core.c 213.3 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 1066 1067 1068 1069 1070

	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.
	 */
	if (task_rq(p) == rq && task_on_rq_queued(p))
		rq = __migrate_task(rq, p, arg->dest_cpu);
	raw_spin_unlock(&rq->lock);
	raw_spin_unlock(&p->pi_lock);

P
Peter Zijlstra 已提交
1071 1072 1073 1074
	local_irq_enable();
	return 0;
}

1075 1076 1077 1078 1079
/*
 * 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
1080 1081 1082 1083 1084
{
	cpumask_copy(&p->cpus_allowed, new_mask);
	p->nr_cpus_allowed = cpumask_weight(new_mask);
}

1085 1086
void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
{
1087 1088 1089
	struct rq *rq = task_rq(p);
	bool queued, running;

1090
	lockdep_assert_held(&p->pi_lock);
1091 1092 1093 1094 1095 1096 1097 1098 1099 1100

	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);
1101
		dequeue_task(rq, p, DEQUEUE_SAVE);
1102 1103 1104 1105
	}
	if (running)
		put_prev_task(rq, p);

1106
	p->sched_class->set_cpus_allowed(p, new_mask);
1107 1108 1109 1110

	if (running)
		p->sched_class->set_curr_task(rq);
	if (queued)
1111
		enqueue_task(rq, p, ENQUEUE_RESTORE);
1112 1113
}

P
Peter Zijlstra 已提交
1114 1115 1116 1117 1118 1119 1120 1121 1122
/*
 * 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.
 */
1123 1124
static int __set_cpus_allowed_ptr(struct task_struct *p,
				  const struct cpumask *new_mask, bool check)
P
Peter Zijlstra 已提交
1125
{
1126
	const struct cpumask *cpu_valid_mask = cpu_active_mask;
P
Peter Zijlstra 已提交
1127
	unsigned int dest_cpu;
1128 1129
	struct rq_flags rf;
	struct rq *rq;
P
Peter Zijlstra 已提交
1130 1131
	int ret = 0;

1132
	rq = task_rq_lock(p, &rf);
P
Peter Zijlstra 已提交
1133

1134 1135 1136 1137 1138 1139 1140
	if (p->flags & PF_KTHREAD) {
		/*
		 * Kernel threads are allowed on online && !active CPUs
		 */
		cpu_valid_mask = cpu_online_mask;
	}

1141 1142 1143 1144 1145 1146 1147 1148 1149
	/*
	 * 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
1150 1151 1152
	if (cpumask_equal(&p->cpus_allowed, new_mask))
		goto out;

1153
	if (!cpumask_intersects(new_mask, cpu_valid_mask)) {
P
Peter Zijlstra 已提交
1154 1155 1156 1157 1158 1159
		ret = -EINVAL;
		goto out;
	}

	do_set_cpus_allowed(p, new_mask);

1160 1161 1162 1163 1164 1165 1166 1167 1168 1169
	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
1170 1171 1172 1173
	/* 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;

1174
	dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
P
Peter Zijlstra 已提交
1175 1176 1177
	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. */
1178
		task_rq_unlock(rq, p, &rf);
P
Peter Zijlstra 已提交
1179 1180 1181
		stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
		tlb_migrate_finish(p->mm);
		return 0;
1182 1183 1184 1185 1186
	} else if (task_on_rq_queued(p)) {
		/*
		 * OK, since we're going to drop the lock immediately
		 * afterwards anyway.
		 */
1187
		lockdep_unpin_lock(&rq->lock, rf.cookie);
1188
		rq = move_queued_task(rq, p, dest_cpu);
1189
		lockdep_repin_lock(&rq->lock, rf.cookie);
1190
	}
P
Peter Zijlstra 已提交
1191
out:
1192
	task_rq_unlock(rq, p, &rf);
P
Peter Zijlstra 已提交
1193 1194 1195

	return ret;
}
1196 1197 1198 1199 1200

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
1201 1202
EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);

I
Ingo Molnar 已提交
1203
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
I
Ingo Molnar 已提交
1204
{
1205 1206 1207 1208 1209
#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
1210
	WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
O
Oleg Nesterov 已提交
1211
			!p->on_rq);
1212

1213 1214 1215 1216 1217 1218 1219 1220 1221
	/*
	 * 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)));

1222
#ifdef CONFIG_LOCKDEP
1223 1224 1225 1226 1227
	/*
	 * 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
1228
	 * see task_group().
1229 1230 1231 1232
	 *
	 * Furthermore, all task_rq users should acquire both locks, see
	 * task_rq_lock().
	 */
1233 1234 1235
	WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
				      lockdep_is_held(&task_rq(p)->lock)));
#endif
1236 1237
#endif

1238
	trace_sched_migrate_task(p, new_cpu);
1239

1240
	if (task_cpu(p) != new_cpu) {
1241
		if (p->sched_class->migrate_task_rq)
1242
			p->sched_class->migrate_task_rq(p);
1243
		p->se.nr_migrations++;
1244
		perf_event_task_migrate(p);
1245
	}
I
Ingo Molnar 已提交
1246 1247

	__set_task_cpu(p, new_cpu);
I
Ingo Molnar 已提交
1248 1249
}

1250 1251
static void __migrate_swap_task(struct task_struct *p, int cpu)
{
1252
	if (task_on_rq_queued(p)) {
1253 1254 1255 1256 1257
		struct rq *src_rq, *dst_rq;

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

1258
		p->on_rq = TASK_ON_RQ_MIGRATING;
1259 1260 1261
		deactivate_task(src_rq, p, 0);
		set_task_cpu(p, cpu);
		activate_task(dst_rq, p, 0);
1262
		p->on_rq = TASK_ON_RQ_QUEUED;
1263 1264 1265 1266 1267
		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
1268
		 * previous cpu our target instead of where it really is.
1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284
		 */
		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;

1285 1286 1287
	if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
		return -EAGAIN;

1288 1289 1290
	src_rq = cpu_rq(arg->src_cpu);
	dst_rq = cpu_rq(arg->dst_cpu);

1291 1292
	double_raw_lock(&arg->src_task->pi_lock,
			&arg->dst_task->pi_lock);
1293
	double_rq_lock(src_rq, dst_rq);
1294

1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313
	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);
1314 1315
	raw_spin_unlock(&arg->dst_task->pi_lock);
	raw_spin_unlock(&arg->src_task->pi_lock);
1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337

	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;

1338 1339 1340 1341
	/*
	 * 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.
	 */
1342 1343 1344 1345 1346 1347 1348 1349 1350
	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;

1351
	trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1352 1353 1354 1355 1356 1357
	ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);

out:
	return ret;
}

L
Linus Torvalds 已提交
1358 1359 1360
/*
 * wait_task_inactive - wait for a thread to unschedule.
 *
R
Roland McGrath 已提交
1361 1362 1363 1364 1365 1366 1367
 * 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
1368 1369 1370 1371 1372 1373
 * 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
1374
unsigned long wait_task_inactive(struct task_struct *p, long match_state)
L
Linus Torvalds 已提交
1375
{
1376
	int running, queued;
1377
	struct rq_flags rf;
R
Roland McGrath 已提交
1378
	unsigned long ncsw;
1379
	struct rq *rq;
L
Linus Torvalds 已提交
1380

1381 1382 1383 1384 1385 1386 1387 1388
	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);
1389

1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400
		/*
		 * 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
1401 1402 1403
		while (task_running(rq, p)) {
			if (match_state && unlikely(p->state != match_state))
				return 0;
1404
			cpu_relax();
R
Roland McGrath 已提交
1405
		}
1406

1407 1408 1409 1410 1411
		/*
		 * 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.
		 */
1412
		rq = task_rq_lock(p, &rf);
1413
		trace_sched_wait_task(p);
1414
		running = task_running(rq, p);
1415
		queued = task_on_rq_queued(p);
R
Roland McGrath 已提交
1416
		ncsw = 0;
1417
		if (!match_state || p->state == match_state)
1418
			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1419
		task_rq_unlock(rq, p, &rf);
1420

R
Roland McGrath 已提交
1421 1422 1423 1424 1425 1426
		/*
		 * If it changed from the expected state, bail out now.
		 */
		if (unlikely(!ncsw))
			break;

1427 1428 1429 1430 1431 1432 1433 1434 1435 1436
		/*
		 * 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;
		}
1437

1438 1439 1440 1441 1442
		/*
		 * It's not enough that it's not actively running,
		 * it must be off the runqueue _entirely_, and not
		 * preempted!
		 *
1443
		 * So if it was still runnable (but just not actively
1444 1445 1446
		 * running right now), it's preempted, and we should
		 * yield - it could be a while.
		 */
1447
		if (unlikely(queued)) {
1448 1449 1450 1451
			ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);

			set_current_state(TASK_UNINTERRUPTIBLE);
			schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1452 1453
			continue;
		}
1454

1455 1456 1457 1458 1459 1460 1461
		/*
		 * 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
1462 1463

	return ncsw;
L
Linus Torvalds 已提交
1464 1465 1466 1467 1468 1469 1470 1471 1472
}

/***
 * 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
1473
 * NOTE: this function doesn't have to take the runqueue lock,
L
Linus Torvalds 已提交
1474 1475 1476 1477 1478
 * 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.
 */
1479
void kick_process(struct task_struct *p)
L
Linus Torvalds 已提交
1480 1481 1482 1483 1484 1485 1486 1487 1488
{
	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
1489
EXPORT_SYMBOL_GPL(kick_process);
L
Linus Torvalds 已提交
1490

1491
/*
1492
 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511
 *
 * 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.
1512
 */
1513 1514
static int select_fallback_rq(int cpu, struct task_struct *p)
{
1515 1516
	int nid = cpu_to_node(cpu);
	const struct cpumask *nodemask = NULL;
1517 1518
	enum { cpuset, possible, fail } state = cpuset;
	int dest_cpu;
1519

1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534
	/*
	 * 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;
		}
1535
	}
1536

1537 1538
	for (;;) {
		/* Any allowed, online CPU? */
1539
		for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1540 1541 1542
			if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu))
				continue;
			if (!cpu_online(dest_cpu))
1543 1544 1545
				continue;
			goto out;
		}
1546

1547
		/* No more Mr. Nice Guy. */
1548 1549
		switch (state) {
		case cpuset:
1550 1551 1552 1553 1554 1555
			if (IS_ENABLED(CONFIG_CPUSETS)) {
				cpuset_cpus_allowed_fallback(p);
				state = possible;
				break;
			}
			/* fall-through */
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574
		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()) {
1575
			printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1576 1577
					task_pid_nr(p), p->comm, cpu);
		}
1578 1579 1580 1581 1582
	}

	return dest_cpu;
}

1583
/*
1584
 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1585
 */
1586
static inline
1587
int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1588
{
1589 1590
	lockdep_assert_held(&p->pi_lock);

1591
	if (tsk_nr_cpus_allowed(p) > 1)
1592
		cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1593 1594
	else
		cpu = cpumask_any(tsk_cpus_allowed(p));
1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605

	/*
	 * 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 ]
	 */
1606
	if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
P
Peter Zijlstra 已提交
1607
		     !cpu_online(cpu)))
1608
		cpu = select_fallback_rq(task_cpu(p), p);
1609 1610

	return cpu;
1611
}
1612 1613 1614 1615 1616 1617

static void update_avg(u64 *avg, u64 sample)
{
	s64 diff = sample - *avg;
	*avg += diff >> 3;
}
1618 1619 1620 1621 1622 1623 1624 1625 1626

#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
1627
#endif /* CONFIG_SMP */
1628

P
Peter Zijlstra 已提交
1629
static void
1630
ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
T
Tejun Heo 已提交
1631
{
P
Peter Zijlstra 已提交
1632
#ifdef CONFIG_SCHEDSTATS
1633 1634
	struct rq *rq = this_rq();

P
Peter Zijlstra 已提交
1635 1636 1637 1638 1639 1640 1641 1642 1643 1644
#ifdef CONFIG_SMP
	int this_cpu = smp_processor_id();

	if (cpu == this_cpu) {
		schedstat_inc(rq, ttwu_local);
		schedstat_inc(p, se.statistics.nr_wakeups_local);
	} else {
		struct sched_domain *sd;

		schedstat_inc(p, se.statistics.nr_wakeups_remote);
1645
		rcu_read_lock();
P
Peter Zijlstra 已提交
1646 1647 1648 1649 1650 1651
		for_each_domain(this_cpu, sd) {
			if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
				schedstat_inc(sd, ttwu_wake_remote);
				break;
			}
		}
1652
		rcu_read_unlock();
P
Peter Zijlstra 已提交
1653
	}
1654 1655 1656 1657

	if (wake_flags & WF_MIGRATED)
		schedstat_inc(p, se.statistics.nr_wakeups_migrate);

P
Peter Zijlstra 已提交
1658 1659 1660
#endif /* CONFIG_SMP */

	schedstat_inc(rq, ttwu_count);
T
Tejun Heo 已提交
1661
	schedstat_inc(p, se.statistics.nr_wakeups);
P
Peter Zijlstra 已提交
1662 1663

	if (wake_flags & WF_SYNC)
T
Tejun Heo 已提交
1664
		schedstat_inc(p, se.statistics.nr_wakeups_sync);
P
Peter Zijlstra 已提交
1665 1666 1667 1668

#endif /* CONFIG_SCHEDSTATS */
}

1669
static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
P
Peter Zijlstra 已提交
1670
{
T
Tejun Heo 已提交
1671
	activate_task(rq, p, en_flags);
1672
	p->on_rq = TASK_ON_RQ_QUEUED;
1673 1674 1675 1676

	/* 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
1677 1678
}

1679 1680 1681
/*
 * Mark the task runnable and perform wakeup-preemption.
 */
1682 1683
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
1684 1685 1686
{
	check_preempt_curr(rq, p, wake_flags);
	p->state = TASK_RUNNING;
1687 1688
	trace_sched_wakeup(p);

T
Tejun Heo 已提交
1689
#ifdef CONFIG_SMP
1690 1691
	if (p->sched_class->task_woken) {
		/*
1692 1693
		 * Our task @p is fully woken up and running; so its safe to
		 * drop the rq->lock, hereafter rq is only used for statistics.
1694
		 */
1695
		lockdep_unpin_lock(&rq->lock, cookie);
T
Tejun Heo 已提交
1696
		p->sched_class->task_woken(rq, p);
1697
		lockdep_repin_lock(&rq->lock, cookie);
1698
	}
T
Tejun Heo 已提交
1699

1700
	if (rq->idle_stamp) {
1701
		u64 delta = rq_clock(rq) - rq->idle_stamp;
1702
		u64 max = 2*rq->max_idle_balance_cost;
T
Tejun Heo 已提交
1703

1704 1705 1706
		update_avg(&rq->avg_idle, delta);

		if (rq->avg_idle > max)
T
Tejun Heo 已提交
1707
			rq->avg_idle = max;
1708

T
Tejun Heo 已提交
1709 1710 1711 1712 1713
		rq->idle_stamp = 0;
	}
#endif
}

1714
static void
1715 1716
ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
		 struct pin_cookie cookie)
1717
{
1718 1719
	int en_flags = ENQUEUE_WAKEUP;

1720 1721
	lockdep_assert_held(&rq->lock);

1722 1723 1724
#ifdef CONFIG_SMP
	if (p->sched_contributes_to_load)
		rq->nr_uninterruptible--;
1725 1726

	if (wake_flags & WF_MIGRATED)
1727
		en_flags |= ENQUEUE_MIGRATED;
1728 1729
#endif

1730
	ttwu_activate(rq, p, en_flags);
1731
	ttwu_do_wakeup(rq, p, wake_flags, cookie);
1732 1733 1734 1735 1736 1737 1738 1739 1740 1741
}

/*
 * 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)
{
1742
	struct rq_flags rf;
1743 1744 1745
	struct rq *rq;
	int ret = 0;

1746
	rq = __task_rq_lock(p, &rf);
1747
	if (task_on_rq_queued(p)) {
1748 1749
		/* check_preempt_curr() may use rq clock */
		update_rq_clock(rq);
1750
		ttwu_do_wakeup(rq, p, wake_flags, rf.cookie);
1751 1752
		ret = 1;
	}
1753
	__task_rq_unlock(rq, &rf);
1754 1755 1756 1757

	return ret;
}

1758
#ifdef CONFIG_SMP
1759
void sched_ttwu_pending(void)
1760 1761
{
	struct rq *rq = this_rq();
P
Peter Zijlstra 已提交
1762
	struct llist_node *llist = llist_del_all(&rq->wake_list);
1763
	struct pin_cookie cookie;
P
Peter Zijlstra 已提交
1764
	struct task_struct *p;
1765
	unsigned long flags;
1766

1767 1768 1769 1770
	if (!llist)
		return;

	raw_spin_lock_irqsave(&rq->lock, flags);
1771
	cookie = lockdep_pin_lock(&rq->lock);
1772

P
Peter Zijlstra 已提交
1773
	while (llist) {
P
Peter Zijlstra 已提交
1774 1775
		int wake_flags = 0;

P
Peter Zijlstra 已提交
1776 1777
		p = llist_entry(llist, struct task_struct, wake_entry);
		llist = llist_next(llist);
P
Peter Zijlstra 已提交
1778 1779 1780 1781 1782

		if (p->sched_remote_wakeup)
			wake_flags = WF_MIGRATED;

		ttwu_do_activate(rq, p, wake_flags, cookie);
1783 1784
	}

1785
	lockdep_unpin_lock(&rq->lock, cookie);
1786
	raw_spin_unlock_irqrestore(&rq->lock, flags);
1787 1788 1789 1790
}

void scheduler_ipi(void)
{
1791 1792 1793 1794 1795
	/*
	 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
	 * TIF_NEED_RESCHED remotely (for the first time) will also send
	 * this IPI.
	 */
1796
	preempt_fold_need_resched();
1797

1798
	if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814
		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
1815
	sched_ttwu_pending();
1816 1817 1818 1819

	/*
	 * Check if someone kicked us for doing the nohz idle load balance.
	 */
1820
	if (unlikely(got_nohz_idle_kick())) {
1821
		this_rq()->idle_balance = 1;
1822
		raise_softirq_irqoff(SCHED_SOFTIRQ);
1823
	}
1824
	irq_exit();
1825 1826
}

P
Peter Zijlstra 已提交
1827
static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags)
1828
{
1829 1830
	struct rq *rq = cpu_rq(cpu);

P
Peter Zijlstra 已提交
1831 1832
	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);

1833 1834 1835 1836 1837 1838
	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);
	}
1839
}
1840

1841 1842 1843 1844 1845
void wake_up_if_idle(int cpu)
{
	struct rq *rq = cpu_rq(cpu);
	unsigned long flags;

1846 1847 1848 1849
	rcu_read_lock();

	if (!is_idle_task(rcu_dereference(rq->curr)))
		goto out;
1850 1851 1852 1853 1854 1855 1856 1857 1858 1859

	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);
	}
1860 1861 1862

out:
	rcu_read_unlock();
1863 1864
}

1865
bool cpus_share_cache(int this_cpu, int that_cpu)
1866 1867 1868
{
	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
}
1869
#endif /* CONFIG_SMP */
1870

1871
static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
1872 1873
{
	struct rq *rq = cpu_rq(cpu);
1874
	struct pin_cookie cookie;
1875

1876
#if defined(CONFIG_SMP)
1877
	if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1878
		sched_clock_cpu(cpu); /* sync clocks x-cpu */
P
Peter Zijlstra 已提交
1879
		ttwu_queue_remote(p, cpu, wake_flags);
1880 1881 1882 1883
		return;
	}
#endif

1884
	raw_spin_lock(&rq->lock);
1885
	cookie = lockdep_pin_lock(&rq->lock);
1886
	ttwu_do_activate(rq, p, wake_flags, cookie);
1887
	lockdep_unpin_lock(&rq->lock, cookie);
1888
	raw_spin_unlock(&rq->lock);
T
Tejun Heo 已提交
1889 1890
}

1891 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
/*
 * 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)
1941
 *   2) smp_cond_load_acquire(!X->on_cpu)
1942 1943 1944 1945 1946 1947 1948 1949 1950 1951
 *
 * 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);
 *
1952
 *                    smp_cond_load_acquire(&X->on_cpu, !VAL);
1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977
 *                    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,
1978
 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire).
1979 1980 1981
 *
 */

T
Tejun Heo 已提交
1982
/**
L
Linus Torvalds 已提交
1983
 * try_to_wake_up - wake up a thread
T
Tejun Heo 已提交
1984
 * @p: the thread to be awakened
L
Linus Torvalds 已提交
1985
 * @state: the mask of task states that can be woken
T
Tejun Heo 已提交
1986
 * @wake_flags: wake modifier flags (WF_*)
L
Linus Torvalds 已提交
1987 1988 1989 1990 1991 1992 1993
 *
 * 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.
 *
1994
 * Return: %true if @p was woken up, %false if it was already running.
T
Tejun Heo 已提交
1995
 * or @state didn't match @p's state.
L
Linus Torvalds 已提交
1996
 */
1997 1998
static int
try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
L
Linus Torvalds 已提交
1999 2000
{
	unsigned long flags;
2001
	int cpu, success = 0;
P
Peter Zijlstra 已提交
2002

2003 2004 2005 2006 2007 2008 2009
	/*
	 * 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();
2010
	raw_spin_lock_irqsave(&p->pi_lock, flags);
P
Peter Zijlstra 已提交
2011
	if (!(p->state & state))
L
Linus Torvalds 已提交
2012 2013
		goto out;

2014 2015
	trace_sched_waking(p);

2016
	success = 1; /* we're going to change ->state */
L
Linus Torvalds 已提交
2017 2018
	cpu = task_cpu(p);

2019 2020
	if (p->on_rq && ttwu_remote(p, wake_flags))
		goto stat;
L
Linus Torvalds 已提交
2021 2022

#ifdef CONFIG_SMP
2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041
	/*
	 * 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
2042
	/*
2043 2044
	 * If the owning (remote) cpu is still in the middle of schedule() with
	 * this task as prev, wait until its done referencing the task.
2045 2046 2047 2048 2049
	 *
	 * 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.
2050
	 */
2051
	smp_cond_load_acquire(&p->on_cpu, !VAL);
L
Linus Torvalds 已提交
2052

2053
	p->sched_contributes_to_load = !!task_contributes_to_load(p);
P
Peter Zijlstra 已提交
2054
	p->state = TASK_WAKING;
2055

2056
	cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
2057 2058
	if (task_cpu(p) != cpu) {
		wake_flags |= WF_MIGRATED;
2059
		set_task_cpu(p, cpu);
2060
	}
L
Linus Torvalds 已提交
2061 2062
#endif /* CONFIG_SMP */

2063
	ttwu_queue(p, cpu, wake_flags);
2064
stat:
2065 2066
	if (schedstat_enabled())
		ttwu_stat(p, cpu, wake_flags);
L
Linus Torvalds 已提交
2067
out:
2068
	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
L
Linus Torvalds 已提交
2069 2070 2071 2072

	return success;
}

T
Tejun Heo 已提交
2073 2074 2075
/**
 * try_to_wake_up_local - try to wake up a local task with rq lock held
 * @p: the thread to be awakened
2076
 * @cookie: context's cookie for pinning
T
Tejun Heo 已提交
2077
 *
2078
 * Put @p on the run-queue if it's not already there. The caller must
T
Tejun Heo 已提交
2079
 * ensure that this_rq() is locked, @p is bound to this_rq() and not
2080
 * the current task.
T
Tejun Heo 已提交
2081
 */
2082
static void try_to_wake_up_local(struct task_struct *p, struct pin_cookie cookie)
T
Tejun Heo 已提交
2083 2084 2085
{
	struct rq *rq = task_rq(p);

2086 2087 2088 2089
	if (WARN_ON_ONCE(rq != this_rq()) ||
	    WARN_ON_ONCE(p == current))
		return;

T
Tejun Heo 已提交
2090 2091
	lockdep_assert_held(&rq->lock);

