interactivity modifiers. Will be RT if the task got
 * RT-boosted. If not then it returns p->normal_prio.
 */
899
static int effective_prio(struct task_struct *p)
900 901 902 903 904 905 906 907 908 909 910 911
{
	p->normal_prio = normal_prio(p);
	/*
	 * If we are RT tasks or we were boosted to RT priority,
	 * keep the priority unchanged. Otherwise, update priority
	 * to the normal priority:
	 */
	if (!rt_prio(p->prio))
		return p->normal_prio;
	return p->prio;
}

L
Linus Torvalds 已提交
912 913 914
/**
 * task_curr - is this task currently executing on a CPU?
 * @p: the task in question.
915 916
 *
 * Return: 1 if the task is currently executing. 0 otherwise.
L
Linus Torvalds 已提交
917
 */
918
inline int task_curr(const struct task_struct *p)
L
Linus Torvalds 已提交
919 920 921 922
{
	return cpu_curr(task_cpu(p)) == p;
}

923
/*
924 925 926 927 928
 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
 * use the balance_callback list if you want balancing.
 *
 * this means any call to check_class_changed() must be followed by a call to
 * balance_callback().
929
 */
930 931
static inline void check_class_changed(struct rq *rq, struct task_struct *p,
				       const struct sched_class *prev_class,
P
Peter Zijlstra 已提交
932
				       int oldprio)
933 934 935
{
	if (prev_class != p->sched_class) {
		if (prev_class->switched_from)
P
Peter Zijlstra 已提交
936
			prev_class->switched_from(rq, p);
937

P
Peter Zijlstra 已提交
938
		p->sched_class->switched_to(rq, p);
939
	} else if (oldprio != p->prio || dl_task(p))
P
Peter Zijlstra 已提交
940
		p->sched_class->prio_changed(rq, p, oldprio);
941 942
}

943
void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
944 945 946 947 948 949 950 951 952 953
{
	const struct sched_class *class;

	if (p->sched_class == rq->curr->sched_class) {
		rq->curr->sched_class->check_preempt_curr(rq, p, flags);
	} else {
		for_each_class(class) {
			if (class == rq->curr->sched_class)
				break;
			if (class == p->sched_class) {
954
				resched_curr(rq);
955 956 957 958 959 960 961 962 963
				break;
			}
		}
	}

	/*
	 * A queue event has occurred, and we're going to schedule.  In
	 * this case, we can save a useless back to back clock update.
	 */
964
	if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
965
		rq_clock_skip_update(rq, true);
966 967
}

L
Linus Torvalds 已提交
968
#ifdef CONFIG_SMP
P
Peter Zijlstra 已提交
969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987
/*
 * This is how migration works:
 *
 * 1) we invoke migration_cpu_stop() on the target CPU using
 *    stop_one_cpu().
 * 2) stopper starts to run (implicitly forcing the migrated thread
 *    off the CPU)
 * 3) it checks whether the migrated task is still in the wrong runqueue.
 * 4) if it's in the wrong runqueue then the migration thread removes
 *    it and puts it into the right queue.
 * 5) stopper completes and stop_one_cpu() returns and the migration
 *    is done.
 */

/*
 * move_queued_task - move a queued task to new rq.
 *
 * Returns (locked) new rq. Old rq's lock is released.
 */
988
static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu)
P
Peter Zijlstra 已提交
989 990 991 992
{
	lockdep_assert_held(&rq->lock);

	p->on_rq = TASK_ON_RQ_MIGRATING;
993
	dequeue_task(rq, p, 0);
P
Peter Zijlstra 已提交
994 995 996 997 998 999 1000 1001
	set_task_cpu(p, new_cpu);
	raw_spin_unlock(&rq->lock);

	rq = cpu_rq(new_cpu);

	raw_spin_lock(&rq->lock);
	BUG_ON(task_cpu(p) != new_cpu);
	enqueue_task(rq, p, 0);
1002
	p->on_rq = TASK_ON_RQ_QUEUED;
P
Peter Zijlstra 已提交
1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021
	check_preempt_curr(rq, p, 0);

	return rq;
}

struct migration_arg {
	struct task_struct *task;
	int dest_cpu;
};

/*
 * Move (not current) task off this cpu, onto dest cpu. We're doing
 * this because either it can't run here any more (set_cpus_allowed()
 * away from this CPU, or CPU going down), or because we're
 * attempting to rebalance this task on exec (sched_exec).
 *
 * So we race with normal scheduler movements, but that's OK, as long
 * as the task is no longer on this CPU.
 */
1022
static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu)
P
Peter Zijlstra 已提交
1023 1024
{
	if (unlikely(!cpu_active(dest_cpu)))
1025
		return rq;
P
Peter Zijlstra 已提交
1026 1027 1028

	/* Affinity changed (again). */
	if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1029
		return rq;
P
Peter Zijlstra 已提交
1030

1031 1032 1033
	rq = move_queued_task(rq, p, dest_cpu);

	return rq;
P
Peter Zijlstra 已提交
1034 1035 1036 1037 1038 1039 1040 1041 1042 1043
}

/*
 * migration_cpu_stop - this will be executed by a highprio stopper thread
 * and performs thread migration by bumping thread off CPU then
 * 'pushing' onto another runqueue.
 */
static int migration_cpu_stop(void *data)
{
	struct migration_arg *arg = data;
1044 1045
	struct task_struct *p = arg->task;
	struct rq *rq = this_rq();
P
Peter Zijlstra 已提交
1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057

	/*
	 * The original target cpu might have gone down and we might
	 * be on another cpu but it doesn't matter.
	 */
	local_irq_disable();
	/*
	 * We need to explicitly wake pending tasks before running
	 * __migrate_task() such that we will not miss enforcing cpus_allowed
	 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
	 */
	sched_ttwu_pending();
1058 1059 1060 1061 1062 1063 1064 1065

	raw_spin_lock(&p->pi_lock);
	raw_spin_lock(&rq->lock);
	/*
	 * If task_rq(p) != rq, it cannot be migrated here, because we're
	 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
	 * we're holding p->pi_lock.
	 */
1066 1067 1068 1069 1070 1071
	if (task_rq(p) == rq) {
		if (task_on_rq_queued(p))
			rq = __migrate_task(rq, p, arg->dest_cpu);
		else
			p->wake_cpu = arg->dest_cpu;
	}
1072 1073 1074
	raw_spin_unlock(&rq->lock);
	raw_spin_unlock(&p->pi_lock);

P
Peter Zijlstra 已提交
1075 1076 1077 1078
	local_irq_enable();
	return 0;
}

1079 1080 1081 1082 1083
/*
 * sched_class::set_cpus_allowed must do the below, but is not required to
 * actually call this function.
 */
void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
P
Peter Zijlstra 已提交
1084 1085 1086 1087 1088
{
	cpumask_copy(&p->cpus_allowed, new_mask);
	p->nr_cpus_allowed = cpumask_weight(new_mask);
}

1089 1090
void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
{
1091 1092 1093
	struct rq *rq = task_rq(p);
	bool queued, running;

1094
	lockdep_assert_held(&p->pi_lock);
1095 1096 1097 1098 1099 1100 1101 1102 1103 1104

	queued = task_on_rq_queued(p);
	running = task_current(rq, p);

	if (queued) {
		/*
		 * Because __kthread_bind() calls this on blocked tasks without
		 * holding rq->lock.
		 */
		lockdep_assert_held(&rq->lock);
1105
		dequeue_task(rq, p, DEQUEUE_SAVE);
1106 1107 1108 1109
	}
	if (running)
		put_prev_task(rq, p);

1110
	p->sched_class->set_cpus_allowed(p, new_mask);
1111 1112 1113 1114

	if (running)
		p->sched_class->set_curr_task(rq);
	if (queued)
1115
		enqueue_task(rq, p, ENQUEUE_RESTORE);
1116 1117
}

P
Peter Zijlstra 已提交
1118 1119 1120 1121 1122 1123 1124 1125 1126
/*
 * Change a given task's CPU affinity. Migrate the thread to a
 * proper CPU and schedule it away if the CPU it's executing on
 * is removed from the allowed bitmask.
 *
 * NOTE: the caller must have a valid reference to the task, the
 * task must not exit() & deallocate itself prematurely. The
 * call is not atomic; no spinlocks may be held.
 */
1127 1128
static int __set_cpus_allowed_ptr(struct task_struct *p,
				  const struct cpumask *new_mask, bool check)
P
Peter Zijlstra 已提交
1129
{
1130
	const struct cpumask *cpu_valid_mask = cpu_active_mask;
P
Peter Zijlstra 已提交
1131
	unsigned int dest_cpu;
1132 1133
	struct rq_flags rf;
	struct rq *rq;
P
Peter Zijlstra 已提交
1134 1135
	int ret = 0;

1136
	rq = task_rq_lock(p, &rf);
P
Peter Zijlstra 已提交
1137

1138 1139 1140 1141 1142 1143 1144
	if (p->flags & PF_KTHREAD) {
		/*
		 * Kernel threads are allowed on online && !active CPUs
		 */
		cpu_valid_mask = cpu_online_mask;
	}

1145 1146 1147 1148 1149 1150 1151 1152 1153
	/*
	 * Must re-check here, to close a race against __kthread_bind(),
	 * sched_setaffinity() is not guaranteed to observe the flag.
	 */
	if (check && (p->flags & PF_NO_SETAFFINITY)) {
		ret = -EINVAL;
		goto out;
	}

P
Peter Zijlstra 已提交
1154 1155 1156
	if (cpumask_equal(&p->cpus_allowed, new_mask))
		goto out;

1157
	if (!cpumask_intersects(new_mask, cpu_valid_mask)) {
P
Peter Zijlstra 已提交
1158 1159 1160 1161 1162 1163
		ret = -EINVAL;
		goto out;
	}

	do_set_cpus_allowed(p, new_mask);

1164 1165 1166 1167 1168 1169 1170 1171 1172 1173
	if (p->flags & PF_KTHREAD) {
		/*
		 * For kernel threads that do indeed end up on online &&
		 * !active we want to ensure they are strict per-cpu threads.
		 */
		WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) &&
			!cpumask_intersects(new_mask, cpu_active_mask) &&
			p->nr_cpus_allowed != 1);
	}

P
Peter Zijlstra 已提交
1174 1175 1176 1177
	/* Can the task run on the task's current CPU? If so, we're done */
	if (cpumask_test_cpu(task_cpu(p), new_mask))
		goto out;

1178
	dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
P
Peter Zijlstra 已提交
1179 1180 1181
	if (task_running(rq, p) || p->state == TASK_WAKING) {
		struct migration_arg arg = { p, dest_cpu };
		/* Need help from migration thread: drop lock and wait. */
1182
		task_rq_unlock(rq, p, &rf);
P
Peter Zijlstra 已提交
1183 1184 1185
		stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
		tlb_migrate_finish(p->mm);
		return 0;
1186 1187 1188 1189 1190
	} else if (task_on_rq_queued(p)) {
		/*
		 * OK, since we're going to drop the lock immediately
		 * afterwards anyway.
		 */
1191
		lockdep_unpin_lock(&rq->lock, rf.cookie);
1192
		rq = move_queued_task(rq, p, dest_cpu);
1193
		lockdep_repin_lock(&rq->lock, rf.cookie);
1194
	}
P
Peter Zijlstra 已提交
1195
out:
1196
	task_rq_unlock(rq, p, &rf);
P
Peter Zijlstra 已提交
1197 1198 1199

	return ret;
}
1200 1201 1202 1203 1204

int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
{
	return __set_cpus_allowed_ptr(p, new_mask, false);
}
P
Peter Zijlstra 已提交
1205 1206
EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);

I
Ingo Molnar 已提交
1207
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
I
Ingo Molnar 已提交
1208
{
1209 1210 1211 1212 1213
#ifdef CONFIG_SCHED_DEBUG
	/*
	 * We should never call set_task_cpu() on a blocked task,
	 * ttwu() will sort out the placement.
	 */
P
Peter Zijlstra 已提交
1214
	WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
O
Oleg Nesterov 已提交
1215
			!p->on_rq);
1216

1217 1218 1219 1220 1221 1222 1223 1224 1225
	/*
	 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
	 * because schedstat_wait_{start,end} rebase migrating task's wait_start
	 * time relying on p->on_rq.
	 */
	WARN_ON_ONCE(p->state == TASK_RUNNING &&
		     p->sched_class == &fair_sched_class &&
		     (p->on_rq && !task_on_rq_migrating(p)));

1226
#ifdef CONFIG_LOCKDEP
1227 1228 1229 1230 1231
	/*
	 * The caller should hold either p->pi_lock or rq->lock, when changing
	 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
	 *
	 * sched_move_task() holds both and thus holding either pins the cgroup,
P
Peter Zijlstra 已提交
1232
	 * see task_group().
1233 1234 1235 1236
	 *
	 * Furthermore, all task_rq users should acquire both locks, see
	 * task_rq_lock().
	 */
1237 1238 1239
	WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
				      lockdep_is_held(&task_rq(p)->lock)));
#endif
1240 1241
#endif

1242
	trace_sched_migrate_task(p, new_cpu);
1243

1244
	if (task_cpu(p) != new_cpu) {
1245
		if (p->sched_class->migrate_task_rq)
1246
			p->sched_class->migrate_task_rq(p);
1247
		p->se.nr_migrations++;
1248
		perf_event_task_migrate(p);
1249
	}
I
Ingo Molnar 已提交
1250 1251

	__set_task_cpu(p, new_cpu);
I
Ingo Molnar 已提交
1252 1253
}

1254 1255
static void __migrate_swap_task(struct task_struct *p, int cpu)
{
1256
	if (task_on_rq_queued(p)) {
1257 1258 1259 1260 1261
		struct rq *src_rq, *dst_rq;

		src_rq = task_rq(p);
		dst_rq = cpu_rq(cpu);

1262
		p->on_rq = TASK_ON_RQ_MIGRATING;
1263 1264 1265
		deactivate_task(src_rq, p, 0);
		set_task_cpu(p, cpu);
		activate_task(dst_rq, p, 0);
1266
		p->on_rq = TASK_ON_RQ_QUEUED;
1267 1268 1269 1270 1271
		check_preempt_curr(dst_rq, p, 0);
	} else {
		/*
		 * Task isn't running anymore; make it appear like we migrated
		 * it before it went to sleep. This means on wakeup we make the
L
Leo Yan 已提交
1272
		 * previous cpu our target instead of where it really is.
1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288
		 */
		p->wake_cpu = cpu;
	}
}

struct migration_swap_arg {
	struct task_struct *src_task, *dst_task;
	int src_cpu, dst_cpu;
};

static int migrate_swap_stop(void *data)
{
	struct migration_swap_arg *arg = data;
	struct rq *src_rq, *dst_rq;
	int ret = -EAGAIN;

1289 1290 1291
	if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
		return -EAGAIN;

1292 1293 1294
	src_rq = cpu_rq(arg->src_cpu);
	dst_rq = cpu_rq(arg->dst_cpu);

1295 1296
	double_raw_lock(&arg->src_task->pi_lock,
			&arg->dst_task->pi_lock);
1297
	double_rq_lock(src_rq, dst_rq);
1298

1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317
	if (task_cpu(arg->dst_task) != arg->dst_cpu)
		goto unlock;

	if (task_cpu(arg->src_task) != arg->src_cpu)
		goto unlock;

	if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
		goto unlock;

	if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
		goto unlock;

	__migrate_swap_task(arg->src_task, arg->dst_cpu);
	__migrate_swap_task(arg->dst_task, arg->src_cpu);

	ret = 0;

unlock:
	double_rq_unlock(src_rq, dst_rq);
1318 1319
	raw_spin_unlock(&arg->dst_task->pi_lock);
	raw_spin_unlock(&arg->src_task->pi_lock);
1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341

	return ret;
}

/*
 * Cross migrate two tasks
 */
int migrate_swap(struct task_struct *cur, struct task_struct *p)
{
	struct migration_swap_arg arg;
	int ret = -EINVAL;

	arg = (struct migration_swap_arg){
		.src_task = cur,
		.src_cpu = task_cpu(cur),
		.dst_task = p,
		.dst_cpu = task_cpu(p),
	};

	if (arg.src_cpu == arg.dst_cpu)
		goto out;

1342 1343 1344 1345
	/*
	 * These three tests are all lockless; this is OK since all of them
	 * will be re-checked with proper locks held further down the line.
	 */
1346 1347 1348 1349 1350 1351 1352 1353 1354
	if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
		goto out;

	if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
		goto out;

	if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
		goto out;

1355
	trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1356 1357 1358 1359 1360 1361
	ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);

out:
	return ret;
}

L
Linus Torvalds 已提交
1362 1363 1364
/*
 * wait_task_inactive - wait for a thread to unschedule.
 *
R
Roland McGrath 已提交
1365 1366 1367 1368 1369 1370 1371
 * If @match_state is nonzero, it's the @p->state value just checked and
 * not expected to change.  If it changes, i.e. @p might have woken up,
 * then return zero.  When we succeed in waiting for @p to be off its CPU,
 * we return a positive number (its total switch count).  If a second call
 * a short while later returns the same number, the caller can be sure that
 * @p has remained unscheduled the whole time.
 *
L
Linus Torvalds 已提交
1372 1373 1374 1375 1376 1377
 * The caller must ensure that the task *will* unschedule sometime soon,
 * else this function might spin for a *long* time. This function can't
 * be called with interrupts off, or it may introduce deadlock with
 * smp_call_function() if an IPI is sent by the same process we are
 * waiting to become inactive.
 */
R
Roland McGrath 已提交
1378
unsigned long wait_task_inactive(struct task_struct *p, long match_state)
L
Linus Torvalds 已提交
1379
{
1380
	int running, queued;
1381
	struct rq_flags rf;
R
Roland McGrath 已提交
1382
	unsigned long ncsw;
1383
	struct rq *rq;
L
Linus Torvalds 已提交
1384

1385 1386 1387 1388 1389 1390 1391 1392
	for (;;) {
		/*
		 * We do the initial early heuristics without holding
		 * any task-queue locks at all. We'll only try to get
		 * the runqueue lock when things look like they will
		 * work out!
		 */
		rq = task_rq(p);
1393

1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404
		/*
		 * If the task is actively running on another CPU
		 * still, just relax and busy-wait without holding
		 * any locks.
		 *
		 * NOTE! Since we don't hold any locks, it's not
		 * even sure that "rq" stays as the right runqueue!
		 * But we don't care, since "task_running()" will
		 * return false if the runqueue has changed and p
		 * is actually now running somewhere else!
		 */
R
Roland McGrath 已提交
1405 1406 1407
		while (task_running(rq, p)) {
			if (match_state && unlikely(p->state != match_state))
				return 0;
1408
			cpu_relax();
R
Roland McGrath 已提交
1409
		}
1410

1411 1412 1413 1414 1415
		/*
		 * Ok, time to look more closely! We need the rq
		 * lock now, to be *sure*. If we're wrong, we'll
		 * just go back and repeat.
		 */
1416
		rq = task_rq_lock(p, &rf);
1417
		trace_sched_wait_task(p);
1418
		running = task_running(rq, p);
1419
		queued = task_on_rq_queued(p);
R
Roland McGrath 已提交
1420
		ncsw = 0;
1421
		if (!match_state || p->state == match_state)
1422
			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1423
		task_rq_unlock(rq, p, &rf);
1424

R
Roland McGrath 已提交
1425 1426 1427 1428 1429 1430
		/*
		 * If it changed from the expected state, bail out now.
		 */
		if (unlikely(!ncsw))
			break;

1431 1432 1433 1434 1435 1436 1437 1438 1439 1440
		/*
		 * Was it really running after all now that we
		 * checked with the proper locks actually held?
		 *
		 * Oops. Go back and try again..
		 */
		if (unlikely(running)) {
			cpu_relax();
			continue;
		}
1441

1442 1443 1444 1445 1446
		/*
		 * It's not enough that it's not actively running,
		 * it must be off the runqueue _entirely_, and not
		 * preempted!
		 *
1447
		 * So if it was still runnable (but just not actively
1448 1449 1450
		 * running right now), it's preempted, and we should
		 * yield - it could be a while.
		 */
1451
		if (unlikely(queued)) {
1452 1453 1454 1455
			ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);

			set_current_state(TASK_UNINTERRUPTIBLE);
			schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1456 1457
			continue;
		}
1458

1459 1460 1461 1462 1463 1464 1465
		/*
		 * Ahh, all good. It wasn't running, and it wasn't
		 * runnable, which means that it will never become
		 * running in the future either. We're all done!
		 */
		break;
	}
R
Roland McGrath 已提交
1466 1467

	return ncsw;
L
Linus Torvalds 已提交
1468 1469 1470 1471 1472 1473 1474 1475 1476
}

/***
 * kick_process - kick a running thread to enter/exit the kernel
 * @p: the to-be-kicked thread
 *
 * Cause a process which is running on another CPU to enter
 * kernel-mode, without any delay. (to get signals handled.)
 *
L
Lucas De Marchi 已提交
1477
 * NOTE: this function doesn't have to take the runqueue lock,
L
Linus Torvalds 已提交
1478 1479 1480 1481 1482
 * because all it wants to ensure is that the remote task enters
 * the kernel. If the IPI races and the task has been migrated
 * to another CPU then no harm is done and the purpose has been
 * achieved as well.
 */
1483
void kick_process(struct task_struct *p)
L
Linus Torvalds 已提交
1484 1485 1486 1487 1488 1489 1490 1491 1492
{
	int cpu;

	preempt_disable();
	cpu = task_cpu(p);
	if ((cpu != smp_processor_id()) && task_curr(p))
		smp_send_reschedule(cpu);
	preempt_enable();
}
R
Rusty Russell 已提交
1493
EXPORT_SYMBOL_GPL(kick_process);
L
Linus Torvalds 已提交
1494

1495
/*
1496
 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515
 *
 * A few notes on cpu_active vs cpu_online:
 *
 *  - cpu_active must be a subset of cpu_online
 *
 *  - on cpu-up we allow per-cpu kthreads on the online && !active cpu,
 *    see __set_cpus_allowed_ptr(). At this point the newly online
 *    cpu isn't yet part of the sched domains, and balancing will not
 *    see it.
 *
 *  - on cpu-down we clear cpu_active() to mask the sched domains and
 *    avoid the load balancer to place new tasks on the to be removed
 *    cpu. Existing tasks will remain running there and will be taken
 *    off.
 *
 * This means that fallback selection must not select !active CPUs.
 * And can assume that any active CPU must be online. Conversely
 * select_task_rq() below may allow selection of !active CPUs in order
 * to satisfy the above rules.
1516
 */
1517 1518
static int select_fallback_rq(int cpu, struct task_struct *p)
{
1519 1520
	int nid = cpu_to_node(cpu);
	const struct cpumask *nodemask = NULL;
1521 1522
	enum { cpuset, possible, fail } state = cpuset;
	int dest_cpu;
1523

1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538
	/*
	 * If the node that the cpu is on has been offlined, cpu_to_node()
	 * will return -1. There is no cpu on the node, and we should
	 * select the cpu on the other node.
	 */
	if (nid != -1) {
		nodemask = cpumask_of_node(nid);

		/* Look for allowed, online CPU in same node. */
		for_each_cpu(dest_cpu, nodemask) {
			if (!cpu_active(dest_cpu))
				continue;
			if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
				return dest_cpu;
		}
1539
	}
1540

1541 1542
	for (;;) {
		/* Any allowed, online CPU? */
1543
		for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1544 1545 1546
			if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu))
				continue;
			if (!cpu_online(dest_cpu))
1547 1548 1549
				continue;
			goto out;
		}
1550

1551
		/* No more Mr. Nice Guy. */
1552 1553
		switch (state) {
		case cpuset:
1554 1555 1556 1557 1558 1559
			if (IS_ENABLED(CONFIG_CPUSETS)) {
				cpuset_cpus_allowed_fallback(p);
				state = possible;
				break;
			}
			/* fall-through */
1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578
		case possible:
			do_set_cpus_allowed(p, cpu_possible_mask);
			state = fail;
			break;

		case fail:
			BUG();
			break;
		}
	}

out:
	if (state != cpuset) {
		/*
		 * Don't tell them about moving exiting tasks or
		 * kernel threads (both mm NULL), since they never
		 * leave kernel.
		 */
		if (p->mm && printk_ratelimit()) {
1579
			printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1580 1581
					task_pid_nr(p), p->comm, cpu);
		}
1582 1583 1584 1585 1586
	}

	return dest_cpu;
}

1587
/*
1588
 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1589
 */
1590
static inline
1591
int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1592
{
1593 1594
	lockdep_assert_held(&p->pi_lock);

1595
	if (tsk_nr_cpus_allowed(p) > 1)
1596
		cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1597 1598
	else
		cpu = cpumask_any(tsk_cpus_allowed(p));
1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609

	/*
	 * In order not to call set_task_cpu() on a blocking task we need
	 * to rely on ttwu() to place the task on a valid ->cpus_allowed
	 * cpu.
	 *
	 * Since this is common to all placement strategies, this lives here.
	 *
	 * [ this allows ->select_task() to simply return task_cpu(p) and
	 *   not worry about this generic constraint ]
	 */
1610
	if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
P
Peter Zijlstra 已提交
1611
		     !cpu_online(cpu)))
1612
		cpu = select_fallback_rq(task_cpu(p), p);
1613 1614

	return cpu;
1615
}
1616 1617 1618 1619 1620 1621

static void update_avg(u64 *avg, u64 sample)
{
	s64 diff = sample - *avg;
	*avg += diff >> 3;
}
1622 1623 1624 1625 1626 1627 1628 1629 1630

#else

static inline int __set_cpus_allowed_ptr(struct task_struct *p,
					 const struct cpumask *new_mask, bool check)
{
	return set_cpus_allowed_ptr(p, new_mask);
}

P
Peter Zijlstra 已提交
1631
#endif /* CONFIG_SMP */
1632

P
Peter Zijlstra 已提交
1633
static void
1634
ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
T
Tejun Heo 已提交
1635
{
1636
	struct rq *rq;
1637

1638 1639 1640 1641
	if (!schedstat_enabled())
		return;

	rq = this_rq();
P
Peter Zijlstra 已提交
1642

1643 1644
#ifdef CONFIG_SMP
	if (cpu == rq->cpu) {
1645 1646
		schedstat_inc(rq->ttwu_local);
		schedstat_inc(p->se.statistics.nr_wakeups_local);
P
Peter Zijlstra 已提交
1647 1648 1649
	} else {
		struct sched_domain *sd;

1650
		schedstat_inc(p->se.statistics.nr_wakeups_remote);
1651
		rcu_read_lock();
1652
		for_each_domain(rq->cpu, sd) {
P
Peter Zijlstra 已提交
1653
			if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1654
				schedstat_inc(sd->ttwu_wake_remote);
P
Peter Zijlstra 已提交
1655 1656 1657
				break;
			}
		}
1658
		rcu_read_unlock();
P
Peter Zijlstra 已提交
1659
	}
1660 1661

	if (wake_flags & WF_MIGRATED)
1662
		schedstat_inc(p->se.statistics.nr_wakeups_migrate);
P
Peter Zijlstra 已提交
1663 1664
#endif /* CONFIG_SMP */

1665 1666
	schedstat_inc(rq->ttwu_count);
	schedstat_inc(p->se.statistics.nr_wakeups);
P
Peter Zijlstra 已提交
1667 1668

	if (wake_flags & WF_SYNC)
1669
		schedstat_inc(p->se.statistics.nr_wakeups_sync);
P
Peter Zijlstra 已提交
1670 1671
}

1672
static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
P
Peter Zijlstra 已提交
1673
{
T
Tejun Heo 已提交
1674
	activate_task(rq, p, en_flags);
1675
	p->on_rq = TASK_ON_RQ_QUEUED;
1676 1677 1678 1679

	/* if a worker is waking up, notify workqueue */
	if (p->flags & PF_WQ_WORKER)
		wq_worker_waking_up(p, cpu_of(rq));
T
Tejun Heo 已提交
1680 1681
}

1682 1683 1684
/*
 * Mark the task runnable and perform wakeup-preemption.
 */
1685 1686
static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
			   struct pin_cookie cookie)
T
Tejun Heo 已提交
1687 1688 1689
{
	check_preempt_curr(rq, p, wake_flags);
	p->state = TASK_RUNNING;
1690 1691
	trace_sched_wakeup(p);

T
Tejun Heo 已提交
1692
#ifdef CONFIG_SMP
1693 1694
	if (p->sched_class->task_woken) {
		/*
1695 1696
		 * Our task @p is fully woken up and running; so its safe to
		 * drop the rq->lock, hereafter rq is only used for statistics.
1697
		 */
1698
		lockdep_unpin_lock(&rq->lock, cookie);
T
Tejun Heo 已提交
1699
		p->sched_class->task_woken(rq, p);
1700
		lockdep_repin_lock(&rq->lock, cookie);
1701
	}
T
Tejun Heo 已提交
1702

1703
	if (rq->idle_stamp) {
1704
		u64 delta = rq_clock(rq) - rq->idle_stamp;
1705
		u64 max = 2*rq->max_idle_balance_cost;
T
Tejun Heo 已提交
1706

1707 1708 1709
		update_avg(&rq->avg_idle, delta);

		if (rq->avg_idle > max)
T
Tejun Heo 已提交
1710
			rq->avg_idle = max;
1711

T
Tejun Heo 已提交
1712 1713 1714 1715 1716
		rq->idle_stamp = 0;
	}
#endif
}

1717
static void
1718 1719
ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
		 struct pin_cookie cookie)
1720
{
1721 1722
	int en_flags = ENQUEUE_WAKEUP;

1723 1724
	lockdep_assert_held(&rq->lock);

1725 1726 1727
#ifdef CONFIG_SMP
	if (p->sched_contributes_to_load)
		rq->nr_uninterruptible--;
1728 1729

	if (wake_flags & WF_MIGRATED)
1730
		en_flags |= ENQUEUE_MIGRATED;
1731 1732
#endif

1733
	ttwu_activate(rq, p, en_flags);
1734
	ttwu_do_wakeup(rq, p, wake_flags, cookie);
1735 1736 1737 1738 1739 1740 1741 1742 1743 1744
}

/*
 * Called in case the task @p isn't fully descheduled from its runqueue,
 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
 * since all we need to do is flip p->state to TASK_RUNNING, since
 * the task is still ->on_rq.
 */
static int ttwu_remote(struct task_struct *p, int wake_flags)
{
1745
	struct rq_flags rf;
1746 1747 1748
	struct rq *rq;
	int ret = 0;

1749
	rq = __task_rq_lock(p, &rf);
1750
	if (task_on_rq_queued(p)) {
1751 1752
		/* check_preempt_curr() may use rq clock */
		update_rq_clock(rq);
1753
		ttwu_do_wakeup(rq, p, wake_flags, rf.cookie);
1754 1755
		ret = 1;
	}
1756
	__task_rq_unlock(rq, &rf);
1757 1758 1759 1760

	return ret;
}

1761
#ifdef CONFIG_SMP
1762
void sched_ttwu_pending(void)
1763 1764
{
	struct rq *rq = this_rq();
P
Peter Zijlstra 已提交
1765
	struct llist_node *llist = llist_del_all(&rq->wake_list);
1766
	struct pin_cookie cookie;
P
Peter Zijlstra 已提交
1767
	struct task_struct *p;
1768
	unsigned long flags;
1769

1770 1771 1772 1773
	if (!llist)
		return;

	raw_spin_lock_irqsave(&rq->lock, flags);
1774
	cookie = lockdep_pin_lock(&rq->lock);
1775

P
Peter Zijlstra 已提交
1776
	while (llist) {
P
Peter Zijlstra 已提交
1777 1778
		int wake_flags = 0;

P
Peter Zijlstra 已提交
1779 1780
		p = llist_entry(llist, struct task_struct, wake_entry);
		llist = llist_next(llist);
P
Peter Zijlstra 已提交
1781 1782 1783 1784 1785

		if (p->sched_remote_wakeup)
			wake_flags = WF_MIGRATED;

		ttwu_do_activate(rq, p, wake_flags, cookie);
1786 1787
	}

1788
	lockdep_unpin_lock(&rq->lock, cookie);
1789
	raw_spin_unlock_irqrestore(&rq->lock, flags);
1790 1791 1792 1793
}

void scheduler_ipi(void)
{
1794 1795 1796 1797 1798
	/*
	 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
	 * TIF_NEED_RESCHED remotely (for the first time) will also send
	 * this IPI.
	 */
1799
	preempt_fold_need_resched();
1800

1801
	if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817
		return;

	/*
	 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
	 * traditionally all their work was done from the interrupt return
	 * path. Now that we actually do some work, we need to make sure
	 * we do call them.
	 *
	 * Some archs already do call them, luckily irq_enter/exit nest
	 * properly.
	 *
	 * Arguably we should visit all archs and update all handlers,
	 * however a fair share of IPIs are still resched only so this would
	 * somewhat pessimize the simple resched case.
	 */
	irq_enter();
P
Peter Zijlstra 已提交
1818
	sched_ttwu_pending();
1819 1820 1821 1822

	/*
	 * Check if someone kicked us for doing the nohz idle load balance.
	 */
1823
	if (unlikely(got_nohz_idle_kick())) {
1824
		this_rq()->idle_balance = 1;
1825
		raise_softirq_irqoff(SCHED_SOFTIRQ);
1826
	}
1827
	irq_exit();
1828 1829
}

P
Peter Zijlstra 已提交
1830
static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags)
1831
{
1832 1833
	struct rq *rq = cpu_rq(cpu);

P
Peter Zijlstra 已提交
1834 1835
	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);

1836 1837 1838 1839 1840 1841
	if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
		if (!set_nr_if_polling(rq->idle))
			smp_send_reschedule(cpu);
		else
			trace_sched_wake_idle_without_ipi(cpu);
	}
1842
}
1843

1844 1845 1846 1847 1848
void wake_up_if_idle(int cpu)
{
	struct rq *rq = cpu_rq(cpu);
	unsigned long flags;

1849 1850 1851 1852
	rcu_read_lock();

	if (!is_idle_task(rcu_dereference(rq->curr)))
		goto out;
1853 1854 1855 1856 1857 1858 1859 1860 1861 1862

	if (set_nr_if_polling(rq->idle)) {
		trace_sched_wake_idle_without_ipi(cpu);
	} else {
		raw_spin_lock_irqsave(&rq->lock, flags);
		if (is_idle_task(rq->curr))
			smp_send_reschedule(cpu);
		/* Else cpu is not in idle, do nothing here */
		raw_spin_unlock_irqrestore(&rq->lock, flags);
	}
1863 1864 1865

out:
	rcu_read_unlock();
1866 1867
}

1868
bool cpus_share_cache(int this_cpu, int that_cpu)
1869 1870 1871
{
	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
}
1872
#endif /* CONFIG_SMP */
1873

1874
static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
1875 1876
{
	struct rq *rq = cpu_rq(cpu);
1877
	struct pin_cookie cookie;
1878

1879
#if defined(CONFIG_SMP)
1880
	if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1881
		sched_clock_cpu(cpu); /* sync clocks x-cpu */
P
Peter Zijlstra 已提交
1882
		ttwu_queue_remote(p, cpu, wake_flags);
1883 1884 1885 1886
		return;
	}
#endif

1887
	raw_spin_lock(&rq->lock);
1888
	cookie = lockdep_pin_lock(&rq->lock);
1889
	ttwu_do_activate(rq, p, wake_flags, cookie);
1890
	lockdep_unpin_lock(&rq->lock, cookie);
1891
	raw_spin_unlock(&rq->lock);
T
Tejun Heo 已提交
1892 1893
}