2092
	if (!raw_spin_trylock(&p->pi_lock)) {
2093 2094 2095 2096 2097 2098
		/*
		 * 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.
		 */
2099
		lockdep_unpin_lock(&rq->lock, cookie);
2100 2101 2102
		raw_spin_unlock(&rq->lock);
		raw_spin_lock(&p->pi_lock);
		raw_spin_lock(&rq->lock);
2103
		lockdep_repin_lock(&rq->lock, cookie);
2104 2105
	}

T
Tejun Heo 已提交
2106
	if (!(p->state & TASK_NORMAL))
2107
		goto out;
T
Tejun Heo 已提交
2108

2109 2110
	trace_sched_waking(p);

2111
	if (!task_on_rq_queued(p))
P
Peter Zijlstra 已提交
2112 2113
		ttwu_activate(rq, p, ENQUEUE_WAKEUP);

2114
	ttwu_do_wakeup(rq, p, 0, cookie);
2115 2116
	if (schedstat_enabled())
		ttwu_stat(p, smp_processor_id(), 0);
2117 2118
out:
	raw_spin_unlock(&p->pi_lock);
T
Tejun Heo 已提交
2119 2120
}

2121 2122 2123 2124 2125
/**
 * 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
2126 2127 2128
 * processes.
 *
 * Return: 1 if the process was woken up, 0 if it was already running.
2129 2130 2131 2132
 *
 * 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.
 */
2133
int wake_up_process(struct task_struct *p)
L
Linus Torvalds 已提交
2134
{
2135
	return try_to_wake_up(p, TASK_NORMAL, 0);
L
Linus Torvalds 已提交
2136 2137 2138
}
EXPORT_SYMBOL(wake_up_process);

2139
int wake_up_state(struct task_struct *p, unsigned int state)
L
Linus Torvalds 已提交
2140 2141 2142 2143
{
	return try_to_wake_up(p, state, 0);
}

2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155
/*
 * 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;
2156 2157 2158

	dl_se->dl_throttled = 0;
	dl_se->dl_yielded = 0;
2159 2160
}

L
Linus Torvalds 已提交
2161 2162 2163
/*
 * Perform scheduler related setup for a newly forked process p.
 * p is forked by current.
I
Ingo Molnar 已提交
2164 2165 2166
 *
 * __sched_fork() is basic setup used by init_idle() too:
 */
2167
static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
I
Ingo Molnar 已提交
2168
{
P
Peter Zijlstra 已提交
2169 2170 2171
	p->on_rq			= 0;

	p->se.on_rq			= 0;
I
Ingo Molnar 已提交
2172 2173
	p->se.exec_start		= 0;
	p->se.sum_exec_runtime		= 0;
2174
	p->se.prev_sum_exec_runtime	= 0;
2175
	p->se.nr_migrations		= 0;
P
Peter Zijlstra 已提交
2176
	p->se.vruntime			= 0;
P
Peter Zijlstra 已提交
2177
	INIT_LIST_HEAD(&p->se.group_node);
I
Ingo Molnar 已提交
2178

2179 2180 2181 2182
#ifdef CONFIG_FAIR_GROUP_SCHED
	p->se.cfs_rq			= NULL;
#endif

I
Ingo Molnar 已提交
2183
#ifdef CONFIG_SCHEDSTATS
2184
	/* Even if schedstat is disabled, there should not be garbage */
2185
	memset(&p->se.statistics, 0, sizeof(p->se.statistics));
I
Ingo Molnar 已提交
2186
#endif
N
Nick Piggin 已提交
2187

2188
	RB_CLEAR_NODE(&p->dl.rb_node);
2189
	init_dl_task_timer(&p->dl);
2190
	__dl_clear_params(p);
2191

P
Peter Zijlstra 已提交
2192
	INIT_LIST_HEAD(&p->rt.run_list);
2193 2194 2195 2196
	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
2197

2198 2199 2200
#ifdef CONFIG_PREEMPT_NOTIFIERS
	INIT_HLIST_HEAD(&p->preempt_notifiers);
#endif
2201 2202 2203

#ifdef CONFIG_NUMA_BALANCING
	if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
2204
		p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
2205 2206 2207
		p->mm->numa_scan_seq = 0;
	}

2208 2209 2210 2211 2212
	if (clone_flags & CLONE_VM)
		p->numa_preferred_nid = current->numa_preferred_nid;
	else
		p->numa_preferred_nid = -1;

2213 2214
	p->node_stamp = 0ULL;
	p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
2215
	p->numa_scan_period = sysctl_numa_balancing_scan_delay;
2216
	p->numa_work.next = &p->numa_work;
2217
	p->numa_faults = NULL;
2218 2219
	p->last_task_numa_placement = 0;
	p->last_sum_exec_runtime = 0;
2220 2221

	p->numa_group = NULL;
2222
#endif /* CONFIG_NUMA_BALANCING */
I
Ingo Molnar 已提交
2223 2224
}

2225 2226
DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);

2227
#ifdef CONFIG_NUMA_BALANCING
2228

2229 2230 2231
void set_numabalancing_state(bool enabled)
{
	if (enabled)
2232
		static_branch_enable(&sched_numa_balancing);
2233
	else
2234
		static_branch_disable(&sched_numa_balancing);
2235
}
2236 2237 2238 2239 2240 2241 2242

#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;
2243
	int state = static_branch_likely(&sched_numa_balancing);
2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258

	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
2259

2260 2261
#ifdef CONFIG_SCHEDSTATS

2262
DEFINE_STATIC_KEY_FALSE(sched_schedstats);
2263
static bool __initdata __sched_schedstats = false;
2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286

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;

2287 2288 2289 2290 2291
	/*
	 * 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.
	 */
2292
	if (!strcmp(str, "enable")) {
2293
		__sched_schedstats = true;
2294 2295
		ret = 1;
	} else if (!strcmp(str, "disable")) {
2296
		__sched_schedstats = false;
2297 2298 2299 2300 2301 2302 2303 2304 2305 2306
		ret = 1;
	}
out:
	if (!ret)
		pr_warn("Unable to parse schedstats=\n");

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

2307 2308 2309 2310 2311
static void __init init_schedstats(void)
{
	set_schedstats(__sched_schedstats);
}

2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331
#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;
}
2332 2333 2334 2335
#endif /* CONFIG_PROC_SYSCTL */
#else  /* !CONFIG_SCHEDSTATS */
static inline void init_schedstats(void) {}
#endif /* CONFIG_SCHEDSTATS */
I
Ingo Molnar 已提交
2336 2337 2338 2339

/*
 * fork()/clone()-time setup:
 */
2340
int sched_fork(unsigned long clone_flags, struct task_struct *p)
I
Ingo Molnar 已提交
2341
{
2342
	unsigned long flags;
I
Ingo Molnar 已提交
2343 2344
	int cpu = get_cpu();

2345
	__sched_fork(clone_flags, p);
2346
	/*
2347
	 * We mark the process as NEW here. This guarantees that
2348 2349 2350
	 * nobody will actually run it, and a signal or other external
	 * event cannot wake it up and insert it on the runqueue either.
	 */
2351
	p->state = TASK_NEW;
I
Ingo Molnar 已提交
2352

2353 2354 2355 2356 2357
	/*
	 * Make sure we do not leak PI boosting priority to the child.
	 */
	p->prio = current->normal_prio;

2358 2359 2360 2361
	/*
	 * Revert to default priority/policy on fork if requested.
	 */
	if (unlikely(p->sched_reset_on_fork)) {
2362
		if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2363
			p->policy = SCHED_NORMAL;
2364
			p->static_prio = NICE_TO_PRIO(0);
2365 2366 2367 2368 2369 2370
			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);
2371

2372 2373 2374 2375 2376 2377
		/*
		 * We don't need the reset flag anymore after the fork. It has
		 * fulfilled its duty:
		 */
		p->sched_reset_on_fork = 0;
	}
2378

2379 2380 2381 2382 2383 2384
	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
2385
		p->sched_class = &fair_sched_class;
2386
	}
2387

2388
	init_entity_runnable_average(&p->se);
P
Peter Zijlstra 已提交
2389

2390 2391 2392 2393 2394 2395 2396
	/*
	 * 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.
	 */
2397
	raw_spin_lock_irqsave(&p->pi_lock, flags);
2398 2399 2400 2401 2402 2403 2404
	/*
	 * 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);
2405
	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2406

2407
#ifdef CONFIG_SCHED_INFO
I
Ingo Molnar 已提交
2408
	if (likely(sched_info_on()))
2409
		memset(&p->sched_info, 0, sizeof(p->sched_info));
L
Linus Torvalds 已提交
2410
#endif
P
Peter Zijlstra 已提交
2411 2412
#if defined(CONFIG_SMP)
	p->on_cpu = 0;
2413
#endif
2414
	init_task_preempt_count(p);
2415
#ifdef CONFIG_SMP
2416
	plist_node_init(&p->pushable_tasks, MAX_PRIO);
2417
	RB_CLEAR_NODE(&p->pushable_dl_tasks);
2418
#endif
2419

N
Nick Piggin 已提交
2420
	put_cpu();
2421
	return 0;
L
Linus Torvalds 已提交
2422 2423
}

2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442
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)
{
2443 2444
	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
			 "sched RCU must be held");
2445 2446 2447
	return &cpu_rq(i)->rd->dl_bw;
}

2448
static inline int dl_bw_cpus(int i)
2449
{
2450 2451 2452
	struct root_domain *rd = cpu_rq(i)->rd;
	int cpus = 0;

2453 2454
	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
			 "sched RCU must be held");
2455 2456 2457 2458
	for_each_cpu_and(i, rd->span, cpu_active_mask)
		cpus++;

	return cpus;
2459 2460 2461 2462 2463 2464 2465
}
#else
inline struct dl_bw *dl_bw_of(int i)
{
	return &cpu_rq(i)->dl.dl_bw;
}

2466
static inline int dl_bw_cpus(int i)
2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478
{
	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.
2479 2480 2481
 *
 * XXX we should delay bw change until the task's 0-lag point, see
 * __setparam_dl().
2482 2483 2484 2485 2486 2487
 */
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));
2488
	u64 period = attr->sched_period ?: attr->sched_deadline;
2489 2490
	u64 runtime = attr->sched_runtime;
	u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2491
	int cpus, err = -1;
2492

2493 2494
	/* !deadline task may carry old deadline bandwidth */
	if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
2495 2496 2497 2498 2499 2500 2501 2502
		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);
2503
	cpus = dl_bw_cpus(task_cpu(p));
2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523
	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
2524 2525 2526 2527 2528 2529 2530
/*
 * 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.
 */
2531
void wake_up_new_task(struct task_struct *p)
L
Linus Torvalds 已提交
2532
{
2533
	struct rq_flags rf;
I
Ingo Molnar 已提交
2534
	struct rq *rq;
2535

2536
	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
2537
	p->state = TASK_RUNNING;
2538 2539 2540 2541 2542
#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
2543 2544 2545
	 *
	 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
	 * as we're not fully set-up yet.
2546
	 */
2547
	__set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2548
#endif
2549
	rq = __task_rq_lock(p, &rf);
2550
	post_init_entity_util_avg(&p->se);
2551

P
Peter Zijlstra 已提交
2552
	activate_task(rq, p, 0);
2553
	p->on_rq = TASK_ON_RQ_QUEUED;
2554
	trace_sched_wakeup_new(p);
P
Peter Zijlstra 已提交
2555
	check_preempt_curr(rq, p, WF_FORK);
2556
#ifdef CONFIG_SMP
2557 2558 2559 2560 2561
	if (p->sched_class->task_woken) {
		/*
		 * Nothing relies on rq->lock after this, so its fine to
		 * drop it.
		 */
2562
		lockdep_unpin_lock(&rq->lock, rf.cookie);
2563
		p->sched_class->task_woken(rq, p);
2564
		lockdep_repin_lock(&rq->lock, rf.cookie);
2565
	}
2566
#endif
2567
	task_rq_unlock(rq, p, &rf);
L
Linus Torvalds 已提交
2568 2569
}

2570 2571
#ifdef CONFIG_PREEMPT_NOTIFIERS

2572 2573
static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;

2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585
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);

2586
/**
2587
 * preempt_notifier_register - tell me when current is being preempted & rescheduled
R
Randy Dunlap 已提交
2588
 * @notifier: notifier struct to register
2589 2590 2591
 */
void preempt_notifier_register(struct preempt_notifier *notifier)
{
2592 2593 2594
	if (!static_key_false(&preempt_notifier_key))
		WARN(1, "registering preempt_notifier while notifiers disabled\n");

2595 2596 2597 2598 2599 2600
	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
2601
 * @notifier: notifier struct to unregister
2602
 *
2603
 * This is *not* safe to call from within a preemption notifier.
2604 2605 2606 2607 2608 2609 2610
 */
void preempt_notifier_unregister(struct preempt_notifier *notifier)
{
	hlist_del(&notifier->link);
}
EXPORT_SYMBOL_GPL(preempt_notifier_unregister);

2611
static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
2612 2613 2614
{
	struct preempt_notifier *notifier;

2615
	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2616 2617 2618
		notifier->ops->sched_in(notifier, raw_smp_processor_id());
}

2619 2620 2621 2622 2623 2624
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);
}

2625
static void
2626 2627
__fire_sched_out_preempt_notifiers(struct task_struct *curr,
				   struct task_struct *next)
2628 2629 2630
{
	struct preempt_notifier *notifier;

2631
	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2632 2633 2634
		notifier->ops->sched_out(notifier, next);
}

2635 2636 2637 2638 2639 2640 2641 2642
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);
}

2643
#else /* !CONFIG_PREEMPT_NOTIFIERS */
2644

2645
static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2646 2647 2648
{
}

2649
static inline void
2650 2651 2652 2653 2654
fire_sched_out_preempt_notifiers(struct task_struct *curr,
				 struct task_struct *next)
{
}

2655
#endif /* CONFIG_PREEMPT_NOTIFIERS */
2656

2657 2658 2659
/**
 * prepare_task_switch - prepare to switch tasks
 * @rq: the runqueue preparing to switch
R
Randy Dunlap 已提交
2660
 * @prev: the current task that is being switched out
2661 2662 2663 2664 2665 2666 2667 2668 2669
 * @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.
 */
2670 2671 2672
static inline void
prepare_task_switch(struct rq *rq, struct task_struct *prev,
		    struct task_struct *next)
2673
{
2674
	sched_info_switch(rq, prev, next);
2675
	perf_event_task_sched_out(prev, next);
2676
	fire_sched_out_preempt_notifiers(prev, next);
2677 2678 2679 2680
	prepare_lock_switch(rq, next);
	prepare_arch_switch(next);
}

L
Linus Torvalds 已提交
2681 2682 2683 2684
/**
 * finish_task_switch - clean up after a task-switch
 * @prev: the thread we just switched away from.
 *
2685 2686 2687 2688
 * 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
2689 2690
 *
 * Note that we may have delayed dropping an mm in context_switch(). If
I
Ingo Molnar 已提交
2691
 * so, we finish that here outside of the runqueue lock. (Doing it
L
Linus Torvalds 已提交
2692 2693
 * with the lock held can cause deadlocks; see schedule() for
 * details.)
2694 2695 2696 2697 2698
 *
 * 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
2699
 */
2700
static struct rq *finish_task_switch(struct task_struct *prev)
L
Linus Torvalds 已提交
2701 2702
	__releases(rq->lock)
{
2703
	struct rq *rq = this_rq();
L
Linus Torvalds 已提交
2704
	struct mm_struct *mm = rq->prev_mm;
O
Oleg Nesterov 已提交
2705
	long prev_state;
L
Linus Torvalds 已提交
2706

2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717
	/*
	 * 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.
	 */
2718 2719 2720 2721
	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);
2722

L
Linus Torvalds 已提交
2723 2724 2725 2726
	rq->prev_mm = NULL;

	/*
	 * A task struct has one reference for the use as "current".
2727
	 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
O
Oleg Nesterov 已提交
2728 2729
	 * schedule one last time. The schedule call will never return, and
	 * the scheduled task must drop that reference.
2730 2731 2732 2733 2734
	 *
	 * 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
2735
	 */
O
Oleg Nesterov 已提交
2736
	prev_state = prev->state;
2737
	vtime_task_switch(prev);
2738
	perf_event_task_sched_in(prev, current);
2739
	finish_lock_switch(rq, prev);
2740
	finish_arch_post_lock_switch();
S
Steven Rostedt 已提交
2741

2742
	fire_sched_in_preempt_notifiers(current);
L
Linus Torvalds 已提交
2743 2744
	if (mm)
		mmdrop(mm);
2745
	if (unlikely(prev_state == TASK_DEAD)) {
2746 2747 2748
		if (prev->sched_class->task_dead)
			prev->sched_class->task_dead(prev);

2749 2750 2751
		/*
		 * Remove function-return probe instances associated with this
		 * task and put them back on the free list.
I
Ingo Molnar 已提交
2752
		 */
2753
		kprobe_flush_task(prev);
L
Linus Torvalds 已提交
2754
		put_task_struct(prev);
2755
	}
2756

2757
	tick_nohz_task_switch();
2758
	return rq;
L
Linus Torvalds 已提交
2759 2760
}

2761 2762 2763
#ifdef CONFIG_SMP

/* rq->lock is NOT held, but preemption is disabled */
2764
static void __balance_callback(struct rq *rq)
2765
{
2766 2767 2768
	struct callback_head *head, *next;
	void (*func)(struct rq *rq);
	unsigned long flags;
2769

2770 2771 2772 2773 2774 2775 2776 2777
	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;
2778

2779
		func(rq);
2780
	}
2781 2782 2783 2784 2785 2786 2787
	raw_spin_unlock_irqrestore(&rq->lock, flags);
}

static inline void balance_callback(struct rq *rq)
{
	if (unlikely(rq->balance_callback))
		__balance_callback(rq);
2788 2789 2790
}

#else
2791

2792
static inline void balance_callback(struct rq *rq)
2793
{
L
Linus Torvalds 已提交
2794 2795
}

2796 2797
#endif

L
Linus Torvalds 已提交
2798 2799 2800 2801
/**
 * schedule_tail - first thing a freshly forked thread must call.
 * @prev: the thread we just switched away from.
 */
2802
asmlinkage __visible void schedule_tail(struct task_struct *prev)
L
Linus Torvalds 已提交
2803 2804
	__releases(rq->lock)
{
2805
	struct rq *rq;
2806

2807 2808 2809 2810 2811 2812 2813 2814 2815
	/*
	 * 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).
	 */

2816
	rq = finish_task_switch(prev);
2817
	balance_callback(rq);
2818
	preempt_enable();
2819

L
Linus Torvalds 已提交
2820
	if (current->set_child_tid)
2821
		put_user(task_pid_vnr(current), current->set_child_tid);
L
Linus Torvalds 已提交
2822 2823 2824
}

/*
2825
 * context_switch - switch to the new MM and the new thread's register state.
L
Linus Torvalds 已提交
2826
 */
2827
static __always_inline struct rq *
2828
context_switch(struct rq *rq, struct task_struct *prev,
2829
	       struct task_struct *next, struct pin_cookie cookie)
L
Linus Torvalds 已提交
2830
{
I
Ingo Molnar 已提交
2831
	struct mm_struct *mm, *oldmm;
L
Linus Torvalds 已提交
2832

2833
	prepare_task_switch(rq, prev, next);
2834

I
Ingo Molnar 已提交
2835 2836
	mm = next->mm;
	oldmm = prev->active_mm;
2837 2838 2839 2840 2841
	/*
	 * For paravirt, this is coupled with an exit in switch_to to
	 * combine the page table reload and the switch backend into
	 * one hypercall.
	 */
2842
	arch_start_context_switch(prev);
2843

2844
	if (!mm) {
L
Linus Torvalds 已提交
2845 2846 2847 2848
		next->active_mm = oldmm;
		atomic_inc(&oldmm->mm_count);
		enter_lazy_tlb(oldmm, next);
	} else
2849
		switch_mm_irqs_off(oldmm, mm, next);
L
Linus Torvalds 已提交
2850

2851
	if (!prev->mm) {
L
Linus Torvalds 已提交
2852 2853 2854
		prev->active_mm = NULL;
		rq->prev_mm = oldmm;
	}
2855 2856 2857 2858 2859 2860
	/*
	 * 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:
	 */
2861
	lockdep_unpin_lock(&rq->lock, cookie);
2862
	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
L
Linus Torvalds 已提交
2863 2864 2865

	/* Here we just switch the register state and the stack. */
	switch_to(prev, next, prev);
I
Ingo Molnar 已提交
2866
	barrier();
2867 2868

	return finish_task_switch(prev);
L
Linus Torvalds 已提交
2869 2870 2871
}

/*
2872
 * nr_running and nr_context_switches:
L
Linus Torvalds 已提交
2873 2874
 *
 * externally visible scheduler statistics: current number of runnable
2875
 * threads, total number of context switches performed since bootup.
L
Linus Torvalds 已提交
2876 2877 2878 2879 2880 2881 2882 2883 2884
 */
unsigned long nr_running(void)
{
	unsigned long i, sum = 0;

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

	return sum;
2885
}
L
Linus Torvalds 已提交
2886

2887 2888
/*
 * Check if only the current task is running on the cpu.
2889 2890 2891 2892 2893 2894 2895 2896 2897 2898
 *
 * 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)
2899 2900 2901
 */
bool single_task_running(void)
{
2902
	return raw_rq()->nr_running == 1;
2903 2904 2905
}
EXPORT_SYMBOL(single_task_running);

L
Linus Torvalds 已提交
2906
unsigned long long nr_context_switches(void)
2907
{
2908 2909
	int i;
	unsigned long long sum = 0;
2910

2911
	for_each_possible_cpu(i)
L
Linus Torvalds 已提交
2912
		sum += cpu_rq(i)->nr_switches;
2913

L
Linus Torvalds 已提交
2914 2915
	return sum;
}
2916

L
Linus Torvalds 已提交
2917 2918 2919
unsigned long nr_iowait(void)
{
	unsigned long i, sum = 0;
2920

2921
	for_each_possible_cpu(i)
L
Linus Torvalds 已提交
2922
		sum += atomic_read(&cpu_rq(i)->nr_iowait);
2923

L
Linus Torvalds 已提交
2924 2925
	return sum;
}
2926

2927
unsigned long nr_iowait_cpu(int cpu)
2928
{
2929
	struct rq *this = cpu_rq(cpu);
2930 2931
	return atomic_read(&this->nr_iowait);
}
2932

2933 2934
void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
{
2935 2936 2937
	struct rq *rq = this_rq();
	*nr_waiters = atomic_read(&rq->nr_iowait);
	*load = rq->load.weight;
2938 2939
}

I
Ingo Molnar 已提交
2940
#ifdef CONFIG_SMP
2941

2942
/*
P
Peter Zijlstra 已提交
2943 2944
 * sched_exec - execve() is a valuable balancing opportunity, because at
 * this point the task has the smallest effective memory and cache footprint.
2945
 */
P
Peter Zijlstra 已提交
2946
void sched_exec(void)
2947
{
P
Peter Zijlstra 已提交
2948
	struct task_struct *p = current;
L
Linus Torvalds 已提交
2949
	unsigned long flags;
2950
	int dest_cpu;
2951

2952
	raw_spin_lock_irqsave(&p->pi_lock, flags);
2953
	dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2954 2955
	if (dest_cpu == smp_processor_id())
		goto unlock;
P
Peter Zijlstra 已提交
2956

2957
	if (likely(cpu_active(dest_cpu))) {
2958
		struct migration_arg arg = { p, dest_cpu };
2959

2960 2961
		raw_spin_unlock_irqrestore(&p->pi_lock, flags);
		stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
L
Linus Torvalds 已提交
2962 2963
		return;
	}
2964
unlock:
2965
	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
L
Linus Torvalds 已提交
2966
}
I
Ingo Molnar 已提交
2967

L
Linus Torvalds 已提交
2968 2969 2970
#endif

DEFINE_PER_CPU(struct kernel_stat, kstat);
2971
DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
L
Linus Torvalds 已提交
2972 2973

EXPORT_PER_CPU_SYMBOL(kstat);
2974
EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
L
Linus Torvalds 已提交
2975

2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992
/*
 * 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);
}

2993 2994 2995 2996 2997 2998 2999
/*
 * 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)
{
3000
	struct rq_flags rf;
3001
	struct rq *rq;
3002
	u64 ns;
3003

3004 3005 3006 3007 3008 3009 3010 3011 3012
#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.
3013 3014
	 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
	 * been accounted, so we're correct here as well.
3015
	 */
3016
	if (!p->on_cpu || !task_on_rq_queued(p))
3017 3018 3019
		return p->se.sum_exec_runtime;
#endif

3020
	rq = task_rq_lock(p, &rf);
3021 3022 3023 3024 3025 3026
	/*
	 * 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)) {
3027
		prefetch_curr_exec_start(p);
3028 3029 3030 3031
		update_rq_clock(rq);
		p->sched_class->update_curr(rq);
	}
	ns = p->se.sum_exec_runtime;
3032
	task_rq_unlock(rq, p, &rf);
3033 3034 3035

	return ns;
}
3036

3037 3038 3039 3040 3041 3042 3043 3044
/*
 * 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
3045
	struct task_struct *curr = rq->curr;
3046 3047

	sched_clock_tick();
I
Ingo Molnar 已提交
3048

3049
	raw_spin_lock(&rq->lock);
3050
	update_rq_clock(rq);
P
Peter Zijlstra 已提交
3051
	curr->sched_class->task_tick(rq, curr, 0);
3052
	cpu_load_update_active(rq);
3053
	calc_global_load_tick(rq);
3054
	raw_spin_unlock(&rq->lock);
3055

3056
	perf_event_task_tick();
3057

3058
#ifdef CONFIG_SMP
3059
	rq->idle_balance = idle_cpu(cpu);
3060
	trigger_load_balance(rq);
3061
#endif
3062
	rq_last_tick_reset(rq);
L
Linus Torvalds 已提交
3063 3064
}

3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075
#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.
3076 3077
 *
 * Return: Maximum deferment in nanoseconds.
3078 3079 3080 3081
 */
u64 scheduler_tick_max_deferment(void)
{
	struct rq *rq = this_rq();
3082
	unsigned long next, now = READ_ONCE(jiffies);
3083 3084 3085 3086 3087 3088

	next = rq->last_sched_tick + HZ;

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

3089
	return jiffies_to_nsecs(next - now);
L
Linus Torvalds 已提交
3090
}
3091
#endif
L
Linus Torvalds 已提交
3092

3093 3094
#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
				defined(CONFIG_PREEMPT_TRACER))
3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108
/*
 * 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);
	}
}
3109

3110
void preempt_count_add(int val)
L
Linus Torvalds 已提交
3111
{
3112
#ifdef CONFIG_DEBUG_PREEMPT
L
Linus Torvalds 已提交
3113 3114 3115
	/*
	 * Underflow?
	 */
3116 3117
	if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
		return;
3118
#endif
3119
	__preempt_count_add(val);
3120
#ifdef CONFIG_DEBUG_PREEMPT
L
Linus Torvalds 已提交
3121 3122 3123
	/*
	 * Spinlock count overflowing soon?
	 */
3124 3125
	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
				PREEMPT_MASK - 10);
3126
#endif
3127
	preempt_latency_start(val);
L
Linus Torvalds 已提交
3128
}
3129
EXPORT_SYMBOL(preempt_count_add);
3130
NOKPROBE_SYMBOL(preempt_count_add);
L
Linus Torvalds 已提交
3131

3132 3133 3134 3135 3136 3137 3138 3139 3140 3141
/*
 * 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());
}

3142
void preempt_count_sub(int val)
L
Linus Torvalds 已提交
3143
{
3144
#ifdef CONFIG_DEBUG_PREEMPT
L
Linus Torvalds 已提交
3145 3146 3147
	/*
	 * Underflow?
	 */
3148
	if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3149
		return;
L
Linus Torvalds 已提交
3150 3151 3152
	/*
	 * Is the spinlock portion underflowing?
	 */
3153 3154 3155
	if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
			!(preempt_count() & PREEMPT_MASK)))
		return;
3156
#endif
3157

3158
	preempt_latency_stop(val);
3159
	__preempt_count_sub(val);
L
Linus Torvalds 已提交
3160
}
3161
EXPORT_SYMBOL(preempt_count_sub);
3162
NOKPROBE_SYMBOL(preempt_count_sub);
L
Linus Torvalds 已提交
3163

3164 3165 3166
#else
static inline void preempt_latency_start(int val) { }
static inline void preempt_latency_stop(int val) { }
L
Linus Torvalds 已提交
3167 3168 3169
#endif

/*
I
Ingo Molnar 已提交
3170
 * Print scheduling while atomic bug:
L
Linus Torvalds 已提交
3171
 */
I
Ingo Molnar 已提交
3172
static noinline void __schedule_bug(struct task_struct *prev)
L
Linus Torvalds 已提交
3173
{
3174 3175 3176
	/* Save this before calling printk(), since that will clobber it */
	unsigned long preempt_disable_ip = get_preempt_disable_ip(current);

3177 3178 3179
	if (oops_in_progress)
		return;

P
Peter Zijlstra 已提交
3180 3181
	printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
		prev->comm, prev->pid, preempt_count());
3182

I
Ingo Molnar 已提交
3183
	debug_show_held_locks(prev);
3184
	print_modules();
I
Ingo Molnar 已提交
3185 3186
	if (irqs_disabled())
		print_irqtrace_events(prev);
3187 3188
	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
	    && in_atomic_preempt_off()) {
3189
		pr_err("Preemption disabled at:");
3190
		print_ip_sym(preempt_disable_ip);
3191 3192
		pr_cont("\n");
	}
3193 3194 3195
	if (panic_on_warn)
		panic("scheduling while atomic\n");

3196
	dump_stack();
3197
	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
I
Ingo Molnar 已提交
3198
}
L
Linus Torvalds 已提交
3199

I
Ingo Molnar 已提交
3200 3201 3202 3203 3204
/*
 * Various schedule()-time debugging checks and statistics:
 */
static inline void schedule_debug(struct task_struct *prev)
{
3205
#ifdef CONFIG_SCHED_STACK_END_CHECK
J
Jann Horn 已提交
3206 3207
	if (task_stack_end_corrupted(prev))
		panic("corrupted stack end detected inside scheduler\n");
3208
#endif
3209

3210
	if (unlikely(in_atomic_preempt_off())) {
I
Ingo Molnar 已提交
3211
		__schedule_bug(prev);
3212 3213
		preempt_count_set(PREEMPT_DISABLED);
	}
3214
	rcu_sleep_check();
I
Ingo Molnar 已提交
3215

L
Linus Torvalds 已提交
3216 3217
	profile_hit(SCHED_PROFILING, __builtin_return_address(0));

3218
	schedstat_inc(this_rq(), sched_count);
I
Ingo Molnar 已提交
3219 3220 3221 3222 3223 3224
}

/*
 * Pick up the highest-prio task:
 */
static inline struct task_struct *
3225
pick_next_task(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie)
I
Ingo Molnar 已提交
3226
{
3227
	const struct sched_class *class = &fair_sched_class;
I
Ingo Molnar 已提交
3228
	struct task_struct *p;
L
Linus Torvalds 已提交
3229 3230

	/*
I
Ingo Molnar 已提交
3231 3232
	 * Optimization: we know that if all tasks are in
	 * the fair class we can call that function directly:
L
Linus Torvalds 已提交
3233
	 */
3234
	if (likely(prev->sched_class == class &&
3235
		   rq->nr_running == rq->cfs.h_nr_running)) {
3236
		p = fair_sched_class.pick_next_task(rq, prev, cookie);
3237 3238 3239 3240 3241
		if (unlikely(p == RETRY_TASK))
			goto again;

		/* assumes fair_sched_class->next == idle_sched_class */
		if (unlikely(!p))
3242
			p = idle_sched_class.pick_next_task(rq, prev, cookie);
3243 3244

		return p;
L
Linus Torvalds 已提交
3245 3246
	}

3247
again:
3248
	for_each_class(class) {
3249
		p = class->pick_next_task(rq, prev, cookie);
3250 3251 3252
		if (p) {
			if (unlikely(p == RETRY_TASK))
				goto again;
I
Ingo Molnar 已提交
3253
			return p;
3254
		}
I
Ingo Molnar 已提交
3255
	}
3256 3257

	BUG(); /* the idle class will always have a runnable task */
I
Ingo Molnar 已提交
3258
}
L
Linus Torvalds 已提交
3259

I
Ingo Molnar 已提交
3260
/*
3261
 * __schedule() is the main scheduler function.
3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295
 *
 * 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
3296
 *
3297
 * WARNING: must be called with preemption disabled!
I
Ingo Molnar 已提交
3298
 */
3299
static void __sched notrace __schedule(bool preempt)
I
Ingo Molnar 已提交
3300 3301
{
	struct task_struct *prev, *next;
3302
	unsigned long *switch_count;
3303
	struct pin_cookie cookie;
I
Ingo Molnar 已提交
3304
	struct rq *rq;
3305
	int cpu;
I
Ingo Molnar 已提交
3306 3307 3308 3309 3310

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

3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321
	/*
	 * do_exit() calls schedule() with preemption disabled as an exception;
	 * however we must fix that up, otherwise the next task will see an
	 * inconsistent (higher) preempt count.
	 *
	 * It also avoids the below schedule_debug() test from complaining
	 * about this.
	 */
	if (unlikely(prev->state == TASK_DEAD))
		preempt_enable_no_resched_notrace();

I
Ingo Molnar 已提交
3322
	schedule_debug(prev);
L
Linus Torvalds 已提交
3323

3324
	if (sched_feat(HRTICK))
M
Mike Galbraith 已提交
3325
		hrtick_clear(rq);
P
Peter Zijlstra 已提交
3326

3327 3328 3329
	local_irq_disable();
	rcu_note_context_switch();

3330 3331 3332 3333 3334 3335
	/*
	 * 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();
3336
	raw_spin_lock(&rq->lock);
3337
	cookie = lockdep_pin_lock(&rq->lock);
L
Linus Torvalds 已提交
3338

3339 3340
	rq->clock_skip_update <<= 1; /* promote REQ to ACT */

3341
	switch_count = &prev->nivcsw;
3342
	if (!preempt && prev->state) {
T
Tejun Heo 已提交
3343
		if (unlikely(signal_pending_state(prev->state, prev))) {
L
Linus Torvalds 已提交
3344
			prev->state = TASK_RUNNING;
T
Tejun Heo 已提交
3345
		} else {
3346 3347 3348
			deactivate_task(rq, prev, DEQUEUE_SLEEP);
			prev->on_rq = 0;

T
Tejun Heo 已提交
3349
			/*
3350 3351 3352
			 * 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
3353 3354 3355 3356
			 */
			if (prev->flags & PF_WQ_WORKER) {
				struct task_struct *to_wakeup;

3357
				to_wakeup = wq_worker_sleeping(prev);
T
Tejun Heo 已提交
3358
				if (to_wakeup)
3359
					try_to_wake_up_local(to_wakeup, cookie);
T
Tejun Heo 已提交
3360 3361
			}
		}
I
Ingo Molnar 已提交
3362
		switch_count = &prev->nvcsw;
L
Linus Torvalds 已提交
3363 3364
	}

3365
	if (task_on_rq_queued(prev))
3366 3367
		update_rq_clock(rq);

3368
	next = pick_next_task(rq, prev, cookie);
3369
	clear_tsk_need_resched(prev);
3370
	clear_preempt_need_resched();
3371
	rq->clock_skip_update = 0;
L
Linus Torvalds 已提交
3372 3373 3374 3375 3376 3377

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

3378
		trace_sched_switch(preempt, prev, next);
3379
		rq = context_switch(rq, prev, next, cookie); /* unlocks the rq */
3380
	} else {
3381
		lockdep_unpin_lock(&rq->lock, cookie);
3382
		raw_spin_unlock_irq(&rq->lock);
3383
	}
L
Linus Torvalds 已提交
3384

3385
	balance_callback(rq);
L
Linus Torvalds 已提交
3386
}
3387
STACK_FRAME_NON_STANDARD(__schedule); /* switch_to() */
3388

3389 3390
static inline void sched_submit_work(struct task_struct *tsk)
{
3391
	if (!tsk->state || tsk_is_pi_blocked(tsk))
3392 3393 3394 3395 3396 3397 3398 3399 3400
		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);
}

3401
asmlinkage __visible void __sched schedule(void)
3402
{
3403 3404 3405
	struct task_struct *tsk = current;

	sched_submit_work(tsk);
3406
	do {
3407
		preempt_disable();
3408
		__schedule(false);
3409
		sched_preempt_enable_no_resched();
3410
	} while (need_resched());
3411
}
L
Linus Torvalds 已提交
3412 3413
EXPORT_SYMBOL(schedule);

3414
#ifdef CONFIG_CONTEXT_TRACKING
3415
asmlinkage __visible void __sched schedule_user(void)
3416 3417 3418 3419 3420 3421
{
	/*
	 * 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.
3422 3423
	 *
	 * NB: There are buggy callers of this function.  Ideally we
3424
	 * should warn if prev_state != CONTEXT_USER, but that will trigger
3425
	 * too frequently to make sense yet.
3426
	 */
3427
	enum ctx_state prev_state = exception_enter();
3428
	schedule();
3429
	exception_exit(prev_state);
3430 3431 3432
}
#endif

3433 3434 3435 3436 3437 3438 3439
/**
 * schedule_preempt_disabled - called with preemption disabled
 *
 * Returns with preemption disabled. Note: preempt_count must be 1
 */
void __sched schedule_preempt_disabled(void)
{
3440
	sched_preempt_enable_no_resched();
3441 3442 3443 3444
	schedule();
	preempt_disable();
}

3445
static void __sched notrace preempt_schedule_common(void)
3446 3447
{
	do {
3448 3449 3450 3451 3452 3453 3454 3455 3456 3457 3458 3459 3460
		/*
		 * 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.
		 */
3461
		preempt_disable_notrace();
3462
		preempt_latency_start(1);
3463
		__schedule(true);
3464
		preempt_latency_stop(1);
3465
		preempt_enable_no_resched_notrace();
3466 3467 3468 3469 3470 3471 3472 3473

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

L
Linus Torvalds 已提交
3474 3475
#ifdef CONFIG_PREEMPT
/*
3476
 * this is the entry point to schedule() from in-kernel preemption
I
Ingo Molnar 已提交
3477
 * off of preempt_enable. Kernel preemptions off return from interrupt
L
Linus Torvalds 已提交
3478 3479
 * occur there and call schedule directly.
 */
3480
asmlinkage __visible void __sched notrace preempt_schedule(void)
L
Linus Torvalds 已提交
3481 3482 3483
{
	/*
	 * If there is a non-zero preempt_count or interrupts are disabled,
I
Ingo Molnar 已提交
3484
	 * we do not want to preempt the current task. Just return..
L
Linus Torvalds 已提交
3485
	 */
3486
	if (likely(!preemptible()))
L
Linus Torvalds 已提交
3487 3488
		return;

3489
	preempt_schedule_common();
L
Linus Torvalds 已提交
3490
}
3491
NOKPROBE_SYMBOL(preempt_schedule);
L
Linus Torvalds 已提交
3492
EXPORT_SYMBOL(preempt_schedule);
3493 3494

/**
3495
 * preempt_schedule_notrace - preempt_schedule called by tracing
3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507
 *
 * 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.
 */
3508
asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
3509 3510 3511 3512 3513 3514 3515
{
	enum ctx_state prev_ctx;

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

	do {
3516 3517 3518 3519 3520 3521 3522 3523 3524 3525 3526 3527 3528
		/*
		 * 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.
		 */
3529
		preempt_disable_notrace();
3530
		preempt_latency_start(1);
3531 3532 3533 3534 3535 3536
		/*
		 * Needs preempt disabled in case user_exit() is traced
		 * and the tracer calls preempt_enable_notrace() causing
		 * an infinite recursion.
		 */
		prev_ctx = exception_enter();
3537
		__schedule(true);
3538 3539
		exception_exit(prev_ctx);

3540
		preempt_latency_stop(1);
3541
		preempt_enable_no_resched_notrace();
3542 3543
	} while (need_resched());
}
3544
EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
3545

3546
#endif /* CONFIG_PREEMPT */
L
Linus Torvalds 已提交
3547 3548

/*
3549
 * this is the entry point to schedule() from kernel preemption
L
Linus Torvalds 已提交
3550 3551 3552 3553
 * off of irq context.
 * Note, that this is called and return with irqs disabled. This will
 * protect us against recursive calling from irq.
 */
3554
asmlinkage __visible void __sched preempt_schedule_irq(void)
L
Linus Torvalds 已提交
3555
{
3556
	enum ctx_state prev_state;
3557

3558
	/* Catch callers which need to be fixed */
3559
	BUG_ON(preempt_count() || !irqs_disabled());
L
Linus Torvalds 已提交
3560

3561 3562
	prev_state = exception_enter();

3563
	do {
3564
		preempt_disable();
3565
		local_irq_enable();
3566
		__schedule(true);
3567
		local_irq_disable();
3568
		sched_preempt_enable_no_resched();
3569
	} while (need_resched());
3570 3571

	exception_exit(prev_state);
L
Linus Torvalds 已提交
3572 3573
}

P
Peter Zijlstra 已提交
3574
int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
I
Ingo Molnar 已提交
3575
			  void *key)
L
Linus Torvalds 已提交
3576
{
P
Peter Zijlstra 已提交
3577
	return try_to_wake_up(curr->private, mode, wake_flags);
L
Linus Torvalds 已提交
3578 3579 3580
}
EXPORT_SYMBOL(default_wake_function);

3581 3582 3583 3584 3585 3586 3587 3588 3589 3590
#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().
 *
3591 3592
 * Used by the rt_mutex code to implement priority inheritance
 * logic. Call site only calls if the priority of the task changed.
3593
 */
3594
void rt_mutex_setprio(struct task_struct *p, int prio)
3595
{
3596
	int oldprio, queued, running, queue_flag = DEQUEUE_SAVE | DEQUEUE_MOVE;
3597
	const struct sched_class *prev_class;
3598 3599
	struct rq_flags rf;
	struct rq *rq;
3600

3601
	BUG_ON(prio > MAX_PRIO);
3602

3603
	rq = __task_rq_lock(p, &rf);
3604

3605 3606 3607 3608 3609 3610 3611 3612 3613 3614 3615 3616 3617 3618 3619 3620 3621 3622
	/*
	 * 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;
	}

3623
	trace_sched_pi_setprio(p, prio);
3624
	oldprio = p->prio;
3625 3626 3627 3628

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

3629
	prev_class = p->sched_class;
3630
	queued = task_on_rq_queued(p);
3631
	running = task_current(rq, p);
3632
	if (queued)
3633
		dequeue_task(rq, p, queue_flag);
3634
	if (running)
3635
		put_prev_task(rq, p);
I
Ingo Molnar 已提交
3636

3637 3638 3639 3640 3641 3642 3643 3644 3645 3646
	/*
	 * 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)) {
3647 3648 3649
		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))) {
3650
			p->dl.dl_boosted = 1;
3651
			queue_flag |= ENQUEUE_REPLENISH;
3652 3653
		} else
			p->dl.dl_boosted = 0;
3654
		p->sched_class = &dl_sched_class;
3655 3656 3657 3658
	} else if (rt_prio(prio)) {
		if (dl_prio(oldprio))
			p->dl.dl_boosted = 0;
		if (oldprio < prio)
3659
			queue_flag |= ENQUEUE_HEAD;
I
Ingo Molnar 已提交
3660
		p->sched_class = &rt_sched_class;
3661 3662 3663
	} else {
		if (dl_prio(oldprio))
			p->dl.dl_boosted = 0;
3664 3665
		if (rt_prio(oldprio))
			p->rt.timeout = 0;
I
Ingo Molnar 已提交
3666
		p->sched_class = &fair_sched_class;
3667
	}
I
Ingo Molnar 已提交
3668

3669 3670
	p->prio = prio;

3671 3672
	if (running)
		p->sched_class->set_curr_task(rq);
3673
	if (queued)
3674
		enqueue_task(rq, p, queue_flag);
3675

P
Peter Zijlstra 已提交
3676
	check_class_changed(rq, p, prev_class, oldprio);
3677
out_unlock:
3678
	preempt_disable(); /* avoid rq from going away on us */
3679
	__task_rq_unlock(rq, &rf);
3680 3681 3682

	balance_callback(rq);
	preempt_enable();
3683 3684
}
#endif
3685

3686
void set_user_nice(struct task_struct *p, long nice)
L
Linus Torvalds 已提交
3687
{
3688
	int old_prio, delta, queued;
3689
	struct rq_flags rf;
3690
	struct rq *rq;
L
Linus Torvalds 已提交
3691

3692
	if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
L
Linus Torvalds 已提交
3693 3694 3695 3696 3697
		return;
	/*
	 * We have to be careful, if called from sys_setpriority(),
	 * the task might be in the middle of scheduling on another CPU.
	 */
3698
	rq = task_rq_lock(p, &rf);
L
Linus Torvalds 已提交
3699 3700 3701 3702
	/*
	 * 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
3703
	 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
L
Linus Torvalds 已提交
3704
	 */
3705
	if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
L
Linus Torvalds 已提交
3706 3707 3708
		p->static_prio = NICE_TO_PRIO(nice);
		goto out_unlock;
	}
3709 3710
	queued = task_on_rq_queued(p);
	if (queued)
3711
		dequeue_task(rq, p, DEQUEUE_SAVE);
L
Linus Torvalds 已提交
3712 3713

	p->static_prio = NICE_TO_PRIO(nice);
3714
	set_load_weight(p);
3715 3716 3717
	old_prio = p->prio;
	p->prio = effective_prio(p);
	delta = p->prio - old_prio;
L
Linus Torvalds 已提交
3718

3719
	if (queued) {
3720
		enqueue_task(rq, p, ENQUEUE_RESTORE);
L
Linus Torvalds 已提交
3721
		/*
3722 3723
		 * If the task increased its priority or is running and
		 * lowered its priority, then reschedule its CPU:
L
Linus Torvalds 已提交
3724
		 */
3725
		if (delta < 0 || (delta > 0 && task_running(rq, p)))
3726
			resched_curr(rq);
L
Linus Torvalds 已提交
3727 3728
	}
out_unlock:
3729
	task_rq_unlock(rq, p, &rf);
L
Linus Torvalds 已提交
3730 3731 3732
}
EXPORT_SYMBOL(set_user_nice);

M
Matt Mackall 已提交
3733 3734 3735 3736 3737
/*
 * can_nice - check if a task can reduce its nice value
 * @p: task
 * @nice: nice value
 */
3738
int can_nice(const struct task_struct *p, const int nice)
M
Matt Mackall 已提交
3739
{
3740
	/* convert nice value [19,-20] to rlimit style value [1,40] */
3741
	int nice_rlim = nice_to_rlimit(nice);
3742

3743
	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
M
Matt Mackall 已提交
3744 3745 3746
		capable(CAP_SYS_NICE));
}

L
Linus Torvalds 已提交
3747 3748 3749 3750 3751 3752 3753 3754 3755
#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.
 */
3756
SYSCALL_DEFINE1(nice, int, increment)
L
Linus Torvalds 已提交
3757
{
3758
	long nice, retval;
L
Linus Torvalds 已提交
3759 3760 3761 3762 3763 3764

	/*
	 * 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.
	 */
3765
	increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3766
	nice = task_nice(current) + increment;
L
Linus Torvalds 已提交
3767

3768
	nice = clamp_val(nice, MIN_NICE, MAX_NICE);
M
Matt Mackall 已提交
3769 3770 3771
	if (increment < 0 && !can_nice(current, nice))
		return -EPERM;

L
Linus Torvalds 已提交
3772 3773 3774 3775 3776 3777 3778 3779 3780 3781 3782 3783 3784 3785
	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.
 *
3786
 * Return: The priority value as seen by users in /proc.
L
Linus Torvalds 已提交
3787 3788 3789
 * RT tasks are offset by -200. Normal tasks are centered
 * around 0, value goes from -16 to +15.
 */
3790
int task_prio(const struct task_struct *p)
L
Linus Torvalds 已提交
3791 3792 3793 3794 3795 3796 3797
{
	return p->prio - MAX_RT_PRIO;
}