1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943
/*
 * Notes on Program-Order guarantees on SMP systems.
 *
 *  MIGRATION
 *
 * The basic program-order guarantee on SMP systems is that when a task [t]
 * migrates, all its activity on its old cpu [c0] happens-before any subsequent
 * execution on its new cpu [c1].
 *
 * For migration (of runnable tasks) this is provided by the following means:
 *
 *  A) UNLOCK of the rq(c0)->lock scheduling out task t
 *  B) migration for t is required to synchronize *both* rq(c0)->lock and
 *     rq(c1)->lock (if not at the same time, then in that order).
 *  C) LOCK of the rq(c1)->lock scheduling in task
 *
 * Transitivity guarantees that B happens after A and C after B.
 * Note: we only require RCpc transitivity.
 * Note: the cpu doing B need not be c0 or c1
 *
 * Example:
 *
 *   CPU0            CPU1            CPU2
 *
 *   LOCK rq(0)->lock
 *   sched-out X
 *   sched-in Y
 *   UNLOCK rq(0)->lock
 *
 *                                   LOCK rq(0)->lock // orders against CPU0
 *                                   dequeue X
 *                                   UNLOCK rq(0)->lock
 *
 *                                   LOCK rq(1)->lock
 *                                   enqueue X
 *                                   UNLOCK rq(1)->lock
 *
 *                   LOCK rq(1)->lock // orders against CPU2
 *                   sched-out Z
 *                   sched-in X
 *                   UNLOCK rq(1)->lock
 *
 *
 *  BLOCKING -- aka. SLEEP + WAKEUP
 *
 * For blocking we (obviously) need to provide the same guarantee as for
 * migration. However the means are completely different as there is no lock
 * chain to provide order. Instead we do:
 *
 *   1) smp_store_release(X->on_cpu, 0)
1944
 *   2) smp_cond_load_acquire(!X->on_cpu)
1945 1946 1947 1948 1949 1950 1951 1952 1953 1954
 *
 * Example:
 *
 *   CPU0 (schedule)  CPU1 (try_to_wake_up) CPU2 (schedule)
 *
 *   LOCK rq(0)->lock LOCK X->pi_lock
 *   dequeue X
 *   sched-out X
 *   smp_store_release(X->on_cpu, 0);
 *
1955
 *                    smp_cond_load_acquire(&X->on_cpu, !VAL);
1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980
 *                    X->state = WAKING
 *                    set_task_cpu(X,2)
 *
 *                    LOCK rq(2)->lock
 *                    enqueue X
 *                    X->state = RUNNING
 *                    UNLOCK rq(2)->lock
 *
 *                                          LOCK rq(2)->lock // orders against CPU1
 *                                          sched-out Z
 *                                          sched-in X
 *                                          UNLOCK rq(2)->lock
 *
 *                    UNLOCK X->pi_lock
 *   UNLOCK rq(0)->lock
 *
 *
 * However; for wakeups there is a second guarantee we must provide, namely we
 * must observe the state that lead to our wakeup. That is, not only must our
 * task observe its own prior state, it must also observe the stores prior to
 * its wakeup.
 *
 * This means that any means of doing remote wakeups must order the CPU doing
 * the wakeup against the CPU the task is going to end up running on. This,
 * however, is already required for the regular Program-Order guarantee above,
1981
 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire).
1982 1983 1984
 *
 */

T
Tejun Heo 已提交
1985
/**
L
Linus Torvalds 已提交
1986
 * try_to_wake_up - wake up a thread
T
Tejun Heo 已提交
1987
 * @p: the thread to be awakened
L
Linus Torvalds 已提交
1988
 * @state: the mask of task states that can be woken
T
Tejun Heo 已提交
1989
 * @wake_flags: wake modifier flags (WF_*)
L
Linus Torvalds 已提交
1990 1991 1992 1993 1994 1995 1996
 *
 * Put it on the run-queue if it's not already there. The "current"
 * thread is always on the run-queue (except when the actual
 * re-schedule is in progress), and as such you're allowed to do
 * the simpler "current->state = TASK_RUNNING" to mark yourself
 * runnable without the overhead of this.
 *
1997
 * Return: %true if @p was woken up, %false if it was already running.
T
Tejun Heo 已提交
1998
 * or @state didn't match @p's state.
L
Linus Torvalds 已提交
1999
 */
2000 2001
static int
try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
L
Linus Torvalds 已提交
2002 2003
{
	unsigned long flags;
2004
	int cpu, success = 0;
P
Peter Zijlstra 已提交
2005

2006 2007 2008 2009 2010 2011 2012
	/*
	 * If we are going to wake up a thread waiting for CONDITION we
	 * need to ensure that CONDITION=1 done by the caller can not be
	 * reordered with p->state check below. This pairs with mb() in
	 * set_current_state() the waiting thread does.
	 */
	smp_mb__before_spinlock();
2013
	raw_spin_lock_irqsave(&p->pi_lock, flags);
P
Peter Zijlstra 已提交
2014
	if (!(p->state & state))
L
Linus Torvalds 已提交
2015 2016
		goto out;

2017 2018
	trace_sched_waking(p);

2019
	success = 1; /* we're going to change ->state */
L
Linus Torvalds 已提交
2020 2021
	cpu = task_cpu(p);

2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043
	/*
	 * Ensure we load p->on_rq _after_ p->state, otherwise it would
	 * be possible to, falsely, observe p->on_rq == 0 and get stuck
	 * in smp_cond_load_acquire() below.
	 *
	 * sched_ttwu_pending()                 try_to_wake_up()
	 *   [S] p->on_rq = 1;                  [L] P->state
	 *       UNLOCK rq->lock  -----.
	 *                              \
	 *				 +---   RMB
	 * schedule()                   /
	 *       LOCK rq->lock    -----'
	 *       UNLOCK rq->lock
	 *
	 * [task p]
	 *   [S] p->state = UNINTERRUPTIBLE     [L] p->on_rq
	 *
	 * Pairs with the UNLOCK+LOCK on rq->lock from the
	 * last wakeup of our task and the schedule that got our task
	 * current.
	 */
	smp_rmb();
2044 2045
	if (p->on_rq && ttwu_remote(p, wake_flags))
		goto stat;
L
Linus Torvalds 已提交
2046 2047

#ifdef CONFIG_SMP
2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066
	/*
	 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
	 * possible to, falsely, observe p->on_cpu == 0.
	 *
	 * One must be running (->on_cpu == 1) in order to remove oneself
	 * from the runqueue.
	 *
	 *  [S] ->on_cpu = 1;	[L] ->on_rq
	 *      UNLOCK rq->lock
	 *			RMB
	 *      LOCK   rq->lock
	 *  [S] ->on_rq = 0;    [L] ->on_cpu
	 *
	 * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
	 * from the consecutive calls to schedule(); the first switching to our
	 * task, the second putting it to sleep.
	 */
	smp_rmb();

P
Peter Zijlstra 已提交
2067
	/*
2068 2069
	 * If the owning (remote) cpu is still in the middle of schedule() with
	 * this task as prev, wait until its done referencing the task.
2070 2071 2072 2073 2074
	 *
	 * Pairs with the smp_store_release() in finish_lock_switch().
	 *
	 * This ensures that tasks getting woken will be fully ordered against
	 * their previous state and preserve Program Order.
2075
	 */
2076
	smp_cond_load_acquire(&p->on_cpu, !VAL);
L
Linus Torvalds 已提交
2077

2078
	p->sched_contributes_to_load = !!task_contributes_to_load(p);
P
Peter Zijlstra 已提交
2079
	p->state = TASK_WAKING;
2080

2081
	cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
2082 2083
	if (task_cpu(p) != cpu) {
		wake_flags |= WF_MIGRATED;
2084
		set_task_cpu(p, cpu);
2085
	}
L
Linus Torvalds 已提交
2086 2087
#endif /* CONFIG_SMP */

2088
	ttwu_queue(p, cpu, wake_flags);
2089
stat:
2090
	ttwu_stat(p, cpu, wake_flags);
L
Linus Torvalds 已提交
2091
out:
2092
	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
L
Linus Torvalds 已提交
2093 2094 2095 2096

	return success;
}

T
Tejun Heo 已提交
2097 2098 2099
/**
 * try_to_wake_up_local - try to wake up a local task with rq lock held
 * @p: the thread to be awakened
2100
 * @cookie: context's cookie for pinning
T
Tejun Heo 已提交
2101
 *
2102
 * Put @p on the run-queue if it's not already there. The caller must
T
Tejun Heo 已提交
2103
 * ensure that this_rq() is locked, @p is bound to this_rq() and not
2104
 * the current task.
T
Tejun Heo 已提交
2105
 */
2106
static void try_to_wake_up_local(struct task_struct *p, struct pin_cookie cookie)
T
Tejun Heo 已提交
2107 2108 2109
{
	struct rq *rq = task_rq(p);

2110 2111 2112 2113
	if (WARN_ON_ONCE(rq != this_rq()) ||
	    WARN_ON_ONCE(p == current))
		return;

T
Tejun Heo 已提交
2114 2115
	lockdep_assert_held(&rq->lock);

2116
	if (!raw_spin_trylock(&p->pi_lock)) {
2117 2118 2119 2120 2121 2122
		/*
		 * This is OK, because current is on_cpu, which avoids it being
		 * picked for load-balance and preemption/IRQs are still
		 * disabled avoiding further scheduler activity on it and we've
		 * not yet picked a replacement task.
		 */
2123
		lockdep_unpin_lock(&rq->lock, cookie);
2124 2125 2126
		raw_spin_unlock(&rq->lock);
		raw_spin_lock(&p->pi_lock);
		raw_spin_lock(&rq->lock);
2127
		lockdep_repin_lock(&rq->lock, cookie);
2128 2129
	}

T
Tejun Heo 已提交
2130
	if (!(p->state & TASK_NORMAL))
2131
		goto out;
T
Tejun Heo 已提交
2132

2133 2134
	trace_sched_waking(p);

2135
	if (!task_on_rq_queued(p))
P
Peter Zijlstra 已提交
2136 2137
		ttwu_activate(rq, p, ENQUEUE_WAKEUP);

2138
	ttwu_do_wakeup(rq, p, 0, cookie);
2139
	ttwu_stat(p, smp_processor_id(), 0);
2140 2141
out:
	raw_spin_unlock(&p->pi_lock);
T
Tejun Heo 已提交
2142 2143
}

2144 2145 2146 2147 2148
/**
 * wake_up_process - Wake up a specific process
 * @p: The process to be woken up.
 *
 * Attempt to wake up the nominated process and move it to the set of runnable
2149 2150 2151
 * processes.
 *
 * Return: 1 if the process was woken up, 0 if it was already running.
2152 2153 2154 2155
 *
 * It may be assumed that this function implies a write memory barrier before
 * changing the task state if and only if any tasks are woken up.
 */
2156
int wake_up_process(struct task_struct *p)
L
Linus Torvalds 已提交
2157
{
2158
	return try_to_wake_up(p, TASK_NORMAL, 0);
L
Linus Torvalds 已提交
2159 2160 2161
}
EXPORT_SYMBOL(wake_up_process);

2162
int wake_up_state(struct task_struct *p, unsigned int state)
L
Linus Torvalds 已提交
2163 2164 2165 2166
{
	return try_to_wake_up(p, state, 0);
}

2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178
/*
 * This function clears the sched_dl_entity static params.
 */
void __dl_clear_params(struct task_struct *p)
{
	struct sched_dl_entity *dl_se = &p->dl;

	dl_se->dl_runtime = 0;
	dl_se->dl_deadline = 0;
	dl_se->dl_period = 0;
	dl_se->flags = 0;
	dl_se->dl_bw = 0;
2179 2180 2181

	dl_se->dl_throttled = 0;
	dl_se->dl_yielded = 0;
2182 2183
}

L
Linus Torvalds 已提交
2184 2185 2186
/*
 * Perform scheduler related setup for a newly forked process p.
 * p is forked by current.
I
Ingo Molnar 已提交
2187 2188 2189
 *
 * __sched_fork() is basic setup used by init_idle() too:
 */
2190
static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
I
Ingo Molnar 已提交
2191
{
P
Peter Zijlstra 已提交
2192 2193 2194
	p->on_rq			= 0;

	p->se.on_rq			= 0;
I
Ingo Molnar 已提交
2195 2196
	p->se.exec_start		= 0;
	p->se.sum_exec_runtime		= 0;
2197
	p->se.prev_sum_exec_runtime	= 0;
2198
	p->se.nr_migrations		= 0;
P
Peter Zijlstra 已提交
2199
	p->se.vruntime			= 0;
P
Peter Zijlstra 已提交
2200
	INIT_LIST_HEAD(&p->se.group_node);
I
Ingo Molnar 已提交
2201

2202 2203 2204 2205
#ifdef CONFIG_FAIR_GROUP_SCHED
	p->se.cfs_rq			= NULL;
#endif

I
Ingo Molnar 已提交
2206
#ifdef CONFIG_SCHEDSTATS
2207
	/* Even if schedstat is disabled, there should not be garbage */
2208
	memset(&p->se.statistics, 0, sizeof(p->se.statistics));
I
Ingo Molnar 已提交
2209
#endif
N
Nick Piggin 已提交
2210

2211
	RB_CLEAR_NODE(&p->dl.rb_node);
2212
	init_dl_task_timer(&p->dl);
2213
	__dl_clear_params(p);
2214

P
Peter Zijlstra 已提交
2215
	INIT_LIST_HEAD(&p->rt.run_list);
2216 2217 2218 2219
	p->rt.timeout		= 0;
	p->rt.time_slice	= sched_rr_timeslice;
	p->rt.on_rq		= 0;
	p->rt.on_list		= 0;
N
Nick Piggin 已提交
2220

2221 2222 2223
#ifdef CONFIG_PREEMPT_NOTIFIERS
	INIT_HLIST_HEAD(&p->preempt_notifiers);
#endif
2224 2225 2226

#ifdef CONFIG_NUMA_BALANCING
	if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
2227
		p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
2228 2229 2230
		p->mm->numa_scan_seq = 0;
	}

2231 2232 2233 2234 2235
	if (clone_flags & CLONE_VM)
		p->numa_preferred_nid = current->numa_preferred_nid;
	else
		p->numa_preferred_nid = -1;

2236 2237
	p->node_stamp = 0ULL;
	p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
2238
	p->numa_scan_period = sysctl_numa_balancing_scan_delay;
2239
	p->numa_work.next = &p->numa_work;
2240
	p->numa_faults = NULL;
2241 2242
	p->last_task_numa_placement = 0;
	p->last_sum_exec_runtime = 0;
2243 2244

	p->numa_group = NULL;
2245
#endif /* CONFIG_NUMA_BALANCING */
I
Ingo Molnar 已提交
2246 2247
}

2248 2249
DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);

2250
#ifdef CONFIG_NUMA_BALANCING
2251

2252 2253 2254
void set_numabalancing_state(bool enabled)
{
	if (enabled)
2255
		static_branch_enable(&sched_numa_balancing);
2256
	else
2257
		static_branch_disable(&sched_numa_balancing);
2258
}
2259 2260 2261 2262 2263 2264 2265

#ifdef CONFIG_PROC_SYSCTL
int sysctl_numa_balancing(struct ctl_table *table, int write,
			 void __user *buffer, size_t *lenp, loff_t *ppos)
{
	struct ctl_table t;
	int err;
2266
	int state = static_branch_likely(&sched_numa_balancing);
2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281

	if (write && !capable(CAP_SYS_ADMIN))
		return -EPERM;

	t = *table;
	t.data = &state;
	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
	if (err < 0)
		return err;
	if (write)
		set_numabalancing_state(state);
	return err;
}
#endif
#endif
I
Ingo Molnar 已提交
2282

2283 2284
#ifdef CONFIG_SCHEDSTATS

2285
DEFINE_STATIC_KEY_FALSE(sched_schedstats);
2286
static bool __initdata __sched_schedstats = false;
2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309

static void set_schedstats(bool enabled)
{
	if (enabled)
		static_branch_enable(&sched_schedstats);
	else
		static_branch_disable(&sched_schedstats);
}

void force_schedstat_enabled(void)
{
	if (!schedstat_enabled()) {
		pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
		static_branch_enable(&sched_schedstats);
	}
}

static int __init setup_schedstats(char *str)
{
	int ret = 0;
	if (!str)
		goto out;

2310 2311 2312 2313 2314
	/*
	 * This code is called before jump labels have been set up, so we can't
	 * change the static branch directly just yet.  Instead set a temporary
	 * variable so init_schedstats() can do it later.
	 */
2315
	if (!strcmp(str, "enable")) {
2316
		__sched_schedstats = true;
2317 2318
		ret = 1;
	} else if (!strcmp(str, "disable")) {
2319
		__sched_schedstats = false;
2320 2321 2322 2323 2324 2325 2326 2327 2328 2329
		ret = 1;
	}
out:
	if (!ret)
		pr_warn("Unable to parse schedstats=\n");

	return ret;
}
__setup("schedstats=", setup_schedstats);

2330 2331 2332 2333 2334
static void __init init_schedstats(void)
{
	set_schedstats(__sched_schedstats);
}

2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354
#ifdef CONFIG_PROC_SYSCTL
int sysctl_schedstats(struct ctl_table *table, int write,
			 void __user *buffer, size_t *lenp, loff_t *ppos)
{
	struct ctl_table t;
	int err;
	int state = static_branch_likely(&sched_schedstats);

	if (write && !capable(CAP_SYS_ADMIN))
		return -EPERM;

	t = *table;
	t.data = &state;
	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
	if (err < 0)
		return err;
	if (write)
		set_schedstats(state);
	return err;
}
2355 2356 2357 2358
#endif /* CONFIG_PROC_SYSCTL */
#else  /* !CONFIG_SCHEDSTATS */
static inline void init_schedstats(void) {}
#endif /* CONFIG_SCHEDSTATS */
I
Ingo Molnar 已提交
2359 2360 2361 2362

/*
 * fork()/clone()-time setup:
 */
2363
int sched_fork(unsigned long clone_flags, struct task_struct *p)
I
Ingo Molnar 已提交
2364
{
2365
	unsigned long flags;
I
Ingo Molnar 已提交
2366 2367
	int cpu = get_cpu();

2368
	__sched_fork(clone_flags, p);
2369
	/*
2370
	 * We mark the process as NEW here. This guarantees that
2371 2372 2373
	 * nobody will actually run it, and a signal or other external
	 * event cannot wake it up and insert it on the runqueue either.
	 */
2374
	p->state = TASK_NEW;
I
Ingo Molnar 已提交
2375

2376 2377 2378 2379 2380
	/*
	 * Make sure we do not leak PI boosting priority to the child.
	 */
	p->prio = current->normal_prio;

2381 2382 2383 2384
	/*
	 * Revert to default priority/policy on fork if requested.
	 */
	if (unlikely(p->sched_reset_on_fork)) {
2385
		if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2386
			p->policy = SCHED_NORMAL;
2387
			p->static_prio = NICE_TO_PRIO(0);
2388 2389 2390 2391 2392 2393
			p->rt_priority = 0;
		} else if (PRIO_TO_NICE(p->static_prio) < 0)
			p->static_prio = NICE_TO_PRIO(0);

		p->prio = p->normal_prio = __normal_prio(p);
		set_load_weight(p);
2394

2395 2396 2397 2398 2399 2400
		/*
		 * We don't need the reset flag anymore after the fork. It has
		 * fulfilled its duty:
		 */
		p->sched_reset_on_fork = 0;
	}
2401

2402 2403 2404 2405 2406 2407
	if (dl_prio(p->prio)) {
		put_cpu();
		return -EAGAIN;
	} else if (rt_prio(p->prio)) {
		p->sched_class = &rt_sched_class;
	} else {
H
Hiroshi Shimamoto 已提交
2408
		p->sched_class = &fair_sched_class;
2409
	}
2410

2411
	init_entity_runnable_average(&p->se);
P
Peter Zijlstra 已提交
2412

2413 2414 2415 2416 2417 2418 2419
	/*
	 * The child is not yet in the pid-hash so no cgroup attach races,
	 * and the cgroup is pinned to this child due to cgroup_fork()
	 * is ran before sched_fork().
	 *
	 * Silence PROVE_RCU.
	 */
2420
	raw_spin_lock_irqsave(&p->pi_lock, flags);
2421 2422 2423 2424 2425 2426 2427
	/*
	 * We're setting the cpu for the first time, we don't migrate,
	 * so use __set_task_cpu().
	 */
	__set_task_cpu(p, cpu);
	if (p->sched_class->task_fork)
		p->sched_class->task_fork(p);
2428
	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2429

2430
#ifdef CONFIG_SCHED_INFO
I
Ingo Molnar 已提交
2431
	if (likely(sched_info_on()))
2432
		memset(&p->sched_info, 0, sizeof(p->sched_info));
L
Linus Torvalds 已提交
2433
#endif
P
Peter Zijlstra 已提交
2434 2435
#if defined(CONFIG_SMP)
	p->on_cpu = 0;
2436
#endif
2437
	init_task_preempt_count(p);
2438
#ifdef CONFIG_SMP
2439
	plist_node_init(&p->pushable_tasks, MAX_PRIO);
2440
	RB_CLEAR_NODE(&p->pushable_dl_tasks);
2441
#endif
2442

N
Nick Piggin 已提交
2443
	put_cpu();
2444
	return 0;
L
Linus Torvalds 已提交
2445 2446
}

2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465
unsigned long to_ratio(u64 period, u64 runtime)
{
	if (runtime == RUNTIME_INF)
		return 1ULL << 20;

	/*
	 * Doing this here saves a lot of checks in all
	 * the calling paths, and returning zero seems
	 * safe for them anyway.
	 */
	if (period == 0)
		return 0;

	return div64_u64(runtime << 20, period);
}

#ifdef CONFIG_SMP
inline struct dl_bw *dl_bw_of(int i)
{
2466 2467
	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
			 "sched RCU must be held");
2468 2469 2470
	return &cpu_rq(i)->rd->dl_bw;
}

2471
static inline int dl_bw_cpus(int i)
2472
{
2473 2474 2475
	struct root_domain *rd = cpu_rq(i)->rd;
	int cpus = 0;

2476 2477
	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
			 "sched RCU must be held");
2478 2479 2480 2481
	for_each_cpu_and(i, rd->span, cpu_active_mask)
		cpus++;

	return cpus;
2482 2483 2484 2485 2486 2487 2488
}
#else
inline struct dl_bw *dl_bw_of(int i)
{
	return &cpu_rq(i)->dl.dl_bw;
}

2489
static inline int dl_bw_cpus(int i)
2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501
{
	return 1;
}
#endif

/*
 * We must be sure that accepting a new task (or allowing changing the
 * parameters of an existing one) is consistent with the bandwidth
 * constraints. If yes, this function also accordingly updates the currently
 * allocated bandwidth to reflect the new situation.
 *
 * This function is called while holding p's rq->lock.
2502 2503 2504
 *
 * XXX we should delay bw change until the task's 0-lag point, see
 * __setparam_dl().
2505 2506 2507 2508 2509 2510
 */
static int dl_overflow(struct task_struct *p, int policy,
		       const struct sched_attr *attr)
{

	struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
2511
	u64 period = attr->sched_period ?: attr->sched_deadline;
2512 2513
	u64 runtime = attr->sched_runtime;
	u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2514
	int cpus, err = -1;
2515

2516 2517
	/* !deadline task may carry old deadline bandwidth */
	if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
2518 2519 2520 2521 2522 2523 2524 2525
		return 0;

	/*
	 * Either if a task, enters, leave, or stays -deadline but changes
	 * its parameters, we may need to update accordingly the total
	 * allocated bandwidth of the container.
	 */
	raw_spin_lock(&dl_b->lock);
2526
	cpus = dl_bw_cpus(task_cpu(p));
2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546
	if (dl_policy(policy) && !task_has_dl_policy(p) &&
	    !__dl_overflow(dl_b, cpus, 0, new_bw)) {
		__dl_add(dl_b, new_bw);
		err = 0;
	} else if (dl_policy(policy) && task_has_dl_policy(p) &&
		   !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
		__dl_clear(dl_b, p->dl.dl_bw);
		__dl_add(dl_b, new_bw);
		err = 0;
	} else if (!dl_policy(policy) && task_has_dl_policy(p)) {
		__dl_clear(dl_b, p->dl.dl_bw);
		err = 0;
	}
	raw_spin_unlock(&dl_b->lock);

	return err;
}

extern void init_dl_bw(struct dl_bw *dl_b);

L
Linus Torvalds 已提交
2547 2548 2549 2550 2551 2552 2553
/*
 * wake_up_new_task - wake up a newly created task for the first time.
 *
 * This function will do some initial scheduler statistics housekeeping
 * that must be done for every newly created context, then puts the task
 * on the runqueue and wakes it.
 */
2554
void wake_up_new_task(struct task_struct *p)
L
Linus Torvalds 已提交
2555
{
2556
	struct rq_flags rf;
I
Ingo Molnar 已提交
2557
	struct rq *rq;
2558

2559
	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
2560
	p->state = TASK_RUNNING;
2561 2562 2563 2564 2565
#ifdef CONFIG_SMP
	/*
	 * Fork balancing, do it here and not earlier because:
	 *  - cpus_allowed can change in the fork path
	 *  - any previously selected cpu might disappear through hotplug
2566 2567 2568
	 *
	 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
	 * as we're not fully set-up yet.
2569
	 */
2570
	__set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2571
#endif
2572
	rq = __task_rq_lock(p, &rf);
2573
	post_init_entity_util_avg(&p->se);
2574

P
Peter Zijlstra 已提交
2575
	activate_task(rq, p, 0);
2576
	p->on_rq = TASK_ON_RQ_QUEUED;
2577
	trace_sched_wakeup_new(p);
P
Peter Zijlstra 已提交
2578
	check_preempt_curr(rq, p, WF_FORK);
2579
#ifdef CONFIG_SMP
2580 2581 2582 2583 2584
	if (p->sched_class->task_woken) {
		/*
		 * Nothing relies on rq->lock after this, so its fine to
		 * drop it.
		 */
2585
		lockdep_unpin_lock(&rq->lock, rf.cookie);
2586
		p->sched_class->task_woken(rq, p);
2587
		lockdep_repin_lock(&rq->lock, rf.cookie);
2588
	}
2589
#endif
2590
	task_rq_unlock(rq, p, &rf);
L
Linus Torvalds 已提交
2591 2592
}

2593 2594
#ifdef CONFIG_PREEMPT_NOTIFIERS

2595 2596
static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;

2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608
void preempt_notifier_inc(void)
{
	static_key_slow_inc(&preempt_notifier_key);
}
EXPORT_SYMBOL_GPL(preempt_notifier_inc);

void preempt_notifier_dec(void)
{
	static_key_slow_dec(&preempt_notifier_key);
}
EXPORT_SYMBOL_GPL(preempt_notifier_dec);

2609
/**
2610
 * preempt_notifier_register - tell me when current is being preempted & rescheduled
R
Randy Dunlap 已提交
2611
 * @notifier: notifier struct to register
2612 2613 2614
 */
void preempt_notifier_register(struct preempt_notifier *notifier)
{
2615 2616 2617
	if (!static_key_false(&preempt_notifier_key))
		WARN(1, "registering preempt_notifier while notifiers disabled\n");

2618 2619 2620 2621 2622 2623
	hlist_add_head(&notifier->link, &current->preempt_notifiers);
}
EXPORT_SYMBOL_GPL(preempt_notifier_register);

/**
 * preempt_notifier_unregister - no longer interested in preemption notifications
R
Randy Dunlap 已提交
2624
 * @notifier: notifier struct to unregister
2625
 *
2626
 * This is *not* safe to call from within a preemption notifier.
2627 2628 2629 2630 2631 2632 2633
 */
void preempt_notifier_unregister(struct preempt_notifier *notifier)
{
	hlist_del(&notifier->link);
}
EXPORT_SYMBOL_GPL(preempt_notifier_unregister);

2634
static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
2635 2636 2637
{
	struct preempt_notifier *notifier;

2638
	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2639 2640 2641
		notifier->ops->sched_in(notifier, raw_smp_processor_id());
}

2642 2643 2644 2645 2646 2647
static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
{
	if (static_key_false(&preempt_notifier_key))
		__fire_sched_in_preempt_notifiers(curr);
}

2648
static void
2649 2650
__fire_sched_out_preempt_notifiers(struct task_struct *curr,
				   struct task_struct *next)
2651 2652 2653
{
	struct preempt_notifier *notifier;

2654
	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2655 2656 2657
		notifier->ops->sched_out(notifier, next);
}

2658 2659 2660 2661 2662 2663 2664 2665
static __always_inline void
fire_sched_out_preempt_notifiers(struct task_struct *curr,
				 struct task_struct *next)
{
	if (static_key_false(&preempt_notifier_key))
		__fire_sched_out_preempt_notifiers(curr, next);
}

2666
#else /* !CONFIG_PREEMPT_NOTIFIERS */
2667

2668
static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2669 2670 2671
{
}

2672
static inline void
2673 2674 2675 2676 2677
fire_sched_out_preempt_notifiers(struct task_struct *curr,
				 struct task_struct *next)
{
}

2678
#endif /* CONFIG_PREEMPT_NOTIFIERS */
2679

2680 2681 2682
/**
 * prepare_task_switch - prepare to switch tasks
 * @rq: the runqueue preparing to switch
R
Randy Dunlap 已提交
2683
 * @prev: the current task that is being switched out
2684 2685 2686 2687 2688 2689 2690 2691 2692
 * @next: the task we are going to switch to.
 *
 * This is called with the rq lock held and interrupts off. It must
 * be paired with a subsequent finish_task_switch after the context
 * switch.
 *
 * prepare_task_switch sets up locking and calls architecture specific
 * hooks.
 */
2693 2694 2695
static inline void
prepare_task_switch(struct rq *rq, struct task_struct *prev,
		    struct task_struct *next)
2696
{
2697
	sched_info_switch(rq, prev, next);
2698
	perf_event_task_sched_out(prev, next);
2699
	fire_sched_out_preempt_notifiers(prev, next);
2700 2701 2702 2703
	prepare_lock_switch(rq, next);
	prepare_arch_switch(next);
}

L
Linus Torvalds 已提交
2704 2705 2706 2707
/**
 * finish_task_switch - clean up after a task-switch
 * @prev: the thread we just switched away from.
 *
2708 2709 2710 2711
 * finish_task_switch must be called after the context switch, paired
 * with a prepare_task_switch call before the context switch.
 * finish_task_switch will reconcile locking set up by prepare_task_switch,
 * and do any other architecture-specific cleanup actions.
L
Linus Torvalds 已提交
2712 2713
 *
 * Note that we may have delayed dropping an mm in context_switch(). If
I
Ingo Molnar 已提交
2714
 * so, we finish that here outside of the runqueue lock. (Doing it
L
Linus Torvalds 已提交
2715 2716
 * with the lock held can cause deadlocks; see schedule() for
 * details.)
2717 2718 2719 2720 2721
 *
 * The context switch have flipped the stack from under us and restored the
 * local variables which were saved when this task called schedule() in the
 * past. prev == current is still correct but we need to recalculate this_rq
 * because prev may have moved to another CPU.
L
Linus Torvalds 已提交
2722
 */
2723
static struct rq *finish_task_switch(struct task_struct *prev)
L
Linus Torvalds 已提交
2724 2725
	__releases(rq->lock)
{
2726
	struct rq *rq = this_rq();
L
Linus Torvalds 已提交
2727
	struct mm_struct *mm = rq->prev_mm;
O
Oleg Nesterov 已提交
2728
	long prev_state;
L
Linus Torvalds 已提交
2729

2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740
	/*
	 * The previous task will have left us with a preempt_count of 2
	 * because it left us after:
	 *
	 *	schedule()
	 *	  preempt_disable();			// 1
	 *	  __schedule()
	 *	    raw_spin_lock_irq(&rq->lock)	// 2
	 *
	 * Also, see FORK_PREEMPT_COUNT.
	 */
2741 2742 2743 2744
	if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
		      "corrupted preempt_count: %s/%d/0x%x\n",
		      current->comm, current->pid, preempt_count()))
		preempt_count_set(FORK_PREEMPT_COUNT);
2745

L
Linus Torvalds 已提交
2746 2747 2748 2749
	rq->prev_mm = NULL;

	/*
	 * A task struct has one reference for the use as "current".
2750
	 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
O
Oleg Nesterov 已提交
2751 2752
	 * schedule one last time. The schedule call will never return, and
	 * the scheduled task must drop that reference.
2753 2754 2755 2756 2757
	 *
	 * We must observe prev->state before clearing prev->on_cpu (in
	 * finish_lock_switch), otherwise a concurrent wakeup can get prev
	 * running on another CPU and we could rave with its RUNNING -> DEAD
	 * transition, resulting in a double drop.
L
Linus Torvalds 已提交
2758
	 */
O
Oleg Nesterov 已提交
2759
	prev_state = prev->state;
2760
	vtime_task_switch(prev);
2761
	perf_event_task_sched_in(prev, current);
2762
	finish_lock_switch(rq, prev);
2763
	finish_arch_post_lock_switch();
S
Steven Rostedt 已提交
2764

2765
	fire_sched_in_preempt_notifiers(current);
L
Linus Torvalds 已提交
2766 2767
	if (mm)
		mmdrop(mm);
2768
	if (unlikely(prev_state == TASK_DEAD)) {
2769 2770 2771
		if (prev->sched_class->task_dead)
			prev->sched_class->task_dead(prev);

2772 2773 2774
		/*
		 * Remove function-return probe instances associated with this
		 * task and put them back on the free list.
I
Ingo Molnar 已提交
2775
		 */
2776
		kprobe_flush_task(prev);
L
Linus Torvalds 已提交
2777
		put_task_struct(prev);
2778
	}
2779

2780
	tick_nohz_task_switch();
2781
	return rq;
L
Linus Torvalds 已提交
2782 2783
}

2784 2785 2786
#ifdef CONFIG_SMP

/* rq->lock is NOT held, but preemption is disabled */
2787
static void __balance_callback(struct rq *rq)
2788
{
2789 2790 2791
	struct callback_head *head, *next;
	void (*func)(struct rq *rq);
	unsigned long flags;
2792

2793 2794 2795 2796 2797 2798 2799 2800
	raw_spin_lock_irqsave(&rq->lock, flags);
	head = rq->balance_callback;
	rq->balance_callback = NULL;
	while (head) {
		func = (void (*)(struct rq *))head->func;
		next = head->next;
		head->next = NULL;
		head = next;
2801

2802
		func(rq);
2803
	}
2804 2805 2806 2807 2808 2809 2810
	raw_spin_unlock_irqrestore(&rq->lock, flags);
}

static inline void balance_callback(struct rq *rq)
{
	if (unlikely(rq->balance_callback))
		__balance_callback(rq);
2811 2812 2813
}

#else
2814

2815
static inline void balance_callback(struct rq *rq)
2816
{
L
Linus Torvalds 已提交
2817 2818
}

2819 2820
#endif

L
Linus Torvalds 已提交
2821 2822 2823 2824
/**
 * schedule_tail - first thing a freshly forked thread must call.
 * @prev: the thread we just switched away from.
 */
2825
asmlinkage __visible void schedule_tail(struct task_struct *prev)
L
Linus Torvalds 已提交
2826 2827
	__releases(rq->lock)
{
2828
	struct rq *rq;
2829

2830 2831 2832 2833 2834 2835 2836 2837 2838
	/*
	 * New tasks start with FORK_PREEMPT_COUNT, see there and
	 * finish_task_switch() for details.
	 *
	 * finish_task_switch() will drop rq->lock() and lower preempt_count
	 * and the preempt_enable() will end up enabling preemption (on
	 * PREEMPT_COUNT kernels).
	 */

2839
	rq = finish_task_switch(prev);
2840
	balance_callback(rq);
2841
	preempt_enable();
2842

L
Linus Torvalds 已提交
2843
	if (current->set_child_tid)
2844
		put_user(task_pid_vnr(current), current->set_child_tid);
L
Linus Torvalds 已提交
2845 2846 2847
}

/*
2848
 * context_switch - switch to the new MM and the new thread's register state.
L
Linus Torvalds 已提交
2849
 */
2850
static __always_inline struct rq *
2851
context_switch(struct rq *rq, struct task_struct *prev,
2852
	       struct task_struct *next, struct pin_cookie cookie)
L
Linus Torvalds 已提交
2853
{
I
Ingo Molnar 已提交
2854
	struct mm_struct *mm, *oldmm;
L
Linus Torvalds 已提交
2855

2856
	prepare_task_switch(rq, prev, next);
2857

I
Ingo Molnar 已提交
2858 2859
	mm = next->mm;
	oldmm = prev->active_mm;
2860 2861 2862 2863 2864
	/*
	 * For paravirt, this is coupled with an exit in switch_to to
	 * combine the page table reload and the switch backend into
	 * one hypercall.
	 */
2865
	arch_start_context_switch(prev);
2866

2867
	if (!mm) {
L
Linus Torvalds 已提交
2868 2869 2870 2871
		next->active_mm = oldmm;
		atomic_inc(&oldmm->mm_count);
		enter_lazy_tlb(oldmm, next);
	} else
2872
		switch_mm_irqs_off(oldmm, mm, next);
L
Linus Torvalds 已提交
2873