/**
 * idle_cpu - is a given cpu idle currently?
 * @cpu: the processor in question.
3798 3799
 *
 * Return: 1 if the CPU is currently idle. 0 otherwise.
L
Linus Torvalds 已提交
3800 3801 3802
 */
int idle_cpu(int cpu)
{
T
Thomas Gleixner 已提交
3803 3804 3805 3806 3807 3808 3809 3810 3811 3812 3813 3814 3815 3816
	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
3817 3818 3819 3820 3821
}

/**
 * idle_task - return the idle task for a given cpu.
 * @cpu: the processor in question.
3822 3823
 *
 * Return: The idle task for the cpu @cpu.
L
Linus Torvalds 已提交
3824
 */
3825
struct task_struct *idle_task(int cpu)
L
Linus Torvalds 已提交
3826 3827 3828 3829 3830 3831 3832
{
	return cpu_rq(cpu)->idle;
}

/**
 * find_process_by_pid - find a process with a matching PID value.
 * @pid: the pid in question.
3833 3834
 *
 * The task of @pid, if found. %NULL otherwise.
L
Linus Torvalds 已提交
3835
 */
A
Alexey Dobriyan 已提交
3836
static struct task_struct *find_process_by_pid(pid_t pid)
L
Linus Torvalds 已提交
3837
{
3838
	return pid ? find_task_by_vpid(pid) : current;
L
Linus Torvalds 已提交
3839 3840
}

3841 3842 3843 3844 3845 3846 3847 3848 3849 3850 3851 3852 3853 3854 3855
/*
 * 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;
3856
	dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3857
	dl_se->flags = attr->sched_flags;
3858
	dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3859 3860 3861 3862 3863 3864 3865 3866 3867 3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878

	/*
	 * 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.
	 */
3879 3880
}

3881 3882 3883 3884 3885 3886
/*
 * sched_setparam() passes in -1 for its policy, to let the functions
 * it calls know not to change it.
 */
#define SETPARAM_POLICY	-1

3887 3888
static void __setscheduler_params(struct task_struct *p,
		const struct sched_attr *attr)
L
Linus Torvalds 已提交
3889
{
3890 3891
	int policy = attr->sched_policy;

3892
	if (policy == SETPARAM_POLICY)
3893 3894
		policy = p->policy;

L
Linus Torvalds 已提交
3895
	p->policy = policy;
3896

3897 3898
	if (dl_policy(policy))
		__setparam_dl(p, attr);
3899
	else if (fair_policy(policy))
3900 3901
		p->static_prio = NICE_TO_PRIO(attr->sched_nice);

3902 3903 3904 3905 3906 3907
	/*
	 * __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;
3908
	p->normal_prio = normal_prio(p);
3909 3910
	set_load_weight(p);
}
3911

3912 3913
/* Actually do priority change: must hold pi & rq lock. */
static void __setscheduler(struct rq *rq, struct task_struct *p,
3914
			   const struct sched_attr *attr, bool keep_boost)
3915 3916
{
	__setscheduler_params(p, attr);
3917

3918
	/*
3919 3920
	 * Keep a potential priority boosting if called from
	 * sched_setscheduler().
3921
	 */
3922 3923 3924 3925
	if (keep_boost)
		p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
	else
		p->prio = normal_prio(p);
3926

3927 3928 3929
	if (dl_prio(p->prio))
		p->sched_class = &dl_sched_class;
	else if (rt_prio(p->prio))
3930 3931 3932
		p->sched_class = &rt_sched_class;
	else
		p->sched_class = &fair_sched_class;
L
Linus Torvalds 已提交
3933
}
3934 3935 3936 3937 3938 3939 3940 3941 3942

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;
3943
	attr->sched_period = dl_se->dl_period;
3944 3945 3946 3947 3948 3949
	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
3950
 * than the runtime, as well as the period of being zero or
3951
 * greater than deadline. Furthermore, we have to be sure that
3952 3953 3954 3955
 * 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).
3956 3957 3958 3959
 */
static bool
__checkparam_dl(const struct sched_attr *attr)
{
3960 3961 3962 3963 3964 3965 3966 3967 3968 3969 3970 3971 3972 3973 3974 3975 3976 3977 3978 3979 3980 3981 3982 3983 3984 3985
	/* 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;
3986 3987
}

3988 3989 3990 3991 3992 3993 3994 3995 3996 3997
/*
 * 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);
3998 3999
	match = (uid_eq(cred->euid, pcred->euid) ||
		 uid_eq(cred->euid, pcred->uid));
4000 4001 4002 4003
	rcu_read_unlock();
	return match;
}

4004 4005 4006 4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017
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;
}

4018 4019
static int __sched_setscheduler(struct task_struct *p,
				const struct sched_attr *attr,
4020
				bool user, bool pi)
L
Linus Torvalds 已提交
4021
{
4022 4023
	int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
		      MAX_RT_PRIO - 1 - attr->sched_priority;
4024
	int retval, oldprio, oldpolicy = -1, queued, running;
4025
	int new_effective_prio, policy = attr->sched_policy;
4026
	const struct sched_class *prev_class;
4027
	struct rq_flags rf;
4028
	int reset_on_fork;
4029
	int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
4030
	struct rq *rq;
L
Linus Torvalds 已提交
4031

4032 4033
	/* may grab non-irq protected spin_locks */
	BUG_ON(in_interrupt());
L
Linus Torvalds 已提交
4034 4035
recheck:
	/* double check policy once rq lock held */
4036 4037
	if (policy < 0) {
		reset_on_fork = p->sched_reset_on_fork;
L
Linus Torvalds 已提交
4038
		policy = oldpolicy = p->policy;
4039
	} else {
4040
		reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
4041

4042
		if (!valid_policy(policy))
4043 4044 4045
			return -EINVAL;
	}

4046 4047 4048
	if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
		return -EINVAL;

L
Linus Torvalds 已提交
4049 4050
	/*
	 * Valid priorities for SCHED_FIFO and SCHED_RR are
I
Ingo Molnar 已提交
4051 4052
	 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
	 * SCHED_BATCH and SCHED_IDLE is 0.
L
Linus Torvalds 已提交
4053
	 */
4054
	if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
4055
	    (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
L
Linus Torvalds 已提交
4056
		return -EINVAL;
4057 4058
	if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
	    (rt_policy(policy) != (attr->sched_priority != 0)))
L
Linus Torvalds 已提交
4059 4060
		return -EINVAL;

4061 4062 4063
	/*
	 * Allow unprivileged RT tasks to decrease priority:
	 */
4064
	if (user && !capable(CAP_SYS_NICE)) {
4065
		if (fair_policy(policy)) {
4066
			if (attr->sched_nice < task_nice(p) &&
4067
			    !can_nice(p, attr->sched_nice))
4068 4069 4070
				return -EPERM;
		}

4071
		if (rt_policy(policy)) {
4072 4073
			unsigned long rlim_rtprio =
					task_rlimit(p, RLIMIT_RTPRIO);
4074 4075 4076 4077 4078 4079

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

			/* can't increase priority */
4080 4081
			if (attr->sched_priority > p->rt_priority &&
			    attr->sched_priority > rlim_rtprio)
4082 4083
				return -EPERM;
		}
4084

4085 4086 4087 4088 4089 4090 4091 4092 4093
		 /*
		  * 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
4094
		/*
4095 4096
		 * 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
4097
		 */
4098
		if (idle_policy(p->policy) && !idle_policy(policy)) {
4099
			if (!can_nice(p, task_nice(p)))
4100 4101
				return -EPERM;
		}
4102

4103
		/* can't change other user's priorities */
4104
		if (!check_same_owner(p))
4105
			return -EPERM;
4106 4107 4108 4109

		/* Normal users shall not reset the sched_reset_on_fork flag */
		if (p->sched_reset_on_fork && !reset_on_fork)
			return -EPERM;
4110
	}
L
Linus Torvalds 已提交
4111

4112
	if (user) {
4113
		retval = security_task_setscheduler(p);
4114 4115 4116 4117
		if (retval)
			return retval;
	}

4118 4119 4120
	/*
	 * make sure no PI-waiters arrive (or leave) while we are
	 * changing the priority of the task:
4121
	 *
L
Lucas De Marchi 已提交
4122
	 * To be able to change p->policy safely, the appropriate
L
Linus Torvalds 已提交
4123 4124
	 * runqueue lock must be held.
	 */
4125
	rq = task_rq_lock(p, &rf);
4126

4127 4128 4129 4130
	/*
	 * Changing the policy of the stop threads its a very bad idea
	 */
	if (p == rq->stop) {
4131
		task_rq_unlock(rq, p, &rf);
4132 4133 4134
		return -EINVAL;
	}

4135
	/*
4136 4137
	 * If not changing anything there's no need to proceed further,
	 * but store a possible modification of reset_on_fork.
4138
	 */
4139
	if (unlikely(policy == p->policy)) {
4140
		if (fair_policy(policy) && attr->sched_nice != task_nice(p))
4141 4142 4143
			goto change;
		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
			goto change;
4144
		if (dl_policy(policy) && dl_param_changed(p, attr))
4145
			goto change;
4146

4147
		p->sched_reset_on_fork = reset_on_fork;
4148
		task_rq_unlock(rq, p, &rf);
4149 4150
		return 0;
	}
4151
change:
4152

4153
	if (user) {
4154
#ifdef CONFIG_RT_GROUP_SCHED
4155 4156 4157 4158 4159
		/*
		 * Do not allow realtime tasks into groups that have no runtime
		 * assigned.
		 */
		if (rt_bandwidth_enabled() && rt_policy(policy) &&
4160 4161
				task_group(p)->rt_bandwidth.rt_runtime == 0 &&
				!task_group_is_autogroup(task_group(p))) {
4162
			task_rq_unlock(rq, p, &rf);
4163 4164 4165
			return -EPERM;
		}
#endif
4166 4167 4168 4169 4170 4171 4172 4173 4174
#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.
			 */
4175 4176
			if (!cpumask_subset(span, &p->cpus_allowed) ||
			    rq->rd->dl_bw.bw == 0) {
4177
				task_rq_unlock(rq, p, &rf);
4178 4179 4180 4181 4182
				return -EPERM;
			}
		}
#endif
	}
4183

L
Linus Torvalds 已提交
4184 4185 4186
	/* recheck policy now with rq lock held */
	if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
		policy = oldpolicy = -1;
4187
		task_rq_unlock(rq, p, &rf);
L
Linus Torvalds 已提交
4188 4189
		goto recheck;
	}
4190 4191 4192 4193 4194 4195

	/*
	 * If setscheduling to SCHED_DEADLINE (or changing the parameters
	 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
	 * is available.
	 */
4196
	if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
4197
		task_rq_unlock(rq, p, &rf);
4198 4199 4200
		return -EBUSY;
	}

4201 4202 4203
	p->sched_reset_on_fork = reset_on_fork;
	oldprio = p->prio;

4204 4205 4206 4207 4208 4209 4210 4211 4212
	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);
4213 4214
		if (new_effective_prio == oldprio)
			queue_flags &= ~DEQUEUE_MOVE;
4215 4216
	}

4217
	queued = task_on_rq_queued(p);
4218
	running = task_current(rq, p);
4219
	if (queued)
4220
		dequeue_task(rq, p, queue_flags);
4221
	if (running)
4222
		put_prev_task(rq, p);
4223

4224
	prev_class = p->sched_class;
4225
	__setscheduler(rq, p, attr, pi);
4226

4227 4228
	if (running)
		p->sched_class->set_curr_task(rq);
4229
	if (queued) {
4230 4231 4232 4233
		/*
		 * We enqueue to tail when the priority of a task is
		 * increased (user space view).
		 */
4234 4235
		if (oldprio < p->prio)
			queue_flags |= ENQUEUE_HEAD;
4236

4237
		enqueue_task(rq, p, queue_flags);
4238
	}
4239

P
Peter Zijlstra 已提交
4240
	check_class_changed(rq, p, prev_class, oldprio);
4241
	preempt_disable(); /* avoid rq from going away on us */
4242
	task_rq_unlock(rq, p, &rf);
4243

4244 4245
	if (pi)
		rt_mutex_adjust_pi(p);
4246

4247 4248 4249 4250 4251
	/*
	 * Run balance callbacks after we've adjusted the PI chain.
	 */
	balance_callback(rq);
	preempt_enable();
4252

L
Linus Torvalds 已提交
4253 4254
	return 0;
}
4255

4256 4257 4258 4259 4260 4261 4262 4263 4264
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),
	};

4265 4266
	/* Fixup the legacy SCHED_RESET_ON_FORK hack. */
	if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
4267 4268 4269 4270 4271
		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
		policy &= ~SCHED_RESET_ON_FORK;
		attr.sched_policy = policy;
	}

4272
	return __sched_setscheduler(p, &attr, check, true);
4273
}
4274 4275 4276 4277 4278 4279
/**
 * 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.
 *
4280 4281
 * Return: 0 on success. An error code otherwise.
 *
4282 4283 4284
 * NOTE that the task may be already dead.
 */
int sched_setscheduler(struct task_struct *p, int policy,
4285
		       const struct sched_param *param)
4286
{
4287
	return _sched_setscheduler(p, policy, param, true);
4288
}
L
Linus Torvalds 已提交
4289 4290
EXPORT_SYMBOL_GPL(sched_setscheduler);

4291 4292
int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
{
4293
	return __sched_setscheduler(p, attr, true, true);
4294 4295 4296
}
EXPORT_SYMBOL_GPL(sched_setattr);

4297 4298 4299 4300 4301 4302 4303 4304 4305 4306
/**
 * 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.
4307 4308
 *
 * Return: 0 on success. An error code otherwise.
4309 4310
 */
int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4311
			       const struct sched_param *param)
4312
{
4313
	return _sched_setscheduler(p, policy, param, false);
4314
}
4315
EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
4316

I
Ingo Molnar 已提交
4317 4318
static int
do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
L
Linus Torvalds 已提交
4319 4320 4321
{
	struct sched_param lparam;
	struct task_struct *p;
4322
	int retval;
L
Linus Torvalds 已提交
4323 4324 4325 4326 4327

	if (!param || pid < 0)
		return -EINVAL;
	if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
		return -EFAULT;
4328 4329 4330

	rcu_read_lock();
	retval = -ESRCH;
L
Linus Torvalds 已提交
4331
	p = find_process_by_pid(pid);
4332 4333 4334
	if (p != NULL)
		retval = sched_setscheduler(p, policy, &lparam);
	rcu_read_unlock();
4335

L
Linus Torvalds 已提交
4336 4337 4338
	return retval;
}

4339 4340 4341 4342 4343 4344 4345 4346 4347 4348 4349 4350 4351 4352 4353 4354 4355 4356 4357 4358 4359 4360 4361 4362 4363 4364 4365 4366 4367 4368 4369 4370 4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381 4382 4383 4384 4385 4386 4387 4388 4389 4390 4391 4392 4393 4394 4395 4396 4397 4398 4399 4400
/*
 * 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?
	 */
4401
	attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
4402

4403
	return 0;
4404 4405 4406

err_size:
	put_user(sizeof(*attr), &uattr->size);
4407
	return -E2BIG;
4408 4409
}

L
Linus Torvalds 已提交
4410 4411 4412 4413 4414
/**
 * 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.
4415 4416
 *
 * Return: 0 on success. An error code otherwise.
L
Linus Torvalds 已提交
4417
 */
4418 4419
SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
		struct sched_param __user *, param)
L
Linus Torvalds 已提交
4420
{
4421 4422 4423 4424
	/* negative values for policy are not valid */
	if (policy < 0)
		return -EINVAL;

L
Linus Torvalds 已提交
4425 4426 4427 4428 4429 4430 4431
	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.
4432 4433
 *
 * Return: 0 on success. An error code otherwise.
L
Linus Torvalds 已提交
4434
 */
4435
SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
L
Linus Torvalds 已提交
4436
{
4437
	return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
L
Linus Torvalds 已提交
4438 4439
}

4440 4441 4442
/**
 * sys_sched_setattr - same as above, but with extended sched_attr
 * @pid: the pid in question.
J
Juri Lelli 已提交
4443
 * @uattr: structure containing the extended parameters.
4444
 * @flags: for future extension.
4445
 */
4446 4447
SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
			       unsigned int, flags)
4448 4449 4450 4451 4452
{
	struct sched_attr attr;
	struct task_struct *p;
	int retval;

4453
	if (!uattr || pid < 0 || flags)
4454 4455
		return -EINVAL;

4456 4457 4458
	retval = sched_copy_attr(uattr, &attr);
	if (retval)
		return retval;
4459

4460
	if ((int)attr.sched_policy < 0)
4461
		return -EINVAL;
4462 4463 4464 4465 4466 4467 4468 4469 4470 4471 4472

	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
4473 4474 4475
/**
 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
 * @pid: the pid in question.
4476 4477 4478
 *
 * Return: On success, the policy of the thread. Otherwise, a negative error
 * code.
L
Linus Torvalds 已提交
4479
 */
4480
SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
L
Linus Torvalds 已提交
4481
{
4482
	struct task_struct *p;
4483
	int retval;
L
Linus Torvalds 已提交
4484 4485

	if (pid < 0)
4486
		return -EINVAL;
L
Linus Torvalds 已提交
4487 4488

	retval = -ESRCH;
4489
	rcu_read_lock();
L
Linus Torvalds 已提交
4490 4491 4492 4493
	p = find_process_by_pid(pid);
	if (p) {
		retval = security_task_getscheduler(p);
		if (!retval)
4494 4495
			retval = p->policy
				| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
L
Linus Torvalds 已提交
4496
	}
4497
	rcu_read_unlock();
L
Linus Torvalds 已提交
4498 4499 4500 4501
	return retval;
}

/**
4502
 * sys_sched_getparam - get the RT priority of a thread
L
Linus Torvalds 已提交
4503 4504
 * @pid: the pid in question.
 * @param: structure containing the RT priority.
4505 4506 4507
 *
 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
 * code.
L
Linus Torvalds 已提交
4508
 */
4509
SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
L
Linus Torvalds 已提交
4510
{
4511
	struct sched_param lp = { .sched_priority = 0 };
4512
	struct task_struct *p;
4513
	int retval;
L
Linus Torvalds 已提交
4514 4515

	if (!param || pid < 0)
4516
		return -EINVAL;
L
Linus Torvalds 已提交
4517

4518
	rcu_read_lock();
L
Linus Torvalds 已提交
4519 4520 4521 4522 4523 4524 4525 4526 4527
	p = find_process_by_pid(pid);
	retval = -ESRCH;
	if (!p)
		goto out_unlock;

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

4528 4529
	if (task_has_rt_policy(p))
		lp.sched_priority = p->rt_priority;
4530
	rcu_read_unlock();
L
Linus Torvalds 已提交
4531 4532 4533 4534 4535 4536 4537 4538 4539

	/*
	 * 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:
4540
	rcu_read_unlock();
L
Linus Torvalds 已提交
4541 4542 4543
	return retval;
}

4544 4545 4546 4547 4548 4549 4550 4551 4552 4553 4554 4555 4556 4557 4558 4559 4560 4561 4562 4563 4564 4565 4566
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)
4567
				return -EFBIG;
4568 4569 4570 4571 4572
		}

		attr->size = usize;
	}

4573
	ret = copy_to_user(uattr, attr, attr->size);
4574 4575 4576
	if (ret)
		return -EFAULT;

4577
	return 0;
4578 4579 4580
}

/**
4581
 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4582
 * @pid: the pid in question.
J
Juri Lelli 已提交
4583
 * @uattr: structure containing the extended parameters.
4584
 * @size: sizeof(attr) for fwd/bwd comp.
4585
 * @flags: for future extension.
4586
 */
4587 4588
SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
		unsigned int, size, unsigned int, flags)
4589 4590 4591 4592 4593 4594 4595 4596
{
	struct sched_attr attr = {
		.size = sizeof(struct sched_attr),
	};
	struct task_struct *p;
	int retval;

	if (!uattr || pid < 0 || size > PAGE_SIZE ||
4597
	    size < SCHED_ATTR_SIZE_VER0 || flags)
4598 4599 4600 4601 4602 4603 4604 4605 4606 4607 4608 4609 4610
		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;
4611 4612
	if (p->sched_reset_on_fork)
		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4613 4614 4615
	if (task_has_dl_policy(p))
		__getparam_dl(p, &attr);
	else if (task_has_rt_policy(p))
4616 4617
		attr.sched_priority = p->rt_priority;
	else
4618
		attr.sched_nice = task_nice(p);
4619 4620 4621 4622 4623 4624 4625 4626 4627 4628 4629

	rcu_read_unlock();

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

out_unlock:
	rcu_read_unlock();
	return retval;
}

4630
long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
L
Linus Torvalds 已提交
4631
{
4632
	cpumask_var_t cpus_allowed, new_mask;
4633 4634
	struct task_struct *p;
	int retval;
L
Linus Torvalds 已提交
4635

4636
	rcu_read_lock();
L
Linus Torvalds 已提交
4637 4638 4639

	p = find_process_by_pid(pid);
	if (!p) {
4640
		rcu_read_unlock();
L
Linus Torvalds 已提交
4641 4642 4643
		return -ESRCH;
	}

4644
	/* Prevent p going away */
L
Linus Torvalds 已提交
4645
	get_task_struct(p);
4646
	rcu_read_unlock();
L
Linus Torvalds 已提交
4647

4648 4649 4650 4651
	if (p->flags & PF_NO_SETAFFINITY) {
		retval = -EINVAL;
		goto out_put_task;
	}
4652 4653 4654 4655 4656 4657 4658 4659
	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
4660
	retval = -EPERM;
E
Eric W. Biederman 已提交
4661 4662 4663 4664
	if (!check_same_owner(p)) {
		rcu_read_lock();
		if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
			rcu_read_unlock();
4665
			goto out_free_new_mask;
E
Eric W. Biederman 已提交
4666 4667 4668
		}
		rcu_read_unlock();
	}
L
Linus Torvalds 已提交
4669

4670
	retval = security_task_setscheduler(p);
4671
	if (retval)
4672
		goto out_free_new_mask;
4673

4674 4675 4676 4677

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

4678 4679 4680 4681 4682 4683 4684
	/*
	 * 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
4685 4686 4687
	if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
		rcu_read_lock();
		if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4688
			retval = -EBUSY;
4689
			rcu_read_unlock();
4690
			goto out_free_new_mask;
4691
		}
4692
		rcu_read_unlock();
4693 4694
	}
#endif
P
Peter Zijlstra 已提交
4695
again:
4696
	retval = __set_cpus_allowed_ptr(p, new_mask, true);
L
Linus Torvalds 已提交
4697

P
Paul Menage 已提交
4698
	if (!retval) {
4699 4700
		cpuset_cpus_allowed(p, cpus_allowed);
		if (!cpumask_subset(new_mask, cpus_allowed)) {
P
Paul Menage 已提交
4701 4702 4703 4704 4705
			/*
			 * We must have raced with a concurrent cpuset
			 * update. Just reset the cpus_allowed to the
			 * cpuset's cpus_allowed
			 */
4706
			cpumask_copy(new_mask, cpus_allowed);
P
Paul Menage 已提交
4707 4708 4709
			goto again;
		}
	}
4710
out_free_new_mask:
4711 4712 4713 4714
	free_cpumask_var(new_mask);
out_free_cpus_allowed:
	free_cpumask_var(cpus_allowed);
out_put_task:
L
Linus Torvalds 已提交
4715 4716 4717 4718 4719
	put_task_struct(p);
	return retval;
}

static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4720
			     struct cpumask *new_mask)
L
Linus Torvalds 已提交
4721
{
4722 4723 4724 4725 4726
	if (len < cpumask_size())
		cpumask_clear(new_mask);
	else if (len > cpumask_size())
		len = cpumask_size();