2874
	if (!prev->mm) {
L
Linus Torvalds 已提交
2875 2876 2877
		prev->active_mm = NULL;
		rq->prev_mm = oldmm;
	}
2878 2879 2880 2881 2882 2883
	/*
	 * Since the runqueue lock will be released by the next
	 * task (which is an invalid locking op but in the case
	 * of the scheduler it's an obvious special-case), so we
	 * do an early lockdep release here:
	 */
2884
	lockdep_unpin_lock(&rq->lock, cookie);
2885
	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
L
Linus Torvalds 已提交
2886 2887 2888

	/* Here we just switch the register state and the stack. */
	switch_to(prev, next, prev);
I
Ingo Molnar 已提交
2889
	barrier();
2890 2891

	return finish_task_switch(prev);
L
Linus Torvalds 已提交
2892 2893 2894
}

/*
2895
 * nr_running and nr_context_switches:
L
Linus Torvalds 已提交
2896 2897
 *
 * externally visible scheduler statistics: current number of runnable
2898
 * threads, total number of context switches performed since bootup.
L
Linus Torvalds 已提交
2899 2900 2901 2902 2903 2904 2905 2906 2907
 */
unsigned long nr_running(void)
{
	unsigned long i, sum = 0;

	for_each_online_cpu(i)
		sum += cpu_rq(i)->nr_running;

	return sum;
2908
}
L
Linus Torvalds 已提交
2909

2910 2911
/*
 * Check if only the current task is running on the cpu.
2912 2913 2914 2915 2916 2917 2918 2919 2920 2921
 *
 * Caution: this function does not check that the caller has disabled
 * preemption, thus the result might have a time-of-check-to-time-of-use
 * race.  The caller is responsible to use it correctly, for example:
 *
 * - from a non-preemptable section (of course)
 *
 * - from a thread that is bound to a single CPU
 *
 * - in a loop with very short iterations (e.g. a polling loop)
2922 2923 2924
 */
bool single_task_running(void)
{
2925
	return raw_rq()->nr_running == 1;
2926 2927 2928
}
EXPORT_SYMBOL(single_task_running);

L
Linus Torvalds 已提交
2929
unsigned long long nr_context_switches(void)
2930
{
2931 2932
	int i;
	unsigned long long sum = 0;
2933

2934
	for_each_possible_cpu(i)
L
Linus Torvalds 已提交
2935
		sum += cpu_rq(i)->nr_switches;
2936

L
Linus Torvalds 已提交
2937 2938
	return sum;
}
2939

L
Linus Torvalds 已提交
2940 2941 2942
unsigned long nr_iowait(void)
{
	unsigned long i, sum = 0;
2943

2944
	for_each_possible_cpu(i)
L
Linus Torvalds 已提交
2945
		sum += atomic_read(&cpu_rq(i)->nr_iowait);
2946

L
Linus Torvalds 已提交
2947 2948
	return sum;
}
2949

2950
unsigned long nr_iowait_cpu(int cpu)
2951
{
2952
	struct rq *this = cpu_rq(cpu);
2953 2954
	return atomic_read(&this->nr_iowait);
}
2955

2956 2957
void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
{
2958 2959 2960
	struct rq *rq = this_rq();
	*nr_waiters = atomic_read(&rq->nr_iowait);
	*load = rq->load.weight;
2961 2962
}

I
Ingo Molnar 已提交
2963
#ifdef CONFIG_SMP
2964

2965
/*
P
Peter Zijlstra 已提交
2966 2967
 * sched_exec - execve() is a valuable balancing opportunity, because at
 * this point the task has the smallest effective memory and cache footprint.
2968
 */
P
Peter Zijlstra 已提交
2969
void sched_exec(void)
2970
{
P
Peter Zijlstra 已提交
2971
	struct task_struct *p = current;
L
Linus Torvalds 已提交
2972
	unsigned long flags;
2973
	int dest_cpu;
2974

2975
	raw_spin_lock_irqsave(&p->pi_lock, flags);
2976
	dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2977 2978
	if (dest_cpu == smp_processor_id())
		goto unlock;
P
Peter Zijlstra 已提交
2979

2980
	if (likely(cpu_active(dest_cpu))) {
2981
		struct migration_arg arg = { p, dest_cpu };
2982

2983 2984
		raw_spin_unlock_irqrestore(&p->pi_lock, flags);
		stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
L
Linus Torvalds 已提交
2985 2986
		return;
	}
2987
unlock:
2988
	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
L
Linus Torvalds 已提交
2989
}
I
Ingo Molnar 已提交
2990

L
Linus Torvalds 已提交
2991 2992 2993
#endif

DEFINE_PER_CPU(struct kernel_stat, kstat);
2994
DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
L
Linus Torvalds 已提交
2995 2996

EXPORT_PER_CPU_SYMBOL(kstat);
2997
EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
L
Linus Torvalds 已提交
2998

2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015
/*
 * The function fair_sched_class.update_curr accesses the struct curr
 * and its field curr->exec_start; when called from task_sched_runtime(),
 * we observe a high rate of cache misses in practice.
 * Prefetching this data results in improved performance.
 */
static inline void prefetch_curr_exec_start(struct task_struct *p)
{
#ifdef CONFIG_FAIR_GROUP_SCHED
	struct sched_entity *curr = (&p->se)->cfs_rq->curr;
#else
	struct sched_entity *curr = (&task_rq(p)->cfs)->curr;
#endif
	prefetch(curr);
	prefetch(&curr->exec_start);
}

3016 3017 3018 3019 3020 3021 3022
/*
 * Return accounted runtime for the task.
 * In case the task is currently running, return the runtime plus current's
 * pending runtime that have not been accounted yet.
 */
unsigned long long task_sched_runtime(struct task_struct *p)
{
3023
	struct rq_flags rf;
3024
	struct rq *rq;
3025
	u64 ns;
3026

3027 3028 3029 3030 3031 3032 3033 3034 3035
#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
	/*
	 * 64-bit doesn't need locks to atomically read a 64bit value.
	 * So we have a optimization chance when the task's delta_exec is 0.
	 * Reading ->on_cpu is racy, but this is ok.
	 *
	 * If we race with it leaving cpu, we'll take a lock. So we're correct.
	 * If we race with it entering cpu, unaccounted time is 0. This is
	 * indistinguishable from the read occurring a few cycles earlier.
3036 3037
	 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
	 * been accounted, so we're correct here as well.
3038
	 */
3039
	if (!p->on_cpu || !task_on_rq_queued(p))
3040 3041 3042
		return p->se.sum_exec_runtime;
#endif

3043
	rq = task_rq_lock(p, &rf);
3044 3045 3046 3047 3048 3049
	/*
	 * Must be ->curr _and_ ->on_rq.  If dequeued, we would
	 * project cycles that may never be accounted to this
	 * thread, breaking clock_gettime().
	 */
	if (task_current(rq, p) && task_on_rq_queued(p)) {
3050
		prefetch_curr_exec_start(p);
3051 3052 3053 3054
		update_rq_clock(rq);
		p->sched_class->update_curr(rq);
	}
	ns = p->se.sum_exec_runtime;
3055
	task_rq_unlock(rq, p, &rf);
3056 3057 3058

	return ns;
}
3059

3060 3061 3062 3063 3064 3065 3066 3067
/*
 * This function gets called by the timer code, with HZ frequency.
 * We call it with interrupts disabled.
 */
void scheduler_tick(void)
{
	int cpu = smp_processor_id();
	struct rq *rq = cpu_rq(cpu);
I
Ingo Molnar 已提交
3068
	struct task_struct *curr = rq->curr;
3069 3070

	sched_clock_tick();
I
Ingo Molnar 已提交
3071

3072
	raw_spin_lock(&rq->lock);
3073
	update_rq_clock(rq);
P
Peter Zijlstra 已提交
3074
	curr->sched_class->task_tick(rq, curr, 0);
3075
	cpu_load_update_active(rq);
3076
	calc_global_load_tick(rq);
3077
	raw_spin_unlock(&rq->lock);
3078

3079
	perf_event_task_tick();
3080

3081
#ifdef CONFIG_SMP
3082
	rq->idle_balance = idle_cpu(cpu);
3083
	trigger_load_balance(rq);
3084
#endif
3085
	rq_last_tick_reset(rq);
L
Linus Torvalds 已提交
3086 3087
}

3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098
#ifdef CONFIG_NO_HZ_FULL
/**
 * scheduler_tick_max_deferment
 *
 * Keep at least one tick per second when a single
 * active task is running because the scheduler doesn't
 * yet completely support full dynticks environment.
 *
 * This makes sure that uptime, CFS vruntime, load
 * balancing, etc... continue to move forward, even
 * with a very low granularity.
3099 3100
 *
 * Return: Maximum deferment in nanoseconds.
3101 3102 3103 3104
 */
u64 scheduler_tick_max_deferment(void)
{
	struct rq *rq = this_rq();
3105
	unsigned long next, now = READ_ONCE(jiffies);
3106 3107 3108 3109 3110 3111

	next = rq->last_sched_tick + HZ;

	if (time_before_eq(next, now))
		return 0;

3112
	return jiffies_to_nsecs(next - now);
L
Linus Torvalds 已提交
3113
}
3114
#endif
L
Linus Torvalds 已提交
3115

3116 3117
#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
				defined(CONFIG_PREEMPT_TRACER))
3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131
/*
 * If the value passed in is equal to the current preempt count
 * then we just disabled preemption. Start timing the latency.
 */
static inline void preempt_latency_start(int val)
{
	if (preempt_count() == val) {
		unsigned long ip = get_lock_parent_ip();
#ifdef CONFIG_DEBUG_PREEMPT
		current->preempt_disable_ip = ip;
#endif
		trace_preempt_off(CALLER_ADDR0, ip);
	}
}
3132

3133
void preempt_count_add(int val)
L
Linus Torvalds 已提交
3134
{
3135
#ifdef CONFIG_DEBUG_PREEMPT
L
Linus Torvalds 已提交
3136 3137 3138
	/*
	 * Underflow?
	 */
3139 3140
	if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
		return;
3141
#endif
3142
	__preempt_count_add(val);
3143
#ifdef CONFIG_DEBUG_PREEMPT
L
Linus Torvalds 已提交
3144 3145 3146
	/*
	 * Spinlock count overflowing soon?
	 */
3147 3148
	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
				PREEMPT_MASK - 10);
3149
#endif
3150
	preempt_latency_start(val);
L
Linus Torvalds 已提交
3151
}
3152
EXPORT_SYMBOL(preempt_count_add);
3153
NOKPROBE_SYMBOL(preempt_count_add);
L
Linus Torvalds 已提交
3154

3155 3156 3157 3158 3159 3160 3161 3162 3163 3164
/*
 * If the value passed in equals to the current preempt count
 * then we just enabled preemption. Stop timing the latency.
 */
static inline void preempt_latency_stop(int val)
{
	if (preempt_count() == val)
		trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
}

3165
void preempt_count_sub(int val)
L
Linus Torvalds 已提交
3166
{
3167
#ifdef CONFIG_DEBUG_PREEMPT
L
Linus Torvalds 已提交
3168 3169 3170
	/*
	 * Underflow?
	 */
3171
	if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3172
		return;
L
Linus Torvalds 已提交
3173 3174 3175
	/*
	 * Is the spinlock portion underflowing?
	 */
3176 3177 3178
	if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
			!(preempt_count() & PREEMPT_MASK)))
		return;
3179
#endif
3180

3181
	preempt_latency_stop(val);
3182
	__preempt_count_sub(val);
L
Linus Torvalds 已提交
3183
}
3184
EXPORT_SYMBOL(preempt_count_sub);
3185
NOKPROBE_SYMBOL(preempt_count_sub);
L
Linus Torvalds 已提交
3186

3187 3188 3189
#else
static inline void preempt_latency_start(int val) { }
static inline void preempt_latency_stop(int val) { }
L
Linus Torvalds 已提交
3190 3191 3192
#endif

/*
I
Ingo Molnar 已提交
3193
 * Print scheduling while atomic bug:
L
Linus Torvalds 已提交
3194
 */
I
Ingo Molnar 已提交
3195
static noinline void __schedule_bug(struct task_struct *prev)
L
Linus Torvalds 已提交
3196
{
3197 3198 3199
	/* Save this before calling printk(), since that will clobber it */
	unsigned long preempt_disable_ip = get_preempt_disable_ip(current);

3200 3201 3202
	if (oops_in_progress)
		return;

P
Peter Zijlstra 已提交
3203 3204
	printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
		prev->comm, prev->pid, preempt_count());
3205

I
Ingo Molnar 已提交
3206
	debug_show_held_locks(prev);
3207
	print_modules();
I
Ingo Molnar 已提交
3208 3209
	if (irqs_disabled())
		print_irqtrace_events(prev);
3210 3211
	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
	    && in_atomic_preempt_off()) {
3212
		pr_err("Preemption disabled at:");
3213
		print_ip_sym(preempt_disable_ip);
3214 3215
		pr_cont("\n");
	}
3216 3217 3218
	if (panic_on_warn)
		panic("scheduling while atomic\n");

3219
	dump_stack();
3220
	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
I
Ingo Molnar 已提交
3221
}
L
Linus Torvalds 已提交
3222

I
Ingo Molnar 已提交
3223 3224 3225 3226 3227
/*
 * Various schedule()-time debugging checks and statistics:
 */
static inline void schedule_debug(struct task_struct *prev)
{
3228
#ifdef CONFIG_SCHED_STACK_END_CHECK
J
Jann Horn 已提交
3229 3230
	if (task_stack_end_corrupted(prev))
		panic("corrupted stack end detected inside scheduler\n");
3231
#endif
3232

3233
	if (unlikely(in_atomic_preempt_off())) {
I
Ingo Molnar 已提交
3234
		__schedule_bug(prev);
3235 3236
		preempt_count_set(PREEMPT_DISABLED);
	}
3237
	rcu_sleep_check();
I
Ingo Molnar 已提交
3238

L
Linus Torvalds 已提交
3239 3240
	profile_hit(SCHED_PROFILING, __builtin_return_address(0));

3241
	schedstat_inc(this_rq()->sched_count);
I
Ingo Molnar 已提交
3242 3243 3244 3245 3246 3247
}

/*
 * Pick up the highest-prio task:
 */
static inline struct task_struct *
3248
pick_next_task(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie)
I
Ingo Molnar 已提交
3249
{
3250
	const struct sched_class *class = &fair_sched_class;
I
Ingo Molnar 已提交
3251
	struct task_struct *p;
L
Linus Torvalds 已提交
3252 3253

	/*
I
Ingo Molnar 已提交
3254 3255
	 * Optimization: we know that if all tasks are in
	 * the fair class we can call that function directly:
L
Linus Torvalds 已提交
3256
	 */
3257
	if (likely(prev->sched_class == class &&
3258
		   rq->nr_running == rq->cfs.h_nr_running)) {
3259
		p = fair_sched_class.pick_next_task(rq, prev, cookie);
3260 3261 3262 3263 3264
		if (unlikely(p == RETRY_TASK))
			goto again;

		/* assumes fair_sched_class->next == idle_sched_class */
		if (unlikely(!p))
3265
			p = idle_sched_class.pick_next_task(rq, prev, cookie);
3266 3267

		return p;
L
Linus Torvalds 已提交
3268 3269
	}

3270
again:
3271
	for_each_class(class) {
3272
		p = class->pick_next_task(rq, prev, cookie);
3273 3274 3275
		if (p) {
			if (unlikely(p == RETRY_TASK))
				goto again;
I
Ingo Molnar 已提交
3276
			return p;
3277
		}
I
Ingo Molnar 已提交
3278
	}
3279 3280

	BUG(); /* the idle class will always have a runnable task */
I
Ingo Molnar 已提交
3281
}
L
Linus Torvalds 已提交
3282

I
Ingo Molnar 已提交
3283
/*
3284
 * __schedule() is the main scheduler function.
3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318
 *
 * The main means of driving the scheduler and thus entering this function are:
 *
 *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
 *
 *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
 *      paths. For example, see arch/x86/entry_64.S.
 *
 *      To drive preemption between tasks, the scheduler sets the flag in timer
 *      interrupt handler scheduler_tick().
 *
 *   3. Wakeups don't really cause entry into schedule(). They add a
 *      task to the run-queue and that's it.
 *
 *      Now, if the new task added to the run-queue preempts the current
 *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
 *      called on the nearest possible occasion:
 *
 *       - If the kernel is preemptible (CONFIG_PREEMPT=y):
 *
 *         - in syscall or exception context, at the next outmost
 *           preempt_enable(). (this might be as soon as the wake_up()'s
 *           spin_unlock()!)
 *
 *         - in IRQ context, return from interrupt-handler to
 *           preemptible context
 *
 *       - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
 *         then at the next:
 *
 *          - cond_resched() call
 *          - explicit schedule() call
 *          - return from syscall or exception to user-space
 *          - return from interrupt-handler to user-space
3319
 *
3320
 * WARNING: must be called with preemption disabled!
I
Ingo Molnar 已提交
3321
 */
3322
static void __sched notrace __schedule(bool preempt)
I
Ingo Molnar 已提交
3323 3324
{
	struct task_struct *prev, *next;
3325
	unsigned long *switch_count;
3326
	struct pin_cookie cookie;
I
Ingo Molnar 已提交
3327
	struct rq *rq;
3328
	int cpu;
I
Ingo Molnar 已提交
3329 3330 3331 3332 3333 3334

	cpu = smp_processor_id();
	rq = cpu_rq(cpu);
	prev = rq->curr;

	schedule_debug(prev);
L
Linus Torvalds 已提交
3335

3336
	if (sched_feat(HRTICK))
M
Mike Galbraith 已提交
3337
		hrtick_clear(rq);
P
Peter Zijlstra 已提交
3338

3339 3340 3341
	local_irq_disable();
	rcu_note_context_switch();

3342 3343 3344 3345 3346 3347
	/*
	 * Make sure that signal_pending_state()->signal_pending() below
	 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
	 * done by the caller to avoid the race with signal_wake_up().
	 */
	smp_mb__before_spinlock();
3348
	raw_spin_lock(&rq->lock);
3349
	cookie = lockdep_pin_lock(&rq->lock);
L
Linus Torvalds 已提交
3350

3351 3352
	rq->clock_skip_update <<= 1; /* promote REQ to ACT */

3353
	switch_count = &prev->nivcsw;
3354
	if (!preempt && prev->state) {
T
Tejun Heo 已提交
3355
		if (unlikely(signal_pending_state(prev->state, prev))) {
L
Linus Torvalds 已提交
3356
			prev->state = TASK_RUNNING;
T
Tejun Heo 已提交
3357
		} else {
3358 3359 3360
			deactivate_task(rq, prev, DEQUEUE_SLEEP);
			prev->on_rq = 0;

T
Tejun Heo 已提交
3361
			/*
3362 3363 3364
			 * If a worker went to sleep, notify and ask workqueue
			 * whether it wants to wake up a task to maintain
			 * concurrency.
T
Tejun Heo 已提交
3365 3366 3367 3368
			 */
			if (prev->flags & PF_WQ_WORKER) {
				struct task_struct *to_wakeup;

3369
				to_wakeup = wq_worker_sleeping(prev);
T
Tejun Heo 已提交
3370
				if (to_wakeup)
3371
					try_to_wake_up_local(to_wakeup, cookie);
T
Tejun Heo 已提交
3372 3373
			}
		}
I
Ingo Molnar 已提交
3374
		switch_count = &prev->nvcsw;
L
Linus Torvalds 已提交
3375 3376
	}

3377
	if (task_on_rq_queued(prev))
3378 3379
		update_rq_clock(rq);

3380
	next = pick_next_task(rq, prev, cookie);
3381
	clear_tsk_need_resched(prev);
3382
	clear_preempt_need_resched();
3383
	rq->clock_skip_update = 0;
L
Linus Torvalds 已提交
3384 3385 3386 3387 3388 3389

	if (likely(prev != next)) {
		rq->nr_switches++;
		rq->curr = next;
		++*switch_count;

3390
		trace_sched_switch(preempt, prev, next);
3391
		rq = context_switch(rq, prev, next, cookie); /* unlocks the rq */
3392
	} else {
3393
		lockdep_unpin_lock(&rq->lock, cookie);
3394
		raw_spin_unlock_irq(&rq->lock);
3395
	}
L
Linus Torvalds 已提交
3396

3397
	balance_callback(rq);
L
Linus Torvalds 已提交
3398
}
3399
STACK_FRAME_NON_STANDARD(__schedule); /* switch_to() */
3400

3401 3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427
void __noreturn do_task_dead(void)
{
	/*
	 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
	 * when the following two conditions become true.
	 *   - There is race condition of mmap_sem (It is acquired by
	 *     exit_mm()), and
	 *   - SMI occurs before setting TASK_RUNINNG.
	 *     (or hypervisor of virtual machine switches to other guest)
	 *  As a result, we may become TASK_RUNNING after becoming TASK_DEAD
	 *
	 * To avoid it, we have to wait for releasing tsk->pi_lock which
	 * is held by try_to_wake_up()
	 */
	smp_mb();
	raw_spin_unlock_wait(&current->pi_lock);

	/* causes final put_task_struct in finish_task_switch(). */
	__set_current_state(TASK_DEAD);
	current->flags |= PF_NOFREEZE;	/* tell freezer to ignore us */
	__schedule(false);
	BUG();
	/* Avoid "noreturn function does return".  */
	for (;;)
		cpu_relax();	/* For when BUG is null */
}

3428 3429
static inline void sched_submit_work(struct task_struct *tsk)
{
3430
	if (!tsk->state || tsk_is_pi_blocked(tsk))
3431 3432 3433 3434 3435 3436 3437 3438 3439
		return;
	/*
	 * If we are going to sleep and we have plugged IO queued,
	 * make sure to submit it to avoid deadlocks.
	 */
	if (blk_needs_flush_plug(tsk))
		blk_schedule_flush_plug(tsk);
}

3440
asmlinkage __visible void __sched schedule(void)
3441
{
3442 3443 3444
	struct task_struct *tsk = current;

	sched_submit_work(tsk);
3445
	do {
3446
		preempt_disable();
3447
		__schedule(false);
3448
		sched_preempt_enable_no_resched();
3449
	} while (need_resched());
3450
}
L
Linus Torvalds 已提交
3451 3452
EXPORT_SYMBOL(schedule);

3453
#ifdef CONFIG_CONTEXT_TRACKING
3454
asmlinkage __visible void __sched schedule_user(void)
3455 3456 3457 3458 3459 3460
{
	/*
	 * If we come here after a random call to set_need_resched(),
	 * or we have been woken up remotely but the IPI has not yet arrived,
	 * we haven't yet exited the RCU idle mode. Do it here manually until
	 * we find a better solution.
3461 3462
	 *
	 * NB: There are buggy callers of this function.  Ideally we
3463
	 * should warn if prev_state != CONTEXT_USER, but that will trigger
3464
	 * too frequently to make sense yet.
3465
	 */
3466
	enum ctx_state prev_state = exception_enter();
3467
	schedule();
3468
	exception_exit(prev_state);
3469 3470 3471
}
#endif

3472 3473 3474 3475 3476 3477 3478
/**
 * schedule_preempt_disabled - called with preemption disabled
 *
 * Returns with preemption disabled. Note: preempt_count must be 1
 */
void __sched schedule_preempt_disabled(void)
{
3479
	sched_preempt_enable_no_resched();
3480 3481 3482 3483
	schedule();
	preempt_disable();
}

3484
static void __sched notrace preempt_schedule_common(void)
3485 3486
{
	do {
3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499
		/*
		 * Because the function tracer can trace preempt_count_sub()
		 * and it also uses preempt_enable/disable_notrace(), if
		 * NEED_RESCHED is set, the preempt_enable_notrace() called
		 * by the function tracer will call this function again and
		 * cause infinite recursion.
		 *
		 * Preemption must be disabled here before the function
		 * tracer can trace. Break up preempt_disable() into two
		 * calls. One to disable preemption without fear of being
		 * traced. The other to still record the preemption latency,
		 * which can also be traced by the function tracer.
		 */
3500
		preempt_disable_notrace();
3501
		preempt_latency_start(1);
3502
		__schedule(true);
3503
		preempt_latency_stop(1);
3504
		preempt_enable_no_resched_notrace();
3505 3506 3507 3508 3509 3510 3511 3512

		/*
		 * Check again in case we missed a preemption opportunity
		 * between schedule and now.
		 */
	} while (need_resched());
}

L
Linus Torvalds 已提交
3513 3514
#ifdef CONFIG_PREEMPT
/*
3515
 * this is the entry point to schedule() from in-kernel preemption
I
Ingo Molnar 已提交
3516
 * off of preempt_enable. Kernel preemptions off return from interrupt
L
Linus Torvalds 已提交
3517 3518
 * occur there and call schedule directly.
 */
3519
asmlinkage __visible void __sched notrace preempt_schedule(void)
L
Linus Torvalds 已提交
3520 3521 3522
{
	/*
	 * If there is a non-zero preempt_count or interrupts are disabled,
I
Ingo Molnar 已提交
3523
	 * we do not want to preempt the current task. Just return..
L
Linus Torvalds 已提交
3524
	 */
3525
	if (likely(!preemptible()))
L
Linus Torvalds 已提交
3526 3527
		return;

3528
	preempt_schedule_common();
L
Linus Torvalds 已提交
3529
}
3530
NOKPROBE_SYMBOL(preempt_schedule);
L
Linus Torvalds 已提交
3531
EXPORT_SYMBOL(preempt_schedule);
3532 3533

/**
3534
 * preempt_schedule_notrace - preempt_schedule called by tracing
3535 3536 3537 3538 3539 3540 3541 3542 3543 3544 3545 3546
 *
 * The tracing infrastructure uses preempt_enable_notrace to prevent
 * recursion and tracing preempt enabling caused by the tracing
 * infrastructure itself. But as tracing can happen in areas coming
 * from userspace or just about to enter userspace, a preempt enable
 * can occur before user_exit() is called. This will cause the scheduler
 * to be called when the system is still in usermode.
 *
 * To prevent this, the preempt_enable_notrace will use this function
 * instead of preempt_schedule() to exit user context if needed before
 * calling the scheduler.
 */
3547
asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
3548 3549 3550 3551 3552 3553 3554
{
	enum ctx_state prev_ctx;

	if (likely(!preemptible()))
		return;

	do {
3555 3556 3557 3558 3559 3560 3561 3562 3563 3564 3565 3566 3567
		/*
		 * Because the function tracer can trace preempt_count_sub()
		 * and it also uses preempt_enable/disable_notrace(), if
		 * NEED_RESCHED is set, the preempt_enable_notrace() called
		 * by the function tracer will call this function again and
		 * cause infinite recursion.
		 *
		 * Preemption must be disabled here before the function
		 * tracer can trace. Break up preempt_disable() into two
		 * calls. One to disable preemption without fear of being
		 * traced. The other to still record the preemption latency,
		 * which can also be traced by the function tracer.
		 */
3568
		preempt_disable_notrace();
3569
		preempt_latency_start(1);
3570 3571 3572 3573 3574 3575
		/*
		 * Needs preempt disabled in case user_exit() is traced
		 * and the tracer calls preempt_enable_notrace() causing
		 * an infinite recursion.
		 */
		prev_ctx = exception_enter();
3576
		__schedule(true);
3577 3578
		exception_exit(prev_ctx);

3579
		preempt_latency_stop(1);
3580
		preempt_enable_no_resched_notrace();
3581 3582
	} while (need_resched());
}
3583
EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
3584

3585
#endif /* CONFIG_PREEMPT */
L
Linus Torvalds 已提交
3586 3587

/*
3588
 * this is the entry point to schedule() from kernel preemption
L
Linus Torvalds 已提交
3589 3590 3591 3592
 * off of irq context.
 * Note, that this is called and return with irqs disabled. This will
 * protect us against recursive calling from irq.
 */
3593
asmlinkage __visible void __sched preempt_schedule_irq(void)
L
Linus Torvalds 已提交
3594
{
3595
	enum ctx_state prev_state;
3596

3597
	/* Catch callers which need to be fixed */
3598
	BUG_ON(preempt_count() || !irqs_disabled());
L
Linus Torvalds 已提交
3599

3600 3601
	prev_state = exception_enter();

3602
	do {
3603
		preempt_disable();
3604
		local_irq_enable();
3605
		__schedule(true);
3606
		local_irq_disable();
3607
		sched_preempt_enable_no_resched();
3608
	} while (need_resched());
3609 3610

	exception_exit(prev_state);
L
Linus Torvalds 已提交
3611 3612
}

P
Peter Zijlstra 已提交
3613
int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
I
Ingo Molnar 已提交
3614
			  void *key)
L
Linus Torvalds 已提交
3615
{
P
Peter Zijlstra 已提交
3616
	return try_to_wake_up(curr->private, mode, wake_flags);
L
Linus Torvalds 已提交
3617 3618 3619
}
EXPORT_SYMBOL(default_wake_function);

3620 3621 3622 3623 3624 3625 3626 3627 3628 3629
#ifdef CONFIG_RT_MUTEXES

/*
 * rt_mutex_setprio - set the current priority of a task
 * @p: task
 * @prio: prio value (kernel-internal form)
 *
 * This function changes the 'effective' priority of a task. It does
 * not touch ->normal_prio like __setscheduler().
 *
3630 3631
 * Used by the rt_mutex code to implement priority inheritance
 * logic. Call site only calls if the priority of the task changed.
3632
 */
3633
void rt_mutex_setprio(struct task_struct *p, int prio)
3634
{
3635
	int oldprio, queued, running, queue_flag = DEQUEUE_SAVE | DEQUEUE_MOVE;
3636
	const struct sched_class *prev_class;
3637 3638
	struct rq_flags rf;
	struct rq *rq;
3639

3640
	BUG_ON(prio > MAX_PRIO);
3641

3642
	rq = __task_rq_lock(p, &rf);
3643

3644 3645 3646 3647 3648 3649 3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660 3661
	/*
	 * Idle task boosting is a nono in general. There is one
	 * exception, when PREEMPT_RT and NOHZ is active:
	 *
	 * The idle task calls get_next_timer_interrupt() and holds
	 * the timer wheel base->lock on the CPU and another CPU wants
	 * to access the timer (probably to cancel it). We can safely
	 * ignore the boosting request, as the idle CPU runs this code
	 * with interrupts disabled and will complete the lock
	 * protected section without being interrupted. So there is no
	 * real need to boost.
	 */
	if (unlikely(p == rq->idle)) {
		WARN_ON(p != rq->curr);
		WARN_ON(p->pi_blocked_on);
		goto out_unlock;
	}

3662
	trace_sched_pi_setprio(p, prio);
3663
	oldprio = p->prio;
3664 3665 3666 3667

	if (oldprio == prio)
		queue_flag &= ~DEQUEUE_MOVE;

3668
	prev_class = p->sched_class;
3669
	queued = task_on_rq_queued(p);
3670
	running = task_current(rq, p);
3671
	if (queued)
3672
		dequeue_task(rq, p, queue_flag);
3673
	if (running)
3674
		put_prev_task(rq, p);
I
Ingo Molnar 已提交
3675

3676 3677 3678 3679 3680 3681 3682 3683 3684 3685
	/*
	 * Boosting condition are:
	 * 1. -rt task is running and holds mutex A
	 *      --> -dl task blocks on mutex A
	 *
	 * 2. -dl task is running and holds mutex A
	 *      --> -dl task blocks on mutex A and could preempt the
	 *          running task
	 */
	if (dl_prio(prio)) {
3686 3687 3688
		struct task_struct *pi_task = rt_mutex_get_top_task(p);
		if (!dl_prio(p->normal_prio) ||
		    (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3689
			p->dl.dl_boosted = 1;
3690
			queue_flag |= ENQUEUE_REPLENISH;
3691 3692
		} else
			p->dl.dl_boosted = 0;
3693
		p->sched_class = &dl_sched_class;
3694 3695 3696 3697
	} else if (rt_prio(prio)) {
		if (dl_prio(oldprio))
			p->dl.dl_boosted = 0;
		if (oldprio < prio)
3698
			queue_flag |= ENQUEUE_HEAD;
I
Ingo Molnar 已提交
3699
		p->sched_class = &rt_sched_class;
3700 3701 3702
	} else {
		if (dl_prio(oldprio))
			p->dl.dl_boosted = 0;
3703 3704
		if (rt_prio(oldprio))
			p->rt.timeout = 0;
I
Ingo Molnar 已提交
3705
		p->sched_class = &fair_sched_class;
3706
	}
I
Ingo Molnar 已提交
3707

3708 3709
	p->prio = prio;

3710 3711
	if (running)
		p->sched_class->set_curr_task(rq);
3712
	if (queued)
3713
		enqueue_task(rq, p, queue_flag);
3714

P
Peter Zijlstra 已提交
3715
	check_class_changed(rq, p, prev_class, oldprio);
3716
out_unlock:
3717
	preempt_disable(); /* avoid rq from going away on us */
3718
	__task_rq_unlock(rq, &rf);
3719 3720 3721

	balance_callback(rq);
	preempt_enable();
3722 3723
}
#endif
3724

3725
void set_user_nice(struct task_struct *p, long nice)
L
Linus Torvalds 已提交
3726
{
3727
	int old_prio, delta, queued;
3728
	struct rq_flags rf;
3729
	struct rq *rq;
L
Linus Torvalds 已提交
3730

3731
	if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
L
Linus Torvalds 已提交
3732 3733 3734 3735 3736
		return;
	/*
	 * We have to be careful, if called from sys_setpriority(),
	 * the task might be in the middle of scheduling on another CPU.
	 */
3737
	rq = task_rq_lock(p, &rf);
L
Linus Torvalds 已提交
3738 3739 3740 3741
	/*
	 * The RT priorities are set via sched_setscheduler(), but we still
	 * allow the 'normal' nice value to be set - but as expected
	 * it wont have any effect on scheduling until the task is
3742
	 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
L
Linus Torvalds 已提交
3743
	 */
3744
	if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
L
Linus Torvalds 已提交
3745 3746 3747
		p->static_prio = NICE_TO_PRIO(nice);
		goto out_unlock;
	}
3748 3749
	queued = task_on_rq_queued(p);
	if (queued)
3750
		dequeue_task(rq, p, DEQUEUE_SAVE);
L
Linus Torvalds 已提交
3751 3752

	p->static_prio = NICE_TO_PRIO(nice);
3753
	set_load_weight(p);
3754 3755 3756
	old_prio = p->prio;
	p->prio = effective_prio(p);
	delta = p->prio - old_prio;
L
Linus Torvalds 已提交
3757

3758
	if (queued) {
3759
		enqueue_task(rq, p, ENQUEUE_RESTORE);
L
Linus Torvalds 已提交
3760
		/*
3761 3762
		 * If the task increased its priority or is running and
		 * lowered its priority, then reschedule its CPU:
L
Linus Torvalds 已提交
3763
		 */
3764
		if (delta < 0 || (delta > 0 && task_running(rq, p)))
3765
			resched_curr(rq);
L
Linus Torvalds 已提交
3766 3767
	}
out_unlock:
3768
	task_rq_unlock(rq, p, &rf);
L
Linus Torvalds 已提交
3769 3770 3771
}
EXPORT_SYMBOL(set_user_nice);

M
Matt Mackall 已提交
3772 3773 3774 3775 3776
/*
 * can_nice - check if a task can reduce its nice value
 * @p: task
 * @nice: nice value
 */
3777
int can_nice(const struct task_struct *p, const int nice)
M
Matt Mackall 已提交
3778
{
3779
	/* convert nice value [19,-20] to rlimit style value [1,40] */
3780
	int nice_rlim = nice_to_rlimit(nice);
3781

3782
	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
M
Matt Mackall 已提交
3783 3784 3785
		capable(CAP_SYS_NICE));
}

L
Linus Torvalds 已提交
3786 3787 3788 3789 3790 3791 3792 3793 3794
#ifdef __ARCH_WANT_SYS_NICE

/*
 * sys_nice - change the priority of the current process.
 * @increment: priority increment
 *
 * sys_setpriority is a more generic, but much slower function that
 * does similar things.
 */
3795
SYSCALL_DEFINE1(nice, int, increment)
L
Linus Torvalds 已提交
3796
{
3797
	long nice, retval;
L
Linus Torvalds 已提交
3798 3799 3800 3801 3802 3803