L
Linus Torvalds 已提交
4727 4728 4729 4730 4731 4732 4733 4734
	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
4735 4736
 *
 * Return: 0 on success. An error code otherwise.
L
Linus Torvalds 已提交
4737
 */
4738 4739
SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
		unsigned long __user *, user_mask_ptr)
L
Linus Torvalds 已提交
4740
{
4741
	cpumask_var_t new_mask;
L
Linus Torvalds 已提交
4742 4743
	int retval;

4744 4745
	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
		return -ENOMEM;
L
Linus Torvalds 已提交
4746

4747 4748 4749 4750 4751
	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
4752 4753
}

4754
long sched_getaffinity(pid_t pid, struct cpumask *mask)
L
Linus Torvalds 已提交
4755
{
4756
	struct task_struct *p;
4757
	unsigned long flags;
L
Linus Torvalds 已提交
4758 4759
	int retval;

4760
	rcu_read_lock();
L
Linus Torvalds 已提交
4761 4762 4763 4764 4765 4766

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

4767 4768 4769 4770
	retval = security_task_getscheduler(p);
	if (retval)
		goto out_unlock;

4771
	raw_spin_lock_irqsave(&p->pi_lock, flags);
4772
	cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4773
	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
L
Linus Torvalds 已提交
4774 4775

out_unlock:
4776
	rcu_read_unlock();
L
Linus Torvalds 已提交
4777

4778
	return retval;
L
Linus Torvalds 已提交
4779 4780 4781 4782 4783 4784 4785
}

/**
 * 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
4786
 *
4787 4788
 * Return: size of CPU mask copied to user_mask_ptr on success. An
 * error code otherwise.
L
Linus Torvalds 已提交
4789
 */
4790 4791
SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
		unsigned long __user *, user_mask_ptr)
L
Linus Torvalds 已提交
4792 4793
{
	int ret;
4794
	cpumask_var_t mask;
L
Linus Torvalds 已提交
4795

A
Anton Blanchard 已提交
4796
	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4797 4798
		return -EINVAL;
	if (len & (sizeof(unsigned long)-1))
L
Linus Torvalds 已提交
4799 4800
		return -EINVAL;

4801 4802
	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
		return -ENOMEM;
L
Linus Torvalds 已提交
4803

4804 4805
	ret = sched_getaffinity(pid, mask);
	if (ret == 0) {
4806
		size_t retlen = min_t(size_t, len, cpumask_size());
4807 4808

		if (copy_to_user(user_mask_ptr, mask, retlen))
4809 4810
			ret = -EFAULT;
		else
4811
			ret = retlen;
4812 4813
	}
	free_cpumask_var(mask);
L
Linus Torvalds 已提交
4814

4815
	return ret;
L
Linus Torvalds 已提交
4816 4817 4818 4819 4820
}

/**
 * sys_sched_yield - yield the current processor to other threads.
 *
I
Ingo Molnar 已提交
4821 4822
 * This function yields the current CPU to other tasks. If there are no
 * other threads running on this CPU then this function will return.
4823 4824
 *
 * Return: 0.
L
Linus Torvalds 已提交
4825
 */
4826
SYSCALL_DEFINE0(sched_yield)
L
Linus Torvalds 已提交
4827
{
4828
	struct rq *rq = this_rq_lock();
L
Linus Torvalds 已提交
4829

4830
	schedstat_inc(rq, yld_count);
4831
	current->sched_class->yield_task(rq);
L
Linus Torvalds 已提交
4832 4833 4834 4835 4836 4837

	/*
	 * Since we are going to call schedule() anyway, there's
	 * no need to preempt or enable interrupts:
	 */
	__release(rq->lock);
4838
	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4839
	do_raw_spin_unlock(&rq->lock);
4840
	sched_preempt_enable_no_resched();
L
Linus Torvalds 已提交
4841 4842 4843 4844 4845 4846

	schedule();

	return 0;
}

4847
int __sched _cond_resched(void)
L
Linus Torvalds 已提交
4848
{
4849
	if (should_resched(0)) {
4850
		preempt_schedule_common();
L
Linus Torvalds 已提交
4851 4852 4853 4854
		return 1;
	}
	return 0;
}
4855
EXPORT_SYMBOL(_cond_resched);
L
Linus Torvalds 已提交
4856 4857

/*
4858
 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
L
Linus Torvalds 已提交
4859 4860
 * call schedule, and on return reacquire the lock.
 *
I
Ingo Molnar 已提交
4861
 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
L
Linus Torvalds 已提交
4862 4863 4864
 * operations here to prevent schedule() from being called twice (once via
 * spin_unlock(), once by hand).
 */
4865
int __cond_resched_lock(spinlock_t *lock)
L
Linus Torvalds 已提交
4866
{
4867
	int resched = should_resched(PREEMPT_LOCK_OFFSET);
J
Jan Kara 已提交
4868 4869
	int ret = 0;

4870 4871
	lockdep_assert_held(lock);

4872
	if (spin_needbreak(lock) || resched) {
L
Linus Torvalds 已提交
4873
		spin_unlock(lock);
P
Peter Zijlstra 已提交
4874
		if (resched)
4875
			preempt_schedule_common();
N
Nick Piggin 已提交
4876 4877
		else
			cpu_relax();
J
Jan Kara 已提交
4878
		ret = 1;
L
Linus Torvalds 已提交
4879 4880
		spin_lock(lock);
	}
J
Jan Kara 已提交
4881
	return ret;
L
Linus Torvalds 已提交
4882
}
4883
EXPORT_SYMBOL(__cond_resched_lock);
L
Linus Torvalds 已提交
4884

4885
int __sched __cond_resched_softirq(void)
L
Linus Torvalds 已提交
4886 4887 4888
{
	BUG_ON(!in_softirq());

4889
	if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
4890
		local_bh_enable();
4891
		preempt_schedule_common();
L
Linus Torvalds 已提交
4892 4893 4894 4895 4896
		local_bh_disable();
		return 1;
	}
	return 0;
}
4897
EXPORT_SYMBOL(__cond_resched_softirq);
L
Linus Torvalds 已提交
4898 4899 4900 4901

/**
 * yield - yield the current processor to other threads.
 *
P
Peter Zijlstra 已提交
4902 4903 4904 4905 4906 4907 4908 4909 4910 4911 4912 4913 4914 4915 4916 4917 4918 4919
 * 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
4920 4921 4922 4923 4924 4925 4926 4927
 */
void __sched yield(void)
{
	set_current_state(TASK_RUNNING);
	sys_sched_yield();
}
EXPORT_SYMBOL(yield);

4928 4929 4930 4931
/**
 * 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
4932 4933
 * @p: target task
 * @preempt: whether task preemption is allowed or not
4934 4935 4936 4937
 *
 * 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.
 *
4938
 * Return:
4939 4940 4941
 *	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.
4942
 */
4943
int __sched yield_to(struct task_struct *p, bool preempt)
4944 4945 4946 4947
{
	struct task_struct *curr = current;
	struct rq *rq, *p_rq;
	unsigned long flags;
4948
	int yielded = 0;
4949 4950 4951 4952 4953 4954

	local_irq_save(flags);
	rq = this_rq();

again:
	p_rq = task_rq(p);
4955 4956 4957 4958 4959 4960 4961 4962 4963
	/*
	 * 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;
	}

4964
	double_rq_lock(rq, p_rq);
4965
	if (task_rq(p) != p_rq) {
4966 4967 4968 4969 4970
		double_rq_unlock(rq, p_rq);
		goto again;
	}

	if (!curr->sched_class->yield_to_task)
4971
		goto out_unlock;
4972 4973

	if (curr->sched_class != p->sched_class)
4974
		goto out_unlock;
4975 4976

	if (task_running(p_rq, p) || p->state)
4977
		goto out_unlock;
4978 4979

	yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4980
	if (yielded) {
4981
		schedstat_inc(rq, yld_count);
4982 4983 4984 4985 4986
		/*
		 * Make p's CPU reschedule; pick_next_entity takes care of
		 * fairness.
		 */
		if (preempt && rq != p_rq)
4987
			resched_curr(p_rq);
4988
	}
4989

4990
out_unlock:
4991
	double_rq_unlock(rq, p_rq);
4992
out_irq:
4993 4994
	local_irq_restore(flags);

4995
	if (yielded > 0)
4996 4997 4998 4999 5000 5001
		schedule();

	return yielded;
}
EXPORT_SYMBOL_GPL(yield_to);

L
Linus Torvalds 已提交
5002
/*
I
Ingo Molnar 已提交
5003
 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
L
Linus Torvalds 已提交
5004 5005 5006 5007
 * that process accounting knows that this is a task in IO wait state.
 */
long __sched io_schedule_timeout(long timeout)
{
5008 5009
	int old_iowait = current->in_iowait;
	struct rq *rq;
L
Linus Torvalds 已提交
5010 5011
	long ret;

5012
	current->in_iowait = 1;
5013
	blk_schedule_flush_plug(current);
5014

5015
	delayacct_blkio_start();
5016
	rq = raw_rq();
L
Linus Torvalds 已提交
5017 5018
	atomic_inc(&rq->nr_iowait);
	ret = schedule_timeout(timeout);
5019
	current->in_iowait = old_iowait;
L
Linus Torvalds 已提交
5020
	atomic_dec(&rq->nr_iowait);
5021
	delayacct_blkio_end();
5022

L
Linus Torvalds 已提交
5023 5024
	return ret;
}
5025
EXPORT_SYMBOL(io_schedule_timeout);
L
Linus Torvalds 已提交
5026 5027 5028 5029 5030

/**
 * sys_sched_get_priority_max - return maximum RT priority.
 * @policy: scheduling class.
 *
5031 5032 5033
 * 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
5034
 */
5035
SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
L
Linus Torvalds 已提交
5036 5037 5038 5039 5040 5041 5042 5043
{
	int ret = -EINVAL;

	switch (policy) {
	case SCHED_FIFO:
	case SCHED_RR:
		ret = MAX_USER_RT_PRIO-1;
		break;
5044
	case SCHED_DEADLINE:
L
Linus Torvalds 已提交
5045
	case SCHED_NORMAL:
5046
	case SCHED_BATCH:
I
Ingo Molnar 已提交
5047
	case SCHED_IDLE:
L
Linus Torvalds 已提交
5048 5049 5050 5051 5052 5053 5054 5055 5056 5057
		ret = 0;
		break;
	}
	return ret;
}

/**
 * sys_sched_get_priority_min - return minimum RT priority.
 * @policy: scheduling class.
 *
5058 5059 5060
 * 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
5061
 */
5062
SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
L
Linus Torvalds 已提交
5063 5064 5065 5066 5067 5068 5069 5070
{
	int ret = -EINVAL;

	switch (policy) {
	case SCHED_FIFO:
	case SCHED_RR:
		ret = 1;
		break;
5071
	case SCHED_DEADLINE:
L
Linus Torvalds 已提交
5072
	case SCHED_NORMAL:
5073
	case SCHED_BATCH:
I
Ingo Molnar 已提交
5074
	case SCHED_IDLE:
L
Linus Torvalds 已提交
5075 5076 5077 5078 5079 5080 5081 5082 5083 5084 5085 5086
		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.
5087 5088 5089
 *
 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
 * an error code.
L
Linus Torvalds 已提交
5090
 */
5091
SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
5092
		struct timespec __user *, interval)
L
Linus Torvalds 已提交
5093
{
5094
	struct task_struct *p;
D
Dmitry Adamushko 已提交
5095
	unsigned int time_slice;
5096 5097
	struct rq_flags rf;
	struct timespec t;
5098
	struct rq *rq;
5099
	int retval;
L
Linus Torvalds 已提交
5100 5101

	if (pid < 0)
5102
		return -EINVAL;
L
Linus Torvalds 已提交
5103 5104

	retval = -ESRCH;
5105
	rcu_read_lock();
L
Linus Torvalds 已提交
5106 5107 5108 5109 5110 5111 5112 5113
	p = find_process_by_pid(pid);
	if (!p)
		goto out_unlock;

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

5114
	rq = task_rq_lock(p, &rf);
5115 5116 5117
	time_slice = 0;
	if (p->sched_class->get_rr_interval)
		time_slice = p->sched_class->get_rr_interval(rq, p);
5118
	task_rq_unlock(rq, p, &rf);
D
Dmitry Adamushko 已提交
5119

5120
	rcu_read_unlock();
D
Dmitry Adamushko 已提交
5121
	jiffies_to_timespec(time_slice, &t);
L
Linus Torvalds 已提交
5122 5123
	retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
	return retval;
5124

L
Linus Torvalds 已提交
5125
out_unlock:
5126
	rcu_read_unlock();
L
Linus Torvalds 已提交
5127 5128 5129
	return retval;
}

5130
static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
5131

5132
void sched_show_task(struct task_struct *p)
L
Linus Torvalds 已提交
5133 5134
{
	unsigned long free = 0;
5135
	int ppid;
5136
	unsigned long state = p->state;
L
Linus Torvalds 已提交
5137

5138 5139
	if (state)
		state = __ffs(state) + 1;
5140
	printk(KERN_INFO "%-15.15s %c", p->comm,
5141
		state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
5142
#if BITS_PER_LONG == 32
L
Linus Torvalds 已提交
5143
	if (state == TASK_RUNNING)
P
Peter Zijlstra 已提交
5144
		printk(KERN_CONT " running  ");
L
Linus Torvalds 已提交
5145
	else
P
Peter Zijlstra 已提交
5146
		printk(KERN_CONT " %08lx ", thread_saved_pc(p));
L
Linus Torvalds 已提交
5147 5148
#else
	if (state == TASK_RUNNING)
P
Peter Zijlstra 已提交
5149
		printk(KERN_CONT "  running task    ");
L
Linus Torvalds 已提交
5150
	else
P
Peter Zijlstra 已提交
5151
		printk(KERN_CONT " %016lx ", thread_saved_pc(p));
L
Linus Torvalds 已提交
5152 5153
#endif
#ifdef CONFIG_DEBUG_STACK_USAGE
5154
	free = stack_not_used(p);
L
Linus Torvalds 已提交
5155
#endif
5156
	ppid = 0;
5157
	rcu_read_lock();
5158 5159
	if (pid_alive(p))
		ppid = task_pid_nr(rcu_dereference(p->real_parent));
5160
	rcu_read_unlock();
P
Peter Zijlstra 已提交
5161
	printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
5162
		task_pid_nr(p), ppid,
5163
		(unsigned long)task_thread_info(p)->flags);
L
Linus Torvalds 已提交
5164

5165
	print_worker_info(KERN_INFO, p);
5166
	show_stack(p, NULL);
L
Linus Torvalds 已提交
5167 5168
}

I
Ingo Molnar 已提交
5169
void show_state_filter(unsigned long state_filter)
L
Linus Torvalds 已提交
5170
{
5171
	struct task_struct *g, *p;
L
Linus Torvalds 已提交
5172

5173
#if BITS_PER_LONG == 32
P
Peter Zijlstra 已提交
5174 5175
	printk(KERN_INFO
		"  task                PC stack   pid father\n");
L
Linus Torvalds 已提交
5176
#else
P
Peter Zijlstra 已提交
5177 5178
	printk(KERN_INFO
		"  task                        PC stack   pid father\n");
L
Linus Torvalds 已提交
5179
#endif
5180
	rcu_read_lock();
5181
	for_each_process_thread(g, p) {
L
Linus Torvalds 已提交
5182 5183
		/*
		 * reset the NMI-timeout, listing all files on a slow
L
Lucas De Marchi 已提交
5184
		 * console might take a lot of time:
5185 5186 5187
		 * 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
5188 5189
		 */
		touch_nmi_watchdog();
5190
		touch_all_softlockup_watchdogs();
I
Ingo Molnar 已提交
5191
		if (!state_filter || (p->state & state_filter))
5192
			sched_show_task(p);
5193
	}
L
Linus Torvalds 已提交
5194

I
Ingo Molnar 已提交
5195
#ifdef CONFIG_SCHED_DEBUG
5196 5197
	if (!state_filter)
		sysrq_sched_debug_show();
I
Ingo Molnar 已提交
5198
#endif
5199
	rcu_read_unlock();
I
Ingo Molnar 已提交
5200 5201 5202
	/*
	 * Only show locks if all tasks are dumped:
	 */
5203
	if (!state_filter)
I
Ingo Molnar 已提交
5204
		debug_show_all_locks();
L
Linus Torvalds 已提交
5205 5206
}

5207
void init_idle_bootup_task(struct task_struct *idle)
I
Ingo Molnar 已提交
5208
{
I
Ingo Molnar 已提交
5209
	idle->sched_class = &idle_sched_class;
I
Ingo Molnar 已提交
5210 5211
}

5212 5213 5214 5215 5216 5217 5218 5219
/**
 * 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.
 */
5220
void init_idle(struct task_struct *idle, int cpu)
L
Linus Torvalds 已提交
5221
{
5222
	struct rq *rq = cpu_rq(cpu);
L
Linus Torvalds 已提交
5223 5224
	unsigned long flags;

5225 5226
	raw_spin_lock_irqsave(&idle->pi_lock, flags);
	raw_spin_lock(&rq->lock);
5227

5228
	__sched_fork(0, idle);
5229
	idle->state = TASK_RUNNING;
I
Ingo Molnar 已提交
5230 5231
	idle->se.exec_start = sched_clock();

5232 5233
	kasan_unpoison_task_stack(idle);

5234 5235 5236 5237 5238 5239 5240 5241 5242
#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
5243 5244 5245 5246 5247 5248 5249 5250 5251 5252 5253
	/*
	 * 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
5254
	__set_task_cpu(idle, cpu);
5255
	rcu_read_unlock();
L
Linus Torvalds 已提交
5256 5257

	rq->curr = rq->idle = idle;
5258
	idle->on_rq = TASK_ON_RQ_QUEUED;
5259
#ifdef CONFIG_SMP
P
Peter Zijlstra 已提交
5260
	idle->on_cpu = 1;
5261
#endif
5262 5263
	raw_spin_unlock(&rq->lock);
	raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
L
Linus Torvalds 已提交
5264 5265

	/* Set the preempt count _outside_ the spinlocks! */
5266
	init_idle_preempt_count(idle, cpu);
5267

I
Ingo Molnar 已提交
5268 5269 5270 5271
	/*
	 * The idle tasks have their own, simple scheduling class:
	 */
	idle->sched_class = &idle_sched_class;
5272
	ftrace_graph_init_idle_task(idle, cpu);
5273
	vtime_init_idle(idle, cpu);
5274
#ifdef CONFIG_SMP
5275 5276
	sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
#endif
I
Ingo Molnar 已提交
5277 5278
}

5279 5280 5281 5282 5283 5284 5285
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;

5286 5287 5288
	if (!cpumask_weight(cur))
		return ret;

5289
	rcu_read_lock_sched();
5290 5291 5292 5293 5294 5295 5296 5297
	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);
5298
	rcu_read_unlock_sched();
5299 5300 5301 5302

	return ret;
}

5303 5304 5305 5306 5307 5308 5309 5310 5311 5312 5313 5314 5315 5316 5317 5318 5319 5320 5321 5322 5323 5324 5325 5326
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);
5327
		struct dl_bw *dl_b;
5328 5329 5330 5331
		bool overflow;
		int cpus;
		unsigned long flags;

5332 5333
		rcu_read_lock_sched();
		dl_b = dl_bw_of(dest_cpu);
5334 5335 5336 5337 5338 5339 5340 5341 5342 5343 5344 5345 5346 5347 5348
		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);
5349
		rcu_read_unlock_sched();
5350 5351 5352 5353 5354 5355 5356

	}
#endif
out:
	return ret;
}

L
Linus Torvalds 已提交
5357 5358
#ifdef CONFIG_SMP

5359 5360
static bool sched_smp_initialized __read_mostly;

5361 5362 5363 5364 5365 5366 5367 5368 5369 5370 5371 5372 5373 5374 5375
#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 */

5376
	trace_sched_move_numa(p, curr_cpu, target_cpu);
5377 5378
	return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
}
5379 5380 5381 5382 5383 5384 5385

/*
 * 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)
{
5386
	bool queued, running;
5387 5388
	struct rq_flags rf;
	struct rq *rq;
5389

5390
	rq = task_rq_lock(p, &rf);
5391
	queued = task_on_rq_queued(p);
5392 5393
	running = task_current(rq, p);

5394
	if (queued)
5395
		dequeue_task(rq, p, DEQUEUE_SAVE);
5396
	if (running)
5397
		put_prev_task(rq, p);
5398 5399 5400 5401 5402

	p->numa_preferred_nid = nid;

	if (running)
		p->sched_class->set_curr_task(rq);
5403
	if (queued)
5404
		enqueue_task(rq, p, ENQUEUE_RESTORE);
5405
	task_rq_unlock(rq, p, &rf);
5406
}
P
Peter Zijlstra 已提交
5407
#endif /* CONFIG_NUMA_BALANCING */
5408

L
Linus Torvalds 已提交
5409
#ifdef CONFIG_HOTPLUG_CPU
5410
/*
5411 5412
 * Ensures that the idle task is using init_mm right before its cpu goes
 * offline.
5413
 */
5414
void idle_task_exit(void)
L
Linus Torvalds 已提交
5415
{
5416
	struct mm_struct *mm = current->active_mm;
5417

5418
	BUG_ON(cpu_online(smp_processor_id()));
5419

5420
	if (mm != &init_mm) {
5421
		switch_mm_irqs_off(mm, &init_mm, current);
5422 5423
		finish_arch_post_lock_switch();
	}
5424
	mmdrop(mm);
L
Linus Torvalds 已提交
5425 5426 5427
}

/*
5428 5429
 * 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
5430 5431 5432
 * 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.
5433 5434
 *
 * Also see the comment "Global load-average calculations".
L
Linus Torvalds 已提交
5435
 */
5436
static void calc_load_migrate(struct rq *rq)
L
Linus Torvalds 已提交
5437
{
5438
	long delta = calc_load_fold_active(rq, 1);
5439 5440
	if (delta)
		atomic_long_add(delta, &calc_load_tasks);
L
Linus Torvalds 已提交
5441 5442
}

5443 5444 5445 5446 5447 5448 5449 5450 5451 5452 5453 5454 5455 5456 5457 5458
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,
};

5459
/*
5460 5461 5462 5463 5464 5465
 * 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
5466
 */
5467
static void migrate_tasks(struct rq *dead_rq)
L
Linus Torvalds 已提交
5468
{
5469
	struct rq *rq = dead_rq;
5470
	struct task_struct *next, *stop = rq->stop;
5471
	struct pin_cookie cookie;
5472
	int dest_cpu;
L
Linus Torvalds 已提交
5473 5474

	/*
5475 5476 5477 5478 5479 5480 5481
	 * 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
5482
	 */
5483
	rq->stop = NULL;
5484

5485 5486 5487 5488 5489 5490 5491
	/*
	 * 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);

5492
	for (;;) {
5493 5494 5495 5496 5497
		/*
		 * There's this thread running, bail when that's the only
		 * remaining thread.
		 */
		if (rq->nr_running == 1)
I
Ingo Molnar 已提交
5498
			break;
5499

5500
		/*
W
Wanpeng Li 已提交
5501
		 * pick_next_task assumes pinned rq->lock.
5502
		 */
5503 5504
		cookie = lockdep_pin_lock(&rq->lock);
		next = pick_next_task(rq, &fake_task, cookie);
5505
		BUG_ON(!next);
D
Dmitry Adamushko 已提交
5506
		next->sched_class->put_prev_task(rq, next);
5507

W
Wanpeng Li 已提交
5508 5509 5510 5511 5512 5513 5514 5515 5516
		/*
		 * 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.
		 */
5517
		lockdep_unpin_lock(&rq->lock, cookie);
W
Wanpeng Li 已提交
5518 5519 5520 5521 5522 5523 5524 5525 5526 5527 5528 5529 5530 5531
		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;
		}

5532
		/* Find suitable destination for @next, with force if needed. */
5533
		dest_cpu = select_fallback_rq(dead_rq->cpu, next);
5534

5535 5536 5537 5538 5539 5540
		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
5541
		raw_spin_unlock(&next->pi_lock);
L
Linus Torvalds 已提交
5542
	}
5543

5544
	rq->stop = stop;
5545
}
L
Linus Torvalds 已提交
5546 5547
#endif /* CONFIG_HOTPLUG_CPU */

5548 5549 5550 5551 5552
static void set_rq_online(struct rq *rq)
{
	if (!rq->online) {
		const struct sched_class *class;

5553
		cpumask_set_cpu(rq->cpu, rq->rd->online);
5554 5555 5556 5557 5558 5559 5560 5561 5562 5563 5564 5565 5566 5567 5568 5569 5570 5571 5572
		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);
		}

5573
		cpumask_clear_cpu(rq->cpu, rq->rd->online);
5574 5575 5576 5577
		rq->online = 0;
	}
}

5578
static void set_cpu_rq_start_time(unsigned int cpu)
L
Linus Torvalds 已提交
5579
{
5580
	struct rq *rq = cpu_rq(cpu);
L
Linus Torvalds 已提交
5581

5582 5583 5584
	rq->age_stamp = sched_clock_cpu(cpu);
}

5585 5586
static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */

5587
#ifdef CONFIG_SCHED_DEBUG
I
Ingo Molnar 已提交
5588

5589
static __read_mostly int sched_debug_enabled;
5590

5591
static int __init sched_debug_setup(char *str)
5592
{
5593
	sched_debug_enabled = 1;
5594 5595 5596

	return 0;
}
5597 5598 5599 5600 5601 5602
early_param("sched_debug", sched_debug_setup);

static inline bool sched_debug(void)
{
	return sched_debug_enabled;
}
5603

5604
static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5605
				  struct cpumask *groupmask)
L
Linus Torvalds 已提交
5606
{
I
Ingo Molnar 已提交
5607
	struct sched_group *group = sd->groups;
L
Linus Torvalds 已提交
5608

5609
	cpumask_clear(groupmask);
I
Ingo Molnar 已提交
5610 5611 5612 5613

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

	if (!(sd->flags & SD_LOAD_BALANCE)) {
P
Peter Zijlstra 已提交
5614
		printk("does not load-balance\n");
I
Ingo Molnar 已提交
5615
		if (sd->parent)
P
Peter Zijlstra 已提交
5616 5617
			printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
					" has parent");
I
Ingo Molnar 已提交
5618
		return -1;
N
Nick Piggin 已提交
5619 5620
	}

5621 5622
	printk(KERN_CONT "span %*pbl level %s\n",
	       cpumask_pr_args(sched_domain_span(sd)), sd->name);
I
Ingo Molnar 已提交
5623

5624
	if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
P
Peter Zijlstra 已提交
5625 5626
		printk(KERN_ERR "ERROR: domain->span does not contain "
				"CPU%d\n", cpu);
I
Ingo Molnar 已提交
5627
	}
5628
	if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
P
Peter Zijlstra 已提交
5629 5630
		printk(KERN_ERR "ERROR: domain->groups does not contain"
				" CPU%d\n", cpu);
I
Ingo Molnar 已提交
5631
	}
L
Linus Torvalds 已提交
5632

I
Ingo Molnar 已提交
5633
	printk(KERN_DEBUG "%*s groups:", level + 1, "");
L
Linus Torvalds 已提交
5634
	do {
I
Ingo Molnar 已提交
5635
		if (!group) {
P
Peter Zijlstra 已提交
5636 5637
			printk("\n");
			printk(KERN_ERR "ERROR: group is NULL\n");
L
Linus Torvalds 已提交
5638 5639 5640
			break;
		}

5641
		if (!cpumask_weight(sched_group_cpus(group))) {
P
Peter Zijlstra 已提交
5642 5643
			printk(KERN_CONT "\n");
			printk(KERN_ERR "ERROR: empty group\n");
I
Ingo Molnar 已提交
5644 5645
			break;
		}
L
Linus Torvalds 已提交
5646

5647 5648
		if (!(sd->flags & SD_OVERLAP) &&
		    cpumask_intersects(groupmask, sched_group_cpus(group))) {
P
Peter Zijlstra 已提交
5649 5650
			printk(KERN_CONT "\n");
			printk(KERN_ERR "ERROR: repeated CPUs\n");
I
Ingo Molnar 已提交
5651 5652
			break;
		}
L
Linus Torvalds 已提交
5653

5654
		cpumask_or(groupmask, groupmask, sched_group_cpus(group));
L
Linus Torvalds 已提交
5655

5656 5657
		printk(KERN_CONT " %*pbl",
		       cpumask_pr_args(sched_group_cpus(group)));
5658
		if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5659 5660
			printk(KERN_CONT " (cpu_capacity = %d)",
				group->sgc->capacity);
5661
		}
L
Linus Torvalds 已提交
5662

I
Ingo Molnar 已提交
5663 5664
		group = group->next;
	} while (group != sd->groups);
P
Peter Zijlstra 已提交
5665
	printk(KERN_CONT "\n");
L
Linus Torvalds 已提交
5666

5667
	if (!cpumask_equal(sched_domain_span(sd), groupmask))
P
Peter Zijlstra 已提交
5668
		printk(KERN_ERR "ERROR: groups don't span domain->span\n");
L
Linus Torvalds 已提交
5669

5670 5671
	if (sd->parent &&
	    !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
P
Peter Zijlstra 已提交
5672 5673
		printk(KERN_ERR "ERROR: parent span is not a superset "
			"of domain->span\n");
I
Ingo Molnar 已提交
5674 5675
	return 0;
}
L
Linus Torvalds 已提交
5676

I
Ingo Molnar 已提交
5677 5678 5679
static void sched_domain_debug(struct sched_domain *sd, int cpu)
{
	int level = 0;
L
Linus Torvalds 已提交
5680

5681
	if (!sched_debug_enabled)
5682 5683
		return;

I
Ingo Molnar 已提交
5684 5685 5686 5687
	if (!sd) {
		printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
		return;
	}
L
Linus Torvalds 已提交
5688

I
Ingo Molnar 已提交
5689 5690 5691
	printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);

	for (;;) {
5692
		if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
I
Ingo Molnar 已提交
5693
			break;
L
Linus Torvalds 已提交
5694 5695
		level++;
		sd = sd->parent;
5696
		if (!sd)
I
Ingo Molnar 已提交
5697 5698
			break;
	}
L
Linus Torvalds 已提交
5699
}
5700
#else /* !CONFIG_SCHED_DEBUG */
5701
# define sched_domain_debug(sd, cpu) do { } while (0)
5702 5703 5704 5705
static inline bool sched_debug(void)
{
	return false;
}
5706
#endif /* CONFIG_SCHED_DEBUG */
L
Linus Torvalds 已提交
5707

5708
static int sd_degenerate(struct sched_domain *sd)
5709
{
5710
	if (cpumask_weight(sched_domain_span(sd)) == 1)
5711 5712 5713 5714 5715 5716
		return 1;

	/* Following flags need at least 2 groups */
	if (sd->flags & (SD_LOAD_BALANCE |
			 SD_BALANCE_NEWIDLE |
			 SD_BALANCE_FORK |
5717
			 SD_BALANCE_EXEC |
5718
			 SD_SHARE_CPUCAPACITY |
5719
			 SD_ASYM_CPUCAPACITY |
5720 5721
			 SD_SHARE_PKG_RESOURCES |
			 SD_SHARE_POWERDOMAIN)) {
5722 5723 5724 5725 5726
		if (sd->groups != sd->groups->next)
			return 0;
	}

	/* Following flags don't use groups */
5727
	if (sd->flags & (SD_WAKE_AFFINE))
5728 5729 5730 5731 5732
		return 0;

	return 1;
}

5733 5734
static int
sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5735 5736 5737 5738 5739 5740
{
	unsigned long cflags = sd->flags, pflags = parent->flags;

	if (sd_degenerate(parent))
		return 1;

5741
	if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5742 5743 5744 5745 5746 5747 5748
		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 |
5749
				SD_BALANCE_EXEC |
5750
				SD_ASYM_CPUCAPACITY |
5751
				SD_SHARE_CPUCAPACITY |
5752
				SD_SHARE_PKG_RESOURCES |
5753 5754
				SD_PREFER_SIBLING |
				SD_SHARE_POWERDOMAIN);
5755 5756
		if (nr_node_ids == 1)
			pflags &= ~SD_SERIALIZE;
5757 5758 5759 5760 5761 5762 5763
	}
	if (~cflags & pflags)
		return 0;

	return 1;
}

5764
static void free_rootdomain(struct rcu_head *rcu)
5765
{
5766
	struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5767

5768
	cpupri_cleanup(&rd->cpupri);
5769
	cpudl_cleanup(&rd->cpudl);
5770
	free_cpumask_var(rd->dlo_mask);
5771 5772 5773 5774 5775 5776
	free_cpumask_var(rd->rto_mask);
	free_cpumask_var(rd->online);
	free_cpumask_var(rd->span);
	kfree(rd);
}

G
Gregory Haskins 已提交
5777 5778
static void rq_attach_root(struct rq *rq, struct root_domain *rd)
{
I
Ingo Molnar 已提交
5779
	struct root_domain *old_rd = NULL;
G
Gregory Haskins 已提交
5780 5781
	unsigned long flags;

5782
	raw_spin_lock_irqsave(&rq->lock, flags);
G
Gregory Haskins 已提交
5783 5784

	if (rq->rd) {
I
Ingo Molnar 已提交
5785
		old_rd = rq->rd;
G
Gregory Haskins 已提交
5786

5787
		if (cpumask_test_cpu(rq->cpu, old_rd->online))
5788
			set_rq_offline(rq);
G
Gregory Haskins 已提交
5789

5790
		cpumask_clear_cpu(rq->cpu, old_rd->span);
5791

I
Ingo Molnar 已提交
5792
		/*
5793
		 * If we dont want to free the old_rd yet then
I
Ingo Molnar 已提交
5794 5795 5796 5797 5798
		 * 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
5799 5800 5801 5802 5803
	}

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

5804
	cpumask_set_cpu(rq->cpu, rd->span);
5805
	if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5806
		set_rq_online(rq);
G
Gregory Haskins 已提交
5807

5808
	raw_spin_unlock_irqrestore(&rq->lock, flags);
I
Ingo Molnar 已提交
5809 5810

	if (old_rd)
5811
		call_rcu_sched(&old_rd->rcu, free_rootdomain);
G
Gregory Haskins 已提交
5812 5813
}

5814
static int init_rootdomain(struct root_domain *rd)
G
Gregory Haskins 已提交
5815 5816 5817
{
	memset(rd, 0, sizeof(*rd));

5818
	if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
5819
		goto out;
5820
	if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
5821
		goto free_span;
5822
	if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5823
		goto free_online;
5824
	if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5825
		goto free_dlo_mask;
5826

5827
	init_dl_bw(&rd->dl_bw);
5828 5829
	if (cpudl_init(&rd->cpudl) != 0)
		goto free_dlo_mask;
5830

5831
	if (cpupri_init(&rd->cpupri) != 0)
5832
		goto free_rto_mask;
5833
	return 0;
5834

5835 5836
free_rto_mask:
	free_cpumask_var(rd->rto_mask);
5837 5838
free_dlo_mask:
	free_cpumask_var(rd->dlo_mask);
5839 5840 5841 5842
free_online:
	free_cpumask_var(rd->online);
free_span:
	free_cpumask_var(rd->span);
5843
out:
5844
	return -ENOMEM;
G
Gregory Haskins 已提交
5845 5846
}

5847 5848 5849 5850 5851 5852
/*
 * 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
5853 5854
static void init_defrootdomain(void)
{
5855
	init_rootdomain(&def_root_domain);
5856

G
Gregory Haskins 已提交
5857 5858 5859
	atomic_set(&def_root_domain.refcount, 1);
}

5860
static struct root_domain *alloc_rootdomain(void)
G
Gregory Haskins 已提交
5861 5862 5863 5864 5865 5866 5867
{
	struct root_domain *rd;

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

5868
	if (init_rootdomain(rd) != 0) {
5869 5870 5871
		kfree(rd);
		return NULL;
	}
G
Gregory Haskins 已提交
5872 5873 5874 5875

	return rd;
}

5876
static void free_sched_groups(struct sched_group *sg, int free_sgc)
5877 5878 5879 5880 5881 5882 5883 5884 5885 5886
{
	struct sched_group *tmp, *first;

	if (!sg)
		return;

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

5887 5888
		if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
			kfree(sg->sgc);
5889 5890 5891 5892 5893 5894

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

5895 5896 5897
static void free_sched_domain(struct rcu_head *rcu)
{
	struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5898 5899 5900 5901 5902 5903 5904 5905

	/*
	 * 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)) {
5906
		kfree(sd->groups->sgc);
5907
		kfree(sd->groups);
5908
	}
5909 5910 5911 5912 5913 5914 5915 5916 5917 5918 5919 5920 5921 5922
	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);
}

5923 5924 5925 5926 5927 5928 5929
/*
 * 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
5930
 * two cpus are in the same cache domain, see cpus_share_cache().
5931 5932
 */
DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5933
DEFINE_PER_CPU(int, sd_llc_size);
5934
DEFINE_PER_CPU(int, sd_llc_id);
5935
DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5936 5937
DEFINE_PER_CPU(struct sched_domain *, sd_busy);
DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5938 5939 5940 5941

static void update_top_cache_domain(int cpu)
{
	struct sched_domain *sd;
5942
	struct sched_domain *busy_sd = NULL;
5943
	int id = cpu;
5944
	int size = 1;
5945 5946

	sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5947
	if (sd) {
5948
		id = cpumask_first(sched_domain_span(sd));
5949
		size = cpumask_weight(sched_domain_span(sd));
5950
		busy_sd = sd->parent; /* sd_busy */
5951
	}
5952
	rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5953 5954

	rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5955
	per_cpu(sd_llc_size, cpu) = size;
5956
	per_cpu(sd_llc_id, cpu) = id;
5957 5958 5959

	sd = lowest_flag_domain(cpu, SD_NUMA);
	rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5960 5961 5962

	sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
	rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5963 5964
}

L
Linus Torvalds 已提交
5965
/*
I
Ingo Molnar 已提交
5966
 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
L
Linus Torvalds 已提交
5967 5968
 * hold the hotplug lock.
 */
I
Ingo Molnar 已提交
5969 5970
static void
cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
L
Linus Torvalds 已提交
5971
{
5972
	struct rq *rq = cpu_rq(cpu);
5973 5974 5975
	struct sched_domain *tmp;

	/* Remove the sched domains which do not contribute to scheduling. */
5976
	for (tmp = sd; tmp; ) {
5977 5978 5979
		struct sched_domain *parent = tmp->parent;
		if (!parent)
			break;
5980

5981
		if (sd_parent_degenerate(tmp, parent)) {
5982
			tmp->parent = parent->parent;
5983 5984
			if (parent->parent)
				parent->parent->child = tmp;
5985 5986 5987 5988 5989 5990 5991
			/*
			 * 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;
5992
			destroy_sched_domain(parent, cpu);
5993 5994
		} else
			tmp = tmp->parent;
5995 5996
	}

5997
	if (sd && sd_degenerate(sd)) {
5998
		tmp = sd;
5999
		sd = sd->parent;
6000
		destroy_sched_domain(tmp, cpu);
6001 6002 6003
		if (sd)
			sd->child = NULL;
	}
L
Linus Torvalds 已提交
6004

6005
	sched_domain_debug(sd, cpu);
L
Linus Torvalds 已提交
6006

G
Gregory Haskins 已提交
6007
	rq_attach_root(rq, rd);
6008
	tmp = rq->sd;
N
Nick Piggin 已提交
6009
	rcu_assign_pointer(rq->sd, sd);
6010
	destroy_sched_domains(tmp, cpu);
6011 6012

	update_top_cache_domain(cpu);
L
Linus Torvalds 已提交
6013 6014 6015 6016 6017
}

/* Setup the mask of cpus configured for isolated domains */
static int __init isolated_cpu_setup(char *str)
{
6018 6019
	int ret;

R
Rusty Russell 已提交
6020
	alloc_bootmem_cpumask_var(&cpu_isolated_map);
6021 6022 6023 6024 6025
	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
6026 6027
	return 1;
}
I
Ingo Molnar 已提交
6028
__setup("isolcpus=", isolated_cpu_setup);
L
Linus Torvalds 已提交
6029

6030
struct s_data {
6031
	struct sched_domain ** __percpu sd;
6032 6033 6034
	struct root_domain	*rd;
};

6035 6036
enum s_alloc {
	sa_rootdomain,
6037
	sa_sd,
6038
	sa_sd_storage,
6039 6040 6041
	sa_none,
};

P
Peter Zijlstra 已提交
6042 6043 6044 6045 6046 6047 6048 6049 6050 6051 6052 6053 6054 6055 6056 6057 6058 6059 6060 6061 6062 6063 6064 6065 6066 6067 6068 6069 6070 6071 6072 6073 6074 6075 6076 6077 6078 6079
/*
 * 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));
}

6080 6081 6082 6083 6084 6085 6086
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;
6087
	struct sched_domain *sibling;
6088 6089 6090 6091 6092 6093 6094 6095 6096 6097
	int i;

	cpumask_clear(covered);

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

		if (cpumask_test_cpu(i, covered))
			continue;

6098
		sibling = *per_cpu_ptr(sdd->sd, i);
P
Peter Zijlstra 已提交
6099 6100

		/* See the comment near build_group_mask(). */
6101
		if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
P
Peter Zijlstra 已提交
6102 6103
			continue;

6104
		sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6105
				GFP_KERNEL, cpu_to_node(cpu));
6106 6107 6108 6109 6110

		if (!sg)
			goto fail;

		sg_span = sched_group_cpus(sg);
6111 6112 6113
		if (sibling->child)
			cpumask_copy(sg_span, sched_domain_span(sibling->child));
		else
6114 6115 6116 6117
			cpumask_set_cpu(i, sg_span);

		cpumask_or(covered, covered, sg_span);

6118 6119
		sg->sgc = *per_cpu_ptr(sdd->sgc, i);
		if (atomic_inc_return(&sg->sgc->ref) == 1)
P
Peter Zijlstra 已提交
6120 6121
			build_group_mask(sd, sg);

6122
		/*
6123
		 * Initialize sgc->capacity such that even if we mess up the
6124 6125 6126
		 * domains and no possible iteration will get us here, we won't
		 * die on a /0 trap.
		 */
6127
		sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
6128

P
Peter Zijlstra 已提交
6129 6130 6131 6132 6133
		/*
		 * 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
6134
		if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
P
Peter Zijlstra 已提交
6135
		    group_balance_cpu(sg) == cpu)
6136 6137 6138 6139 6140 6141 6142 6143 6144 6145 6146 6147 6148 6149 6150 6151 6152 6153 6154
			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;
}

6155
static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
L
Linus Torvalds 已提交
6156
{
6157 6158
	struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
	struct sched_domain *child = sd->child;
L
Linus Torvalds 已提交
6159

6160 6161
	if (child)
		cpu = cpumask_first(sched_domain_span(child));
6162

6163
	if (sg) {
6164
		*sg = *per_cpu_ptr(sdd->sg, cpu);
6165 6166
		(*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
		atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
6167
	}
6168 6169

	return cpu;
6170 6171
}

6172
/*
6173 6174
 * 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,
6175
 * and ->cpu_capacity to 0.
6176 6177
 *
 * Assumes the sched_domain tree is fully constructed
6178
 */
6179 6180
static int
build_sched_groups(struct sched_domain *sd, int cpu)
L
Linus Torvalds 已提交
6181
{
6182 6183 6184
	struct sched_group *first = NULL, *last = NULL;
	struct sd_data *sdd = sd->private;
	const struct cpumask *span = sched_domain_span(sd);
6185
	struct cpumask *covered;
6186
	int i;
6187

6188 6189 6190
	get_group(cpu, sdd, &sd->groups);
	atomic_inc(&sd->groups->ref);

6191
	if (cpu != cpumask_first(span))
6192 6193
		return 0;

6194 6195 6196
	lockdep_assert_held(&sched_domains_mutex);
	covered = sched_domains_tmpmask;

6197
	cpumask_clear(covered);
6198

6199 6200
	for_each_cpu(i, span) {
		struct sched_group *sg;
6201
		int group, j;
6202

6203 6204
		if (cpumask_test_cpu(i, covered))
			continue;
6205

6206
		group = get_group(i, sdd, &sg);
P
Peter Zijlstra 已提交
6207
		cpumask_setall(sched_group_mask(sg));
6208

6209 6210 6211
		for_each_cpu(j, span) {
			if (get_group(j, sdd, NULL) != group)
				continue;
6212

6213 6214 6215
			cpumask_set_cpu(j, covered);
			cpumask_set_cpu(j, sched_group_cpus(sg));
		}
6216

6217 6218 6219 6220 6221 6222 6223
		if (!first)
			first = sg;
		if (last)
			last->next = sg;
		last = sg;
	}
	last->next = first;
6224 6225

	return 0;
6226
}
6227

6228
/*
6229
 * Initialize sched groups cpu_capacity.
6230
 *
6231
 * cpu_capacity indicates the capacity of sched group, which is used while
6232
 * distributing the load between different sched groups in a sched domain.
6233 6234 6235 6236
 * 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.
6237
 */
6238
static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
6239
{
6240
	struct sched_group *sg = sd->groups;
6241

6242
	WARN_ON(!sg);
6243 6244 6245 6246 6247

	do {
		sg->group_weight = cpumask_weight(sched_group_cpus(sg));
		sg = sg->next;
	} while (sg != sd->groups);
6248

P
Peter Zijlstra 已提交
6249
	if (cpu != group_balance_cpu(sg))
6250
		return;
6251

6252 6253
	update_group_capacity(sd, cpu);
	atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
6254 6255
}

6256 6257 6258 6259 6260
/*
 * Initializers for schedule domains
 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
 */

6261
static int default_relax_domain_level = -1;
6262
int sched_domain_level_max;
6263 6264 6265

static int __init setup_relax_domain_level(char *str)
{
6266 6267
	if (kstrtoint(str, 0, &default_relax_domain_level))
		pr_warn("Unable to set relax_domain_level\n");
6268

6269 6270 6271 6272 6273 6274 6275 6276 6277 6278 6279 6280 6281 6282 6283 6284 6285 6286
	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 */
6287
		sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6288 6289
	} else {
		/* turn on idle balance on this domain */
6290
		sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6291 6292 6293
	}
}

6294 6295 6296
static void __sdt_free(const struct cpumask *cpu_map);
static int __sdt_alloc(const struct cpumask *cpu_map);

6297 6298 6299 6300 6301
static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
				 const struct cpumask *cpu_map)
{
	switch (what) {
	case sa_rootdomain:
6302 6303
		if (!atomic_read(&d->rd->refcount))
			free_rootdomain(&d->rd->rcu); /* fall through */
6304 6305
	case sa_sd:
		free_percpu(d->sd); /* fall through */
6306
	case sa_sd_storage:
6307
		__sdt_free(cpu_map); /* fall through */
6308 6309 6310 6311
	case sa_none:
		break;
	}
}
6312

6313 6314 6315
static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
						   const struct cpumask *cpu_map)
{
6316 6317
	memset(d, 0, sizeof(*d));

6318 6319
	if (__sdt_alloc(cpu_map))
		return sa_sd_storage;
6320 6321 6322
	d->sd = alloc_percpu(struct sched_domain *);
	if (!d->sd)
		return sa_sd_storage;
6323
	d->rd = alloc_rootdomain();
6324
	if (!d->rd)
6325
		return sa_sd;
6326 6327
	return sa_rootdomain;
}
G
Gregory Haskins 已提交
6328

6329 6330 6331 6332 6333 6334 6335 6336 6337 6338 6339 6340
/*
 * 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;

6341
	if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6342
		*per_cpu_ptr(sdd->sg, cpu) = NULL;
6343

6344 6345
	if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
		*per_cpu_ptr(sdd->sgc, cpu) = NULL;
6346 6347
}

6348 6349
#ifdef CONFIG_NUMA
static int sched_domains_numa_levels;
6350
enum numa_topology_type sched_numa_topology_type;
6351
static int *sched_domains_numa_distance;
6352
int sched_max_numa_distance;
6353 6354
static struct cpumask ***sched_domains_numa_masks;
static int sched_domains_curr_level;
6355
#endif
6356