	/*
	 * Setpriority might change our priority at the same moment.
	 * We don't have to worry. Conceptually one call occurs first
	 * and we have a single winner.
	 */
3804
	increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3805
	nice = task_nice(current) + increment;
L
Linus Torvalds 已提交
3806

3807
	nice = clamp_val(nice, MIN_NICE, MAX_NICE);
M
Matt Mackall 已提交
3808 3809 3810
	if (increment < 0 && !can_nice(current, nice))
		return -EPERM;

L
Linus Torvalds 已提交
3811 3812 3813 3814 3815 3816 3817 3818 3819 3820 3821 3822 3823 3824
	retval = security_task_setnice(current, nice);
	if (retval)
		return retval;

	set_user_nice(current, nice);
	return 0;
}

#endif

/**
 * task_prio - return the priority value of a given task.
 * @p: the task in question.
 *
3825
 * Return: The priority value as seen by users in /proc.
L
Linus Torvalds 已提交
3826 3827 3828
 * RT tasks are offset by -200. Normal tasks are centered
 * around 0, value goes from -16 to +15.
 */
3829
int task_prio(const struct task_struct *p)
L
Linus Torvalds 已提交
3830 3831 3832 3833 3834 3835 3836
{
	return p->prio - MAX_RT_PRIO;
}

/**
 * idle_cpu - is a given cpu idle currently?
 * @cpu: the processor in question.
3837 3838
 *
 * Return: 1 if the CPU is currently idle. 0 otherwise.
L
Linus Torvalds 已提交
3839 3840 3841
 */
int idle_cpu(int cpu)
{
T
Thomas Gleixner 已提交
3842 3843 3844 3845 3846 3847 3848 3849 3850 3851 3852 3853 3854 3855
	struct rq *rq = cpu_rq(cpu);

	if (rq->curr != rq->idle)
		return 0;

	if (rq->nr_running)
		return 0;

#ifdef CONFIG_SMP
	if (!llist_empty(&rq->wake_list))
		return 0;
#endif

	return 1;
L
Linus Torvalds 已提交
3856 3857 3858 3859 3860
}

/**
 * idle_task - return the idle task for a given cpu.
 * @cpu: the processor in question.
3861 3862
 *
 * Return: The idle task for the cpu @cpu.
L
Linus Torvalds 已提交
3863
 */
3864
struct task_struct *idle_task(int cpu)
L
Linus Torvalds 已提交
3865 3866 3867 3868 3869 3870 3871
{
	return cpu_rq(cpu)->idle;
}

/**
 * find_process_by_pid - find a process with a matching PID value.
 * @pid: the pid in question.
3872 3873
 *
 * The task of @pid, if found. %NULL otherwise.
L
Linus Torvalds 已提交
3874
 */
A
Alexey Dobriyan 已提交
3875
static struct task_struct *find_process_by_pid(pid_t pid)
L
Linus Torvalds 已提交
3876
{
3877
	return pid ? find_task_by_vpid(pid) : current;
L
Linus Torvalds 已提交
3878 3879
}

3880 3881 3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892 3893 3894
/*
 * This function initializes the sched_dl_entity of a newly becoming
 * SCHED_DEADLINE task.
 *
 * Only the static values are considered here, the actual runtime and the
 * absolute deadline will be properly calculated when the task is enqueued
 * for the first time with its new policy.
 */
static void
__setparam_dl(struct task_struct *p, const struct sched_attr *attr)
{
	struct sched_dl_entity *dl_se = &p->dl;

	dl_se->dl_runtime = attr->sched_runtime;
	dl_se->dl_deadline = attr->sched_deadline;
3895
	dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3896
	dl_se->flags = attr->sched_flags;
3897
	dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3898 3899 3900 3901 3902 3903 3904 3905 3906 3907 3908 3909 3910 3911 3912 3913 3914 3915 3916 3917

	/*
	 * Changing the parameters of a task is 'tricky' and we're not doing
	 * the correct thing -- also see task_dead_dl() and switched_from_dl().
	 *
	 * What we SHOULD do is delay the bandwidth release until the 0-lag
	 * point. This would include retaining the task_struct until that time
	 * and change dl_overflow() to not immediately decrement the current
	 * amount.
	 *
	 * Instead we retain the current runtime/deadline and let the new
	 * parameters take effect after the current reservation period lapses.
	 * This is safe (albeit pessimistic) because the 0-lag point is always
	 * before the current scheduling deadline.
	 *
	 * We can still have temporary overloads because we do not delay the
	 * change in bandwidth until that time; so admission control is
	 * not on the safe side. It does however guarantee tasks will never
	 * consume more than promised.
	 */
3918 3919
}

3920 3921 3922 3923 3924 3925
/*
 * sched_setparam() passes in -1 for its policy, to let the functions
 * it calls know not to change it.
 */
#define SETPARAM_POLICY	-1

3926 3927
static void __setscheduler_params(struct task_struct *p,
		const struct sched_attr *attr)
L
Linus Torvalds 已提交
3928
{
3929 3930
	int policy = attr->sched_policy;

3931
	if (policy == SETPARAM_POLICY)
3932 3933
		policy = p->policy;

L
Linus Torvalds 已提交
3934
	p->policy = policy;
3935

3936 3937
	if (dl_policy(policy))
		__setparam_dl(p, attr);
3938
	else if (fair_policy(policy))
3939 3940
		p->static_prio = NICE_TO_PRIO(attr->sched_nice);

3941 3942 3943 3944 3945 3946
	/*
	 * __sched_setscheduler() ensures attr->sched_priority == 0 when
	 * !rt_policy. Always setting this ensures that things like
	 * getparam()/getattr() don't report silly values for !rt tasks.
	 */
	p->rt_priority = attr->sched_priority;
3947
	p->normal_prio = normal_prio(p);
3948 3949
	set_load_weight(p);
}
3950

3951 3952
/* Actually do priority change: must hold pi & rq lock. */
static void __setscheduler(struct rq *rq, struct task_struct *p,
3953
			   const struct sched_attr *attr, bool keep_boost)
3954 3955
{
	__setscheduler_params(p, attr);
3956

3957
	/*
3958 3959
	 * Keep a potential priority boosting if called from
	 * sched_setscheduler().
3960
	 */
3961 3962 3963 3964
	if (keep_boost)
		p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
	else
		p->prio = normal_prio(p);
3965

3966 3967 3968
	if (dl_prio(p->prio))
		p->sched_class = &dl_sched_class;
	else if (rt_prio(p->prio))
3969 3970 3971
		p->sched_class = &rt_sched_class;
	else
		p->sched_class = &fair_sched_class;
L
Linus Torvalds 已提交
3972
}
3973 3974 3975 3976 3977 3978 3979 3980 3981

static void
__getparam_dl(struct task_struct *p, struct sched_attr *attr)
{
	struct sched_dl_entity *dl_se = &p->dl;

	attr->sched_priority = p->rt_priority;
	attr->sched_runtime = dl_se->dl_runtime;
	attr->sched_deadline = dl_se->dl_deadline;
3982
	attr->sched_period = dl_se->dl_period;
3983 3984 3985 3986 3987 3988
	attr->sched_flags = dl_se->flags;
}

/*
 * This function validates the new parameters of a -deadline task.
 * We ask for the deadline not being zero, and greater or equal
3989
 * than the runtime, as well as the period of being zero or
3990
 * greater than deadline. Furthermore, we have to be sure that
3991 3992 3993 3994
 * user parameters are above the internal resolution of 1us (we
 * check sched_runtime only since it is always the smaller one) and
 * below 2^63 ns (we have to check both sched_deadline and
 * sched_period, as the latter can be zero).
3995 3996 3997 3998
 */
static bool
__checkparam_dl(const struct sched_attr *attr)
{
3999 4000 4001 4002 4003 4004 4005 4006 4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017 4018 4019 4020 4021 4022 4023 4024
	/* deadline != 0 */
	if (attr->sched_deadline == 0)
		return false;

	/*
	 * Since we truncate DL_SCALE bits, make sure we're at least
	 * that big.
	 */
	if (attr->sched_runtime < (1ULL << DL_SCALE))
		return false;

	/*
	 * Since we use the MSB for wrap-around and sign issues, make
	 * sure it's not set (mind that period can be equal to zero).
	 */
	if (attr->sched_deadline & (1ULL << 63) ||
	    attr->sched_period & (1ULL << 63))
		return false;

	/* runtime <= deadline <= period (if period != 0) */
	if ((attr->sched_period != 0 &&
	     attr->sched_period < attr->sched_deadline) ||
	    attr->sched_deadline < attr->sched_runtime)
		return false;

	return true;
4025 4026
}

4027 4028 4029 4030 4031 4032 4033 4034 4035 4036
/*
 * check the target process has a UID that matches the current process's
 */
static bool check_same_owner(struct task_struct *p)
{
	const struct cred *cred = current_cred(), *pcred;
	bool match;

	rcu_read_lock();
	pcred = __task_cred(p);
4037 4038
	match = (uid_eq(cred->euid, pcred->euid) ||
		 uid_eq(cred->euid, pcred->uid));
4039 4040 4041 4042
	rcu_read_unlock();
	return match;
}

4043 4044 4045 4046 4047 4048 4049 4050 4051 4052 4053 4054 4055 4056
static bool dl_param_changed(struct task_struct *p,
		const struct sched_attr *attr)
{
	struct sched_dl_entity *dl_se = &p->dl;

	if (dl_se->dl_runtime != attr->sched_runtime ||
		dl_se->dl_deadline != attr->sched_deadline ||
		dl_se->dl_period != attr->sched_period ||
		dl_se->flags != attr->sched_flags)
		return true;

	return false;
}

4057 4058
static int __sched_setscheduler(struct task_struct *p,
				const struct sched_attr *attr,
4059
				bool user, bool pi)
L
Linus Torvalds 已提交
4060
{
4061 4062
	int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
		      MAX_RT_PRIO - 1 - attr->sched_priority;
4063
	int retval, oldprio, oldpolicy = -1, queued, running;
4064
	int new_effective_prio, policy = attr->sched_policy;
4065
	const struct sched_class *prev_class;
4066
	struct rq_flags rf;
4067
	int reset_on_fork;
4068
	int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
4069
	struct rq *rq;
L
Linus Torvalds 已提交
4070

4071 4072
	/* may grab non-irq protected spin_locks */
	BUG_ON(in_interrupt());
L
Linus Torvalds 已提交
4073 4074
recheck:
	/* double check policy once rq lock held */
4075 4076
	if (policy < 0) {
		reset_on_fork = p->sched_reset_on_fork;
L
Linus Torvalds 已提交
4077
		policy = oldpolicy = p->policy;
4078
	} else {
4079
		reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
4080

4081
		if (!valid_policy(policy))
4082 4083 4084
			return -EINVAL;
	}

4085 4086 4087
	if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
		return -EINVAL;

L
Linus Torvalds 已提交
4088 4089
	/*
	 * Valid priorities for SCHED_FIFO and SCHED_RR are
I
Ingo Molnar 已提交
4090 4091
	 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
	 * SCHED_BATCH and SCHED_IDLE is 0.
L
Linus Torvalds 已提交
4092
	 */
4093
	if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
4094
	    (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
L
Linus Torvalds 已提交
4095
		return -EINVAL;
4096 4097
	if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
	    (rt_policy(policy) != (attr->sched_priority != 0)))
L
Linus Torvalds 已提交
4098 4099
		return -EINVAL;

4100 4101 4102
	/*
	 * Allow unprivileged RT tasks to decrease priority:
	 */
4103
	if (user && !capable(CAP_SYS_NICE)) {
4104
		if (fair_policy(policy)) {
4105
			if (attr->sched_nice < task_nice(p) &&
4106
			    !can_nice(p, attr->sched_nice))
4107 4108 4109
				return -EPERM;
		}

4110
		if (rt_policy(policy)) {
4111 4112
			unsigned long rlim_rtprio =
					task_rlimit(p, RLIMIT_RTPRIO);
4113 4114 4115 4116 4117 4118

			/* can't set/change the rt policy */
			if (policy != p->policy && !rlim_rtprio)
				return -EPERM;

			/* can't increase priority */
4119 4120
			if (attr->sched_priority > p->rt_priority &&
			    attr->sched_priority > rlim_rtprio)
4121 4122
				return -EPERM;
		}
4123

4124 4125 4126 4127 4128 4129 4130 4131 4132
		 /*
		  * Can't set/change SCHED_DEADLINE policy at all for now
		  * (safest behavior); in the future we would like to allow
		  * unprivileged DL tasks to increase their relative deadline
		  * or reduce their runtime (both ways reducing utilization)
		  */
		if (dl_policy(policy))
			return -EPERM;

I
Ingo Molnar 已提交
4133
		/*
4134 4135
		 * Treat SCHED_IDLE as nice 20. Only allow a switch to
		 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
I
Ingo Molnar 已提交
4136
		 */
4137
		if (idle_policy(p->policy) && !idle_policy(policy)) {
4138
			if (!can_nice(p, task_nice(p)))
4139 4140
				return -EPERM;
		}
4141

4142
		/* can't change other user's priorities */
4143
		if (!check_same_owner(p))
4144
			return -EPERM;
4145 4146 4147 4148

		/* Normal users shall not reset the sched_reset_on_fork flag */
		if (p->sched_reset_on_fork && !reset_on_fork)
			return -EPERM;
4149
	}
L
Linus Torvalds 已提交
4150

4151
	if (user) {
4152
		retval = security_task_setscheduler(p);
4153 4154 4155 4156
		if (retval)
			return retval;
	}

4157 4158 4159
	/*
	 * make sure no PI-waiters arrive (or leave) while we are
	 * changing the priority of the task:
4160
	 *
L
Lucas De Marchi 已提交
4161
	 * To be able to change p->policy safely, the appropriate
L
Linus Torvalds 已提交
4162 4163
	 * runqueue lock must be held.
	 */
4164
	rq = task_rq_lock(p, &rf);
4165

4166 4167 4168 4169
	/*
	 * Changing the policy of the stop threads its a very bad idea
	 */
	if (p == rq->stop) {
4170
		task_rq_unlock(rq, p, &rf);
4171 4172 4173
		return -EINVAL;
	}

4174
	/*
4175 4176
	 * If not changing anything there's no need to proceed further,
	 * but store a possible modification of reset_on_fork.
4177
	 */
4178
	if (unlikely(policy == p->policy)) {
4179
		if (fair_policy(policy) && attr->sched_nice != task_nice(p))
4180 4181 4182
			goto change;
		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
			goto change;
4183
		if (dl_policy(policy) && dl_param_changed(p, attr))
4184
			goto change;
4185

4186
		p->sched_reset_on_fork = reset_on_fork;
4187
		task_rq_unlock(rq, p, &rf);
4188 4189
		return 0;
	}
4190
change:
4191

4192
	if (user) {
4193
#ifdef CONFIG_RT_GROUP_SCHED
4194 4195 4196 4197 4198
		/*
		 * Do not allow realtime tasks into groups that have no runtime
		 * assigned.
		 */
		if (rt_bandwidth_enabled() && rt_policy(policy) &&
4199 4200
				task_group(p)->rt_bandwidth.rt_runtime == 0 &&
				!task_group_is_autogroup(task_group(p))) {
4201
			task_rq_unlock(rq, p, &rf);
4202 4203 4204
			return -EPERM;
		}
#endif
4205 4206 4207 4208 4209 4210 4211 4212 4213
#ifdef CONFIG_SMP
		if (dl_bandwidth_enabled() && dl_policy(policy)) {
			cpumask_t *span = rq->rd->span;

			/*
			 * Don't allow tasks with an affinity mask smaller than
			 * the entire root_domain to become SCHED_DEADLINE. We
			 * will also fail if there's no bandwidth available.
			 */
4214 4215
			if (!cpumask_subset(span, &p->cpus_allowed) ||
			    rq->rd->dl_bw.bw == 0) {
4216
				task_rq_unlock(rq, p, &rf);
4217 4218 4219 4220 4221
				return -EPERM;
			}
		}
#endif
	}
4222

L
Linus Torvalds 已提交
4223 4224 4225
	/* recheck policy now with rq lock held */
	if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
		policy = oldpolicy = -1;
4226
		task_rq_unlock(rq, p, &rf);
L
Linus Torvalds 已提交
4227 4228
		goto recheck;
	}
4229 4230 4231 4232 4233 4234

	/*
	 * If setscheduling to SCHED_DEADLINE (or changing the parameters
	 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
	 * is available.
	 */
4235
	if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
4236
		task_rq_unlock(rq, p, &rf);
4237 4238 4239
		return -EBUSY;
	}

4240 4241 4242
	p->sched_reset_on_fork = reset_on_fork;
	oldprio = p->prio;

4243 4244 4245 4246 4247 4248 4249 4250 4251
	if (pi) {
		/*
		 * Take priority boosted tasks into account. If the new
		 * effective priority is unchanged, we just store the new
		 * normal parameters and do not touch the scheduler class and
		 * the runqueue. This will be done when the task deboost
		 * itself.
		 */
		new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
4252 4253
		if (new_effective_prio == oldprio)
			queue_flags &= ~DEQUEUE_MOVE;
4254 4255
	}

4256
	queued = task_on_rq_queued(p);
4257
	running = task_current(rq, p);
4258
	if (queued)
4259
		dequeue_task(rq, p, queue_flags);
4260
	if (running)
4261
		put_prev_task(rq, p);
4262

4263
	prev_class = p->sched_class;
4264
	__setscheduler(rq, p, attr, pi);
4265

4266 4267
	if (running)
		p->sched_class->set_curr_task(rq);
4268
	if (queued) {
4269 4270 4271 4272
		/*
		 * We enqueue to tail when the priority of a task is
		 * increased (user space view).
		 */
4273 4274
		if (oldprio < p->prio)
			queue_flags |= ENQUEUE_HEAD;
4275

4276
		enqueue_task(rq, p, queue_flags);
4277
	}
4278

P
Peter Zijlstra 已提交
4279
	check_class_changed(rq, p, prev_class, oldprio);
4280
	preempt_disable(); /* avoid rq from going away on us */
4281
	task_rq_unlock(rq, p, &rf);
4282

4283 4284
	if (pi)
		rt_mutex_adjust_pi(p);
4285

4286 4287 4288 4289 4290
	/*
	 * Run balance callbacks after we've adjusted the PI chain.
	 */
	balance_callback(rq);
	preempt_enable();
4291

L
Linus Torvalds 已提交
4292 4293
	return 0;
}
4294

4295 4296 4297 4298 4299 4300 4301 4302 4303
static int _sched_setscheduler(struct task_struct *p, int policy,
			       const struct sched_param *param, bool check)
{
	struct sched_attr attr = {
		.sched_policy   = policy,
		.sched_priority = param->sched_priority,
		.sched_nice	= PRIO_TO_NICE(p->static_prio),
	};

4304 4305
	/* Fixup the legacy SCHED_RESET_ON_FORK hack. */
	if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
4306 4307 4308 4309 4310
		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
		policy &= ~SCHED_RESET_ON_FORK;
		attr.sched_policy = policy;
	}

4311
	return __sched_setscheduler(p, &attr, check, true);
4312
}
4313 4314 4315 4316 4317 4318
/**
 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
 * @p: the task in question.
 * @policy: new policy.
 * @param: structure containing the new RT priority.
 *
4319 4320
 * Return: 0 on success. An error code otherwise.
 *
4321 4322 4323
 * NOTE that the task may be already dead.
 */
int sched_setscheduler(struct task_struct *p, int policy,
4324
		       const struct sched_param *param)
4325
{
4326
	return _sched_setscheduler(p, policy, param, true);
4327
}
L
Linus Torvalds 已提交
4328 4329
EXPORT_SYMBOL_GPL(sched_setscheduler);

4330 4331
int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
{
4332
	return __sched_setscheduler(p, attr, true, true);
4333 4334 4335
}
EXPORT_SYMBOL_GPL(sched_setattr);

4336 4337 4338 4339 4340 4341 4342 4343 4344 4345
/**
 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
 * @p: the task in question.
 * @policy: new policy.
 * @param: structure containing the new RT priority.
 *
 * Just like sched_setscheduler, only don't bother checking if the
 * current context has permission.  For example, this is needed in
 * stop_machine(): we create temporary high priority worker threads,
 * but our caller might not have that capability.
4346 4347
 *
 * Return: 0 on success. An error code otherwise.
4348 4349
 */
int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4350
			       const struct sched_param *param)
4351
{
4352
	return _sched_setscheduler(p, policy, param, false);
4353
}
4354
EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
4355

I
Ingo Molnar 已提交
4356 4357
static int
do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
L
Linus Torvalds 已提交
4358 4359 4360
{
	struct sched_param lparam;
	struct task_struct *p;
4361
	int retval;
L
Linus Torvalds 已提交
4362 4363 4364 4365 4366

	if (!param || pid < 0)
		return -EINVAL;
	if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
		return -EFAULT;
4367 4368 4369

	rcu_read_lock();
	retval = -ESRCH;
L
Linus Torvalds 已提交
4370
	p = find_process_by_pid(pid);
4371 4372 4373
	if (p != NULL)
		retval = sched_setscheduler(p, policy, &lparam);
	rcu_read_unlock();
4374

L
Linus Torvalds 已提交
4375 4376 4377
	return retval;
}

4378 4379 4380 4381 4382 4383 4384 4385 4386 4387 4388 4389 4390 4391 4392 4393 4394 4395 4396 4397 4398 4399 4400 4401 4402 4403 4404 4405 4406 4407 4408 4409 4410 4411 4412 4413 4414 4415 4416 4417 4418 4419 4420 4421 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 4433 4434 4435 4436 4437 4438 4439
/*
 * Mimics kernel/events/core.c perf_copy_attr().
 */
static int sched_copy_attr(struct sched_attr __user *uattr,
			   struct sched_attr *attr)
{
	u32 size;
	int ret;

	if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
		return -EFAULT;

	/*
	 * zero the full structure, so that a short copy will be nice.
	 */
	memset(attr, 0, sizeof(*attr));

	ret = get_user(size, &uattr->size);
	if (ret)
		return ret;

	if (size > PAGE_SIZE)	/* silly large */
		goto err_size;

	if (!size)		/* abi compat */
		size = SCHED_ATTR_SIZE_VER0;

	if (size < SCHED_ATTR_SIZE_VER0)
		goto err_size;

	/*
	 * If we're handed a bigger struct than we know of,
	 * ensure all the unknown bits are 0 - i.e. new
	 * user-space does not rely on any kernel feature
	 * extensions we dont know about yet.
	 */
	if (size > sizeof(*attr)) {
		unsigned char __user *addr;
		unsigned char __user *end;
		unsigned char val;

		addr = (void __user *)uattr + sizeof(*attr);
		end  = (void __user *)uattr + size;

		for (; addr < end; addr++) {
			ret = get_user(val, addr);
			if (ret)
				return ret;
			if (val)
				goto err_size;
		}
		size = sizeof(*attr);
	}

	ret = copy_from_user(attr, uattr, size);
	if (ret)
		return -EFAULT;

	/*
	 * XXX: do we want to be lenient like existing syscalls; or do we want
	 * to be strict and return an error on out-of-bounds values?
	 */
4440
	attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
4441

4442
	return 0;
4443 4444 4445

err_size:
	put_user(sizeof(*attr), &uattr->size);
4446
	return -E2BIG;
4447 4448
}

L
Linus Torvalds 已提交
4449 4450 4451 4452 4453
/**
 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
 * @pid: the pid in question.
 * @policy: new policy.
 * @param: structure containing the new RT priority.
4454 4455
 *
 * Return: 0 on success. An error code otherwise.
L
Linus Torvalds 已提交
4456
 */
4457 4458
SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
		struct sched_param __user *, param)
L
Linus Torvalds 已提交
4459
{
4460 4461 4462 4463
	/* negative values for policy are not valid */
	if (policy < 0)
		return -EINVAL;

L
Linus Torvalds 已提交
4464 4465 4466 4467 4468 4469 4470
	return do_sched_setscheduler(pid, policy, param);
}

/**
 * sys_sched_setparam - set/change the RT priority of a thread
 * @pid: the pid in question.
 * @param: structure containing the new RT priority.
4471 4472
 *
 * Return: 0 on success. An error code otherwise.
L
Linus Torvalds 已提交
4473
 */
4474
SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
L
Linus Torvalds 已提交
4475
{
4476
	return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
L
Linus Torvalds 已提交
4477 4478
}

4479 4480 4481
/**
 * sys_sched_setattr - same as above, but with extended sched_attr
 * @pid: the pid in question.
J
Juri Lelli 已提交
4482
 * @uattr: structure containing the extended parameters.
4483
 * @flags: for future extension.
4484
 */
4485 4486
SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
			       unsigned int, flags)
4487 4488 4489 4490 4491
{
	struct sched_attr attr;
	struct task_struct *p;
	int retval;

4492
	if (!uattr || pid < 0 || flags)
4493 4494
		return -EINVAL;

4495 4496 4497
	retval = sched_copy_attr(uattr, &attr);
	if (retval)
		return retval;
4498

4499
	if ((int)attr.sched_policy < 0)
4500
		return -EINVAL;
4501 4502 4503 4504 4505 4506 4507 4508 4509 4510 4511

	rcu_read_lock();
	retval = -ESRCH;
	p = find_process_by_pid(pid);
	if (p != NULL)
		retval = sched_setattr(p, &attr);
	rcu_read_unlock();

	return retval;
}

L
Linus Torvalds 已提交
4512 4513 4514
/**
 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
 * @pid: the pid in question.
4515 4516 4517
 *
 * Return: On success, the policy of the thread. Otherwise, a negative error
 * code.
L
Linus Torvalds 已提交
4518
 */
4519
SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
L
Linus Torvalds 已提交
4520
{
4521
	struct task_struct *p;
4522
	int retval;
L
Linus Torvalds 已提交
4523 4524

	if (pid < 0)
4525
		return -EINVAL;
L
Linus Torvalds 已提交
4526 4527

	retval = -ESRCH;
4528
	rcu_read_lock();
L
Linus Torvalds 已提交
4529 4530 4531 4532
	p = find_process_by_pid(pid);
	if (p) {
		retval = security_task_getscheduler(p);
		if (!retval)
4533 4534
			retval = p->policy
				| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
L
Linus Torvalds 已提交
4535
	}
4536
	rcu_read_unlock();
L
Linus Torvalds 已提交
4537 4538 4539 4540
	return retval;
}

/**
4541
 * sys_sched_getparam - get the RT priority of a thread
L
Linus Torvalds 已提交
4542 4543
 * @pid: the pid in question.
 * @param: structure containing the RT priority.
4544 4545 4546
 *
 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
 * code.
L
Linus Torvalds 已提交
4547
 */
4548
SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
L
Linus Torvalds 已提交
4549
{
4550
	struct sched_param lp = { .sched_priority = 0 };
4551
	struct task_struct *p;
4552
	int retval;
L
Linus Torvalds 已提交
4553 4554

	if (!param || pid < 0)
4555
		return -EINVAL;
L
Linus Torvalds 已提交
4556

4557
	rcu_read_lock();
L
Linus Torvalds 已提交
4558 4559 4560 4561 4562 4563 4564 4565 4566
	p = find_process_by_pid(pid);
	retval = -ESRCH;
	if (!p)
		goto out_unlock;

	retval = security_task_getscheduler(p);
	if (retval)
		goto out_unlock;

4567 4568
	if (task_has_rt_policy(p))
		lp.sched_priority = p->rt_priority;
4569
	rcu_read_unlock();
L
Linus Torvalds 已提交
4570 4571 4572 4573 4574 4575 4576 4577 4578

	/*
	 * This one might sleep, we cannot do it with a spinlock held ...
	 */
	retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;

	return retval;

out_unlock:
4579
	rcu_read_unlock();
L
Linus Torvalds 已提交
4580 4581 4582
	return retval;
}

4583 4584 4585 4586 4587 4588 4589 4590 4591 4592 4593 4594 4595 4596 4597 4598 4599 4600 4601 4602 4603 4604 4605
static int sched_read_attr(struct sched_attr __user *uattr,
			   struct sched_attr *attr,
			   unsigned int usize)
{
	int ret;

	if (!access_ok(VERIFY_WRITE, uattr, usize))
		return -EFAULT;

	/*
	 * If we're handed a smaller struct than we know of,
	 * ensure all the unknown bits are 0 - i.e. old
	 * user-space does not get uncomplete information.
	 */
	if (usize < sizeof(*attr)) {
		unsigned char *addr;
		unsigned char *end;

		addr = (void *)attr + usize;
		end  = (void *)attr + sizeof(*attr);

		for (; addr < end; addr++) {
			if (*addr)
4606
				return -EFBIG;
4607 4608 4609 4610 4611
		}

		attr->size = usize;
	}

4612
	ret = copy_to_user(uattr, attr, attr->size);
4613 4614 4615
	if (ret)
		return -EFAULT;

4616
	return 0;
4617 4618 4619
}

/**
4620
 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4621
 * @pid: the pid in question.
J
Juri Lelli 已提交
4622
 * @uattr: structure containing the extended parameters.
4623
 * @size: sizeof(attr) for fwd/bwd comp.
4624
 * @flags: for future extension.
4625
 */
4626 4627
SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
		unsigned int, size, unsigned int, flags)
4628 4629 4630 4631 4632 4633 4634 4635
{
	struct sched_attr attr = {
		.size = sizeof(struct sched_attr),
	};
	struct task_struct *p;
	int retval;

	if (!uattr || pid < 0 || size > PAGE_SIZE ||
4636
	    size < SCHED_ATTR_SIZE_VER0 || flags)
4637 4638 4639 4640 4641 4642 4643 4644 4645 4646 4647 4648 4649
		return -EINVAL;

	rcu_read_lock();
	p = find_process_by_pid(pid);
	retval = -ESRCH;
	if (!p)
		goto out_unlock;

	retval = security_task_getscheduler(p);
	if (retval)
		goto out_unlock;

	attr.sched_policy = p->policy;
4650 4651
	if (p->sched_reset_on_fork)
		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4652 4653 4654
	if (task_has_dl_policy(p))
		__getparam_dl(p, &attr);
	else if (task_has_rt_policy(p))
4655 4656
		attr.sched_priority = p->rt_priority;
	else
4657
		attr.sched_nice = task_nice(p);
4658 4659 4660 4661 4662 4663 4664 4665 4666 4667 4668

	rcu_read_unlock();

	retval = sched_read_attr(uattr, &attr, size);
	return retval;

out_unlock:
	rcu_read_unlock();
	return retval;
}

4669
long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
L
Linus Torvalds 已提交
4670
{
4671
	cpumask_var_t cpus_allowed, new_mask;
4672 4673
	struct task_struct *p;
	int retval;
L
Linus Torvalds 已提交
4674

4675
	rcu_read_lock();
L
Linus Torvalds 已提交
4676 4677 4678

	p = find_process_by_pid(pid);
	if (!p) {
4679
		rcu_read_unlock();
L
Linus Torvalds 已提交
4680 4681 4682
		return -ESRCH;
	}

4683
	/* Prevent p going away */
L
Linus Torvalds 已提交
4684
	get_task_struct(p);
4685
	rcu_read_unlock();
L
Linus Torvalds 已提交
4686

4687 4688 4689 4690
	if (p->flags & PF_NO_SETAFFINITY) {
		retval = -EINVAL;
		goto out_put_task;
	}
4691 4692 4693 4694 4695 4696 4697 4698
	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
		retval = -ENOMEM;
		goto out_put_task;
	}
	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
		retval = -ENOMEM;
		goto out_free_cpus_allowed;
	}
L
Linus Torvalds 已提交
4699
	retval = -EPERM;
E
Eric W. Biederman 已提交
4700 4701 4702 4703
	if (!check_same_owner(p)) {
		rcu_read_lock();
		if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
			rcu_read_unlock();
4704
			goto out_free_new_mask;
E
Eric W. Biederman 已提交
4705 4706 4707
		}
		rcu_read_unlock();
	}
L
Linus Torvalds 已提交
4708

4709
	retval = security_task_setscheduler(p);
4710
	if (retval)
4711
		goto out_free_new_mask;
4712

4713 4714 4715 4716

	cpuset_cpus_allowed(p, cpus_allowed);
	cpumask_and(new_mask, in_mask, cpus_allowed);

4717 4718 4719 4720 4721 4722 4723
	/*
	 * Since bandwidth control happens on root_domain basis,
	 * if admission test is enabled, we only admit -deadline
	 * tasks allowed to run on all the CPUs in the task's
	 * root_domain.
	 */
#ifdef CONFIG_SMP
4724 4725 4726
	if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
		rcu_read_lock();
		if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4727
			retval = -EBUSY;
4728
			rcu_read_unlock();
4729
			goto out_free_new_mask;
4730
		}
4731
		rcu_read_unlock();
4732 4733
	}
#endif
P
Peter Zijlstra 已提交
4734
again:
4735
	retval = __set_cpus_allowed_ptr(p, new_mask, true);
L
Linus Torvalds 已提交
4736

P
Paul Menage 已提交
4737
	if (!retval) {
4738 4739
		cpuset_cpus_allowed(p, cpus_allowed);
		if (!cpumask_subset(new_mask, cpus_allowed)) {
P
Paul Menage 已提交
4740 4741 4742 4743 4744
			/*
			 * We must have raced with a concurrent cpuset
			 * update. Just reset the cpus_allowed to the
			 * cpuset's cpus_allowed
			 */
4745
			cpumask_copy(new_mask, cpus_allowed);
P
Paul Menage 已提交
4746 4747 4748
			goto again;
		}
	}
4749
out_free_new_mask:
4750 4751 4752 4753
	free_cpumask_var(new_mask);
out_free_cpus_allowed:
	free_cpumask_var(cpus_allowed);
out_put_task:
L
Linus Torvalds 已提交
4754 4755 4756 4757 4758
	put_task_struct(p);
	return retval;
}

static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4759
			     struct cpumask *new_mask)
L
Linus Torvalds 已提交
4760
{
4761 4762 4763 4764 4765
	if (len < cpumask_size())
		cpumask_clear(new_mask);
	else if (len > cpumask_size())
		len = cpumask_size();

L
Linus Torvalds 已提交
4766 4767 4768 4769 4770 4771 4772 4773
	return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
}

/**
 * sys_sched_setaffinity - set the cpu affinity of a process
 * @pid: pid of the process
 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
 * @user_mask_ptr: user-space pointer to the new cpu mask
4774 4775
 *
 * Return: 0 on success. An error code otherwise.
L
Linus Torvalds 已提交
4776
 */
4777 4778
SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
		unsigned long __user *, user_mask_ptr)
L
Linus Torvalds 已提交
4779
{
4780
	cpumask_var_t new_mask;
L
Linus Torvalds 已提交
4781 4782
	int retval;

4783 4784
	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
		return -ENOMEM;
L
Linus Torvalds 已提交
4785

4786 4787 4788 4789 4790
	retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
	if (retval == 0)
		retval = sched_setaffinity(pid, new_mask);
	free_cpumask_var(new_mask);
	return retval;
L
Linus Torvalds 已提交
4791 4792
}

4793
long sched_getaffinity(pid_t pid, struct cpumask *mask)
L
Linus Torvalds 已提交
4794
{
4795
	struct task_struct *p;
4796
	unsigned long flags;
L
Linus Torvalds 已提交
4797 4798
	int retval;

4799
	rcu_read_lock();
L
Linus Torvalds 已提交
4800 4801 4802 4803 4804 4805

	retval = -ESRCH;
	p = find_process_by_pid(pid);
	if (!p)
		goto out_unlock;

4806 4807 4808 4809
	retval = security_task_getscheduler(p);
	if (retval)
		goto out_unlock;

4810
	raw_spin_lock_irqsave(&p->pi_lock, flags);
4811
	cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4812
	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
L
Linus Torvalds 已提交
4813 4814

out_unlock:
4815
	rcu_read_unlock();
L
Linus Torvalds 已提交
4816

4817
	return retval;
L
Linus Torvalds 已提交
4818 4819 4820 4821 4822 4823 4824
}

/**
 * sys_sched_getaffinity - get the cpu affinity of a process
 * @pid: pid of the process
 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4825
 *
4826 4827
 * Return: size of CPU mask copied to user_mask_ptr on success. An
 * error code otherwise.
L
Linus Torvalds 已提交
4828
 */
4829 4830
SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
		unsigned long __user *, user_mask_ptr)
L
Linus Torvalds 已提交
4831 4832
{
	int ret;
4833
	cpumask_var_t mask;
L
Linus Torvalds 已提交
4834