6357 6358 6359
/*
 * SD_flags allowed in topology descriptions.
 *
6360 6361 6362
 * These flags are purely descriptive of the topology and do not prescribe
 * behaviour. Behaviour is artificial and mapped in the below sd_init()
 * function:
6363
 *
6364 6365 6366 6367
 *   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
6368
 *   SD_ASYM_CPUCAPACITY    - describes mixed capacity topologies
6369 6370 6371 6372 6373
 *
 * 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
6374 6375
 */
#define TOPOLOGY_SD_FLAGS		\
6376
	(SD_SHARE_CPUCAPACITY |		\
6377 6378
	 SD_SHARE_PKG_RESOURCES |	\
	 SD_NUMA |			\
6379
	 SD_ASYM_PACKING |		\
6380
	 SD_ASYM_CPUCAPACITY |		\
6381
	 SD_SHARE_POWERDOMAIN)
6382 6383

static struct sched_domain *
6384 6385
sd_init(struct sched_domain_topology_level *tl,
	struct sched_domain *child, int cpu)
6386 6387
{
	struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6388 6389 6390 6391 6392 6393 6394 6395 6396 6397 6398 6399 6400 6401 6402 6403
	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;
6404 6405 6406 6407 6408

	*sd = (struct sched_domain){
		.min_interval		= sd_weight,
		.max_interval		= 2*sd_weight,
		.busy_factor		= 32,
6409
		.imbalance_pct		= 125,
6410 6411 6412 6413

		.cache_nice_tries	= 0,
		.busy_idx		= 0,
		.idle_idx		= 0,
6414 6415 6416 6417 6418 6419
		.newidle_idx		= 0,
		.wake_idx		= 0,
		.forkexec_idx		= 0,

		.flags			= 1*SD_LOAD_BALANCE
					| 1*SD_BALANCE_NEWIDLE
6420 6421
					| 1*SD_BALANCE_EXEC
					| 1*SD_BALANCE_FORK
6422
					| 0*SD_BALANCE_WAKE
6423
					| 1*SD_WAKE_AFFINE
6424
					| 0*SD_SHARE_CPUCAPACITY
6425
					| 0*SD_SHARE_PKG_RESOURCES
6426
					| 0*SD_SERIALIZE
6427
					| 0*SD_PREFER_SIBLING
6428 6429
					| 0*SD_NUMA
					| sd_flags
6430
					,
6431

6432 6433
		.last_balance		= jiffies,
		.balance_interval	= sd_weight,
6434
		.smt_gain		= 0,
6435 6436
		.max_newidle_lb_cost	= 0,
		.next_decay_max_lb_cost	= jiffies,
6437
		.child			= child,
6438 6439 6440
#ifdef CONFIG_SCHED_DEBUG
		.name			= tl->name,
#endif
6441 6442 6443
	};

	/*
6444
	 * Convert topological properties into behaviour.
6445
	 */
6446

6447
	if (sd->flags & SD_SHARE_CPUCAPACITY) {
6448
		sd->flags |= SD_PREFER_SIBLING;
6449 6450 6451 6452 6453 6454 6455 6456 6457 6458 6459 6460 6461 6462 6463 6464 6465 6466 6467 6468 6469 6470 6471 6472 6473 6474 6475 6476 6477 6478
		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;
6479 6480 6481 6482

	return sd;
}

6483 6484 6485 6486 6487 6488 6489 6490 6491 6492 6493 6494 6495 6496
/*
 * 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, },
};

6497 6498
static struct sched_domain_topology_level *sched_domain_topology =
	default_topology;
6499 6500 6501 6502 6503 6504 6505 6506 6507 6508 6509

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

void set_sched_topology(struct sched_domain_topology_level *tl)
{
	sched_domain_topology = tl;
}

#ifdef CONFIG_NUMA

6510 6511 6512 6513 6514
static const struct cpumask *sd_numa_mask(int cpu)
{
	return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
}

6515 6516 6517 6518 6519 6520 6521 6522 6523 6524 6525 6526 6527 6528 6529 6530 6531 6532 6533 6534 6535
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");
}

6536
bool find_numa_distance(int distance)
6537 6538 6539 6540 6541 6542 6543 6544 6545 6546 6547 6548 6549 6550
{
	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;
}

6551 6552 6553 6554 6555 6556 6557 6558 6559 6560 6561 6562 6563 6564 6565 6566 6567 6568 6569 6570 6571 6572 6573 6574 6575
/*
 * 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;

6576
	if (sched_domains_numa_levels <= 1) {
6577
		sched_numa_topology_type = NUMA_DIRECT;
6578 6579
		return;
	}
6580 6581 6582 6583 6584 6585 6586 6587 6588 6589 6590 6591 6592 6593 6594 6595 6596 6597 6598 6599 6600 6601 6602

	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;
		}
	}
}

6603 6604 6605 6606 6607 6608 6609 6610 6611 6612 6613 6614 6615 6616 6617 6618 6619 6620 6621 6622 6623
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++) {
6624 6625 6626 6627 6628 6629 6630 6631 6632 6633 6634 6635 6636 6637 6638 6639 6640 6641 6642 6643 6644 6645 6646 6647
			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;
6648
		}
6649 6650 6651 6652 6653 6654

		/*
		 * In case of sched_debug() we verify the above assumption.
		 */
		if (!sched_debug())
			break;
6655
	}
6656 6657 6658 6659

	if (!level)
		return;

6660 6661 6662 6663
	/*
	 * 'level' contains the number of unique distances, excluding the
	 * identity distance node_distance(i,i).
	 *
V
Viresh Kumar 已提交
6664
	 * The sched_domains_numa_distance[] array includes the actual distance
6665 6666 6667
	 * numbers.
	 */

6668 6669 6670 6671 6672 6673 6674 6675 6676 6677 6678
	/*
	 * 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;

6679 6680 6681 6682 6683 6684 6685 6686 6687 6688 6689 6690 6691 6692 6693
	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++) {
6694
			struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6695 6696 6697 6698 6699
			if (!mask)
				return;

			sched_domains_numa_masks[i][j] = mask;

6700
			for_each_node(k) {
6701
				if (node_distance(j, k) > sched_domains_numa_distance[i])
6702 6703 6704 6705 6706 6707 6708
					continue;

				cpumask_or(mask, mask, cpumask_of_node(k));
			}
		}
	}

6709 6710 6711
	/* Compute default topology size */
	for (i = 0; sched_domain_topology[i].mask; i++);

6712
	tl = kzalloc((i + level + 1) *
6713 6714 6715 6716 6717 6718 6719
			sizeof(struct sched_domain_topology_level), GFP_KERNEL);
	if (!tl)
		return;

	/*
	 * Copy the default topology bits..
	 */
6720 6721
	for (i = 0; sched_domain_topology[i].mask; i++)
		tl[i] = sched_domain_topology[i];
6722 6723 6724 6725 6726 6727 6728

	/*
	 * .. 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,
6729
			.sd_flags = cpu_numa_flags,
6730 6731
			.flags = SDTL_OVERLAP,
			.numa_level = j,
6732
			SD_INIT_NAME(NUMA)
6733 6734 6735 6736
		};
	}

	sched_domain_topology = tl;
6737 6738

	sched_domains_numa_levels = level;
6739
	sched_max_numa_distance = sched_domains_numa_distance[level - 1];
6740 6741

	init_numa_topology_type();
6742
}
6743

6744
static void sched_domains_numa_masks_set(unsigned int cpu)
6745 6746
{
	int node = cpu_to_node(cpu);
6747
	int i, j;
6748 6749 6750 6751 6752 6753 6754 6755 6756

	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]);
		}
	}
}

6757
static void sched_domains_numa_masks_clear(unsigned int cpu)
6758 6759
{
	int i, j;
6760

6761 6762 6763 6764 6765 6766
	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]);
	}
}

6767
#else
6768 6769 6770
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) { }
6771 6772
#endif /* CONFIG_NUMA */

6773 6774 6775 6776 6777
static int __sdt_alloc(const struct cpumask *cpu_map)
{
	struct sched_domain_topology_level *tl;
	int j;

6778
	for_each_sd_topology(tl) {
6779 6780 6781 6782 6783 6784 6785 6786 6787 6788
		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;

6789 6790
		sdd->sgc = alloc_percpu(struct sched_group_capacity *);
		if (!sdd->sgc)
6791 6792
			return -ENOMEM;

6793 6794 6795
		for_each_cpu(j, cpu_map) {
			struct sched_domain *sd;
			struct sched_group *sg;
6796
			struct sched_group_capacity *sgc;
6797

P
Peter Zijlstra 已提交
6798
			sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6799 6800 6801 6802 6803 6804 6805 6806 6807 6808 6809
					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;

6810 6811
			sg->next = sg;

6812
			*per_cpu_ptr(sdd->sg, j) = sg;
6813

6814
			sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6815
					GFP_KERNEL, cpu_to_node(j));
6816
			if (!sgc)
6817 6818
				return -ENOMEM;

6819
			*per_cpu_ptr(sdd->sgc, j) = sgc;
6820 6821 6822 6823 6824 6825 6826 6827 6828 6829 6830
		}
	}

	return 0;
}

static void __sdt_free(const struct cpumask *cpu_map)
{
	struct sched_domain_topology_level *tl;
	int j;

6831
	for_each_sd_topology(tl) {
6832 6833 6834
		struct sd_data *sdd = &tl->data;

		for_each_cpu(j, cpu_map) {
6835 6836 6837 6838 6839 6840 6841 6842 6843 6844 6845
			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));
6846 6847
			if (sdd->sgc)
				kfree(*per_cpu_ptr(sdd->sgc, j));
6848 6849
		}
		free_percpu(sdd->sd);
6850
		sdd->sd = NULL;
6851
		free_percpu(sdd->sg);
6852
		sdd->sg = NULL;
6853 6854
		free_percpu(sdd->sgc);
		sdd->sgc = NULL;
6855 6856 6857
	}
}

6858
struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6859 6860
		const struct cpumask *cpu_map, struct sched_domain_attr *attr,
		struct sched_domain *child, int cpu)
6861
{
6862
	struct sched_domain *sd = sd_init(tl, child, cpu);
6863 6864

	cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6865 6866 6867
	if (child) {
		sd->level = child->level + 1;
		sched_domain_level_max = max(sched_domain_level_max, sd->level);
6868
		child->parent = sd;
P
Peter Zijlstra 已提交
6869 6870 6871 6872 6873 6874 6875 6876 6877 6878 6879 6880 6881 6882

		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));
		}

6883
	}
6884
	set_domain_attribute(sd, attr);
6885 6886 6887 6888

	return sd;
}

6889 6890 6891 6892
/*
 * Build sched domains for a given set of cpus and attach the sched domains
 * to the individual cpus
 */
6893 6894
static int build_sched_domains(const struct cpumask *cpu_map,
			       struct sched_domain_attr *attr)
6895
{
6896
	enum s_alloc alloc_state;
6897
	struct sched_domain *sd;
6898
	struct s_data d;
6899
	int i, ret = -ENOMEM;
6900

6901 6902 6903
	alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
	if (alloc_state != sa_rootdomain)
		goto error;
6904

6905
	/* Set up domains for cpus specified by the cpu_map. */
6906
	for_each_cpu(i, cpu_map) {
6907 6908
		struct sched_domain_topology_level *tl;

6909
		sd = NULL;
6910
		for_each_sd_topology(tl) {
6911
			sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6912 6913
			if (tl == sched_domain_topology)
				*per_cpu_ptr(d.sd, i) = sd;
6914 6915
			if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
				sd->flags |= SD_OVERLAP;
6916 6917
			if (cpumask_equal(cpu_map, sched_domain_span(sd)))
				break;
6918
		}
6919 6920 6921 6922 6923 6924
	}

	/* 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));
6925 6926 6927 6928 6929 6930 6931
			if (sd->flags & SD_OVERLAP) {
				if (build_overlap_sched_groups(sd, i))
					goto error;
			} else {
				if (build_sched_groups(sd, i))
					goto error;
			}
6932
		}
6933
	}
6934

6935
	/* Calculate CPU capacity for physical packages and nodes */
6936 6937 6938
	for (i = nr_cpumask_bits-1; i >= 0; i--) {
		if (!cpumask_test_cpu(i, cpu_map))
			continue;
6939

6940 6941
		for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
			claim_allocations(i, sd);
6942
			init_sched_groups_capacity(i, sd);
6943
		}
6944
	}
6945

L
Linus Torvalds 已提交
6946
	/* Attach the domains */
6947
	rcu_read_lock();
6948
	for_each_cpu(i, cpu_map) {
6949
		sd = *per_cpu_ptr(d.sd, i);
6950
		cpu_attach_domain(sd, d.rd, i);
L
Linus Torvalds 已提交
6951
	}
6952
	rcu_read_unlock();
6953

6954
	ret = 0;
6955
error:
6956
	__free_domain_allocs(&d, alloc_state, cpu_map);
6957
	return ret;
L
Linus Torvalds 已提交
6958
}
P
Paul Jackson 已提交
6959

6960
static cpumask_var_t *doms_cur;	/* current sched domains */
P
Paul Jackson 已提交
6961
static int ndoms_cur;		/* number of sched domains in 'doms_cur' */
I
Ingo Molnar 已提交
6962 6963
static struct sched_domain_attr *dattr_cur;
				/* attribues of custom domains in 'doms_cur' */
P
Paul Jackson 已提交
6964 6965 6966

/*
 * Special case: If a kmalloc of a doms_cur partition (array of
6967 6968
 * cpumask) fails, then fallback to a single sched domain,
 * as determined by the single cpumask fallback_doms.
P
Paul Jackson 已提交
6969
 */
6970
static cpumask_var_t fallback_doms;
P
Paul Jackson 已提交
6971

6972 6973 6974 6975 6976
/*
 * 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.
 */
6977
int __weak arch_update_cpu_topology(void)
6978
{
6979
	return 0;
6980 6981
}

6982 6983 6984 6985 6986 6987 6988 6989 6990 6991 6992 6993 6994 6995 6996 6997 6998 6999 7000 7001 7002 7003 7004 7005 7006
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);
}

7007
/*
I
Ingo Molnar 已提交
7008
 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
P
Paul Jackson 已提交
7009 7010
 * For now this just excludes isolated cpus, but could be used to
 * exclude other special cases in the future.
7011
 */
7012
static int init_sched_domains(const struct cpumask *cpu_map)
7013
{
7014 7015
	int err;

7016
	arch_update_cpu_topology();
P
Paul Jackson 已提交
7017
	ndoms_cur = 1;
7018
	doms_cur = alloc_sched_domains(ndoms_cur);
P
Paul Jackson 已提交
7019
	if (!doms_cur)
7020 7021
		doms_cur = &fallback_doms;
	cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
7022
	err = build_sched_domains(doms_cur[0], NULL);
7023
	register_sched_domain_sysctl();
7024 7025

	return err;
7026 7027 7028 7029 7030 7031
}

/*
 * Detach sched domains from a group of cpus specified in cpu_map
 * These cpus will now be attached to the NULL domain
 */
7032
static void detach_destroy_domains(const struct cpumask *cpu_map)
7033 7034 7035
{
	int i;

7036
	rcu_read_lock();
7037
	for_each_cpu(i, cpu_map)
G
Gregory Haskins 已提交
7038
		cpu_attach_domain(NULL, &def_root_domain, i);
7039
	rcu_read_unlock();
7040 7041
}

7042 7043 7044 7045 7046 7047 7048 7049 7050 7051 7052 7053 7054 7055 7056 7057
/* 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
7058 7059
/*
 * Partition sched domains as specified by the 'ndoms_new'
I
Ingo Molnar 已提交
7060
 * cpumasks in the array doms_new[] of cpumasks. This compares
P
Paul Jackson 已提交
7061 7062 7063
 * doms_new[] to the current sched domain partitioning, doms_cur[].
 * It destroys each deleted domain and builds each new domain.
 *
7064
 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
I
Ingo Molnar 已提交
7065 7066 7067
 * 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
7068 7069 7070
 * current 'doms_cur' domains and in the new 'doms_new', we can leave
 * it as it is.
 *
7071 7072 7073 7074 7075 7076
 * 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
7077
 *
7078
 * If doms_new == NULL it will be replaced with cpu_online_mask.
7079 7080
 * ndoms_new == 0 is a special case for destroying existing domains,
 * and it will not create the default domain.
7081
 *
P
Paul Jackson 已提交
7082 7083
 * Call with hotplug lock held
 */
7084
void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
7085
			     struct sched_domain_attr *dattr_new)
P
Paul Jackson 已提交
7086
{
7087
	int i, j, n;
7088
	int new_topology;
P
Paul Jackson 已提交
7089

7090
	mutex_lock(&sched_domains_mutex);
7091

7092 7093 7094
	/* always unregister in case we don't destroy any domains */
	unregister_sched_domain_sysctl();

7095 7096 7097
	/* Let architecture update cpu core mappings. */
	new_topology = arch_update_cpu_topology();

7098
	n = doms_new ? ndoms_new : 0;
P
Paul Jackson 已提交
7099 7100 7101

	/* Destroy deleted domains */
	for (i = 0; i < ndoms_cur; i++) {
7102
		for (j = 0; j < n && !new_topology; j++) {
7103
			if (cpumask_equal(doms_cur[i], doms_new[j])
7104
			    && dattrs_equal(dattr_cur, i, dattr_new, j))
P
Paul Jackson 已提交
7105 7106 7107
				goto match1;
		}
		/* no match - a current sched domain not in new doms_new[] */
7108
		detach_destroy_domains(doms_cur[i]);
P
Paul Jackson 已提交
7109 7110 7111 7112
match1:
		;
	}

7113
	n = ndoms_cur;
7114
	if (doms_new == NULL) {
7115
		n = 0;
7116
		doms_new = &fallback_doms;
7117
		cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
7118
		WARN_ON_ONCE(dattr_new);
7119 7120
	}

P
Paul Jackson 已提交
7121 7122
	/* Build new domains */
	for (i = 0; i < ndoms_new; i++) {
7123
		for (j = 0; j < n && !new_topology; j++) {
7124
			if (cpumask_equal(doms_new[i], doms_cur[j])
7125
			    && dattrs_equal(dattr_new, i, dattr_cur, j))
P
Paul Jackson 已提交
7126 7127 7128
				goto match2;
		}
		/* no match - add a new doms_new */
7129
		build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
P
Paul Jackson 已提交
7130 7131 7132 7133 7134
match2:
		;
	}

	/* Remember the new sched domains */
7135 7136
	if (doms_cur != &fallback_doms)
		free_sched_domains(doms_cur, ndoms_cur);
7137
	kfree(dattr_cur);	/* kfree(NULL) is safe */
P
Paul Jackson 已提交
7138
	doms_cur = doms_new;
7139
	dattr_cur = dattr_new;
P
Paul Jackson 已提交
7140
	ndoms_cur = ndoms_new;
7141 7142

	register_sched_domain_sysctl();
7143

7144
	mutex_unlock(&sched_domains_mutex);
P
Paul Jackson 已提交
7145 7146
}

7147 7148
static int num_cpus_frozen;	/* used to mark begin/end of suspend/resume */

L
Linus Torvalds 已提交
7149
/*
7150 7151 7152
 * Update cpusets according to cpu_active mask.  If cpusets are
 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
 * around partition_sched_domains().
7153 7154 7155
 *
 * 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
7156
 */
7157
static void cpuset_cpu_active(void)
7158
{
7159
	if (cpuhp_tasks_frozen) {
7160 7161 7162 7163 7164 7165 7166 7167 7168
		/*
		 * 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);
7169
			return;
7170 7171 7172 7173 7174 7175
		}
		/*
		 * This is the last CPU online operation. So fall through and
		 * restore the original sched domains by considering the
		 * cpuset configurations.
		 */
7176
	}
7177
	cpuset_update_active_cpus(true);
7178
}
7179

7180
static int cpuset_cpu_inactive(unsigned int cpu)
7181
{
7182 7183
	unsigned long flags;
	struct dl_bw *dl_b;
7184 7185
	bool overflow;
	int cpus;
7186

7187
	if (!cpuhp_tasks_frozen) {
7188 7189
		rcu_read_lock_sched();
		dl_b = dl_bw_of(cpu);
7190

7191 7192 7193 7194
		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);
7195

7196
		rcu_read_unlock_sched();
7197

7198
		if (overflow)
7199
			return -EBUSY;
7200
		cpuset_update_active_cpus(false);
7201
	} else {
7202 7203
		num_cpus_frozen++;
		partition_sched_domains(1, NULL, NULL);
7204
	}
7205
	return 0;
7206 7207
}

7208
int sched_cpu_activate(unsigned int cpu)
7209
{
7210 7211 7212
	struct rq *rq = cpu_rq(cpu);
	unsigned long flags;

7213
	set_cpu_active(cpu, true);
7214

7215
	if (sched_smp_initialized) {
7216
		sched_domains_numa_masks_set(cpu);
7217
		cpuset_cpu_active();
7218
	}
7219 7220 7221 7222 7223 7224 7225 7226 7227 7228 7229 7230 7231 7232 7233 7234 7235 7236 7237

	/*
	 * 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();

7238
	return 0;
7239 7240
}

7241
int sched_cpu_deactivate(unsigned int cpu)
7242 7243 7244
{
	int ret;

7245
	set_cpu_active(cpu, false);
7246 7247 7248 7249 7250 7251 7252 7253 7254 7255 7256 7257 7258 7259
	/*
	 * 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();
7260 7261 7262 7263 7264 7265 7266 7267

	if (!sched_smp_initialized)
		return 0;

	ret = cpuset_cpu_inactive(cpu);
	if (ret) {
		set_cpu_active(cpu, true);
		return ret;
7268
	}
7269 7270
	sched_domains_numa_masks_clear(cpu);
	return 0;
7271 7272
}

7273 7274 7275 7276 7277 7278 7279 7280
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();
}

7281 7282 7283
int sched_cpu_starting(unsigned int cpu)
{
	set_cpu_rq_start_time(cpu);
7284
	sched_rq_cpu_starting(cpu);
7285
	return 0;
7286 7287
}

7288 7289 7290 7291 7292 7293 7294 7295 7296 7297 7298 7299 7300 7301 7302 7303 7304 7305
#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();
7306
	nohz_balance_exit_idle(cpu);
7307
	hrtick_clear(rq);
7308 7309 7310 7311
	return 0;
}
#endif

L
Linus Torvalds 已提交
7312 7313
void __init sched_init_smp(void)
{
7314 7315 7316
	cpumask_var_t non_isolated_cpus;

	alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
7317
	alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
7318

7319 7320
	sched_init_numa();

7321 7322 7323 7324 7325
	/*
	 * 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.
	 */
7326
	mutex_lock(&sched_domains_mutex);
7327
	init_sched_domains(cpu_active_mask);
7328 7329 7330
	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);
7331
	mutex_unlock(&sched_domains_mutex);
7332

7333
	/* Move init over to a non-isolated CPU */
7334
	if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
7335
		BUG();
I
Ingo Molnar 已提交
7336
	sched_init_granularity();
7337
	free_cpumask_var(non_isolated_cpus);
7338

7339
	init_sched_rt_class();
7340
	init_sched_dl_class();
7341
	sched_smp_initialized = true;
L
Linus Torvalds 已提交
7342
}
7343 7344 7345

static int __init migration_init(void)
{
7346
	sched_rq_cpu_starting(smp_processor_id());
7347
	return 0;
L
Linus Torvalds 已提交
7348
}
7349 7350
early_initcall(migration_init);

L
Linus Torvalds 已提交
7351 7352 7353
#else
void __init sched_init_smp(void)
{
I
Ingo Molnar 已提交
7354
	sched_init_granularity();
L
Linus Torvalds 已提交
7355 7356 7357 7358 7359 7360 7361 7362 7363 7364
}
#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);
}