A
Anton Blanchard 已提交
4835
	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4836 4837
		return -EINVAL;
	if (len & (sizeof(unsigned long)-1))
L
Linus Torvalds 已提交
4838 4839
		return -EINVAL;

4840 4841
	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
		return -ENOMEM;
L
Linus Torvalds 已提交
4842

4843 4844
	ret = sched_getaffinity(pid, mask);
	if (ret == 0) {
4845
		size_t retlen = min_t(size_t, len, cpumask_size());
4846 4847

		if (copy_to_user(user_mask_ptr, mask, retlen))
4848 4849
			ret = -EFAULT;
		else
4850
			ret = retlen;
4851 4852
	}
	free_cpumask_var(mask);
L
Linus Torvalds 已提交
4853

4854
	return ret;
L
Linus Torvalds 已提交
4855 4856 4857 4858 4859
}

/**
 * sys_sched_yield - yield the current processor to other threads.
 *
I
Ingo Molnar 已提交
4860 4861
 * This function yields the current CPU to other tasks. If there are no
 * other threads running on this CPU then this function will return.
4862 4863
 *
 * Return: 0.
L
Linus Torvalds 已提交
4864
 */
4865
SYSCALL_DEFINE0(sched_yield)
L
Linus Torvalds 已提交
4866
{
4867
	struct rq *rq = this_rq_lock();
L
Linus Torvalds 已提交
4868

4869
	schedstat_inc(rq->yld_count);
4870
	current->sched_class->yield_task(rq);
L
Linus Torvalds 已提交
4871 4872 4873 4874 4875 4876

	/*
	 * Since we are going to call schedule() anyway, there's
	 * no need to preempt or enable interrupts:
	 */
	__release(rq->lock);
4877
	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4878
	do_raw_spin_unlock(&rq->lock);
4879
	sched_preempt_enable_no_resched();
L
Linus Torvalds 已提交
4880 4881 4882 4883 4884 4885

	schedule();

	return 0;
}

4886
#ifndef CONFIG_PREEMPT
4887
int __sched _cond_resched(void)
L
Linus Torvalds 已提交
4888
{
4889
	if (should_resched(0)) {
4890
		preempt_schedule_common();
L
Linus Torvalds 已提交
4891 4892 4893 4894
		return 1;
	}
	return 0;
}
4895
EXPORT_SYMBOL(_cond_resched);
4896
#endif
L
Linus Torvalds 已提交
4897 4898

/*
4899
 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
L
Linus Torvalds 已提交
4900 4901
 * call schedule, and on return reacquire the lock.
 *
I
Ingo Molnar 已提交
4902
 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
L
Linus Torvalds 已提交
4903 4904 4905
 * operations here to prevent schedule() from being called twice (once via
 * spin_unlock(), once by hand).
 */
4906
int __cond_resched_lock(spinlock_t *lock)
L
Linus Torvalds 已提交
4907
{
4908
	int resched = should_resched(PREEMPT_LOCK_OFFSET);
J
Jan Kara 已提交
4909 4910
	int ret = 0;

4911 4912
	lockdep_assert_held(lock);

4913
	if (spin_needbreak(lock) || resched) {
L
Linus Torvalds 已提交
4914
		spin_unlock(lock);
P
Peter Zijlstra 已提交
4915
		if (resched)
4916
			preempt_schedule_common();
N
Nick Piggin 已提交
4917 4918
		else
			cpu_relax();
J
Jan Kara 已提交
4919
		ret = 1;
L
Linus Torvalds 已提交
4920 4921
		spin_lock(lock);
	}
J
Jan Kara 已提交
4922
	return ret;
L
Linus Torvalds 已提交
4923
}
4924
EXPORT_SYMBOL(__cond_resched_lock);
L
Linus Torvalds 已提交
4925

4926
int __sched __cond_resched_softirq(void)
L
Linus Torvalds 已提交
4927 4928 4929
{
	BUG_ON(!in_softirq());

4930
	if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
4931
		local_bh_enable();
4932
		preempt_schedule_common();
L
Linus Torvalds 已提交
4933 4934 4935 4936 4937
		local_bh_disable();
		return 1;
	}
	return 0;
}
4938
EXPORT_SYMBOL(__cond_resched_softirq);
L
Linus Torvalds 已提交
4939 4940 4941 4942

/**
 * yield - yield the current processor to other threads.
 *
P
Peter Zijlstra 已提交
4943 4944 4945 4946 4947 4948 4949 4950 4951 4952 4953 4954 4955 4956 4957 4958 4959 4960
 * Do not ever use this function, there's a 99% chance you're doing it wrong.
 *
 * The scheduler is at all times free to pick the calling task as the most
 * eligible task to run, if removing the yield() call from your code breaks
 * it, its already broken.
 *
 * Typical broken usage is:
 *
 * while (!event)
 * 	yield();
 *
 * where one assumes that yield() will let 'the other' process run that will
 * make event true. If the current task is a SCHED_FIFO task that will never
 * happen. Never use yield() as a progress guarantee!!
 *
 * If you want to use yield() to wait for something, use wait_event().
 * If you want to use yield() to be 'nice' for others, use cond_resched().
 * If you still want to use yield(), do not!
L
Linus Torvalds 已提交
4961 4962 4963 4964 4965 4966 4967 4968
 */
void __sched yield(void)
{
	set_current_state(TASK_RUNNING);
	sys_sched_yield();
}
EXPORT_SYMBOL(yield);

4969 4970 4971 4972
/**
 * yield_to - yield the current processor to another thread in
 * your thread group, or accelerate that thread toward the
 * processor it's on.
R
Randy Dunlap 已提交
4973 4974
 * @p: target task
 * @preempt: whether task preemption is allowed or not
4975 4976 4977 4978
 *
 * It's the caller's job to ensure that the target task struct
 * can't go away on us before we can do any checks.
 *
4979
 * Return:
4980 4981 4982
 *	true (>0) if we indeed boosted the target task.
 *	false (0) if we failed to boost the target.
 *	-ESRCH if there's no task to yield to.
4983
 */
4984
int __sched yield_to(struct task_struct *p, bool preempt)
4985 4986 4987 4988
{
	struct task_struct *curr = current;
	struct rq *rq, *p_rq;
	unsigned long flags;
4989
	int yielded = 0;
4990 4991 4992 4993 4994 4995

	local_irq_save(flags);
	rq = this_rq();

again:
	p_rq = task_rq(p);
4996 4997 4998 4999 5000 5001 5002 5003 5004
	/*
	 * If we're the only runnable task on the rq and target rq also
	 * has only one task, there's absolutely no point in yielding.
	 */
	if (rq->nr_running == 1 && p_rq->nr_running == 1) {
		yielded = -ESRCH;
		goto out_irq;
	}

5005
	double_rq_lock(rq, p_rq);
5006
	if (task_rq(p) != p_rq) {
5007 5008 5009 5010 5011
		double_rq_unlock(rq, p_rq);
		goto again;
	}

	if (!curr->sched_class->yield_to_task)
5012
		goto out_unlock;
5013 5014

	if (curr->sched_class != p->sched_class)
5015
		goto out_unlock;
5016 5017

	if (task_running(p_rq, p) || p->state)
5018
		goto out_unlock;
5019 5020

	yielded = curr->sched_class->yield_to_task(rq, p, preempt);
5021
	if (yielded) {
5022
		schedstat_inc(rq->yld_count);
5023 5024 5025 5026 5027
		/*
		 * Make p's CPU reschedule; pick_next_entity takes care of
		 * fairness.
		 */
		if (preempt && rq != p_rq)
5028
			resched_curr(p_rq);
5029
	}
5030

5031
out_unlock:
5032
	double_rq_unlock(rq, p_rq);
5033
out_irq:
5034 5035
	local_irq_restore(flags);

5036
	if (yielded > 0)
5037 5038 5039 5040 5041 5042
		schedule();

	return yielded;
}
EXPORT_SYMBOL_GPL(yield_to);

L
Linus Torvalds 已提交
5043
/*
I
Ingo Molnar 已提交
5044
 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
L
Linus Torvalds 已提交
5045 5046 5047 5048
 * that process accounting knows that this is a task in IO wait state.
 */
long __sched io_schedule_timeout(long timeout)
{
5049 5050
	int old_iowait = current->in_iowait;
	struct rq *rq;
L
Linus Torvalds 已提交
5051 5052
	long ret;

5053
	current->in_iowait = 1;
5054
	blk_schedule_flush_plug(current);
5055

5056
	delayacct_blkio_start();
5057
	rq = raw_rq();
L
Linus Torvalds 已提交
5058 5059
	atomic_inc(&rq->nr_iowait);
	ret = schedule_timeout(timeout);
5060
	current->in_iowait = old_iowait;
L
Linus Torvalds 已提交
5061
	atomic_dec(&rq->nr_iowait);
5062
	delayacct_blkio_end();
5063

L
Linus Torvalds 已提交
5064 5065
	return ret;
}
5066
EXPORT_SYMBOL(io_schedule_timeout);
L
Linus Torvalds 已提交
5067 5068 5069 5070 5071

/**
 * sys_sched_get_priority_max - return maximum RT priority.
 * @policy: scheduling class.
 *
5072 5073 5074
 * Return: On success, this syscall returns the maximum
 * rt_priority that can be used by a given scheduling class.
 * On failure, a negative error code is returned.
L
Linus Torvalds 已提交
5075
 */
5076
SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
L
Linus Torvalds 已提交
5077 5078 5079 5080 5081 5082 5083 5084
{
	int ret = -EINVAL;

	switch (policy) {
	case SCHED_FIFO:
	case SCHED_RR:
		ret = MAX_USER_RT_PRIO-1;
		break;
5085
	case SCHED_DEADLINE:
L
Linus Torvalds 已提交
5086
	case SCHED_NORMAL:
5087
	case SCHED_BATCH:
I
Ingo Molnar 已提交
5088
	case SCHED_IDLE:
L
Linus Torvalds 已提交
5089 5090 5091 5092 5093 5094 5095 5096 5097 5098
		ret = 0;
		break;
	}
	return ret;
}

/**
 * sys_sched_get_priority_min - return minimum RT priority.
 * @policy: scheduling class.
 *
5099 5100 5101
 * Return: On success, this syscall returns the minimum
 * rt_priority that can be used by a given scheduling class.
 * On failure, a negative error code is returned.
L
Linus Torvalds 已提交
5102
 */
5103
SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
L
Linus Torvalds 已提交
5104 5105 5106 5107 5108 5109 5110 5111
{
	int ret = -EINVAL;

	switch (policy) {
	case SCHED_FIFO:
	case SCHED_RR:
		ret = 1;
		break;
5112
	case SCHED_DEADLINE:
L
Linus Torvalds 已提交
5113
	case SCHED_NORMAL:
5114
	case SCHED_BATCH:
I
Ingo Molnar 已提交
5115
	case SCHED_IDLE:
L
Linus Torvalds 已提交
5116 5117 5118 5119 5120 5121 5122 5123 5124 5125 5126 5127
		ret = 0;
	}
	return ret;
}

/**
 * sys_sched_rr_get_interval - return the default timeslice of a process.
 * @pid: pid of the process.
 * @interval: userspace pointer to the timeslice value.
 *
 * this syscall writes the default timeslice value of a given process
 * into the user-space timespec buffer. A value of '0' means infinity.
5128 5129 5130
 *
 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
 * an error code.
L
Linus Torvalds 已提交
5131
 */
5132
SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
5133
		struct timespec __user *, interval)
L
Linus Torvalds 已提交
5134
{
5135
	struct task_struct *p;
D
Dmitry Adamushko 已提交
5136
	unsigned int time_slice;
5137 5138
	struct rq_flags rf;
	struct timespec t;
5139
	struct rq *rq;
5140
	int retval;
L
Linus Torvalds 已提交
5141 5142

	if (pid < 0)
5143
		return -EINVAL;
L
Linus Torvalds 已提交
5144 5145

	retval = -ESRCH;
5146
	rcu_read_lock();
L
Linus Torvalds 已提交
5147 5148 5149 5150 5151 5152 5153 5154
	p = find_process_by_pid(pid);
	if (!p)
		goto out_unlock;

	retval = security_task_getscheduler(p);
	if (retval)
		goto out_unlock;

5155
	rq = task_rq_lock(p, &rf);
5156 5157 5158
	time_slice = 0;
	if (p->sched_class->get_rr_interval)
		time_slice = p->sched_class->get_rr_interval(rq, p);
5159
	task_rq_unlock(rq, p, &rf);
D
Dmitry Adamushko 已提交
5160

5161
	rcu_read_unlock();
D
Dmitry Adamushko 已提交
5162
	jiffies_to_timespec(time_slice, &t);
L
Linus Torvalds 已提交
5163 5164
	retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
	return retval;
5165

L
Linus Torvalds 已提交
5166
out_unlock:
5167
	rcu_read_unlock();
L
Linus Torvalds 已提交
5168 5169 5170
	return retval;
}

5171
static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
5172

5173
void sched_show_task(struct task_struct *p)
L
Linus Torvalds 已提交
5174 5175
{
	unsigned long free = 0;
5176
	int ppid;
5177
	unsigned long state = p->state;
L
Linus Torvalds 已提交
5178

5179 5180
	if (state)
		state = __ffs(state) + 1;
5181
	printk(KERN_INFO "%-15.15s %c", p->comm,
5182
		state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
5183
#if BITS_PER_LONG == 32
L
Linus Torvalds 已提交
5184
	if (state == TASK_RUNNING)
P
Peter Zijlstra 已提交
5185
		printk(KERN_CONT " running  ");
L
Linus Torvalds 已提交
5186
	else
P
Peter Zijlstra 已提交
5187
		printk(KERN_CONT " %08lx ", thread_saved_pc(p));
L
Linus Torvalds 已提交
5188 5189
#else
	if (state == TASK_RUNNING)
P
Peter Zijlstra 已提交
5190
		printk(KERN_CONT "  running task    ");
L
Linus Torvalds 已提交
5191
	else
P
Peter Zijlstra 已提交
5192
		printk(KERN_CONT " %016lx ", thread_saved_pc(p));
L
Linus Torvalds 已提交
5193 5194
#endif
#ifdef CONFIG_DEBUG_STACK_USAGE
5195
	free = stack_not_used(p);
L
Linus Torvalds 已提交
5196
#endif
5197
	ppid = 0;
5198
	rcu_read_lock();
5199 5200
	if (pid_alive(p))
		ppid = task_pid_nr(rcu_dereference(p->real_parent));
5201
	rcu_read_unlock();
P
Peter Zijlstra 已提交
5202
	printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
5203
		task_pid_nr(p), ppid,
5204
		(unsigned long)task_thread_info(p)->flags);
L
Linus Torvalds 已提交
5205

5206
	print_worker_info(KERN_INFO, p);
5207
	show_stack(p, NULL);
L
Linus Torvalds 已提交
5208 5209
}

I
Ingo Molnar 已提交
5210
void show_state_filter(unsigned long state_filter)
L
Linus Torvalds 已提交
5211
{
5212
	struct task_struct *g, *p;
L
Linus Torvalds 已提交
5213

5214
#if BITS_PER_LONG == 32
P
Peter Zijlstra 已提交
5215 5216
	printk(KERN_INFO
		"  task                PC stack   pid father\n");
L
Linus Torvalds 已提交
5217
#else
P
Peter Zijlstra 已提交
5218 5219
	printk(KERN_INFO
		"  task                        PC stack   pid father\n");
L
Linus Torvalds 已提交
5220
#endif
5221
	rcu_read_lock();
5222
	for_each_process_thread(g, p) {
L
Linus Torvalds 已提交
5223 5224
		/*
		 * reset the NMI-timeout, listing all files on a slow
L
Lucas De Marchi 已提交
5225
		 * console might take a lot of time:
5226 5227 5228
		 * Also, reset softlockup watchdogs on all CPUs, because
		 * another CPU might be blocked waiting for us to process
		 * an IPI.
L
Linus Torvalds 已提交
5229 5230
		 */
		touch_nmi_watchdog();
5231
		touch_all_softlockup_watchdogs();
I
Ingo Molnar 已提交
5232
		if (!state_filter || (p->state & state_filter))
5233
			sched_show_task(p);
5234
	}
L
Linus Torvalds 已提交
5235

I
Ingo Molnar 已提交
5236
#ifdef CONFIG_SCHED_DEBUG
5237 5238
	if (!state_filter)
		sysrq_sched_debug_show();
I
Ingo Molnar 已提交
5239
#endif
5240
	rcu_read_unlock();
I
Ingo Molnar 已提交
5241 5242 5243
	/*
	 * Only show locks if all tasks are dumped:
	 */
5244
	if (!state_filter)
I
Ingo Molnar 已提交
5245
		debug_show_all_locks();
L
Linus Torvalds 已提交
5246 5247
}

5248
void init_idle_bootup_task(struct task_struct *idle)
I
Ingo Molnar 已提交
5249
{
I
Ingo Molnar 已提交
5250
	idle->sched_class = &idle_sched_class;
I
Ingo Molnar 已提交
5251 5252
}

5253 5254 5255 5256 5257 5258 5259 5260
/**
 * init_idle - set up an idle thread for a given CPU
 * @idle: task in question
 * @cpu: cpu the idle task belongs to
 *
 * NOTE: this function does not set the idle thread's NEED_RESCHED
 * flag, to make booting more robust.
 */
5261
void init_idle(struct task_struct *idle, int cpu)
L
Linus Torvalds 已提交
5262
{
5263
	struct rq *rq = cpu_rq(cpu);
L
Linus Torvalds 已提交
5264 5265
	unsigned long flags;

5266 5267
	raw_spin_lock_irqsave(&idle->pi_lock, flags);
	raw_spin_lock(&rq->lock);
5268

5269
	__sched_fork(0, idle);
5270
	idle->state = TASK_RUNNING;
I
Ingo Molnar 已提交
5271 5272
	idle->se.exec_start = sched_clock();

5273 5274
	kasan_unpoison_task_stack(idle);

5275 5276 5277 5278 5279 5280 5281 5282 5283
#ifdef CONFIG_SMP
	/*
	 * Its possible that init_idle() gets called multiple times on a task,
	 * in that case do_set_cpus_allowed() will not do the right thing.
	 *
	 * And since this is boot we can forgo the serialization.
	 */
	set_cpus_allowed_common(idle, cpumask_of(cpu));
#endif
5284 5285 5286 5287 5288 5289 5290 5291 5292 5293 5294
	/*
	 * We're having a chicken and egg problem, even though we are
	 * holding rq->lock, the cpu isn't yet set to this cpu so the
	 * lockdep check in task_group() will fail.
	 *
	 * Similar case to sched_fork(). / Alternatively we could
	 * use task_rq_lock() here and obtain the other rq->lock.
	 *
	 * Silence PROVE_RCU
	 */
	rcu_read_lock();
I
Ingo Molnar 已提交
5295
	__set_task_cpu(idle, cpu);
5296
	rcu_read_unlock();
L
Linus Torvalds 已提交
5297 5298

	rq->curr = rq->idle = idle;
5299
	idle->on_rq = TASK_ON_RQ_QUEUED;
5300
#ifdef CONFIG_SMP
P
Peter Zijlstra 已提交
5301
	idle->on_cpu = 1;
5302
#endif
5303 5304
	raw_spin_unlock(&rq->lock);
	raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
L
Linus Torvalds 已提交
5305 5306

	/* Set the preempt count _outside_ the spinlocks! */
5307
	init_idle_preempt_count(idle, cpu);
5308

I
Ingo Molnar 已提交
5309 5310 5311 5312
	/*
	 * The idle tasks have their own, simple scheduling class:
	 */
	idle->sched_class = &idle_sched_class;
5313
	ftrace_graph_init_idle_task(idle, cpu);
5314
	vtime_init_idle(idle, cpu);
5315
#ifdef CONFIG_SMP
5316 5317
	sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
#endif
I
Ingo Molnar 已提交
5318 5319
}

5320 5321 5322 5323 5324 5325 5326
int cpuset_cpumask_can_shrink(const struct cpumask *cur,
			      const struct cpumask *trial)
{
	int ret = 1, trial_cpus;
	struct dl_bw *cur_dl_b;
	unsigned long flags;

5327 5328 5329
	if (!cpumask_weight(cur))
		return ret;

5330
	rcu_read_lock_sched();
5331 5332 5333 5334 5335 5336 5337 5338
	cur_dl_b = dl_bw_of(cpumask_any(cur));
	trial_cpus = cpumask_weight(trial);

	raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
	if (cur_dl_b->bw != -1 &&
	    cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
		ret = 0;
	raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
5339
	rcu_read_unlock_sched();
5340 5341 5342 5343

	return ret;
}

5344 5345 5346 5347 5348 5349 5350 5351 5352 5353 5354 5355 5356 5357 5358 5359 5360 5361 5362 5363 5364 5365 5366 5367
int task_can_attach(struct task_struct *p,
		    const struct cpumask *cs_cpus_allowed)
{
	int ret = 0;

	/*
	 * Kthreads which disallow setaffinity shouldn't be moved
	 * to a new cpuset; we don't want to change their cpu
	 * affinity and isolating such threads by their set of
	 * allowed nodes is unnecessary.  Thus, cpusets are not
	 * applicable for such threads.  This prevents checking for
	 * success of set_cpus_allowed_ptr() on all attached tasks
	 * before cpus_allowed may be changed.
	 */
	if (p->flags & PF_NO_SETAFFINITY) {
		ret = -EINVAL;
		goto out;
	}

#ifdef CONFIG_SMP
	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
					      cs_cpus_allowed)) {
		unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
							cs_cpus_allowed);
5368
		struct dl_bw *dl_b;
5369 5370 5371 5372
		bool overflow;
		int cpus;
		unsigned long flags;

5373 5374
		rcu_read_lock_sched();
		dl_b = dl_bw_of(dest_cpu);
5375 5376 5377 5378 5379 5380 5381 5382 5383 5384 5385 5386 5387 5388 5389
		raw_spin_lock_irqsave(&dl_b->lock, flags);
		cpus = dl_bw_cpus(dest_cpu);
		overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
		if (overflow)
			ret = -EBUSY;
		else {
			/*
			 * We reserve space for this task in the destination
			 * root_domain, as we can't fail after this point.
			 * We will free resources in the source root_domain
			 * later on (see set_cpus_allowed_dl()).
			 */
			__dl_add(dl_b, p->dl.dl_bw);
		}
		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5390
		rcu_read_unlock_sched();
5391 5392 5393 5394 5395 5396 5397

	}
#endif
out:
	return ret;
}

L
Linus Torvalds 已提交
5398 5399
#ifdef CONFIG_SMP

5400 5401
static bool sched_smp_initialized __read_mostly;

5402 5403 5404 5405 5406 5407 5408 5409 5410 5411 5412 5413 5414 5415 5416
#ifdef CONFIG_NUMA_BALANCING
/* Migrate current task p to target_cpu */
int migrate_task_to(struct task_struct *p, int target_cpu)
{
	struct migration_arg arg = { p, target_cpu };
	int curr_cpu = task_cpu(p);

	if (curr_cpu == target_cpu)
		return 0;

	if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
		return -EINVAL;

	/* TODO: This is not properly updating schedstats */

5417
	trace_sched_move_numa(p, curr_cpu, target_cpu);
5418 5419
	return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
}
5420 5421 5422 5423 5424 5425 5426

/*
 * Requeue a task on a given node and accurately track the number of NUMA
 * tasks on the runqueues
 */
void sched_setnuma(struct task_struct *p, int nid)
{
5427
	bool queued, running;
5428 5429
	struct rq_flags rf;
	struct rq *rq;
5430

5431
	rq = task_rq_lock(p, &rf);
5432
	queued = task_on_rq_queued(p);
5433 5434
	running = task_current(rq, p);

5435
	if (queued)
5436
		dequeue_task(rq, p, DEQUEUE_SAVE);
5437
	if (running)
5438
		put_prev_task(rq, p);
5439 5440 5441 5442 5443

	p->numa_preferred_nid = nid;

	if (running)
		p->sched_class->set_curr_task(rq);
5444
	if (queued)
5445
		enqueue_task(rq, p, ENQUEUE_RESTORE);
5446
	task_rq_unlock(rq, p, &rf);
5447
}
P
Peter Zijlstra 已提交
5448
#endif /* CONFIG_NUMA_BALANCING */
5449

L
Linus Torvalds 已提交
5450
#ifdef CONFIG_HOTPLUG_CPU
5451
/*
5452 5453
 * Ensures that the idle task is using init_mm right before its cpu goes
 * offline.
5454
 */
5455
void idle_task_exit(void)
L
Linus Torvalds 已提交
5456
{
5457
	struct mm_struct *mm = current->active_mm;
5458

5459
	BUG_ON(cpu_online(smp_processor_id()));
5460

5461
	if (mm != &init_mm) {
5462
		switch_mm_irqs_off(mm, &init_mm, current);
5463 5464
		finish_arch_post_lock_switch();
	}
5465
	mmdrop(mm);
L
Linus Torvalds 已提交
5466 5467 5468
}

/*
5469 5470
 * Since this CPU is going 'away' for a while, fold any nr_active delta
 * we might have. Assumes we're called after migrate_tasks() so that the
5471 5472 5473
 * nr_active count is stable. We need to take the teardown thread which
 * is calling this into account, so we hand in adjust = 1 to the load
 * calculation.
5474 5475
 *
 * Also see the comment "Global load-average calculations".
L
Linus Torvalds 已提交
5476
 */
5477
static void calc_load_migrate(struct rq *rq)
L
Linus Torvalds 已提交
5478
{
5479
	long delta = calc_load_fold_active(rq, 1);
5480 5481
	if (delta)
		atomic_long_add(delta, &calc_load_tasks);
L
Linus Torvalds 已提交
5482 5483
}

5484 5485 5486 5487 5488 5489 5490 5491 5492 5493 5494 5495 5496 5497 5498 5499
static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
{
}

static const struct sched_class fake_sched_class = {
	.put_prev_task = put_prev_task_fake,
};

static struct task_struct fake_task = {
	/*
	 * Avoid pull_{rt,dl}_task()
	 */
	.prio = MAX_PRIO + 1,
	.sched_class = &fake_sched_class,
};

5500
/*
5501 5502 5503 5504 5505 5506
 * Migrate all tasks from the rq, sleeping tasks will be migrated by
 * try_to_wake_up()->select_task_rq().
 *
 * Called with rq->lock held even though we'er in stop_machine() and
 * there's no concurrency possible, we hold the required locks anyway
 * because of lock validation efforts.
L
Linus Torvalds 已提交
5507
 */
5508
static void migrate_tasks(struct rq *dead_rq)
L
Linus Torvalds 已提交
5509
{
5510
	struct rq *rq = dead_rq;
5511
	struct task_struct *next, *stop = rq->stop;
5512
	struct pin_cookie cookie;
5513
	int dest_cpu;
L
Linus Torvalds 已提交
5514 5515

	/*
5516 5517 5518 5519 5520 5521 5522
	 * Fudge the rq selection such that the below task selection loop
	 * doesn't get stuck on the currently eligible stop task.
	 *
	 * We're currently inside stop_machine() and the rq is either stuck
	 * in the stop_machine_cpu_stop() loop, or we're executing this code,
	 * either way we should never end up calling schedule() until we're
	 * done here.
L
Linus Torvalds 已提交
5523
	 */
5524
	rq->stop = NULL;
5525

5526 5527 5528 5529 5530 5531 5532
	/*
	 * put_prev_task() and pick_next_task() sched
	 * class method both need to have an up-to-date
	 * value of rq->clock[_task]
	 */
	update_rq_clock(rq);

5533
	for (;;) {
5534 5535 5536 5537 5538
		/*
		 * There's this thread running, bail when that's the only
		 * remaining thread.
		 */
		if (rq->nr_running == 1)
I
Ingo Molnar 已提交
5539
			break;
5540

5541
		/*
W
Wanpeng Li 已提交
5542
		 * pick_next_task assumes pinned rq->lock.
5543
		 */
5544 5545
		cookie = lockdep_pin_lock(&rq->lock);
		next = pick_next_task(rq, &fake_task, cookie);
5546
		BUG_ON(!next);
D
Dmitry Adamushko 已提交
5547
		next->sched_class->put_prev_task(rq, next);
5548

W
Wanpeng Li 已提交
5549 5550 5551 5552 5553 5554 5555 5556 5557
		/*
		 * Rules for changing task_struct::cpus_allowed are holding
		 * both pi_lock and rq->lock, such that holding either
		 * stabilizes the mask.
		 *
		 * Drop rq->lock is not quite as disastrous as it usually is
		 * because !cpu_active at this point, which means load-balance
		 * will not interfere. Also, stop-machine.
		 */
5558
		lockdep_unpin_lock(&rq->lock, cookie);
W
Wanpeng Li 已提交
5559 5560 5561 5562 5563 5564 5565 5566 5567 5568 5569 5570 5571 5572
		raw_spin_unlock(&rq->lock);
		raw_spin_lock(&next->pi_lock);
		raw_spin_lock(&rq->lock);

		/*
		 * Since we're inside stop-machine, _nothing_ should have
		 * changed the task, WARN if weird stuff happened, because in
		 * that case the above rq->lock drop is a fail too.
		 */
		if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
			raw_spin_unlock(&next->pi_lock);
			continue;
		}

5573
		/* Find suitable destination for @next, with force if needed. */
5574
		dest_cpu = select_fallback_rq(dead_rq->cpu, next);
5575

5576 5577 5578 5579 5580 5581
		rq = __migrate_task(rq, next, dest_cpu);
		if (rq != dead_rq) {
			raw_spin_unlock(&rq->lock);
			rq = dead_rq;
			raw_spin_lock(&rq->lock);
		}
W
Wanpeng Li 已提交
5582
		raw_spin_unlock(&next->pi_lock);
L
Linus Torvalds 已提交
5583
	}
5584

5585
	rq->stop = stop;
5586
}
L
Linus Torvalds 已提交
5587 5588
#endif /* CONFIG_HOTPLUG_CPU */

5589 5590 5591 5592 5593
static void set_rq_online(struct rq *rq)
{
	if (!rq->online) {
		const struct sched_class *class;

5594
		cpumask_set_cpu(rq->cpu, rq->rd->online);
5595 5596 5597 5598 5599 5600 5601 5602 5603 5604 5605 5606 5607 5608 5609 5610 5611 5612 5613
		rq->online = 1;

		for_each_class(class) {
			if (class->rq_online)
				class->rq_online(rq);
		}
	}
}

static void set_rq_offline(struct rq *rq)
{
	if (rq->online) {
		const struct sched_class *class;

		for_each_class(class) {
			if (class->rq_offline)
				class->rq_offline(rq);
		}

5614
		cpumask_clear_cpu(rq->cpu, rq->rd->online);
5615 5616 5617 5618
		rq->online = 0;
	}
}

5619
static void set_cpu_rq_start_time(unsigned int cpu)
L
Linus Torvalds 已提交
5620
{
5621
	struct rq *rq = cpu_rq(cpu);
L
Linus Torvalds 已提交
5622

5623 5624 5625
	rq->age_stamp = sched_clock_cpu(cpu);
}

5626 5627
static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */

5628
#ifdef CONFIG_SCHED_DEBUG
I
Ingo Molnar 已提交
5629

5630
static __read_mostly int sched_debug_enabled;
5631

5632
static int __init sched_debug_setup(char *str)
5633
{
5634
	sched_debug_enabled = 1;
5635 5636 5637

	return 0;
}
5638 5639 5640 5641 5642 5643
early_param("sched_debug", sched_debug_setup);

static inline bool sched_debug(void)
{
	return sched_debug_enabled;
}
5644

5645
static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5646
				  struct cpumask *groupmask)
L
Linus Torvalds 已提交
5647
{
I
Ingo Molnar 已提交
5648
	struct sched_group *group = sd->groups;
L
Linus Torvalds 已提交
5649

5650
	cpumask_clear(groupmask);
I
Ingo Molnar 已提交
5651 5652 5653 5654

	printk(KERN_DEBUG "%*s domain %d: ", level, "", level);

	if (!(sd->flags & SD_LOAD_BALANCE)) {
P
Peter Zijlstra 已提交
5655
		printk("does not load-balance\n");
I
Ingo Molnar 已提交
5656
		if (sd->parent)
P
Peter Zijlstra 已提交
5657 5658
			printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
					" has parent");
I
Ingo Molnar 已提交
5659
		return -1;
N
Nick Piggin 已提交
5660 5661
	}

5662 5663
	printk(KERN_CONT "span %*pbl level %s\n",
	       cpumask_pr_args(sched_domain_span(sd)), sd->name);
I
Ingo Molnar 已提交
5664

5665
	if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
P
Peter Zijlstra 已提交
5666 5667
		printk(KERN_ERR "ERROR: domain->span does not contain "
				"CPU%d\n", cpu);
I
Ingo Molnar 已提交
5668
	}
5669
	if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
P
Peter Zijlstra 已提交
5670 5671
		printk(KERN_ERR "ERROR: domain->groups does not contain"
				" CPU%d\n", cpu);
I
Ingo Molnar 已提交
5672
	}
L
Linus Torvalds 已提交
5673

I
Ingo Molnar 已提交
5674
	printk(KERN_DEBUG "%*s groups:", level + 1, "");
L
Linus Torvalds 已提交
5675
	do {
I
Ingo Molnar 已提交
5676
		if (!group) {
P
Peter Zijlstra 已提交
5677 5678
			printk("\n");
			printk(KERN_ERR "ERROR: group is NULL\n");
L
Linus Torvalds 已提交
5679 5680 5681
			break;
		}

5682
		if (!cpumask_weight(sched_group_cpus(group))) {
P
Peter Zijlstra 已提交
5683 5684
			printk(KERN_CONT "\n");
			printk(KERN_ERR "ERROR: empty group\n");
I
Ingo Molnar 已提交
5685 5686
			break;
		}
L
Linus Torvalds 已提交
5687

5688 5689
		if (!(sd->flags & SD_OVERLAP) &&
		    cpumask_intersects(groupmask, sched_group_cpus(group))) {
P
Peter Zijlstra 已提交
5690 5691
			printk(KERN_CONT "\n");
			printk(KERN_ERR "ERROR: repeated CPUs\n");
I
Ingo Molnar 已提交
5692 5693
			break;
		}
L
Linus Torvalds 已提交
5694

5695
		cpumask_or(groupmask, groupmask, sched_group_cpus(group));
L
Linus Torvalds 已提交
5696

5697 5698
		printk(KERN_CONT " %*pbl",
		       cpumask_pr_args(sched_group_cpus(group)));
5699
		if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5700 5701
			printk(KERN_CONT " (cpu_capacity = %d)",
				group->sgc->capacity);
5702
		}
L
Linus Torvalds 已提交
5703

I
Ingo Molnar 已提交
5704 5705
		group = group->next;
	} while (group != sd->groups);
P
Peter Zijlstra 已提交
5706
	printk(KERN_CONT "\n");
L
Linus Torvalds 已提交
5707

5708
	if (!cpumask_equal(sched_domain_span(sd), groupmask))
P
Peter Zijlstra 已提交
5709
		printk(KERN_ERR "ERROR: groups don't span domain->span\n");
L
Linus Torvalds 已提交
5710

5711 5712
	if (sd->parent &&
	    !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
P
Peter Zijlstra 已提交
5713 5714
		printk(KERN_ERR "ERROR: parent span is not a superset "
			"of domain->span\n");
I
Ingo Molnar 已提交
5715 5716
	return 0;
}
L
Linus Torvalds 已提交
5717

I
Ingo Molnar 已提交
5718 5719 5720
static void sched_domain_debug(struct sched_domain *sd, int cpu)
{
	int level = 0;
L
Linus Torvalds 已提交
5721

5722
	if (!sched_debug_enabled)
5723 5724
		return;

I
Ingo Molnar 已提交
5725 5726 5727 5728
	if (!sd) {
		printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
		return;
	}
L
Linus Torvalds 已提交
5729

I
Ingo Molnar 已提交
5730 5731 5732
	printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);

	for (;;) {
5733
		if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
I
Ingo Molnar 已提交
5734
			break;
L
Linus Torvalds 已提交
5735 5736
		level++;
		sd = sd->parent;
5737
		if (!sd)
I
Ingo Molnar 已提交
5738 5739
			break;
	}
L
Linus Torvalds 已提交
5740
}
5741
#else /* !CONFIG_SCHED_DEBUG */
5742 5743

# define sched_debug_enabled 0
5744
# define sched_domain_debug(sd, cpu) do { } while (0)
5745 5746 5747 5748
static inline bool sched_debug(void)
{
	return false;
}
5749
#endif /* CONFIG_SCHED_DEBUG */
L
Linus Torvalds 已提交
5750

5751
static int sd_degenerate(struct sched_domain *sd)
5752
{
5753
	if (cpumask_weight(sched_domain_span(sd)) == 1)
5754 5755 5756 5757 5758 5759
		return 1;

	/* Following flags need at least 2 groups */
	if (sd->flags & (SD_LOAD_BALANCE |
			 SD_BALANCE_NEWIDLE |
			 SD_BALANCE_FORK |
5760
			 SD_BALANCE_EXEC |
5761
			 SD_SHARE_CPUCAPACITY |
5762
			 SD_ASYM_CPUCAPACITY |
5763 5764
			 SD_SHARE_PKG_RESOURCES |
			 SD_SHARE_POWERDOMAIN)) {
5765 5766 5767 5768 5769
		if (sd->groups != sd->groups->next)
			return 0;
	}

	/* Following flags don't use groups */
5770
	if (sd->flags & (SD_WAKE_AFFINE))
5771 5772 5773 5774 5775
		return 0;

	return 1;
}

5776 5777
static int
sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5778 5779 5780 5781 5782 5783
{
	unsigned long cflags = sd->flags, pflags = parent->flags;

	if (sd_degenerate(parent))
		return 1;

5784
	if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5785 5786 5787 5788 5789 5790 5791
		return 0;

	/* Flags needing groups don't count if only 1 group in parent */
	if (parent->groups == parent->groups->next) {
		pflags &= ~(SD_LOAD_BALANCE |
				SD_BALANCE_NEWIDLE |
				SD_BALANCE_FORK |
5792
				SD_BALANCE_EXEC |
5793
				SD_ASYM_CPUCAPACITY |
5794
				SD_SHARE_CPUCAPACITY |
5795
				SD_SHARE_PKG_RESOURCES |
5796 5797
				SD_PREFER_SIBLING |
				SD_SHARE_POWERDOMAIN);
5798 5799
		if (nr_node_ids == 1)
			pflags &= ~SD_SERIALIZE;
5800 5801 5802 5803 5804 5805 5806
	}
	if (~cflags & pflags)
		return 0;

	return 1;
}

5807
static void free_rootdomain(struct rcu_head *rcu)
5808
{
5809
	struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5810

5811
	cpupri_cleanup(&rd->cpupri);
5812
	cpudl_cleanup(&rd->cpudl);
5813
	free_cpumask_var(rd->dlo_mask);
5814 5815 5816 5817 5818 5819
	free_cpumask_var(rd->rto_mask);
	free_cpumask_var(rd->online);
	free_cpumask_var(rd->span);
	kfree(rd);
}

G
Gregory Haskins 已提交
5820 5821
static void rq_attach_root(struct rq *rq, struct root_domain *rd)
{
I
Ingo Molnar 已提交
5822
	struct root_domain *old_rd = NULL;
G
Gregory Haskins 已提交
5823 5824
	unsigned long flags;

5825
	raw_spin_lock_irqsave(&rq->lock, flags);
G
Gregory Haskins 已提交
5826 5827

	if (rq->rd) {
I
Ingo Molnar 已提交
5828
		old_rd = rq->rd;
G
Gregory Haskins 已提交
5829

5830
		if (cpumask_test_cpu(rq->cpu, old_rd->online))
5831
			set_rq_offline(rq);
G
Gregory Haskins 已提交
5832

5833
		cpumask_clear_cpu(rq->cpu, old_rd->span);
5834

I
Ingo Molnar 已提交
5835
		/*
5836
		 * If we dont want to free the old_rd yet then
I
Ingo Molnar 已提交
5837 5838 5839 5840 5841
		 * set old_rd to NULL to skip the freeing later
		 * in this function:
		 */
		if (!atomic_dec_and_test(&old_rd->refcount))
			old_rd = NULL;
G
Gregory Haskins 已提交
5842 5843 5844 5845 5846
	}

	atomic_inc(&rd->refcount);
	rq->rd = rd;

5847
	cpumask_set_cpu(rq->cpu, rd->span);
5848
	if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5849
		set_rq_online(rq);
G
Gregory Haskins 已提交
5850

5851
	raw_spin_unlock_irqrestore(&rq->lock, flags);
I
Ingo Molnar 已提交
5852 5853

	if (old_rd)
5854
		call_rcu_sched(&old_rd->rcu, free_rootdomain);
G
Gregory Haskins 已提交
5855 5856
}

5857
static int init_rootdomain(struct root_domain *rd)
G
Gregory Haskins 已提交
5858 5859 5860
{
	memset(rd, 0, sizeof(*rd));

5861
	if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
5862
		goto out;
5863
	if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
5864
		goto free_span;
5865
	if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5866
		goto free_online;
5867
	if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5868
		goto free_dlo_mask;
5869

5870
	init_dl_bw(&rd->dl_bw);
5871 5872
	if (cpudl_init(&rd->cpudl) != 0)
		goto free_dlo_mask;
5873

5874
	if (cpupri_init(&rd->cpupri) != 0)
5875
		goto free_rto_mask;
5876
	return 0;
5877

5878 5879
free_rto_mask:
	free_cpumask_var(rd->rto_mask);
5880 5881
free_dlo_mask:
	free_cpumask_var(rd->dlo_mask);
5882 5883 5884 5885
free_online:
	free_cpumask_var(rd->online);
free_span:
	free_cpumask_var(rd->span);
5886
out:
5887
	return -ENOMEM;
G
Gregory Haskins 已提交
5888 5889
}

5890 5891 5892 5893 5894 5895
/*
 * By default the system creates a single root-domain with all cpus as
 * members (mimicking the global state we have today).
 */
struct root_domain def_root_domain;

G
Gregory Haskins 已提交
5896 5897
static void init_defrootdomain(void)
{
5898
	init_rootdomain(&def_root_domain);
5899

G
Gregory Haskins 已提交
5900 5901 5902
	atomic_set(&def_root_domain.refcount, 1);
}

5903
static struct root_domain *alloc_rootdomain(void)
G
Gregory Haskins 已提交
5904 5905 5906 5907 5908 5909 5910
{
	struct root_domain *rd;

	rd = kmalloc(sizeof(*rd), GFP_KERNEL);
	if (!rd)
		return NULL;

5911
	if (init_rootdomain(rd) != 0) {
5912 5913 5914
		kfree(rd);
		return NULL;
	}
G
Gregory Haskins 已提交
5915 5916 5917 5918

	return rd;
}

5919
static void free_sched_groups(struct sched_group *sg, int free_sgc)
5920 5921 5922 5923 5924 5925 5926 5927 5928 5929
{
	struct sched_group *tmp, *first;

	if (!sg)
		return;

	first = sg;
	do {
		tmp = sg->next;

5930 5931
		if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
			kfree(sg->sgc);
5932 5933 5934 5935 5936 5937

		kfree(sg);
		sg = tmp;
	} while (sg != first);
}

5938 5939 5940
static void free_sched_domain(struct rcu_head *rcu)
{
	struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5941 5942 5943 5944 5945 5946 5947 5948

	/*
	 * If its an overlapping domain it has private groups, iterate and
	 * nuke them all.
	 */
	if (sd->flags & SD_OVERLAP) {
		free_sched_groups(sd->groups, 1);
	} else if (atomic_dec_and_test(&sd->groups->ref)) {
5949
		kfree(sd->groups->sgc);
5950
		kfree(sd->groups);
5951
	}
5952 5953 5954 5955 5956 5957 5958 5959 5960 5961 5962 5963 5964 5965
	kfree(sd);
}

static void destroy_sched_domain(struct sched_domain *sd, int cpu)
{
	call_rcu(&sd->rcu, free_sched_domain);
}

static void destroy_sched_domains(struct sched_domain *sd, int cpu)
{
	for (; sd; sd = sd->parent)
		destroy_sched_domain(sd, cpu);
}

5966 5967 5968 5969 5970 5971 5972
/*
 * Keep a special pointer to the highest sched_domain that has
 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
 * allows us to avoid some pointer chasing select_idle_sibling().
 *
 * Also keep a unique ID per domain (we use the first cpu number in
 * the cpumask of the domain), this allows us to quickly tell if
5973
 * two cpus are in the same cache domain, see cpus_share_cache().
5974 5975
 */
DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5976
DEFINE_PER_CPU(int, sd_llc_size);
5977
DEFINE_PER_CPU(int, sd_llc_id);
5978
DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5979 5980
DEFINE_PER_CPU(struct sched_domain *, sd_busy);
DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5981 5982 5983 5984

static void update_top_cache_domain(int cpu)
{
	struct sched_domain *sd;
5985
	struct sched_domain *busy_sd = NULL;
5986
	int id = cpu;
5987
	int size = 1;
5988 5989

	sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5990
	if (sd) {
5991
		id = cpumask_first(sched_domain_span(sd));
5992
		size = cpumask_weight(sched_domain_span(sd));
5993
		busy_sd = sd->parent; /* sd_busy */
5994
	}
5995
	rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5996 5997

	rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5998
	per_cpu(sd_llc_size, cpu) = size;
5999
	per_cpu(sd_llc_id, cpu) = id;
6000 6001 6002

	sd = lowest_flag_domain(cpu, SD_NUMA);
	rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
6003 6004 6005

	sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
	rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
6006 6007
}

L
Linus Torvalds 已提交
6008
/*
I
Ingo Molnar 已提交
6009
 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
L
Linus Torvalds 已提交
6010 6011
 * hold the hotplug lock.
 */
I
Ingo Molnar 已提交
6012 6013
static void
cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
L
Linus Torvalds 已提交
6014
{
6015
	struct rq *rq = cpu_rq(cpu);
6016 6017 6018
	struct sched_domain *tmp;

	/* Remove the sched domains which do not contribute to scheduling. */
6019
	for (tmp = sd; tmp; ) {
6020 6021 6022
		struct sched_domain *parent = tmp->parent;
		if (!parent)
			break;
6023

6024
		if (sd_parent_degenerate(tmp, parent)) {
6025
			tmp->parent = parent->parent;
6026 6027
			if (parent->parent)
				parent->parent->child = tmp;
6028 6029 6030 6031 6032 6033 6034
			/*
			 * Transfer SD_PREFER_SIBLING down in case of a
			 * degenerate parent; the spans match for this
			 * so the property transfers.
			 */
			if (parent->flags & SD_PREFER_SIBLING)
				tmp->flags |= SD_PREFER_SIBLING;
6035
			destroy_sched_domain(parent, cpu);
6036 6037
		} else
			tmp = tmp->parent;
6038 6039
	}

6040
	if (sd && sd_degenerate(sd)) {
6041
		tmp = sd;
6042
		sd = sd->parent;
6043
		destroy_sched_domain(tmp, cpu);
6044 6045 6046
		if (sd)
			sd->child = NULL;
	}
L
Linus Torvalds 已提交
6047

6048
	sched_domain_debug(sd, cpu);
L
Linus Torvalds 已提交
6049

G
Gregory Haskins 已提交
6050
	rq_attach_root(rq, rd);
6051
	tmp = rq->sd;
N
Nick Piggin 已提交
6052
	rcu_assign_pointer(rq->sd, sd);
6053
	destroy_sched_domains(tmp, cpu);
6054 6055

	update_top_cache_domain(cpu);
L
Linus Torvalds 已提交
6056 6057 6058 6059 6060
}

/* Setup the mask of cpus configured for isolated domains */
static int __init isolated_cpu_setup(char *str)
{
6061 6062
	int ret;

R
Rusty Russell 已提交
6063
	alloc_bootmem_cpumask_var(&cpu_isolated_map);
6064 6065 6066 6067 6068
	ret = cpulist_parse(str, cpu_isolated_map);
	if (ret) {
		pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids);
		return 0;
	}
L
Linus Torvalds 已提交
6069 6070
	return 1;
}
I
Ingo Molnar 已提交
6071
__setup("isolcpus=", isolated_cpu_setup);
L
Linus Torvalds 已提交
6072

6073
struct s_data {
6074
	struct sched_domain ** __percpu sd;
6075 6076 6077
	struct root_domain	*rd;
};

6078 6079
enum s_alloc {
	sa_rootdomain,
6080
	sa_sd,
6081
	sa_sd_storage,
6082 6083 6084
	sa_none,
};

P
Peter Zijlstra 已提交
6085 6086 6087 6088 6089 6090 6091 6092 6093 6094 6095 6096 6097 6098 6099 6100 6101 6102 6103 6104 6105 6106 6107 6108 6109 6110 6111 6112 6113 6114 6115 6116 6117 6118 6119 6120 6121 6122
/*
 * Build an iteration mask that can exclude certain CPUs from the upwards
 * domain traversal.
 *
 * Asymmetric node setups can result in situations where the domain tree is of
 * unequal depth, make sure to skip domains that already cover the entire
 * range.
 *
 * In that case build_sched_domains() will have terminated the iteration early
 * and our sibling sd spans will be empty. Domains should always include the
 * cpu they're built on, so check that.
 *
 */
static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
{
	const struct cpumask *span = sched_domain_span(sd);
	struct sd_data *sdd = sd->private;
	struct sched_domain *sibling;
	int i;

	for_each_cpu(i, span) {
		sibling = *per_cpu_ptr(sdd->sd, i);
		if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
			continue;

		cpumask_set_cpu(i, sched_group_mask(sg));
	}
}

/*
 * Return the canonical balance cpu for this group, this is the first cpu
 * of this group that's also in the iteration mask.
 */
int group_balance_cpu(struct sched_group *sg)
{
	return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
}

6123 6124 6125 6126 6127 6128 6129
static int
build_overlap_sched_groups(struct sched_domain *sd, int cpu)
{
	struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
	const struct cpumask *span = sched_domain_span(sd);
	struct cpumask *covered = sched_domains_tmpmask;
	struct sd_data *sdd = sd->private;
6130
	struct sched_domain *sibling;
6131 6132 6133 6134 6135 6136 6137 6138 6139 6140
	int i;

	cpumask_clear(covered);

	for_each_cpu(i, span) {
		struct cpumask *sg_span;

		if (cpumask_test_cpu(i, covered))
			continue;

6141
		sibling = *per_cpu_ptr(sdd->sd, i);
P
Peter Zijlstra 已提交
6142 6143

		/* See the comment near build_group_mask(). */
6144
		if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
P
Peter Zijlstra 已提交
6145 6146
			continue;

6147
		sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6148
				GFP_KERNEL, cpu_to_node(cpu));
6149 6150 6151 6152 6153

		if (!sg)
			goto fail;

		sg_span = sched_group_cpus(sg);
6154 6155 6156
		if (sibling->child)
			cpumask_copy(sg_span, sched_domain_span(sibling->child));
		else
6157 6158 6159 6160
			cpumask_set_cpu(i, sg_span);

		cpumask_or(covered, covered, sg_span);

6161 6162
		sg->sgc = *per_cpu_ptr(sdd->sgc, i);
		if (atomic_inc_return(&sg->sgc->ref) == 1)
P
Peter Zijlstra 已提交
6163 6164
			build_group_mask(sd, sg);

6165
		/*
6166
		 * Initialize sgc->capacity such that even if we mess up the
6167 6168 6169
		 * domains and no possible iteration will get us here, we won't
		 * die on a /0 trap.
		 */
6170
		sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
6171

P
Peter Zijlstra 已提交
6172 6173 6174 6175 6176
		/*
		 * Make sure the first group of this domain contains the
		 * canonical balance cpu. Otherwise the sched_domain iteration
		 * breaks. See update_sg_lb_stats().
		 */
P
Peter Zijlstra 已提交
6177
		if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
P
Peter Zijlstra 已提交
6178
		    group_balance_cpu(sg) == cpu)
6179 6180 6181 6182 6183 6184 6185 6186 6187 6188 6189 6190 6191 6192 6193 6194 6195 6196 6197
			groups = sg;

		if (!first)
			first = sg;
		if (last)
			last->next = sg;
		last = sg;
		last->next = first;
	}
	sd->groups = groups;

	return 0;

fail:
	free_sched_groups(first, 0);

	return -ENOMEM;
}

6198
static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
L
Linus Torvalds 已提交
6199
{
6200 6201
	struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
	struct sched_domain *child = sd->child;
L
Linus Torvalds 已提交
6202

6203 6204
	if (child)
		cpu = cpumask_first(sched_domain_span(child));
6205

6206
	if (sg) {
6207
		*sg = *per_cpu_ptr(sdd->sg, cpu);
6208 6209
		(*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
		atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
6210
	}
6211 6212

	return cpu;
6213 6214
}

6215
/*
6216 6217
 * build_sched_groups will build a circular linked list of the groups
 * covered by the given span, and will set each group's ->cpumask correctly,
6218
 * and ->cpu_capacity to 0.
6219 6220
 *
 * Assumes the sched_domain tree is fully constructed
6221
 */
6222 6223
static int
build_sched_groups(struct sched_domain *sd, int cpu)
L
Linus Torvalds 已提交
6224
{
6225 6226 6227
	struct sched_group *first = NULL, *last = NULL;
	struct sd_data *sdd = sd->private;
	const struct cpumask *span = sched_domain_span(sd);
6228
	struct cpumask *covered;
6229
	int i;
6230

6231 6232 6233
	get_group(cpu, sdd, &sd->groups);
	atomic_inc(&sd->groups->ref);

6234
	if (cpu != cpumask_first(span))
6235 6236
		return 0;

6237 6238 6239
	lockdep_assert_held(&sched_domains_mutex);
	covered = sched_domains_tmpmask;

6240
	cpumask_clear(covered);
6241

6242 6243
	for_each_cpu(i, span) {
		struct sched_group *sg;
6244
		int group, j;
6245

6246 6247
		if (cpumask_test_cpu(i, covered))
			continue;
6248

6249
		group = get_group(i, sdd, &sg);
P
Peter Zijlstra 已提交
6250
		cpumask_setall(sched_group_mask(sg));
6251

6252 6253 6254
		for_each_cpu(j, span) {
			if (get_group(j, sdd, NULL) != group)
				continue;
6255

6256 6257 6258
			cpumask_set_cpu(j, covered);
			cpumask_set_cpu(j, sched_group_cpus(sg));
		}
6259

6260 6261 6262 6263 6264 6265 6266
		if (!first)
			first = sg;
		if (last)
			last->next = sg;
		last = sg;
	}
	last->next = first;
6267 6268

	return 0;
6269
}
6270

6271
/*
6272
 * Initialize sched groups cpu_capacity.
6273
 *
6274
 * cpu_capacity indicates the capacity of sched group, which is used while
6275
 * distributing the load between different sched groups in a sched domain.
6276 6277 6278 6279
 * Typically cpu_capacity for all the groups in a sched domain will be same
 * unless there are asymmetries in the topology. If there are asymmetries,
 * group having more cpu_capacity will pickup more load compared to the
 * group having less cpu_capacity.
6280
 */
6281
static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
6282
{
6283
	struct sched_group *sg = sd->groups;
6284

6285
	WARN_ON(!sg);
6286 6287 6288 6289 6290

	do {
		sg->group_weight = cpumask_weight(sched_group_cpus(sg));
		sg = sg->next;
	} while (sg != sd->groups);
6291

P
Peter Zijlstra 已提交
6292
	if (cpu != group_balance_cpu(sg))
6293
		return;
6294

6295 6296
	update_group_capacity(sd, cpu);
	atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
6297 6298
}

6299 6300 6301 6302 6303
/*
 * Initializers for schedule domains
 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
 */

6304
static int default_relax_domain_level = -1;
6305
int sched_domain_level_max;
6306 6307 6308

static int __init setup_relax_domain_level(char *str)
{
6309 6310
	if (kstrtoint(str, 0, &default_relax_domain_level))
		pr_warn("Unable to set relax_domain_level\n");
6311

6312 6313 6314 6315 6316 6317 6318 6319 6320 6321 6322 6323 6324 6325 6326 6327 6328 6329
	return 1;
}
__setup("relax_domain_level=", setup_relax_domain_level);

static void set_domain_attribute(struct sched_domain *sd,
				 struct sched_domain_attr *attr)
{
	int request;

	if (!attr || attr->relax_domain_level < 0) {
		if (default_relax_domain_level < 0)
			return;
		else
			request = default_relax_domain_level;
	} else
		request = attr->relax_domain_level;
	if (request < sd->level) {
		/* turn off idle balance on this domain */
6330
		sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6331 6332
	} else {
		/* turn on idle balance on this domain */
6333
		sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6334 6335 6336
	}
}

6337 6338 6339
static void __sdt_free(const struct cpumask *cpu_map);
static int __sdt_alloc(const struct cpumask *cpu_map);

6340 6341 6342 6343 6344
static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
				 const struct cpumask *cpu_map)
{
	switch (what) {
	case sa_rootdomain:
6345 6346
		if (!atomic_read(&d->rd->refcount))
			free_rootdomain(&d->rd->rcu); /* fall through */
6347 6348
	case sa_sd:
		free_percpu(d->sd); /* fall through */
6349
	case sa_sd_storage:
6350
		__sdt_free(cpu_map); /* fall through */
6351 6352 6353 6354
	case sa_none:
		break;
	}
}
6355

6356 6357 6358
static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
						   const struct cpumask *cpu_map)
{
6359 6360
	memset(d, 0, sizeof(*d));

6361 6362
	if (__sdt_alloc(cpu_map))
		return sa_sd_storage;
6363 6364 6365
	d->sd = alloc_percpu(struct sched_domain *);
	if (!d->sd)
		return sa_sd_storage;
6366
	d->rd = alloc_rootdomain();
6367
	if (!d->rd)
6368
		return sa_sd;
6369 6370
	return sa_rootdomain;
}
G
Gregory Haskins 已提交
6371

6372 6373 6374 6375 6376 6377 6378 6379 6380 6381 6382 6383
/*
 * NULL the sd_data elements we've used to build the sched_domain and
 * sched_group structure so that the subsequent __free_domain_allocs()
 * will not free the data we're using.
 */
static void claim_allocations(int cpu, struct sched_domain *sd)
{
	struct sd_data *sdd = sd->private;

	WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
	*per_cpu_ptr(sdd->sd, cpu) = NULL;

6384
	if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6385
		*per_cpu_ptr(sdd->sg, cpu) = NULL;
6386

6387 6388
	if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
		*per_cpu_ptr(sdd->sgc, cpu) = NULL;
6389 6390
}

6391 6392
#ifdef CONFIG_NUMA
static int sched_domains_numa_levels;
6393
enum numa_topology_type sched_numa_topology_type;
6394
static int *sched_domains_numa_distance;
6395
int sched_max_numa_distance;
6396 6397
static struct cpumask ***sched_domains_numa_masks;
static int sched_domains_curr_level;
6398
#endif
6399

6400 6401 6402
/*
 * SD_flags allowed in topology descriptions.
 *
6403 6404 6405
 * These flags are purely descriptive of the topology and do not prescribe
 * behaviour. Behaviour is artificial and mapped in the below sd_init()
 * function:
6406
 *
6407 6408 6409 6410
 *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
 *   SD_SHARE_PKG_RESOURCES - describes shared caches
 *   SD_NUMA                - describes NUMA topologies
 *   SD_SHARE_POWERDOMAIN   - describes shared power domain
6411
 *   SD_ASYM_CPUCAPACITY    - describes mixed capacity topologies
6412 6413 6414 6415 6416
 *
 * Odd one out, which beside describing the topology has a quirk also
 * prescribes the desired behaviour that goes along with it:
 *
 *   SD_ASYM_PACKING        - describes SMT quirks
6417 6418
 */
#define TOPOLOGY_SD_FLAGS		\
6419
	(SD_SHARE_CPUCAPACITY |		\
6420 6421
	 SD_SHARE_PKG_RESOURCES |	\
	 SD_NUMA |			\
6422
	 SD_ASYM_PACKING |		\
6423
	 SD_ASYM_CPUCAPACITY |		\
6424
	 SD_SHARE_POWERDOMAIN)
6425 6426

static struct sched_domain *
6427 6428
sd_init(struct sched_domain_topology_level *tl,
	struct sched_domain *child, int cpu)
6429 6430
{
	struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6431 6432 6433 6434 6435 6436 6437 6438 6439 6440 6441 6442 6443 6444 6445 6446
	int sd_weight, sd_flags = 0;

#ifdef CONFIG_NUMA
	/*
	 * Ugly hack to pass state to sd_numa_mask()...
	 */
	sched_domains_curr_level = tl->numa_level;
#endif

	sd_weight = cpumask_weight(tl->mask(cpu));

	if (tl->sd_flags)
		sd_flags = (*tl->sd_flags)();
	if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
			"wrong sd_flags in topology description\n"))
		sd_flags &= ~TOPOLOGY_SD_FLAGS;
6447 6448 6449 6450 6451

	*sd = (struct sched_domain){
		.min_interval		= sd_weight,
		.max_interval		= 2*sd_weight,
		.busy_factor		= 32,
6452
		.imbalance_pct		= 125,
6453 6454 6455 6456

		.cache_nice_tries	= 0,
		.busy_idx		= 0,
		.idle_idx		= 0,
6457 6458 6459 6460 6461 6462
		.newidle_idx		= 0,
		.wake_idx		= 0,
		.forkexec_idx		= 0,

		.flags			= 1*SD_LOAD_BALANCE
					| 1*SD_BALANCE_NEWIDLE
6463 6464
					| 1*SD_BALANCE_EXEC
					| 1*SD_BALANCE_FORK
6465
					| 0*SD_BALANCE_WAKE
6466
					| 1*SD_WAKE_AFFINE
6467
					| 0*SD_SHARE_CPUCAPACITY
6468
					| 0*SD_SHARE_PKG_RESOURCES
6469
					| 0*SD_SERIALIZE
6470
					| 0*SD_PREFER_SIBLING
6471 6472
					| 0*SD_NUMA
					| sd_flags
6473
					,
6474

6475 6476
		.last_balance		= jiffies,
		.balance_interval	= sd_weight,
6477
		.smt_gain		= 0,
6478 6479
		.max_newidle_lb_cost	= 0,
		.next_decay_max_lb_cost	= jiffies,
6480
		.child			= child,
6481 6482 6483
#ifdef CONFIG_SCHED_DEBUG
		.name			= tl->name,
#endif
6484 6485 6486
	};

	/*
6487
	 * Convert topological properties into behaviour.
6488
	 */
6489

6490 6491 6492 6493 6494 6495 6496
	if (sd->flags & SD_ASYM_CPUCAPACITY) {
		struct sched_domain *t = sd;

		for_each_lower_domain(t)
			t->flags |= SD_BALANCE_WAKE;
	}

6497
	if (sd->flags & SD_SHARE_CPUCAPACITY) {
6498
		sd->flags |= SD_PREFER_SIBLING;
6499 6500 6501 6502 6503 6504 6505 6506 6507 6508 6509 6510 6511 6512 6513 6514 6515 6516 6517 6518 6519 6520 6521 6522 6523 6524 6525 6526 6527 6528
		sd->imbalance_pct = 110;
		sd->smt_gain = 1178; /* ~15% */

	} else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
		sd->imbalance_pct = 117;
		sd->cache_nice_tries = 1;
		sd->busy_idx = 2;

#ifdef CONFIG_NUMA
	} else if (sd->flags & SD_NUMA) {
		sd->cache_nice_tries = 2;
		sd->busy_idx = 3;
		sd->idle_idx = 2;

		sd->flags |= SD_SERIALIZE;
		if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
			sd->flags &= ~(SD_BALANCE_EXEC |
				       SD_BALANCE_FORK |
				       SD_WAKE_AFFINE);
		}

#endif
	} else {
		sd->flags |= SD_PREFER_SIBLING;
		sd->cache_nice_tries = 1;
		sd->busy_idx = 2;
		sd->idle_idx = 1;
	}

	sd->private = &tl->data;
6529 6530 6531 6532

	return sd;
}

6533 6534 6535 6536 6537 6538 6539 6540 6541 6542 6543 6544 6545 6546
/*
 * Topology list, bottom-up.
 */
static struct sched_domain_topology_level default_topology[] = {
#ifdef CONFIG_SCHED_SMT
	{ cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
#endif
#ifdef CONFIG_SCHED_MC
	{ cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
#endif
	{ cpu_cpu_mask, SD_INIT_NAME(DIE) },
	{ NULL, },
};

6547 6548
static struct sched_domain_topology_level *sched_domain_topology =
	default_topology;
6549 6550 6551 6552 6553 6554

#define for_each_sd_topology(tl)			\
	for (tl = sched_domain_topology; tl->mask; tl++)

void set_sched_topology(struct sched_domain_topology_level *tl)
{
6555 6556 6557
	if (WARN_ON_ONCE(sched_smp_initialized))
		return;

6558 6559 6560 6561 6562
	sched_domain_topology = tl;
}

#ifdef CONFIG_NUMA

6563 6564 6565 6566 6567
static const struct cpumask *sd_numa_mask(int cpu)
{
	return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
}

6568 6569 6570 6571 6572 6573 6574 6575 6576 6577 6578 6579 6580 6581 6582 6583 6584 6585 6586 6587 6588
static void sched_numa_warn(const char *str)
{
	static int done = false;
	int i,j;

	if (done)
		return;

	done = true;

	printk(KERN_WARNING "ERROR: %s\n\n", str);

	for (i = 0; i < nr_node_ids; i++) {
		printk(KERN_WARNING "  ");
		for (j = 0; j < nr_node_ids; j++)
			printk(KERN_CONT "%02d ", node_distance(i,j));
		printk(KERN_CONT "\n");
	}
	printk(KERN_WARNING "\n");
}

6589
bool find_numa_distance(int distance)
6590 6591 6592 6593 6594 6595 6596 6597 6598 6599 6600 6601 6602 6603
{
	int i;

	if (distance == node_distance(0, 0))
		return true;

	for (i = 0; i < sched_domains_numa_levels; i++) {
		if (sched_domains_numa_distance[i] == distance)
			return true;
	}

	return false;
}

6604 6605 6606 6607 6608 6609 6610 6611 6612 6613 6614 6615 6616 6617 6618 6619 6620 6621 6622 6623 6624 6625 6626 6627 6628
/*
 * A system can have three types of NUMA topology:
 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
 *
 * The difference between a glueless mesh topology and a backplane
 * topology lies in whether communication between not directly
 * connected nodes goes through intermediary nodes (where programs
 * could run), or through backplane controllers. This affects
 * placement of programs.
 *
 * The type of topology can be discerned with the following tests:
 * - If the maximum distance between any nodes is 1 hop, the system
 *   is directly connected.
 * - If for two nodes A and B, located N > 1 hops away from each other,
 *   there is an intermediary node C, which is < N hops away from both
 *   nodes A and B, the system is a glueless mesh.
 */
static void init_numa_topology_type(void)
{
	int a, b, c, n;

	n = sched_max_numa_distance;

6629
	if (sched_domains_numa_levels <= 1) {
6630
		sched_numa_topology_type = NUMA_DIRECT;
6631 6632
		return;
	}
6633 6634 6635 6636 6637 6638 6639 6640 6641 6642 6643 6644 6645 6646 6647 6648 6649 6650 6651 6652 6653 6654 6655

	for_each_online_node(a) {
		for_each_online_node(b) {
			/* Find two nodes furthest removed from each other. */
			if (node_distance(a, b) < n)
				continue;

			/* Is there an intermediary node between a and b? */
			for_each_online_node(c) {
				if (node_distance(a, c) < n &&
				    node_distance(b, c) < n) {
					sched_numa_topology_type =
							NUMA_GLUELESS_MESH;
					return;
				}
			}

			sched_numa_topology_type = NUMA_BACKPLANE;
			return;
		}
	}
}

6656 6657 6658 6659 6660 6661 6662 6663 6664 6665 6666 6667 6668 6669 6670 6671 6672 6673 6674 6675 6676
static void sched_init_numa(void)
{
	int next_distance, curr_distance = node_distance(0, 0);
	struct sched_domain_topology_level *tl;
	int level = 0;
	int i, j, k;

	sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
	if (!sched_domains_numa_distance)
		return;

	/*
	 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
	 * unique distances in the node_distance() table.
	 *
	 * Assumes node_distance(0,j) includes all distances in
	 * node_distance(i,j) in order to avoid cubic time.
	 */
	next_distance = curr_distance;
	for (i = 0; i < nr_node_ids; i++) {
		for (j = 0; j < nr_node_ids; j++) {
6677 6678 6679 6680 6681 6682 6683 6684 6685 6686 6687 6688 6689 6690 6691 6692 6693 6694 6695 6696 6697 6698 6699 6700
			for (k = 0; k < nr_node_ids; k++) {
				int distance = node_distance(i, k);

				if (distance > curr_distance &&
				    (distance < next_distance ||
				     next_distance == curr_distance))
					next_distance = distance;

				/*
				 * While not a strong assumption it would be nice to know
				 * about cases where if node A is connected to B, B is not
				 * equally connected to A.
				 */
				if (sched_debug() && node_distance(k, i) != distance)
					sched_numa_warn("Node-distance not symmetric");

				if (sched_debug() && i && !find_numa_distance(distance))
					sched_numa_warn("Node-0 not representative");
			}
			if (next_distance != curr_distance) {
				sched_domains_numa_distance[level++] = next_distance;
				sched_domains_numa_levels = level;
				curr_distance = next_distance;
			} else break;
6701
		}
6702 6703 6704 6705 6706 6707

		/*
		 * In case of sched_debug() we verify the above assumption.
		 */
		if (!sched_debug())
			break;
6708
	}
6709 6710 6711 6712

	if (!level)
		return;

6713 6714 6715 6716
	/*
	 * 'level' contains the number of unique distances, excluding the
	 * identity distance node_distance(i,i).
	 *
V
Viresh Kumar 已提交
6717
	 * The sched_domains_numa_distance[] array includes the actual distance
6718 6719 6720
	 * numbers.
	 */

6721 6722 6723 6724 6725 6726 6727 6728 6729 6730 6731
	/*
	 * Here, we should temporarily reset sched_domains_numa_levels to 0.
	 * If it fails to allocate memory for array sched_domains_numa_masks[][],
	 * the array will contain less then 'level' members. This could be
	 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
	 * in other functions.
	 *
	 * We reset it to 'level' at the end of this function.
	 */
	sched_domains_numa_levels = 0;

6732 6733 6734 6735 6736 6737 6738 6739 6740 6741 6742 6743 6744 6745 6746
	sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
	if (!sched_domains_numa_masks)
		return;

	/*
	 * Now for each level, construct a mask per node which contains all
	 * cpus of nodes that are that many hops away from us.
	 */
	for (i = 0; i < level; i++) {
		sched_domains_numa_masks[i] =
			kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
		if (!sched_domains_numa_masks[i])
			return;

		for (j = 0; j < nr_node_ids; j++) {
6747
			struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6748 6749 6750 6751 6752
			if (!mask)
				return;

			sched_domains_numa_masks[i][j] = mask;

6753
			for_each_node(k) {
6754
				if (node_distance(j, k) > sched_domains_numa_distance[i])
6755 6756 6757 6758 6759 6760 6761
					continue;

				cpumask_or(mask, mask, cpumask_of_node(k));
			}
		}
	}

6762 6763 6764
	/* Compute default topology size */
	for (i = 0; sched_domain_topology[i].mask; i++);

6765
	tl = kzalloc((i + level + 1) *
6766 6767 6768 6769 6770 6771 6772
			sizeof(struct sched_domain_topology_level), GFP_KERNEL);
	if (!tl)
		return;

	/*
	 * Copy the default topology bits..
	 */
6773 6774
	for (i = 0; sched_domain_topology[i].mask; i++)
		tl[i] = sched_domain_topology[i];
6775 6776 6777 6778 6779 6780 6781

	/*
	 * .. and append 'j' levels of NUMA goodness.
	 */
	for (j = 0; j < level; i++, j++) {
		tl[i] = (struct sched_domain_topology_level){
			.mask = sd_numa_mask,
6782
			.sd_flags = cpu_numa_flags,
6783 6784
			.flags = SDTL_OVERLAP,
			.numa_level = j,
6785
			SD_INIT_NAME(NUMA)
6786 6787 6788 6789
		};
	}

	sched_domain_topology = tl;
6790 6791

	sched_domains_numa_levels = level;
6792
	sched_max_numa_distance = sched_domains_numa_distance[level - 1];
6793 6794

	init_numa_topology_type();
6795
}
6796

6797
static void sched_domains_numa_masks_set(unsigned int cpu)
6798 6799
{
	int node = cpu_to_node(cpu);
6800
	int i, j;
6801 6802 6803 6804 6805 6806 6807 6808 6809

	for (i = 0; i < sched_domains_numa_levels; i++) {
		for (j = 0; j < nr_node_ids; j++) {
			if (node_distance(j, node) <= sched_domains_numa_distance[i])
				cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
		}
	}
}

6810
static void sched_domains_numa_masks_clear(unsigned int cpu)
6811 6812
{
	int i, j;
6813

6814 6815 6816 6817 6818 6819
	for (i = 0; i < sched_domains_numa_levels; i++) {
		for (j = 0; j < nr_node_ids; j++)
			cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
	}
}

6820
#else
6821 6822 6823
static inline void sched_init_numa(void) { }
static void sched_domains_numa_masks_set(unsigned int cpu) { }
static void sched_domains_numa_masks_clear(unsigned int cpu) { }
6824 6825
#endif /* CONFIG_NUMA */

6826 6827 6828 6829 6830
static int __sdt_alloc(const struct cpumask *cpu_map)
{
	struct sched_domain_topology_level *tl;
	int j;

6831
	for_each_sd_topology(tl) {
6832 6833 6834 6835 6836 6837 6838 6839 6840 6841
		struct sd_data *sdd = &tl->data;

		sdd->sd = alloc_percpu(struct sched_domain *);
		if (!sdd->sd)
			return -ENOMEM;

		sdd->sg = alloc_percpu(struct sched_group *);
		if (!sdd->sg)
			return -ENOMEM;

6842 6843
		sdd->sgc = alloc_percpu(struct sched_group_capacity *);
		if (!sdd->sgc)
6844 6845
			return -ENOMEM;

6846 6847 6848
		for_each_cpu(j, cpu_map) {
			struct sched_domain *sd;
			struct sched_group *sg;
6849
			struct sched_group_capacity *sgc;
6850

P
Peter Zijlstra 已提交
6851
			sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6852 6853 6854 6855 6856 6857 6858 6859 6860 6861 6862
					GFP_KERNEL, cpu_to_node(j));
			if (!sd)
				return -ENOMEM;

			*per_cpu_ptr(sdd->sd, j) = sd;

			sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
					GFP_KERNEL, cpu_to_node(j));
			if (!sg)
				return -ENOMEM;

6863 6864
			sg->next = sg;

6865
			*per_cpu_ptr(sdd->sg, j) = sg;
6866

6867
			sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6868
					GFP_KERNEL, cpu_to_node(j));
6869
			if (!sgc)
6870 6871
				return -ENOMEM;

6872
			*per_cpu_ptr(sdd->sgc, j) = sgc;
6873 6874 6875 6876 6877 6878 6879 6880 6881 6882 6883
		}
	}

	return 0;
}

static void __sdt_free(const struct cpumask *cpu_map)
{
	struct sched_domain_topology_level *tl;
	int j;

6884
	for_each_sd_topology(tl) {
6885 6886 6887
		struct sd_data *sdd = &tl->data;

		for_each_cpu(j, cpu_map) {
6888 6889 6890 6891 6892 6893 6894 6895 6896 6897 6898
			struct sched_domain *sd;

			if (sdd->sd) {
				sd = *per_cpu_ptr(sdd->sd, j);
				if (sd && (sd->flags & SD_OVERLAP))
					free_sched_groups(sd->groups, 0);
				kfree(*per_cpu_ptr(sdd->sd, j));
			}

			if (sdd->sg)
				kfree(*per_cpu_ptr(sdd->sg, j));
6899 6900
			if (sdd->sgc)
				kfree(*per_cpu_ptr(sdd->sgc, j));
6901 6902
		}
		free_percpu(sdd->sd);
6903
		sdd->sd = NULL;
6904
		free_percpu(sdd->sg);
6905
		sdd->sg = NULL;
6906 6907
		free_percpu(sdd->sgc);
		sdd->sgc = NULL;
6908 6909 6910
	}
}

6911
struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6912 6913
		const struct cpumask *cpu_map, struct sched_domain_attr *attr,
		struct sched_domain *child, int cpu)
6914
{
6915
	struct sched_domain *sd = sd_init(tl, child, cpu);
6916 6917

	cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6918 6919 6920
	if (child) {
		sd->level = child->level + 1;
		sched_domain_level_max = max(sched_domain_level_max, sd->level);
6921
		child->parent = sd;
P
Peter Zijlstra 已提交
6922 6923 6924 6925 6926 6927 6928 6929 6930 6931 6932 6933 6934 6935

		if (!cpumask_subset(sched_domain_span(child),
				    sched_domain_span(sd))) {
			pr_err("BUG: arch topology borken\n");
#ifdef CONFIG_SCHED_DEBUG
			pr_err("     the %s domain not a subset of the %s domain\n",
					child->name, sd->name);
#endif
			/* Fixup, ensure @sd has at least @child cpus. */
			cpumask_or(sched_domain_span(sd),
				   sched_domain_span(sd),
				   sched_domain_span(child));
		}

6936
	}
6937
	set_domain_attribute(sd, attr);
6938 6939 6940 6941

	return sd;
}

6942 6943 6944 6945
/*
 * Build sched domains for a given set of cpus and attach the sched domains
 * to the individual cpus
 */
6946 6947
static int build_sched_domains(const struct cpumask *cpu_map,
			       struct sched_domain_attr *attr)
6948
{
6949
	enum s_alloc alloc_state;
6950
	struct sched_domain *sd;
6951
	struct s_data d;
6952
	struct rq *rq = NULL;
6953
	int i, ret = -ENOMEM;
6954

6955 6956 6957
	alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
	if (alloc_state != sa_rootdomain)
		goto error;
6958

6959
	/* Set up domains for cpus specified by the cpu_map. */
6960
	for_each_cpu(i, cpu_map) {
6961 6962
		struct sched_domain_topology_level *tl;

6963
		sd = NULL;
6964
		for_each_sd_topology(tl) {
6965
			sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6966 6967
			if (tl == sched_domain_topology)
				*per_cpu_ptr(d.sd, i) = sd;
6968 6969
			if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
				sd->flags |= SD_OVERLAP;
6970 6971
			if (cpumask_equal(cpu_map, sched_domain_span(sd)))
				break;
6972
		}
6973 6974 6975 6976 6977 6978
	}

	/* Build the groups for the domains */
	for_each_cpu(i, cpu_map) {
		for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
			sd->span_weight = cpumask_weight(sched_domain_span(sd));
6979 6980 6981 6982 6983 6984 6985
			if (sd->flags & SD_OVERLAP) {
				if (build_overlap_sched_groups(sd, i))
					goto error;
			} else {
				if (build_sched_groups(sd, i))
					goto error;
			}
6986
		}
6987
	}
6988

6989
	/* Calculate CPU capacity for physical packages and nodes */
6990 6991 6992
	for (i = nr_cpumask_bits-1; i >= 0; i--) {
		if (!cpumask_test_cpu(i, cpu_map))
			continue;
6993

6994 6995
		for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
			claim_allocations(i, sd);
6996
			init_sched_groups_capacity(i, sd);
6997
		}
6998
	}
6999

L
Linus Torvalds 已提交
7000
	/* Attach the domains */
7001
	rcu_read_lock();
7002
	for_each_cpu(i, cpu_map) {
7003
		rq = cpu_rq(i);
7004
		sd = *per_cpu_ptr(d.sd, i);
7005 7006 7007 7008 7009

		/* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
		if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
			WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);

7010
		cpu_attach_domain(sd, d.rd, i);
L
Linus Torvalds 已提交
7011
	}
7012
	rcu_read_unlock();
7013

7014
	if (rq && sched_debug_enabled) {
7015 7016 7017 7018
		pr_info("span: %*pbl (max cpu_capacity = %lu)\n",
			cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
	}

7019
	ret = 0;
7020
error:
7021
	__free_domain_allocs(&d, alloc_state, cpu_map);
7022
	return ret;
L
Linus Torvalds 已提交
7023
}
P
Paul Jackson 已提交
7024

7025
static cpumask_var_t *doms_cur;	/* current sched domains */
P
Paul Jackson 已提交
7026
static int ndoms_cur;		/* number of sched domains in 'doms_cur' */
I
Ingo Molnar 已提交
7027 7028
static struct sched_domain_attr *dattr_cur;
				/* attribues of custom domains in 'doms_cur' */
P
Paul Jackson 已提交
7029 7030 7031

/*
 * Special case: If a kmalloc of a doms_cur partition (array of
7032 7033
 * cpumask) fails, then fallback to a single sched domain,
 * as determined by the single cpumask fallback_doms.
P
Paul Jackson 已提交
7034
 */
7035
static cpumask_var_t fallback_doms;
P
Paul Jackson 已提交
7036

7037 7038 7039 7040 7041
/*
 * arch_update_cpu_topology lets virtualized architectures update the
 * cpu core maps. It is supposed to return 1 if the topology changed
 * or 0 if it stayed the same.
 */
7042
int __weak arch_update_cpu_topology(void)
7043
{
7044
	return 0;
7045 7046
}

7047 7048 7049 7050 7051 7052 7053 7054 7055 7056 7057 7058 7059 7060 7061 7062 7063 7064 7065 7066 7067 7068 7069 7070 7071
cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
{
	int i;
	cpumask_var_t *doms;

	doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
	if (!doms)
		return NULL;
	for (i = 0; i < ndoms; i++) {
		if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
			free_sched_domains(doms, i);
			return NULL;
		}
	}
	return doms;
}

void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
{
	unsigned int i;
	for (i = 0; i < ndoms; i++)
		free_cpumask_var(doms[i]);
	kfree(doms);
}

7072
/*
I
Ingo Molnar 已提交
7073
 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
P
Paul Jackson 已提交
7074 7075
 * For now this just excludes isolated cpus, but could be used to
 * exclude other special cases in the future.
7076
 */
7077
static int init_sched_domains(const struct cpumask *cpu_map)
7078
{
7079 7080
	int err;

7081
	arch_update_cpu_topology();
P
Paul Jackson 已提交
7082
	ndoms_cur = 1;
7083
	doms_cur = alloc_sched_domains(ndoms_cur);
P
Paul Jackson 已提交
7084
	if (!doms_cur)
7085 7086
		doms_cur = &fallback_doms;
	cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
7087
	err = build_sched_domains(doms_cur[0], NULL);
7088
	register_sched_domain_sysctl();
7089 7090

	return err;
7091 7092 7093 7094 7095 7096
}

/*
 * Detach sched domains from a group of cpus specified in cpu_map
 * These cpus will now be attached to the NULL domain
 */
7097
static void detach_destroy_domains(const struct cpumask *cpu_map)
7098 7099 7100
{
	int i;

7101
	rcu_read_lock();
7102
	for_each_cpu(i, cpu_map)
G
Gregory Haskins 已提交
7103
		cpu_attach_domain(NULL, &def_root_domain, i);
7104
	rcu_read_unlock();
7105 7106
}

7107 7108 7109 7110 7111 7112 7113 7114 7115 7116 7117 7118 7119 7120 7121 7122
/* handle null as "default" */
static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
			struct sched_domain_attr *new, int idx_new)
{
	struct sched_domain_attr tmp;

	/* fast path */
	if (!new && !cur)
		return 1;

	tmp = SD_ATTR_INIT;
	return !memcmp(cur ? (cur + idx_cur) : &tmp,
			new ? (new + idx_new) : &tmp,
			sizeof(struct sched_domain_attr));
}

P
Paul Jackson 已提交
7123 7124
/*
 * Partition sched domains as specified by the 'ndoms_new'
I
Ingo Molnar 已提交
7125
 * cpumasks in the array doms_new[] of cpumasks. This compares
P
Paul Jackson 已提交
7126 7127 7128
 * doms_new[] to the current sched domain partitioning, doms_cur[].
 * It destroys each deleted domain and builds each new domain.
 *
7129
 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
I
Ingo Molnar 已提交
7130 7131 7132
 * The masks don't intersect (don't overlap.) We should setup one
 * sched domain for each mask. CPUs not in any of the cpumasks will
 * not be load balanced. If the same cpumask appears both in the
P
Paul Jackson 已提交
7133 7134 7135
 * current 'doms_cur' domains and in the new 'doms_new', we can leave
 * it as it is.
 *
7136 7137 7138 7139 7140 7141
 * The passed in 'doms_new' should be allocated using
 * alloc_sched_domains.  This routine takes ownership of it and will
 * free_sched_domains it when done with it. If the caller failed the
 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
 * and partition_sched_domains() will fallback to the single partition
 * 'fallback_doms', it also forces the domains to be rebuilt.
P
Paul Jackson 已提交
7142
 *
7143
 * If doms_new == NULL it will be replaced with cpu_online_mask.
7144 7145
 * ndoms_new == 0 is a special case for destroying existing domains,
 * and it will not create the default domain.
7146
 *
P
Paul Jackson 已提交
7147 7148
 * Call with hotplug lock held
 */
7149
void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
7150
			     struct sched_domain_attr *dattr_new)
P
Paul Jackson 已提交
7151
{
7152
	int i, j, n;
7153
	int new_topology;
P
Paul Jackson 已提交
7154

7155
	mutex_lock(&sched_domains_mutex);
7156

7157 7158 7159
	/* always unregister in case we don't destroy any domains */
	unregister_sched_domain_sysctl();

7160 7161 7162
	/* Let architecture update cpu core mappings. */
	new_topology = arch_update_cpu_topology();

7163
	n = doms_new ? ndoms_new : 0;
P
Paul Jackson 已提交
7164 7165 7166

	/* Destroy deleted domains */
	for (i = 0; i < ndoms_cur; i++) {
7167
		for (j = 0; j < n && !new_topology; j++) {
7168
			if (cpumask_equal(doms_cur[i], doms_new[j])
7169
			    && dattrs_equal(dattr_cur, i, dattr_new, j))
P
Paul Jackson 已提交
7170 7171 7172
				goto match1;
		}
		/* no match - a current sched domain not in new doms_new[] */
7173
		detach_destroy_domains(doms_cur[i]);
P
Paul Jackson 已提交
7174 7175 7176 7177
match1:
		;
	}

7178
	n = ndoms_cur;
7179
	if (doms_new == NULL) {
7180
		n = 0;
7181
		doms_new = &fallback_doms;
7182
		cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
7183
		WARN_ON_ONCE(dattr_new);
7184 7185
	}

P
Paul Jackson 已提交
7186 7187
	/* Build new domains */
	for (i = 0; i < ndoms_new; i++) {
7188
		for (j = 0; j < n && !new_topology; j++) {
7189
			if (cpumask_equal(doms_new[i], doms_cur[j])
7190
			    && dattrs_equal(dattr_new, i, dattr_cur, j))
P
Paul Jackson 已提交
7191 7192 7193
				goto match2;
		}
		/* no match - add a new doms_new */
7194
		build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
P
Paul Jackson 已提交
7195 7196 7197 7198 7199
match2:
		;
	}

	/* Remember the new sched domains */
7200 7201
	if (doms_cur != &fallback_doms)
		free_sched_domains(doms_cur, ndoms_cur);
7202
	kfree(dattr_cur);	/* kfree(NULL) is safe */
P
Paul Jackson 已提交
7203
	doms_cur = doms_new;
7204
	dattr_cur = dattr_new;
P
Paul Jackson 已提交
7205
	ndoms_cur = ndoms_new;
7206 7207

	register_sched_domain_sysctl();
7208

7209
	mutex_unlock(&sched_domains_mutex);
P
Paul Jackson 已提交
7210 7211
}

7212 7213
static int num_cpus_frozen;	/* used to mark begin/end of suspend/resume */

L
Linus Torvalds 已提交
7214
/*
7215 7216 7217
 * Update cpusets according to cpu_active mask.  If cpusets are
 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
 * around partition_sched_domains().
7218 7219 7220
 *
 * If we come here as part of a suspend/resume, don't touch cpusets because we
 * want to restore it back to its original state upon resume anyway.
L
Linus Torvalds 已提交
7221
 */
7222
static void cpuset_cpu_active(void)
7223
{
7224
	if (cpuhp_tasks_frozen) {
7225 7226 7227 7228 7229 7230 7231 7232 7233
		/*
		 * num_cpus_frozen tracks how many CPUs are involved in suspend
		 * resume sequence. As long as this is not the last online
		 * operation in the resume sequence, just build a single sched
		 * domain, ignoring cpusets.
		 */
		num_cpus_frozen--;
		if (likely(num_cpus_frozen)) {
			partition_sched_domains(1, NULL, NULL);
7234
			return;
7235 7236 7237 7238 7239 7240
		}
		/*
		 * This is the last CPU online operation. So fall through and
		 * restore the original sched domains by considering the
		 * cpuset configurations.
		 */
7241
	}
7242
	cpuset_update_active_cpus(true);
7243
}
7244

7245
static int cpuset_cpu_inactive(unsigned int cpu)
7246
{
7247 7248
	unsigned long flags;
	struct dl_bw *dl_b;
7249 7250
	bool overflow;
	int cpus;
7251

7252
	if (!cpuhp_tasks_frozen) {
7253 7254
		rcu_read_lock_sched();
		dl_b = dl_bw_of(cpu);
7255

7256 7257 7258 7259
		raw_spin_lock_irqsave(&dl_b->lock, flags);
		cpus = dl_bw_cpus(cpu);
		overflow = __dl_overflow(dl_b, cpus, 0, 0);
		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7260

7261
		rcu_read_unlock_sched();
7262

7263
		if (overflow)
7264
			return -EBUSY;
7265
		cpuset_update_active_cpus(false);
7266
	} else {
7267 7268
		num_cpus_frozen++;
		partition_sched_domains(1, NULL, NULL);
7269
	}
7270
	return 0;
7271 7272
}

7273
int sched_cpu_activate(unsigned int cpu)
7274
{
7275 7276 7277
	struct rq *rq = cpu_rq(cpu);
	unsigned long flags;

7278
	set_cpu_active(cpu, true);
7279

7280
	if (sched_smp_initialized) {
7281
		sched_domains_numa_masks_set(cpu);
7282
		cpuset_cpu_active();
7283
	}
7284 7285 7286 7287 7288 7289 7290 7291 7292 7293 7294 7295 7296 7297 7298 7299 7300 7301 7302

	/*
	 * Put the rq online, if not already. This happens:
	 *
	 * 1) In the early boot process, because we build the real domains
	 *    after all cpus have been brought up.
	 *
	 * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
	 *    domains.
	 */
	raw_spin_lock_irqsave(&rq->lock, flags);
	if (rq->rd) {
		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
		set_rq_online(rq);
	}
	raw_spin_unlock_irqrestore(&rq->lock, flags);

	update_max_interval();

7303
	return 0;
7304 7305
}

7306
int sched_cpu_deactivate(unsigned int cpu)
7307 7308 7309
{
	int ret;

7310
	set_cpu_active(cpu, false);
7311 7312 7313 7314 7315 7316 7317 7318 7319 7320 7321 7322 7323 7324
	/*
	 * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU
	 * users of this state to go away such that all new such users will
	 * observe it.
	 *
	 * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
	 * not imply sync_sched(), so wait for both.
	 *
	 * Do sync before park smpboot threads to take care the rcu boost case.
	 */
	if (IS_ENABLED(CONFIG_PREEMPT))
		synchronize_rcu_mult(call_rcu, call_rcu_sched);
	else
		synchronize_rcu();
7325 7326 7327 7328 7329 7330 7331 7332

	if (!sched_smp_initialized)
		return 0;

	ret = cpuset_cpu_inactive(cpu);
	if (ret) {
		set_cpu_active(cpu, true);
		return ret;
7333
	}
7334 7335
	sched_domains_numa_masks_clear(cpu);
	return 0;
7336 7337
}

7338 7339 7340 7341 7342 7343 7344 7345
static void sched_rq_cpu_starting(unsigned int cpu)
{
	struct rq *rq = cpu_rq(cpu);

	rq->calc_load_update = calc_load_update;
	update_max_interval();
}

7346 7347 7348
int sched_cpu_starting(unsigned int cpu)
{
	set_cpu_rq_start_time(cpu);
7349
	sched_rq_cpu_starting(cpu);
7350
	return 0;
7351 7352
}

7353 7354 7355 7356 7357 7358 7359 7360 7361 7362 7363 7364 7365 7366 7367 7368 7369 7370
#ifdef CONFIG_HOTPLUG_CPU
int sched_cpu_dying(unsigned int cpu)
{
	struct rq *rq = cpu_rq(cpu);
	unsigned long flags;

	/* Handle pending wakeups and then migrate everything off */
	sched_ttwu_pending();
	raw_spin_lock_irqsave(&rq->lock, flags);
	if (rq->rd) {
		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
		set_rq_offline(rq);
	}
	migrate_tasks(rq);
	BUG_ON(rq->nr_running != 1);
	raw_spin_unlock_irqrestore(&rq->lock, flags);
	calc_load_migrate(rq);
	update_max_interval();
7371
	nohz_balance_exit_idle(cpu);
7372
	hrtick_clear(rq);
7373 7374 7375 7376
	return 0;
}
#endif

L
Linus Torvalds 已提交
7377 7378
void __init sched_init_smp(void)
{
7379 7380 7381
	cpumask_var_t non_isolated_cpus;

	alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
7382
	alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
7383

7384 7385
	sched_init_numa();

7386 7387 7388 7389 7390
	/*
	 * There's no userspace yet to cause hotplug operations; hence all the
	 * cpu masks are stable and all blatant races in the below code cannot
	 * happen.
	 */
7391
	mutex_lock(&sched_domains_mutex);
7392
	init_sched_domains(cpu_active_mask);
7393 7394 7395
	cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
	if (cpumask_empty(non_isolated_cpus))
		cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
7396
	mutex_unlock(&sched_domains_mutex);
7397

7398
	/* Move init over to a non-isolated CPU */
7399
	if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
7400
		BUG();
I
Ingo Molnar 已提交
7401
	sched_init_granularity();
7402
	free_cpumask_var(non_isolated_cpus);
7403

7404
	init_sched_rt_class();
7405
	init_sched_dl_class();
7406
	sched_smp_initialized = true;
L
Linus Torvalds 已提交
7407
}
7408 7409 7410

static int __init migration_init(void)
{
7411
	sched_rq_cpu_starting(smp_processor_id());
7412
	return 0;
L
Linus Torvalds 已提交
7413
}
7414 7415
early_initcall(migration_init);

L
Linus Torvalds 已提交
7416 7417 7418
#else
void __init sched_init_smp(void)
{
I
Ingo Molnar 已提交
7419
	sched_init_granularity();
L
Linus Torvalds 已提交
7420 7421 7422 7423 7424 7425 7426 7427 7428 7429
}
#endif /* CONFIG_SMP */

int in_sched_functions(unsigned long addr)
{
	return in_lock_functions(addr) ||
		(addr >= (unsigned long)__sched_text_start
		&& addr < (unsigned long)__sched_text_end);
}

7430
#ifdef CONFIG_CGROUP_SCHED
7431 7432 7433 7434
/*
 * Default task group.
 * Every task in system belongs to this group at bootup.
 */
7435
struct task_group root_task_group;
7436
LIST_HEAD(task_groups);
7437 7438 7439

/* Cacheline aligned slab cache for task_group */
static struct kmem_cache *task_group_cache __read_mostly;
7440
#endif
P
Peter Zijlstra 已提交
7441

7442
DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
P
Peter Zijlstra 已提交
7443

L
Linus Torvalds 已提交
7444 7445
void __init sched_init(void)
{
I
Ingo Molnar 已提交
7446
	int i, j;
7447 7448 7449 7450 7451 7452 7453 7454 7455
	unsigned long alloc_size = 0, ptr;

#ifdef CONFIG_FAIR_GROUP_SCHED
	alloc_size += 2 * nr_cpu_ids * sizeof(void **);
#endif
#ifdef CONFIG_RT_GROUP_SCHED
	alloc_size += 2 * nr_cpu_ids * sizeof(void **);
#endif
	if (alloc_size) {
7456
		ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
7457 7458

#ifdef CONFIG_FAIR_GROUP_SCHED
7459
		root_task_group.se = (struct sched_entity **)ptr;
7460 7461
		ptr += nr_cpu_ids * sizeof(void **);

7462
		root_task_group.cfs_rq = (struct cfs_rq **)ptr;
7463
		ptr += nr_cpu_ids * sizeof(void **);
7464

7465
#endif /* CONFIG_FAIR_GROUP_SCHED */
7466
#ifdef CONFIG_RT_GROUP_SCHED
7467
		root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7468 7469
		ptr += nr_cpu_ids * sizeof(void **);

7470
		root_task_group.rt_rq = (struct rt_rq **)ptr;
7471 7472
		ptr += nr_cpu_ids * sizeof(void **);

7473
#endif /* CONFIG_RT_GROUP_SCHED */
7474
	}
7475
#ifdef CONFIG_CPUMASK_OFFSTACK
7476 7477 7478
	for_each_possible_cpu(i) {
		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
7479
	}
7480
#endif /* CONFIG_CPUMASK_OFFSTACK */
I
Ingo Molnar 已提交
7481

7482 7483 7484
	init_rt_bandwidth(&def_rt_bandwidth,
			global_rt_period(), global_rt_runtime());
	init_dl_bandwidth(&def_dl_bandwidth,
7485
			global_rt_period(), global_rt_runtime());
7486

G
Gregory Haskins 已提交
7487 7488 7489 7490
#ifdef CONFIG_SMP
	init_defrootdomain();
#endif

7491
#ifdef CONFIG_RT_GROUP_SCHED
7492
	init_rt_bandwidth(&root_task_group.rt_bandwidth,
7493
			global_rt_period(), global_rt_runtime());
7494
#endif /* CONFIG_RT_GROUP_SCHED */
7495

D
Dhaval Giani 已提交
7496
#ifdef CONFIG_CGROUP_SCHED
7497 7498
	task_group_cache = KMEM_CACHE(task_group, 0);

7499 7500
	list_add(&root_task_group.list, &task_groups);
	INIT_LIST_HEAD(&root_task_group.children);
7501
	INIT_LIST_HEAD(&root_task_group.siblings);
7502
	autogroup_init(&init_task);
D
Dhaval Giani 已提交
7503
#endif /* CONFIG_CGROUP_SCHED */
P
Peter Zijlstra 已提交
7504

7505
	for_each_possible_cpu(i) {
7506
		struct rq *rq;
L
Linus Torvalds 已提交
7507 7508

		rq = cpu_rq(i);
7509
		raw_spin_lock_init(&rq->lock);
N
Nick Piggin 已提交
7510
		rq->nr_running = 0;
7511 7512
		rq->calc_load_active = 0;
		rq->calc_load_update = jiffies + LOAD_FREQ;
7513
		init_cfs_rq(&rq->cfs);
7514 7515
		init_rt_rq(&rq->rt);
		init_dl_rq(&rq->dl);
I
Ingo Molnar 已提交
7516
#ifdef CONFIG_FAIR_GROUP_SCHED
7517
		root_task_group.shares = ROOT_TASK_GROUP_LOAD;
P
Peter Zijlstra 已提交
7518
		INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
D
Dhaval Giani 已提交
7519
		/*
7520
		 * How much cpu bandwidth does root_task_group get?
D
Dhaval Giani 已提交
7521 7522 7523 7524
		 *
		 * In case of task-groups formed thr' the cgroup filesystem, it
		 * gets 100% of the cpu resources in the system. This overall
		 * system cpu resource is divided among the tasks of
7525
		 * root_task_group and its child task-groups in a fair manner,
D
Dhaval Giani 已提交
7526 7527 7528
		 * based on each entity's (task or task-group's) weight
		 * (se->load.weight).
		 *
7529
		 * In other words, if root_task_group has 10 tasks of weight
D
Dhaval Giani 已提交
7530 7531 7532
		 * 1024) and two child groups A0 and A1 (of weight 1024 each),
		 * then A0's share of the cpu resource is:
		 *
7533
		 *	A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
D
Dhaval Giani 已提交
7534
		 *
7535 7536
		 * We achieve this by letting root_task_group's tasks sit
		 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
D
Dhaval Giani 已提交
7537
		 */
7538
		init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7539
		init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
D
Dhaval Giani 已提交
7540 7541 7542
#endif /* CONFIG_FAIR_GROUP_SCHED */

		rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7543
#ifdef CONFIG_RT_GROUP_SCHED
7544
		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
I
Ingo Molnar 已提交
7545
#endif
L
Linus Torvalds 已提交
7546

I
Ingo Molnar 已提交
7547 7548
		for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
			rq->cpu_load[j] = 0;
7549

L
Linus Torvalds 已提交
7550
#ifdef CONFIG_SMP
N
Nick Piggin 已提交
7551
		rq->sd = NULL;
G
Gregory Haskins 已提交
7552
		rq->rd = NULL;
7553
		rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
7554
		rq->balance_callback = NULL;
L
Linus Torvalds 已提交
7555
		rq->active_balance = 0;
I
Ingo Molnar 已提交
7556
		rq->next_balance = jiffies;
L
Linus Torvalds 已提交
7557
		rq->push_cpu = 0;
7558
		rq->cpu = i;
7559
		rq->online = 0;
7560 7561
		rq->idle_stamp = 0;
		rq->avg_idle = 2*sysctl_sched_migration_cost;
7562
		rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7563 7564 7565

		INIT_LIST_HEAD(&rq->cfs_tasks);

7566
		rq_attach_root(rq, &def_root_domain);
7567
#ifdef CONFIG_NO_HZ_COMMON
7568
		rq->last_load_update_tick = jiffies;
7569
		rq->nohz_flags = 0;
7570
#endif
7571 7572 7573
#ifdef CONFIG_NO_HZ_FULL
		rq->last_sched_tick = 0;
#endif
7574
#endif /* CONFIG_SMP */
P
Peter Zijlstra 已提交
7575
		init_rq_hrtick(rq);
L
Linus Torvalds 已提交
7576 7577 7578
		atomic_set(&rq->nr_iowait, 0);
	}

7579
	set_load_weight(&init_task);
7580

L
Linus Torvalds 已提交
7581 7582 7583 7584 7585 7586 7587 7588 7589 7590 7591 7592 7593
	/*
	 * The boot idle thread does lazy MMU switching as well:
	 */
	atomic_inc(&init_mm.mm_count);
	enter_lazy_tlb(&init_mm, current);

	/*
	 * Make us the idle thread. Technically, schedule() should not be
	 * called from this thread, however somewhere below it might be,
	 * but because we are the idle thread, we just pick up running again
	 * when this runqueue becomes "idle".
	 */
	init_idle(current, smp_processor_id());
7594 7595 7596

	calc_load_update = jiffies + LOAD_FREQ;

7597
#ifdef CONFIG_SMP
7598
	zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
R
Rusty Russell 已提交
7599 7600 7601
	/* May be allocated at isolcpus cmdline parse time */
	if (cpu_isolated_map == NULL)
		zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7602
	idle_thread_set_boot_cpu();
7603
	set_cpu_rq_start_time(smp_processor_id());
7604 7605
#endif
	init_sched_fair_class();
7606

7607 7608
	init_schedstats();

7609
	scheduler_running = 1;
L
Linus Torvalds 已提交
7610 7611
}

7612
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7613 7614
static inline int preempt_count_equals(int preempt_offset)
{
7615
	int nested = preempt_count() + rcu_preempt_depth();
7616

A
Arnd Bergmann 已提交
7617
	return (nested == preempt_offset);
7618 7619
}

7620
void __might_sleep(const char *file, int line, int preempt_offset)
L
Linus Torvalds 已提交
7621
{
P
Peter Zijlstra 已提交
7622 7623 7624 7625 7626
	/*
	 * Blocking primitives will set (and therefore destroy) current->state,
	 * since we will exit with TASK_RUNNING make sure we enter with it,
	 * otherwise we will destroy state.
	 */
7627
	WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
P
Peter Zijlstra 已提交
7628 7629 7630 7631
			"do not call blocking ops when !TASK_RUNNING; "
			"state=%lx set at [<%p>] %pS\n",
			current->state,
			(void *)current->task_state_change,
7632
			(void *)current->task_state_change);
P
Peter Zijlstra 已提交
7633

7634 7635 7636 7637 7638
	___might_sleep(file, line, preempt_offset);
}
EXPORT_SYMBOL(__might_sleep);

void ___might_sleep(const char *file, int line, int preempt_offset)
L
Linus Torvalds 已提交
7639 7640
{
	static unsigned long prev_jiffy;	/* ratelimiting */
7641
	unsigned long preempt_disable_ip;
L
Linus Torvalds 已提交
7642

7643
	rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7644 7645
	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
	     !is_idle_task(current)) ||
7646
	    system_state != SYSTEM_RUNNING || oops_in_progress)
I
Ingo Molnar 已提交
7647 7648 7649 7650 7651
		return;
	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
		return;
	prev_jiffy = jiffies;

7652 7653 7654
	/* Save this before calling printk(), since that will clobber it */
	preempt_disable_ip = get_preempt_disable_ip(current);

P
Peter Zijlstra 已提交
7655 7656 7657 7658 7659 7660 7661
	printk(KERN_ERR
		"BUG: sleeping function called from invalid context at %s:%d\n",
			file, line);
	printk(KERN_ERR
		"in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
			in_atomic(), irqs_disabled(),
			current->pid, current->comm);
I
Ingo Molnar 已提交
7662

7663 7664 7665
	if (task_stack_end_corrupted(current))
		printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");

I
Ingo Molnar 已提交
7666 7667 7668
	debug_show_held_locks(current);
	if (irqs_disabled())
		print_irqtrace_events(current);
7669 7670
	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
	    && !preempt_count_equals(preempt_offset)) {
7671
		pr_err("Preemption disabled at:");
7672
		print_ip_sym(preempt_disable_ip);
7673 7674
		pr_cont("\n");
	}
I
Ingo Molnar 已提交
7675
	dump_stack();
7676
	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
L
Linus Torvalds 已提交
7677
}
7678
EXPORT_SYMBOL(___might_sleep);
L
Linus Torvalds 已提交
7679 7680 7681
#endif

#ifdef CONFIG_MAGIC_SYSRQ
7682
void normalize_rt_tasks(void)
7683
{
7684
	struct task_struct *g, *p;
7685 7686 7687
	struct sched_attr attr = {
		.sched_policy = SCHED_NORMAL,
	};
L
Linus Torvalds 已提交
7688

7689
	read_lock(&tasklist_lock);
7690
	for_each_process_thread(g, p) {
7691 7692 7693
		/*
		 * Only normalize user tasks:
		 */
7694
		if (p->flags & PF_KTHREAD)
7695 7696
			continue;

7697 7698 7699 7700
		p->se.exec_start = 0;
		schedstat_set(p->se.statistics.wait_start,  0);
		schedstat_set(p->se.statistics.sleep_start, 0);
		schedstat_set(p->se.statistics.block_start, 0);
I
Ingo Molnar 已提交
7701

7702
		if (!dl_task(p) && !rt_task(p)) {
I
Ingo Molnar 已提交
7703 7704 7705 7706
			/*
			 * Renice negative nice level userspace
			 * tasks back to 0:
			 */
7707
			if (task_nice(p) < 0)
I
Ingo Molnar 已提交
7708
				set_user_nice(p, 0);
L
Linus Torvalds 已提交
7709
			continue;
I
Ingo Molnar 已提交
7710
		}
L
Linus Torvalds 已提交
7711

7712
		__sched_setscheduler(p, &attr, false, false);
7713
	}
7714
	read_unlock(&tasklist_lock);
L
Linus Torvalds 已提交
7715 7716 7717
}

#endif /* CONFIG_MAGIC_SYSRQ */
7718

7719
#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7720
/*
7721
 * These functions are only useful for the IA64 MCA handling, or kdb.
7722 7723 7724 7725 7726 7727 7728 7729 7730 7731 7732 7733 7734
 *
 * They can only be called when the whole system has been
 * stopped - every CPU needs to be quiescent, and no scheduling
 * activity can take place. Using them for anything else would
 * be a serious bug, and as a result, they aren't even visible
 * under any other configuration.
 */

/**
 * curr_task - return the current task for a given cpu.
 * @cpu: the processor in question.
 *
 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7735 7736
 *
 * Return: The current task for @cpu.
7737
 */
7738
struct task_struct *curr_task(int cpu)
7739 7740 7741 7742
{
	return cpu_curr(cpu);
}

7743 7744 7745
#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */

#ifdef CONFIG_IA64
7746 7747 7748 7749 7750 7751
/**
 * set_curr_task - set the current task for a given cpu.
 * @cpu: the processor in question.
 * @p: the task pointer to set.
 *
 * Description: This function must only be used when non-maskable interrupts
I
Ingo Molnar 已提交
7752 7753
 * are serviced on a separate stack. It allows the architecture to switch the
 * notion of the current task on a cpu in a non-blocking manner. This function
7754 7755 7756 7757 7758 7759 7760
 * must be called with all CPU's synchronized, and interrupts disabled, the
 * and caller must save the original value of the current task (see
 * curr_task() above) and restore that value before reenabling interrupts and
 * re-starting the system.
 *
 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
 */
7761
void set_curr_task(int cpu, struct task_struct *p)
7762 7763 7764 7765 7766
{
	cpu_curr(cpu) = p;
}

#endif
S
Srivatsa Vaddagiri 已提交
7767

D
Dhaval Giani 已提交
7768
#ifdef CONFIG_CGROUP_SCHED
7769 7770 7771
/* task_group_lock serializes the addition/removal of task groups */
static DEFINE_SPINLOCK(task_group_lock);

7772
static void sched_free_group(struct task_group *tg)
7773 7774 7775
{
	free_fair_sched_group(tg);
	free_rt_sched_group(tg);
7776
	autogroup_free(tg);
7777
	kmem_cache_free(task_group_cache, tg);
7778 7779 7780
}

/* allocate runqueue etc for a new task group */
7781
struct task_group *sched_create_group(struct task_group *parent)
7782 7783 7784
{
	struct task_group *tg;

7785
	tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
7786 7787 7788
	if (!tg)
		return ERR_PTR(-ENOMEM);

7789
	if (!alloc_fair_sched_group(tg, parent))
7790 7791
		goto err;

7792
	if (!alloc_rt_sched_group(tg, parent))
7793 7794
		goto err;

7795 7796 7797
	return tg;

err:
7798
	sched_free_group(tg);
7799 7800 7801 7802 7803 7804 7805
	return ERR_PTR(-ENOMEM);
}

void sched_online_group(struct task_group *tg, struct task_group *parent)
{
	unsigned long flags;

7806
	spin_lock_irqsave(&task_group_lock, flags);
P
Peter Zijlstra 已提交
7807
	list_add_rcu(&tg->list, &task_groups);
P
Peter Zijlstra 已提交
7808 7809 7810 7811 7812

	WARN_ON(!parent); /* root should already exist */

	tg->parent = parent;
	INIT_LIST_HEAD(&tg->children);
7813
	list_add_rcu(&tg->siblings, &parent->children);
7814
	spin_unlock_irqrestore(&task_group_lock, flags);
7815 7816

	online_fair_sched_group(tg);
S
Srivatsa Vaddagiri 已提交
7817 7818
}

7819
/* rcu callback to free various structures associated with a task group */
7820
static void sched_free_group_rcu(struct rcu_head *rhp)
S
Srivatsa Vaddagiri 已提交
7821 7822
{
	/* now it should be safe to free those cfs_rqs */
7823
	sched_free_group(container_of(rhp, struct task_group, rcu));
S
Srivatsa Vaddagiri 已提交
7824 7825
}

7826
void sched_destroy_group(struct task_group *tg)
7827 7828
{
	/* wait for possible concurrent references to cfs_rqs complete */
7829
	call_rcu(&tg->rcu, sched_free_group_rcu);
7830 7831 7832
}

void sched_offline_group(struct task_group *tg)
S
Srivatsa Vaddagiri 已提交
7833
{
7834
	unsigned long flags;
S
Srivatsa Vaddagiri 已提交
7835

7836
	/* end participation in shares distribution */
7837
	unregister_fair_sched_group(tg);
7838 7839

	spin_lock_irqsave(&task_group_lock, flags);
P
Peter Zijlstra 已提交
7840
	list_del_rcu(&tg->list);
P
Peter Zijlstra 已提交
7841
	list_del_rcu(&tg->siblings);
7842
	spin_unlock_irqrestore(&task_group_lock, flags);
S
Srivatsa Vaddagiri 已提交
7843 7844
}

7845
static void sched_change_group(struct task_struct *tsk, int type)
S
Srivatsa Vaddagiri 已提交
7846
{
P
Peter Zijlstra 已提交
7847
	struct task_group *tg;
S
Srivatsa Vaddagiri 已提交
7848

7849 7850 7851 7852 7853 7854
	/*
	 * All callers are synchronized by task_rq_lock(); we do not use RCU
	 * which is pointless here. Thus, we pass "true" to task_css_check()
	 * to prevent lockdep warnings.
	 */
	tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
P
Peter Zijlstra 已提交
7855 7856 7857 7858
			  struct task_group, css);
	tg = autogroup_task_group(tsk, tg);
	tsk->sched_task_group = tg;

P
Peter Zijlstra 已提交
7859
#ifdef CONFIG_FAIR_GROUP_SCHED
7860 7861
	if (tsk->sched_class->task_change_group)
		tsk->sched_class->task_change_group(tsk, type);
7862
	else
P
Peter Zijlstra 已提交
7863
#endif
7864
		set_task_rq(tsk, task_cpu(tsk));
7865 7866 7867 7868 7869 7870 7871 7872 7873 7874 7875 7876 7877 7878 7879 7880 7881 7882 7883 7884 7885 7886 7887 7888 7889 7890
}

/*
 * Change task's runqueue when it moves between groups.
 *
 * The caller of this function should have put the task in its new group by
 * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
 * its new group.
 */
void sched_move_task(struct task_struct *tsk)
{
	int queued, running;
	struct rq_flags rf;
	struct rq *rq;

	rq = task_rq_lock(tsk, &rf);

	running = task_current(rq, tsk);
	queued = task_on_rq_queued(tsk);

	if (queued)
		dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE);
	if (unlikely(running))
		put_prev_task(rq, tsk);

	sched_change_group(tsk, TASK_MOVE_GROUP);
P
Peter Zijlstra 已提交
7891

7892 7893
	if (unlikely(running))
		tsk->sched_class->set_curr_task(rq);
7894
	if (queued)
7895
		enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
S
Srivatsa Vaddagiri 已提交
7896

7897
	task_rq_unlock(rq, tsk, &rf);
S
Srivatsa Vaddagiri 已提交
7898
}
D
Dhaval Giani 已提交
7899
#endif /* CONFIG_CGROUP_SCHED */
S
Srivatsa Vaddagiri 已提交
7900

7901 7902 7903 7904 7905
#ifdef CONFIG_RT_GROUP_SCHED
/*
 * Ensure that the real time constraints are schedulable.
 */
static DEFINE_MUTEX(rt_constraints_mutex);
P
Peter Zijlstra 已提交
7906

P
Peter Zijlstra 已提交
7907 7908
/* Must be called with tasklist_lock held */
static inline int tg_has_rt_tasks(struct task_group *tg)
7909
{
P
Peter Zijlstra 已提交
7910
	struct task_struct *g, *p;
7911

7912 7913 7914 7915 7916 7917
	/*
	 * Autogroups do not have RT tasks; see autogroup_create().
	 */
	if (task_group_is_autogroup(tg))
		return 0;

7918
	for_each_process_thread(g, p) {
7919
		if (rt_task(p) && task_group(p) == tg)
P
Peter Zijlstra 已提交
7920
			return 1;
7921
	}
7922

P
Peter Zijlstra 已提交
7923 7924
	return 0;
}
7925

P
Peter Zijlstra 已提交
7926 7927 7928 7929 7930
struct rt_schedulable_data {
	struct task_group *tg;
	u64 rt_period;
	u64 rt_runtime;
};
7931

7932
static int tg_rt_schedulable(struct task_group *tg, void *data)
P
Peter Zijlstra 已提交
7933 7934 7935 7936 7937
{
	struct rt_schedulable_data *d = data;
	struct task_group *child;
	unsigned long total, sum = 0;
	u64 period, runtime;
7938

P
Peter Zijlstra 已提交
7939 7940
	period = ktime_to_ns(tg->rt_bandwidth.rt_period);
	runtime = tg->rt_bandwidth.rt_runtime;
7941

P
Peter Zijlstra 已提交
7942 7943 7944
	if (tg == d->tg) {
		period = d->rt_period;
		runtime = d->rt_runtime;
7945 7946
	}

7947 7948 7949 7950 7951
	/*
	 * Cannot have more runtime than the period.
	 */
	if (runtime > period && runtime != RUNTIME_INF)
		return -EINVAL;
P
Peter Zijlstra 已提交
7952

7953 7954 7955
	/*
	 * Ensure we don't starve existing RT tasks.
	 */
P
Peter Zijlstra 已提交
7956 7957
	if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
		return -EBUSY;
P
Peter Zijlstra 已提交
7958

P
Peter Zijlstra 已提交
7959
	total = to_ratio(period, runtime);
P
Peter Zijlstra 已提交
7960

7961 7962 7963 7964 7965
	/*
	 * Nobody can have more than the global setting allows.
	 */
	if (total > to_ratio(global_rt_period(), global_rt_runtime()))
		return -EINVAL;
P
Peter Zijlstra 已提交
7966

7967 7968 7969
	/*
	 * The sum of our children's runtime should not exceed our own.
	 */
P
Peter Zijlstra 已提交
7970 7971 7972
	list_for_each_entry_rcu(child, &tg->children, siblings) {
		period = ktime_to_ns(child->rt_bandwidth.rt_period);
		runtime = child->rt_bandwidth.rt_runtime;
P
Peter Zijlstra 已提交
7973

P
Peter Zijlstra 已提交
7974 7975 7976 7977
		if (child == d->tg) {
			period = d->rt_period;
			runtime = d->rt_runtime;
		}
P
Peter Zijlstra 已提交
7978

P
Peter Zijlstra 已提交
7979
		sum += to_ratio(period, runtime);
P
Peter Zijlstra 已提交
7980
	}
P
Peter Zijlstra 已提交
7981

P
Peter Zijlstra 已提交
7982 7983 7984 7985
	if (sum > total)
		return -EINVAL;

	return 0;
P
Peter Zijlstra 已提交
7986 7987
}

P
Peter Zijlstra 已提交
7988
static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7989
{
7990 7991
	int ret;

P
Peter Zijlstra 已提交
7992 7993 7994 7995 7996 7997
	struct rt_schedulable_data data = {
		.tg = tg,
		.rt_period = period,
		.rt_runtime = runtime,
	};

7998 7999 8000 8001 8002
	rcu_read_lock();
	ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
	rcu_read_unlock();

	return ret;
8003 8004
}

8005
static int tg_set_rt_bandwidth(struct task_group *tg,
8006
		u64 rt_period, u64 rt_runtime)
P
Peter Zijlstra 已提交
8007
{
P
Peter Zijlstra 已提交
8008
	int i, err = 0;
P
Peter Zijlstra 已提交
8009

8010 8011 8012 8013 8014 8015 8016 8017 8018 8019 8020
	/*
	 * Disallowing the root group RT runtime is BAD, it would disallow the
	 * kernel creating (and or operating) RT threads.
	 */
	if (tg == &root_task_group && rt_runtime == 0)
		return -EINVAL;

	/* No period doesn't make any sense. */
	if (rt_period == 0)
		return -EINVAL;

P
Peter Zijlstra 已提交
8021
	mutex_lock(&rt_constraints_mutex);
8022
	read_lock(&tasklist_lock);
P
Peter Zijlstra 已提交
8023 8024
	err = __rt_schedulable(tg, rt_period, rt_runtime);
	if (err)
P
Peter Zijlstra 已提交
8025
		goto unlock;
P
Peter Zijlstra 已提交
8026

8027
	raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
8028 8029
	tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
	tg->rt_bandwidth.rt_runtime = rt_runtime;
P
Peter Zijlstra 已提交
8030 8031 8032 8033

	for_each_possible_cpu(i) {
		struct rt_rq *rt_rq = tg->rt_rq[i];

8034
		raw_spin_lock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
8035
		rt_rq->rt_runtime = rt_runtime;
8036
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
8037
	}
8038
	raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
P
Peter Zijlstra 已提交
8039
unlock:
8040
	read_unlock(&tasklist_lock);
P
Peter Zijlstra 已提交
8041 8042 8043
	mutex_unlock(&rt_constraints_mutex);

	return err;
P
Peter Zijlstra 已提交
8044 8045
}

8046
static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
8047 8048 8049 8050 8051 8052 8053 8054
{
	u64 rt_runtime, rt_period;

	rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
	rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
	if (rt_runtime_us < 0)
		rt_runtime = RUNTIME_INF;

8055
	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
8056 8057
}

8058
static long sched_group_rt_runtime(struct task_group *tg)
P
Peter Zijlstra 已提交
8059 8060 8061
{
	u64 rt_runtime_us;

8062
	if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
P
Peter Zijlstra 已提交
8063 8064
		return -1;

8065
	rt_runtime_us = tg->rt_bandwidth.rt_runtime;
P
Peter Zijlstra 已提交
8066 8067 8068
	do_div(rt_runtime_us, NSEC_PER_USEC);
	return rt_runtime_us;
}
8069

8070
static int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
8071 8072 8073
{
	u64 rt_runtime, rt_period;

8074
	rt_period = rt_period_us * NSEC_PER_USEC;
8075 8076
	rt_runtime = tg->rt_bandwidth.rt_runtime;

8077
	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
8078 8079
}

8080
static long sched_group_rt_period(struct task_group *tg)
8081 8082 8083 8084 8085 8086 8087
{
	u64 rt_period_us;

	rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
	do_div(rt_period_us, NSEC_PER_USEC);
	return rt_period_us;
}
8088
#endif /* CONFIG_RT_GROUP_SCHED */
8089

8090
#ifdef CONFIG_RT_GROUP_SCHED
8091 8092 8093 8094 8095
static int sched_rt_global_constraints(void)
{
	int ret = 0;

	mutex_lock(&rt_constraints_mutex);
P
Peter Zijlstra 已提交
8096
	read_lock(&tasklist_lock);
8097
	ret = __rt_schedulable(NULL, 0, 0);
P
Peter Zijlstra 已提交
8098
	read_unlock(&tasklist_lock);
8099 8100 8101 8102
	mutex_unlock(&rt_constraints_mutex);

	return ret;
}
8103

8104
static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
8105 8106 8107 8108 8109 8110 8111 8112
{
	/* Don't accept realtime tasks when there is no way for them to run */
	if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
		return 0;

	return 1;
}

8113
#else /* !CONFIG_RT_GROUP_SCHED */
8114 8115
static int sched_rt_global_constraints(void)
{
P
Peter Zijlstra 已提交
8116
	unsigned long flags;
8117
	int i;
8118

8119
	raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
P
Peter Zijlstra 已提交
8120 8121 8122
	for_each_possible_cpu(i) {
		struct rt_rq *rt_rq = &cpu_rq(i)->rt;

8123
		raw_spin_lock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
8124
		rt_rq->rt_runtime = global_rt_runtime();
8125
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
8126
	}
8127
	raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
P
Peter Zijlstra 已提交
8128

8129
	return 0;
8130
}
8131
#endif /* CONFIG_RT_GROUP_SCHED */
8132

8133
static int sched_dl_global_validate(void)
8134
{
8135 8136
	u64 runtime = global_rt_runtime();
	u64 period = global_rt_period();
8137
	u64 new_bw = to_ratio(period, runtime);
8138
	struct dl_bw *dl_b;
8139
	int cpu, ret = 0;
8140
	unsigned long flags;
8141 8142 8143 8144 8145 8146 8147 8148 8149 8150

	/*
	 * Here we want to check the bandwidth not being set to some
	 * value smaller than the currently allocated bandwidth in
	 * any of the root_domains.
	 *
	 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
	 * cycling on root_domains... Discussion on different/better
	 * solutions is welcome!
	 */
8151
	for_each_possible_cpu(cpu) {
8152 8153
		rcu_read_lock_sched();
		dl_b = dl_bw_of(cpu);
8154

8155
		raw_spin_lock_irqsave(&dl_b->lock, flags);
8156 8157
		if (new_bw < dl_b->total_bw)
			ret = -EBUSY;
8158
		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
8159

8160 8161
		rcu_read_unlock_sched();

8162 8163
		if (ret)
			break;
8164 8165
	}

8166
	return ret;
8167 8168
}

8169
static void sched_dl_do_global(void)
8170
{
8171
	u64 new_bw = -1;
8172
	struct dl_bw *dl_b;
8173
	int cpu;
8174
	unsigned long flags;
8175

8176 8177 8178 8179 8180 8181 8182 8183 8184 8185
	def_dl_bandwidth.dl_period = global_rt_period();
	def_dl_bandwidth.dl_runtime = global_rt_runtime();

	if (global_rt_runtime() != RUNTIME_INF)
		new_bw = to_ratio(global_rt_period(), global_rt_runtime());

	/*
	 * FIXME: As above...
	 */
	for_each_possible_cpu(cpu) {
8186 8187
		rcu_read_lock_sched();
		dl_b = dl_bw_of(cpu);
8188

8189
		raw_spin_lock_irqsave(&dl_b->lock, flags);
8190
		dl_b->bw = new_bw;
8191
		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
8192 8193

		rcu_read_unlock_sched();
8194
	}
8195 8196 8197 8198 8199 8200 8201
}

static int sched_rt_global_validate(void)
{
	if (sysctl_sched_rt_period <= 0)
		return -EINVAL;

8202 8203
	if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
		(sysctl_sched_rt_runtime > sysctl_sched_rt_period))
8204 8205 8206 8207 8208 8209 8210 8211 8212
		return -EINVAL;

	return 0;
}

static void sched_rt_do_global(void)
{
	def_rt_bandwidth.rt_runtime = global_rt_runtime();
	def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
8213 8214
}

8215
int sched_rt_handler(struct ctl_table *table, int write,
8216
		void __user *buffer, size_t *lenp,
8217 8218 8219 8220
		loff_t *ppos)
{
	int old_period, old_runtime;
	static DEFINE_MUTEX(mutex);
8221
	int ret;
8222 8223 8224 8225 8226

	mutex_lock(&mutex);
	old_period = sysctl_sched_rt_period;
	old_runtime = sysctl_sched_rt_runtime;

8227
	ret = proc_dointvec(table, write, buffer, lenp, ppos);
8228 8229

	if (!ret && write) {
8230 8231 8232 8233
		ret = sched_rt_global_validate();
		if (ret)
			goto undo;

8234
		ret = sched_dl_global_validate();
8235 8236 8237
		if (ret)
			goto undo;

8238
		ret = sched_rt_global_constraints();
8239 8240 8241 8242 8243 8244 8245 8246 8247 8248
		if (ret)
			goto undo;

		sched_rt_do_global();
		sched_dl_do_global();
	}
	if (0) {
undo:
		sysctl_sched_rt_period = old_period;
		sysctl_sched_rt_runtime = old_runtime;
8249 8250 8251 8252 8253
	}
	mutex_unlock(&mutex);

	return ret;
}
8254

8255
int sched_rr_handler(struct ctl_table *table, int write,
8256 8257 8258 8259 8260 8261 8262 8263
		void __user *buffer, size_t *lenp,
		loff_t *ppos)
{
	int ret;
	static DEFINE_MUTEX(mutex);

	mutex_lock(&mutex);
	ret = proc_dointvec(table, write, buffer, lenp, ppos);
8264 8265
	/* make sure that internally we keep jiffies */
	/* also, writing zero resets timeslice to default */
8266
	if (!ret && write) {
8267 8268
		sched_rr_timeslice = sched_rr_timeslice <= 0 ?
			RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
8269 8270 8271 8272 8273
	}
	mutex_unlock(&mutex);
	return ret;
}

8274
#ifdef CONFIG_CGROUP_SCHED
8275

8276
static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
8277
{
8278
	return css ? container_of(css, struct task_group, css) : NULL;
8279 8280
}

8281 8282
static struct cgroup_subsys_state *
cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
8283
{
8284 8285
	struct task_group *parent = css_tg(parent_css);
	struct task_group *tg;
8286

8287
	if (!parent) {
8288
		/* This is early initialization for the top cgroup */
8289
		return &root_task_group.css;
8290 8291
	}

8292
	tg = sched_create_group(parent);
8293 8294 8295
	if (IS_ERR(tg))
		return ERR_PTR(-ENOMEM);

8296 8297
	sched_online_group(tg, parent);

8298 8299 8300
	return &tg->css;
}

8301
static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
8302
{
8303
	struct task_group *tg = css_tg(css);
8304

8305
	sched_offline_group(tg);
8306 8307
}

8308
static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
8309
{
8310
	struct task_group *tg = css_tg(css);
8311

8312 8313 8314 8315
	/*
	 * Relies on the RCU grace period between css_released() and this.
	 */
	sched_free_group(tg);
8316 8317
}

8318 8319 8320 8321
/*
 * This is called before wake_up_new_task(), therefore we really only
 * have to set its group bits, all the other stuff does not apply.
 */
8322
static void cpu_cgroup_fork(struct task_struct *task)
8323
{
8324 8325 8326 8327 8328 8329 8330 8331
	struct rq_flags rf;
	struct rq *rq;

	rq = task_rq_lock(task, &rf);

	sched_change_group(task, TASK_SET_GROUP);

	task_rq_unlock(rq, task, &rf);
8332 8333
}

8334
static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
8335
{
8336
	struct task_struct *task;
8337
	struct cgroup_subsys_state *css;
8338
	int ret = 0;
8339

8340
	cgroup_taskset_for_each(task, css, tset) {
8341
#ifdef CONFIG_RT_GROUP_SCHED
8342
		if (!sched_rt_can_attach(css_tg(css), task))
8343
			return -EINVAL;
8344
#else
8345 8346 8347
		/* We don't support RT-tasks being in separate groups */
		if (task->sched_class != &fair_sched_class)
			return -EINVAL;
8348
#endif
8349 8350 8351 8352 8353 8354 8355 8356 8357 8358 8359 8360 8361 8362 8363 8364
		/*
		 * Serialize against wake_up_new_task() such that if its
		 * running, we're sure to observe its full state.
		 */
		raw_spin_lock_irq(&task->pi_lock);
		/*
		 * Avoid calling sched_move_task() before wake_up_new_task()
		 * has happened. This would lead to problems with PELT, due to
		 * move wanting to detach+attach while we're not attached yet.
		 */
		if (task->state == TASK_NEW)
			ret = -EINVAL;
		raw_spin_unlock_irq(&task->pi_lock);

		if (ret)
			break;
8365
	}
8366
	return ret;
8367
}
8368

8369
static void cpu_cgroup_attach(struct cgroup_taskset *tset)
8370
{
8371
	struct task_struct *task;
8372
	struct cgroup_subsys_state *css;
8373

8374
	cgroup_taskset_for_each(task, css, tset)
8375
		sched_move_task(task);
8376 8377
}

8378
#ifdef CONFIG_FAIR_GROUP_SCHED
8379 8380
static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
				struct cftype *cftype, u64 shareval)
8381
{
8382
	return sched_group_set_shares(css_tg(css), scale_load(shareval));
8383 8384
}

8385 8386
static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
			       struct cftype *cft)
8387
{
8388
	struct task_group *tg = css_tg(css);
8389

8390
	return (u64) scale_load_down(tg->shares);
8391
}
8392 8393

#ifdef CONFIG_CFS_BANDWIDTH
8394 8395
static DEFINE_MUTEX(cfs_constraints_mutex);

8396 8397 8398
const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */

8399 8400
static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);

8401 8402
static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
{
8403
	int i, ret = 0, runtime_enabled, runtime_was_enabled;
8404
	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8405 8406 8407 8408 8409 8410 8411 8412 8413 8414 8415 8416 8417 8418 8419 8420 8421 8422 8423 8424

	if (tg == &root_task_group)
		return -EINVAL;

	/*
	 * Ensure we have at some amount of bandwidth every period.  This is
	 * to prevent reaching a state of large arrears when throttled via
	 * entity_tick() resulting in prolonged exit starvation.
	 */
	if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
		return -EINVAL;

	/*
	 * Likewise, bound things on the otherside by preventing insane quota
	 * periods.  This also allows us to normalize in computing quota
	 * feasibility.
	 */
	if (period > max_cfs_quota_period)
		return -EINVAL;

8425 8426 8427 8428 8429
	/*
	 * Prevent race between setting of cfs_rq->runtime_enabled and
	 * unthrottle_offline_cfs_rqs().
	 */
	get_online_cpus();
8430 8431 8432 8433 8434
	mutex_lock(&cfs_constraints_mutex);
	ret = __cfs_schedulable(tg, period, quota);
	if (ret)
		goto out_unlock;

8435
	runtime_enabled = quota != RUNTIME_INF;
8436
	runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
8437 8438 8439 8440 8441 8442
	/*
	 * If we need to toggle cfs_bandwidth_used, off->on must occur
	 * before making related changes, and on->off must occur afterwards
	 */
	if (runtime_enabled && !runtime_was_enabled)
		cfs_bandwidth_usage_inc();
8443 8444 8445
	raw_spin_lock_irq(&cfs_b->lock);
	cfs_b->period = ns_to_ktime(period);
	cfs_b->quota = quota;
8446

P
Paul Turner 已提交
8447
	__refill_cfs_bandwidth_runtime(cfs_b);
8448
	/* restart the period timer (if active) to handle new period expiry */
P
Peter Zijlstra 已提交
8449 8450
	if (runtime_enabled)
		start_cfs_bandwidth(cfs_b);
8451 8452
	raw_spin_unlock_irq(&cfs_b->lock);

8453
	for_each_online_cpu(i) {
8454
		struct cfs_rq *cfs_rq = tg->cfs_rq[i];
8455
		struct rq *rq = cfs_rq->rq;
8456 8457

		raw_spin_lock_irq(&rq->lock);
8458
		cfs_rq->runtime_enabled = runtime_enabled;
8459
		cfs_rq->runtime_remaining = 0;
8460

8461
		if (cfs_rq->throttled)
8462
			unthrottle_cfs_rq(cfs_rq);
8463 8464
		raw_spin_unlock_irq(&rq->lock);
	}
8465 8466
	if (runtime_was_enabled && !runtime_enabled)
		cfs_bandwidth_usage_dec();
8467 8468
out_unlock:
	mutex_unlock(&cfs_constraints_mutex);
8469
	put_online_cpus();
8470

8471
	return ret;
8472 8473 8474 8475 8476 8477
}

int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
{
	u64 quota, period;

8478
	period = ktime_to_ns(tg->cfs_bandwidth.period);
8479 8480 8481 8482 8483 8484 8485 8486 8487 8488 8489 8490
	if (cfs_quota_us < 0)
		quota = RUNTIME_INF;
	else
		quota = (u64)cfs_quota_us * NSEC_PER_USEC;

	return tg_set_cfs_bandwidth(tg, period, quota);
}

long tg_get_cfs_quota(struct task_group *tg)
{
	u64 quota_us;

8491
	if (tg->cfs_bandwidth.quota == RUNTIME_INF)
8492 8493
		return -1;

8494
	quota_us = tg->cfs_bandwidth.quota;
8495 8496 8497 8498 8499 8500 8501 8502 8503 8504
	do_div(quota_us, NSEC_PER_USEC);

	return quota_us;
}

int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
{
	u64 quota, period;

	period = (u64)cfs_period_us * NSEC_PER_USEC;
8505
	quota = tg->cfs_bandwidth.quota;
8506 8507 8508 8509 8510 8511 8512 8513

	return tg_set_cfs_bandwidth(tg, period, quota);
}

long tg_get_cfs_period(struct task_group *tg)
{
	u64 cfs_period_us;

8514
	cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
8515 8516 8517 8518 8519
	do_div(cfs_period_us, NSEC_PER_USEC);

	return cfs_period_us;
}

8520 8521
static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
				  struct cftype *cft)
8522
{
8523
	return tg_get_cfs_quota(css_tg(css));
8524 8525
}

8526 8527
static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
				   struct cftype *cftype, s64 cfs_quota_us)
8528
{
8529
	return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
8530 8531
}

8532 8533
static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
				   struct cftype *cft)
8534
{
8535
	return tg_get_cfs_period(css_tg(css));
8536 8537
}

8538 8539
static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
				    struct cftype *cftype, u64 cfs_period_us)
8540
{
8541
	return tg_set_cfs_period(css_tg(css), cfs_period_us);
8542 8543
}

8544 8545 8546 8547 8548 8549 8550 8551 8552 8553 8554 8555 8556 8557 8558 8559 8560 8561 8562 8563 8564 8565 8566 8567 8568 8569 8570 8571 8572 8573 8574 8575
struct cfs_schedulable_data {
	struct task_group *tg;
	u64 period, quota;
};

/*
 * normalize group quota/period to be quota/max_period
 * note: units are usecs
 */
static u64 normalize_cfs_quota(struct task_group *tg,
			       struct cfs_schedulable_data *d)
{
	u64 quota, period;

	if (tg == d->tg) {
		period = d->period;
		quota = d->quota;
	} else {
		period = tg_get_cfs_period(tg);
		quota = tg_get_cfs_quota(tg);
	}

	/* note: these should typically be equivalent */
	if (quota == RUNTIME_INF || quota == -1)
		return RUNTIME_INF;

	return to_ratio(period, quota);
}

static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
{
	struct cfs_schedulable_data *d = data;
8576
	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8577 8578 8579 8580 8581
	s64 quota = 0, parent_quota = -1;

	if (!tg->parent) {
		quota = RUNTIME_INF;
	} else {
8582
		struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
8583 8584

		quota = normalize_cfs_quota(tg, d);
8585
		parent_quota = parent_b->hierarchical_quota;
8586 8587 8588 8589 8590 8591 8592 8593 8594 8595

		/*
		 * ensure max(child_quota) <= parent_quota, inherit when no
		 * limit is set
		 */
		if (quota == RUNTIME_INF)
			quota = parent_quota;
		else if (parent_quota != RUNTIME_INF && quota > parent_quota)
			return -EINVAL;
	}
8596
	cfs_b->hierarchical_quota = quota;
8597 8598 8599 8600 8601 8602

	return 0;
}

static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
{
8603
	int ret;
8604 8605 8606 8607 8608 8609 8610 8611 8612 8613 8614
	struct cfs_schedulable_data data = {
		.tg = tg,
		.period = period,
		.quota = quota,
	};

	if (quota != RUNTIME_INF) {
		do_div(data.period, NSEC_PER_USEC);
		do_div(data.quota, NSEC_PER_USEC);
	}

8615 8616 8617 8618 8619
	rcu_read_lock();
	ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
	rcu_read_unlock();

	return ret;
8620
}
8621

8622
static int cpu_stats_show(struct seq_file *sf, void *v)
8623
{
8624
	struct task_group *tg = css_tg(seq_css(sf));
8625
	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8626

8627 8628 8629
	seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
	seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
	seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
8630 8631 8632

	return 0;
}
8633
#endif /* CONFIG_CFS_BANDWIDTH */
8634
#endif /* CONFIG_FAIR_GROUP_SCHED */
8635

8636
#ifdef CONFIG_RT_GROUP_SCHED
8637 8638
static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
				struct cftype *cft, s64 val)
P
Peter Zijlstra 已提交
8639
{
8640
	return sched_group_set_rt_runtime(css_tg(css), val);
P
Peter Zijlstra 已提交
8641 8642
}

8643 8644
static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
			       struct cftype *cft)
P
Peter Zijlstra 已提交
8645
{
8646
	return sched_group_rt_runtime(css_tg(css));
P
Peter Zijlstra 已提交
8647
}
8648

8649 8650
static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
				    struct cftype *cftype, u64 rt_period_us)
8651
{
8652
	return sched_group_set_rt_period(css_tg(css), rt_period_us);
8653 8654
}

8655 8656
static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
				   struct cftype *cft)
8657
{
8658
	return sched_group_rt_period(css_tg(css));
8659
}
8660
#endif /* CONFIG_RT_GROUP_SCHED */
P
Peter Zijlstra 已提交
8661

8662
static struct cftype cpu_files[] = {
8663
#ifdef CONFIG_FAIR_GROUP_SCHED
8664 8665
	{
		.name = "shares",
8666 8667
		.read_u64 = cpu_shares_read_u64,
		.write_u64 = cpu_shares_write_u64,
8668
	},
8669
#endif
8670 8671 8672 8673 8674 8675 8676 8677 8678 8679 8680
#ifdef CONFIG_CFS_BANDWIDTH
	{
		.name = "cfs_quota_us",
		.read_s64 = cpu_cfs_quota_read_s64,
		.write_s64 = cpu_cfs_quota_write_s64,
	},
	{
		.name = "cfs_period_us",
		.read_u64 = cpu_cfs_period_read_u64,
		.write_u64 = cpu_cfs_period_write_u64,
	},
8681 8682
	{
		.name = "stat",
8683
		.seq_show = cpu_stats_show,
8684
	},
8685
#endif
8686
#ifdef CONFIG_RT_GROUP_SCHED
P
Peter Zijlstra 已提交
8687
	{
P
Peter Zijlstra 已提交
8688
		.name = "rt_runtime_us",
8689 8690
		.read_s64 = cpu_rt_runtime_read,
		.write_s64 = cpu_rt_runtime_write,
P
Peter Zijlstra 已提交
8691
	},
8692 8693
	{
		.name = "rt_period_us",
8694 8695
		.read_u64 = cpu_rt_period_read_uint,
		.write_u64 = cpu_rt_period_write_uint,
8696
	},
8697
#endif
8698
	{ }	/* terminate */
8699 8700
};

8701
struct cgroup_subsys cpu_cgrp_subsys = {
8702
	.css_alloc	= cpu_cgroup_css_alloc,
8703
	.css_released	= cpu_cgroup_css_released,
8704
	.css_free	= cpu_cgroup_css_free,
8705
	.fork		= cpu_cgroup_fork,
8706 8707
	.can_attach	= cpu_cgroup_can_attach,
	.attach		= cpu_cgroup_attach,
8708
	.legacy_cftypes	= cpu_files,
8709
	.early_init	= true,
8710 8711
};

8712
#endif	/* CONFIG_CGROUP_SCHED */
8713

8714 8715 8716 8717 8718
void dump_cpu_task(int cpu)
{
	pr_info("Task dump for CPU %d:\n", cpu);
	sched_show_task(cpu_curr(cpu));
}
8719 8720 8721 8722 8723 8724 8725 8726 8727 8728 8729 8730 8731 8732 8733 8734 8735 8736 8737 8738 8739 8740 8741 8742 8743 8744 8745 8746 8747 8748 8749 8750 8751 8752 8753 8754 8755 8756 8757 8758 8759

/*
 * Nice levels are multiplicative, with a gentle 10% change for every
 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
 * nice 1, it will get ~10% less CPU time than another CPU-bound task
 * that remained on nice 0.
 *
 * The "10% effect" is relative and cumulative: from _any_ nice level,
 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
 * If a task goes up by ~10% and another task goes down by ~10% then
 * the relative distance between them is ~25%.)
 */
const int sched_prio_to_weight[40] = {
 /* -20 */     88761,     71755,     56483,     46273,     36291,
 /* -15 */     29154,     23254,     18705,     14949,     11916,
 /* -10 */      9548,      7620,      6100,      4904,      3906,
 /*  -5 */      3121,      2501,      1991,      1586,      1277,
 /*   0 */      1024,       820,       655,       526,       423,
 /*   5 */       335,       272,       215,       172,       137,
 /*  10 */       110,        87,        70,        56,        45,
 /*  15 */        36,        29,        23,        18,        15,
};

/*
 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
 *
 * In cases where the weight does not change often, we can use the
 * precalculated inverse to speed up arithmetics by turning divisions
 * into multiplications:
 */
const u32 sched_prio_to_wmult[40] = {
 /* -20 */     48388,     59856,     76040,     92818,    118348,
 /* -15 */    147320,    184698,    229616,    287308,    360437,
 /* -10 */    449829,    563644,    704093,    875809,   1099582,
 /*  -5 */   1376151,   1717300,   2157191,   2708050,   3363326,
 /*   0 */   4194304,   5237765,   6557202,   8165337,  10153587,
 /*   5 */  12820798,  15790321,  19976592,  24970740,  31350126,
 /*  10 */  39045157,  49367440,  61356676,  76695844,  95443717,
 /*  15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};