7365
#ifdef CONFIG_CGROUP_SCHED
7366 7367 7368 7369
/*
 * Default task group.
 * Every task in system belongs to this group at bootup.
 */
7370
struct task_group root_task_group;
7371
LIST_HEAD(task_groups);
7372 7373 7374

/* Cacheline aligned slab cache for task_group */
static struct kmem_cache *task_group_cache __read_mostly;
7375
#endif
P
Peter Zijlstra 已提交
7376

7377
DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
P
Peter Zijlstra 已提交
7378

L
Linus Torvalds 已提交
7379 7380
void __init sched_init(void)
{
I
Ingo Molnar 已提交
7381
	int i, j;
7382 7383 7384 7385 7386 7387 7388 7389 7390
	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) {
7391
		ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
7392 7393

#ifdef CONFIG_FAIR_GROUP_SCHED
7394
		root_task_group.se = (struct sched_entity **)ptr;
7395 7396
		ptr += nr_cpu_ids * sizeof(void **);

7397
		root_task_group.cfs_rq = (struct cfs_rq **)ptr;
7398
		ptr += nr_cpu_ids * sizeof(void **);
7399

7400
#endif /* CONFIG_FAIR_GROUP_SCHED */
7401
#ifdef CONFIG_RT_GROUP_SCHED
7402
		root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7403 7404
		ptr += nr_cpu_ids * sizeof(void **);

7405
		root_task_group.rt_rq = (struct rt_rq **)ptr;
7406 7407
		ptr += nr_cpu_ids * sizeof(void **);

7408
#endif /* CONFIG_RT_GROUP_SCHED */
7409
	}
7410
#ifdef CONFIG_CPUMASK_OFFSTACK
7411 7412 7413
	for_each_possible_cpu(i) {
		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
7414
	}
7415
#endif /* CONFIG_CPUMASK_OFFSTACK */
I
Ingo Molnar 已提交
7416

7417 7418 7419
	init_rt_bandwidth(&def_rt_bandwidth,
			global_rt_period(), global_rt_runtime());
	init_dl_bandwidth(&def_dl_bandwidth,
7420
			global_rt_period(), global_rt_runtime());
7421

G
Gregory Haskins 已提交
7422 7423 7424 7425
#ifdef CONFIG_SMP
	init_defrootdomain();
#endif

7426
#ifdef CONFIG_RT_GROUP_SCHED
7427
	init_rt_bandwidth(&root_task_group.rt_bandwidth,
7428
			global_rt_period(), global_rt_runtime());
7429
#endif /* CONFIG_RT_GROUP_SCHED */
7430

D
Dhaval Giani 已提交
7431
#ifdef CONFIG_CGROUP_SCHED
7432 7433
	task_group_cache = KMEM_CACHE(task_group, 0);

7434 7435
	list_add(&root_task_group.list, &task_groups);
	INIT_LIST_HEAD(&root_task_group.children);
7436
	INIT_LIST_HEAD(&root_task_group.siblings);
7437
	autogroup_init(&init_task);
D
Dhaval Giani 已提交
7438
#endif /* CONFIG_CGROUP_SCHED */
P
Peter Zijlstra 已提交
7439

7440
	for_each_possible_cpu(i) {
7441
		struct rq *rq;
L
Linus Torvalds 已提交
7442 7443

		rq = cpu_rq(i);
7444
		raw_spin_lock_init(&rq->lock);
N
Nick Piggin 已提交
7445
		rq->nr_running = 0;
7446 7447
		rq->calc_load_active = 0;
		rq->calc_load_update = jiffies + LOAD_FREQ;
7448
		init_cfs_rq(&rq->cfs);
7449 7450
		init_rt_rq(&rq->rt);
		init_dl_rq(&rq->dl);
I
Ingo Molnar 已提交
7451
#ifdef CONFIG_FAIR_GROUP_SCHED
7452
		root_task_group.shares = ROOT_TASK_GROUP_LOAD;
P
Peter Zijlstra 已提交
7453
		INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
D
Dhaval Giani 已提交
7454
		/*
7455
		 * How much cpu bandwidth does root_task_group get?
D
Dhaval Giani 已提交
7456 7457 7458 7459
		 *
		 * 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
7460
		 * root_task_group and its child task-groups in a fair manner,
D
Dhaval Giani 已提交
7461 7462 7463
		 * based on each entity's (task or task-group's) weight
		 * (se->load.weight).
		 *
7464
		 * In other words, if root_task_group has 10 tasks of weight
D
Dhaval Giani 已提交
7465 7466 7467
		 * 1024) and two child groups A0 and A1 (of weight 1024 each),
		 * then A0's share of the cpu resource is:
		 *
7468
		 *	A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
D
Dhaval Giani 已提交
7469
		 *
7470 7471
		 * 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
7472
		 */
7473
		init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7474
		init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
D
Dhaval Giani 已提交
7475 7476 7477
#endif /* CONFIG_FAIR_GROUP_SCHED */

		rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7478
#ifdef CONFIG_RT_GROUP_SCHED
7479
		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
I
Ingo Molnar 已提交
7480
#endif
L
Linus Torvalds 已提交
7481

I
Ingo Molnar 已提交
7482 7483
		for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
			rq->cpu_load[j] = 0;
7484

L
Linus Torvalds 已提交
7485
#ifdef CONFIG_SMP
N
Nick Piggin 已提交
7486
		rq->sd = NULL;
G
Gregory Haskins 已提交
7487
		rq->rd = NULL;
7488
		rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
7489
		rq->balance_callback = NULL;
L
Linus Torvalds 已提交
7490
		rq->active_balance = 0;
I
Ingo Molnar 已提交
7491
		rq->next_balance = jiffies;
L
Linus Torvalds 已提交
7492
		rq->push_cpu = 0;
7493
		rq->cpu = i;
7494
		rq->online = 0;
7495 7496
		rq->idle_stamp = 0;
		rq->avg_idle = 2*sysctl_sched_migration_cost;
7497
		rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7498 7499 7500

		INIT_LIST_HEAD(&rq->cfs_tasks);

7501
		rq_attach_root(rq, &def_root_domain);
7502
#ifdef CONFIG_NO_HZ_COMMON
7503
		rq->last_load_update_tick = jiffies;
7504
		rq->nohz_flags = 0;
7505
#endif
7506 7507 7508
#ifdef CONFIG_NO_HZ_FULL
		rq->last_sched_tick = 0;
#endif
7509
#endif /* CONFIG_SMP */
P
Peter Zijlstra 已提交
7510
		init_rq_hrtick(rq);
L
Linus Torvalds 已提交
7511 7512 7513
		atomic_set(&rq->nr_iowait, 0);
	}

7514
	set_load_weight(&init_task);
7515

7516 7517 7518 7519
#ifdef CONFIG_PREEMPT_NOTIFIERS
	INIT_HLIST_HEAD(&init_task.preempt_notifiers);
#endif

L
Linus Torvalds 已提交
7520 7521 7522 7523 7524 7525
	/*
	 * The boot idle thread does lazy MMU switching as well:
	 */
	atomic_inc(&init_mm.mm_count);
	enter_lazy_tlb(&init_mm, current);

7526 7527 7528 7529 7530
	/*
	 * During early bootup we pretend to be a normal task:
	 */
	current->sched_class = &fair_sched_class;

L
Linus Torvalds 已提交
7531 7532 7533 7534 7535 7536 7537
	/*
	 * 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());
7538 7539 7540

	calc_load_update = jiffies + LOAD_FREQ;

7541
#ifdef CONFIG_SMP
7542
	zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
R
Rusty Russell 已提交
7543 7544 7545
	/* May be allocated at isolcpus cmdline parse time */
	if (cpu_isolated_map == NULL)
		zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7546
	idle_thread_set_boot_cpu();
7547
	set_cpu_rq_start_time(smp_processor_id());
7548 7549
#endif
	init_sched_fair_class();
7550

7551 7552
	init_schedstats();

7553
	scheduler_running = 1;
L
Linus Torvalds 已提交
7554 7555
}

7556
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7557 7558
static inline int preempt_count_equals(int preempt_offset)
{
7559
	int nested = preempt_count() + rcu_preempt_depth();
7560

A
Arnd Bergmann 已提交
7561
	return (nested == preempt_offset);
7562 7563
}

7564
void __might_sleep(const char *file, int line, int preempt_offset)
L
Linus Torvalds 已提交
7565
{
P
Peter Zijlstra 已提交
7566 7567 7568 7569 7570
	/*
	 * 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.
	 */
7571
	WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
P
Peter Zijlstra 已提交
7572 7573 7574 7575
			"do not call blocking ops when !TASK_RUNNING; "
			"state=%lx set at [<%p>] %pS\n",
			current->state,
			(void *)current->task_state_change,
7576
			(void *)current->task_state_change);
P
Peter Zijlstra 已提交
7577

7578 7579 7580 7581 7582
	___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
7583 7584
{
	static unsigned long prev_jiffy;	/* ratelimiting */
7585
	unsigned long preempt_disable_ip;
L
Linus Torvalds 已提交
7586

7587
	rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7588 7589
	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
	     !is_idle_task(current)) ||
7590
	    system_state != SYSTEM_RUNNING || oops_in_progress)
I
Ingo Molnar 已提交
7591 7592 7593 7594 7595
		return;
	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
		return;
	prev_jiffy = jiffies;

7596 7597 7598
	/* Save this before calling printk(), since that will clobber it */
	preempt_disable_ip = get_preempt_disable_ip(current);

P
Peter Zijlstra 已提交
7599 7600 7601 7602 7603 7604 7605
	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
7606

7607 7608 7609
	if (task_stack_end_corrupted(current))
		printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");

I
Ingo Molnar 已提交
7610 7611 7612
	debug_show_held_locks(current);
	if (irqs_disabled())
		print_irqtrace_events(current);
7613 7614
	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
	    && !preempt_count_equals(preempt_offset)) {
7615
		pr_err("Preemption disabled at:");
7616
		print_ip_sym(preempt_disable_ip);
7617 7618
		pr_cont("\n");
	}
I
Ingo Molnar 已提交
7619
	dump_stack();
7620
	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
L
Linus Torvalds 已提交
7621
}
7622
EXPORT_SYMBOL(___might_sleep);
L
Linus Torvalds 已提交
7623 7624 7625
#endif

#ifdef CONFIG_MAGIC_SYSRQ
7626
void normalize_rt_tasks(void)
7627
{
7628
	struct task_struct *g, *p;
7629 7630 7631
	struct sched_attr attr = {
		.sched_policy = SCHED_NORMAL,
	};
L
Linus Torvalds 已提交
7632

7633
	read_lock(&tasklist_lock);
7634
	for_each_process_thread(g, p) {
7635 7636 7637
		/*
		 * Only normalize user tasks:
		 */
7638
		if (p->flags & PF_KTHREAD)
7639 7640
			continue;

I
Ingo Molnar 已提交
7641 7642
		p->se.exec_start		= 0;
#ifdef CONFIG_SCHEDSTATS
7643 7644 7645
		p->se.statistics.wait_start	= 0;
		p->se.statistics.sleep_start	= 0;
		p->se.statistics.block_start	= 0;
I
Ingo Molnar 已提交
7646
#endif
I
Ingo Molnar 已提交
7647

7648
		if (!dl_task(p) && !rt_task(p)) {
I
Ingo Molnar 已提交
7649 7650 7651 7652
			/*
			 * Renice negative nice level userspace
			 * tasks back to 0:
			 */
7653
			if (task_nice(p) < 0)
I
Ingo Molnar 已提交
7654
				set_user_nice(p, 0);
L
Linus Torvalds 已提交
7655
			continue;
I
Ingo Molnar 已提交
7656
		}
L
Linus Torvalds 已提交
7657

7658
		__sched_setscheduler(p, &attr, false, false);
7659
	}
7660
	read_unlock(&tasklist_lock);
L
Linus Torvalds 已提交
7661 7662 7663
}

#endif /* CONFIG_MAGIC_SYSRQ */
7664

7665
#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7666
/*
7667
 * These functions are only useful for the IA64 MCA handling, or kdb.
7668 7669 7670 7671 7672 7673 7674 7675 7676 7677 7678 7679 7680
 *
 * 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!
7681 7682
 *
 * Return: The current task for @cpu.
7683
 */
7684
struct task_struct *curr_task(int cpu)
7685 7686 7687 7688
{
	return cpu_curr(cpu);
}

7689 7690 7691
#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */

#ifdef CONFIG_IA64
7692 7693 7694 7695 7696 7697
/**
 * 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
7698 7699
 * 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
7700 7701 7702 7703 7704 7705 7706
 * 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!
 */
7707
void set_curr_task(int cpu, struct task_struct *p)
7708 7709 7710 7711 7712
{
	cpu_curr(cpu) = p;
}

#endif
S
Srivatsa Vaddagiri 已提交
7713

D
Dhaval Giani 已提交
7714
#ifdef CONFIG_CGROUP_SCHED
7715 7716 7717
/* task_group_lock serializes the addition/removal of task groups */
static DEFINE_SPINLOCK(task_group_lock);

7718
static void sched_free_group(struct task_group *tg)
7719 7720 7721
{
	free_fair_sched_group(tg);
	free_rt_sched_group(tg);
7722
	autogroup_free(tg);
7723
	kmem_cache_free(task_group_cache, tg);
7724 7725 7726
}

/* allocate runqueue etc for a new task group */
7727
struct task_group *sched_create_group(struct task_group *parent)
7728 7729 7730
{
	struct task_group *tg;

7731
	tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
7732 7733 7734
	if (!tg)
		return ERR_PTR(-ENOMEM);

7735
	if (!alloc_fair_sched_group(tg, parent))
7736 7737
		goto err;

7738
	if (!alloc_rt_sched_group(tg, parent))
7739 7740
		goto err;

7741 7742 7743
	return tg;

err:
7744
	sched_free_group(tg);
7745 7746 7747 7748 7749 7750 7751
	return ERR_PTR(-ENOMEM);
}

void sched_online_group(struct task_group *tg, struct task_group *parent)
{
	unsigned long flags;

7752
	spin_lock_irqsave(&task_group_lock, flags);
P
Peter Zijlstra 已提交
7753
	list_add_rcu(&tg->list, &task_groups);
P
Peter Zijlstra 已提交
7754 7755 7756 7757 7758

	WARN_ON(!parent); /* root should already exist */

	tg->parent = parent;
	INIT_LIST_HEAD(&tg->children);
7759
	list_add_rcu(&tg->siblings, &parent->children);
7760
	spin_unlock_irqrestore(&task_group_lock, flags);
7761 7762

	online_fair_sched_group(tg);
S
Srivatsa Vaddagiri 已提交
7763 7764
}

7765
/* rcu callback to free various structures associated with a task group */
7766
static void sched_free_group_rcu(struct rcu_head *rhp)
S
Srivatsa Vaddagiri 已提交
7767 7768
{
	/* now it should be safe to free those cfs_rqs */
7769
	sched_free_group(container_of(rhp, struct task_group, rcu));
S
Srivatsa Vaddagiri 已提交
7770 7771
}

7772
void sched_destroy_group(struct task_group *tg)
7773 7774
{
	/* wait for possible concurrent references to cfs_rqs complete */
7775
	call_rcu(&tg->rcu, sched_free_group_rcu);
7776 7777 7778
}

void sched_offline_group(struct task_group *tg)
S
Srivatsa Vaddagiri 已提交
7779
{
7780
	unsigned long flags;
S
Srivatsa Vaddagiri 已提交
7781

7782
	/* end participation in shares distribution */
7783
	unregister_fair_sched_group(tg);
7784 7785

	spin_lock_irqsave(&task_group_lock, flags);
P
Peter Zijlstra 已提交
7786
	list_del_rcu(&tg->list);
P
Peter Zijlstra 已提交
7787
	list_del_rcu(&tg->siblings);
7788
	spin_unlock_irqrestore(&task_group_lock, flags);
S
Srivatsa Vaddagiri 已提交
7789 7790
}

7791
static void sched_change_group(struct task_struct *tsk, int type)
S
Srivatsa Vaddagiri 已提交
7792
{
P
Peter Zijlstra 已提交
7793
	struct task_group *tg;
S
Srivatsa Vaddagiri 已提交
7794

7795 7796 7797 7798 7799 7800
	/*
	 * 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
7801 7802 7803 7804
			  struct task_group, css);
	tg = autogroup_task_group(tsk, tg);
	tsk->sched_task_group = tg;

P
Peter Zijlstra 已提交
7805
#ifdef CONFIG_FAIR_GROUP_SCHED
7806 7807
	if (tsk->sched_class->task_change_group)
		tsk->sched_class->task_change_group(tsk, type);
7808
	else
P
Peter Zijlstra 已提交
7809
#endif
7810
		set_task_rq(tsk, task_cpu(tsk));
7811 7812 7813 7814 7815 7816 7817 7818 7819 7820 7821 7822 7823 7824 7825 7826 7827 7828 7829 7830 7831 7832 7833 7834 7835 7836
}

/*
 * 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
7837

7838 7839
	if (unlikely(running))
		tsk->sched_class->set_curr_task(rq);
7840
	if (queued)
7841
		enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
S
Srivatsa Vaddagiri 已提交
7842

7843
	task_rq_unlock(rq, tsk, &rf);
S
Srivatsa Vaddagiri 已提交
7844
}
D
Dhaval Giani 已提交
7845
#endif /* CONFIG_CGROUP_SCHED */
S
Srivatsa Vaddagiri 已提交
7846

7847 7848 7849 7850 7851
#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
7852

P
Peter Zijlstra 已提交
7853 7854
/* Must be called with tasklist_lock held */
static inline int tg_has_rt_tasks(struct task_group *tg)
7855
{
P
Peter Zijlstra 已提交
7856
	struct task_struct *g, *p;
7857

7858 7859 7860 7861 7862 7863
	/*
	 * Autogroups do not have RT tasks; see autogroup_create().
	 */
	if (task_group_is_autogroup(tg))
		return 0;

7864
	for_each_process_thread(g, p) {
7865
		if (rt_task(p) && task_group(p) == tg)
P
Peter Zijlstra 已提交
7866
			return 1;
7867
	}
7868

P
Peter Zijlstra 已提交
7869 7870
	return 0;
}
7871

P
Peter Zijlstra 已提交
7872 7873 7874 7875 7876
struct rt_schedulable_data {
	struct task_group *tg;
	u64 rt_period;
	u64 rt_runtime;
};
7877

7878
static int tg_rt_schedulable(struct task_group *tg, void *data)
P
Peter Zijlstra 已提交
7879 7880 7881 7882 7883
{
	struct rt_schedulable_data *d = data;
	struct task_group *child;
	unsigned long total, sum = 0;
	u64 period, runtime;
7884

P
Peter Zijlstra 已提交
7885 7886
	period = ktime_to_ns(tg->rt_bandwidth.rt_period);
	runtime = tg->rt_bandwidth.rt_runtime;
7887

P
Peter Zijlstra 已提交
7888 7889 7890
	if (tg == d->tg) {
		period = d->rt_period;
		runtime = d->rt_runtime;
7891 7892
	}

7893 7894 7895 7896 7897
	/*
	 * Cannot have more runtime than the period.
	 */
	if (runtime > period && runtime != RUNTIME_INF)
		return -EINVAL;
P
Peter Zijlstra 已提交
7898

7899 7900 7901
	/*
	 * Ensure we don't starve existing RT tasks.
	 */
P
Peter Zijlstra 已提交
7902 7903
	if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
		return -EBUSY;
P
Peter Zijlstra 已提交
7904

P
Peter Zijlstra 已提交
7905
	total = to_ratio(period, runtime);
P
Peter Zijlstra 已提交
7906

7907 7908 7909 7910 7911
	/*
	 * 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
7912

7913 7914 7915
	/*
	 * The sum of our children's runtime should not exceed our own.
	 */
P
Peter Zijlstra 已提交
7916 7917 7918
	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
7919

P
Peter Zijlstra 已提交
7920 7921 7922 7923
		if (child == d->tg) {
			period = d->rt_period;
			runtime = d->rt_runtime;
		}
P
Peter Zijlstra 已提交
7924

P
Peter Zijlstra 已提交
7925
		sum += to_ratio(period, runtime);
P
Peter Zijlstra 已提交
7926
	}
P
Peter Zijlstra 已提交
7927

P
Peter Zijlstra 已提交
7928 7929 7930 7931
	if (sum > total)
		return -EINVAL;

	return 0;
P
Peter Zijlstra 已提交
7932 7933
}

P
Peter Zijlstra 已提交
7934
static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7935
{
7936 7937
	int ret;

P
Peter Zijlstra 已提交
7938 7939 7940 7941 7942 7943
	struct rt_schedulable_data data = {
		.tg = tg,
		.rt_period = period,
		.rt_runtime = runtime,
	};

7944 7945 7946 7947 7948
	rcu_read_lock();
	ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
	rcu_read_unlock();

	return ret;
7949 7950
}

7951
static int tg_set_rt_bandwidth(struct task_group *tg,
7952
		u64 rt_period, u64 rt_runtime)
P
Peter Zijlstra 已提交
7953
{
P
Peter Zijlstra 已提交
7954
	int i, err = 0;
P
Peter Zijlstra 已提交
7955

7956 7957 7958 7959 7960 7961 7962 7963 7964 7965 7966
	/*
	 * 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
7967
	mutex_lock(&rt_constraints_mutex);
7968
	read_lock(&tasklist_lock);
P
Peter Zijlstra 已提交
7969 7970
	err = __rt_schedulable(tg, rt_period, rt_runtime);
	if (err)
P
Peter Zijlstra 已提交
7971
		goto unlock;
P
Peter Zijlstra 已提交
7972

7973
	raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7974 7975
	tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
	tg->rt_bandwidth.rt_runtime = rt_runtime;
P
Peter Zijlstra 已提交
7976 7977 7978 7979

	for_each_possible_cpu(i) {
		struct rt_rq *rt_rq = tg->rt_rq[i];

7980
		raw_spin_lock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
7981
		rt_rq->rt_runtime = rt_runtime;
7982
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
7983
	}
7984
	raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
P
Peter Zijlstra 已提交
7985
unlock:
7986
	read_unlock(&tasklist_lock);
P
Peter Zijlstra 已提交
7987 7988 7989
	mutex_unlock(&rt_constraints_mutex);

	return err;
P
Peter Zijlstra 已提交
7990 7991
}

7992
static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7993 7994 7995 7996 7997 7998 7999 8000
{
	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;

8001
	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
8002 8003
}

8004
static long sched_group_rt_runtime(struct task_group *tg)
P
Peter Zijlstra 已提交
8005 8006 8007
{
	u64 rt_runtime_us;

8008
	if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
P
Peter Zijlstra 已提交
8009 8010
		return -1;

8011
	rt_runtime_us = tg->rt_bandwidth.rt_runtime;
P
Peter Zijlstra 已提交
8012 8013 8014
	do_div(rt_runtime_us, NSEC_PER_USEC);
	return rt_runtime_us;
}
8015

8016
static int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
8017 8018 8019
{
	u64 rt_runtime, rt_period;

8020
	rt_period = rt_period_us * NSEC_PER_USEC;
8021 8022
	rt_runtime = tg->rt_bandwidth.rt_runtime;

8023
	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
8024 8025
}

8026
static long sched_group_rt_period(struct task_group *tg)
8027 8028 8029 8030 8031 8032 8033
{
	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;
}
8034
#endif /* CONFIG_RT_GROUP_SCHED */
8035

8036
#ifdef CONFIG_RT_GROUP_SCHED
8037 8038 8039 8040 8041
static int sched_rt_global_constraints(void)
{
	int ret = 0;

	mutex_lock(&rt_constraints_mutex);
P
Peter Zijlstra 已提交
8042
	read_lock(&tasklist_lock);
8043
	ret = __rt_schedulable(NULL, 0, 0);
P
Peter Zijlstra 已提交
8044
	read_unlock(&tasklist_lock);
8045 8046 8047 8048
	mutex_unlock(&rt_constraints_mutex);

	return ret;
}
8049

8050
static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
8051 8052 8053 8054 8055 8056 8057 8058
{
	/* 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;
}

8059
#else /* !CONFIG_RT_GROUP_SCHED */
8060 8061
static int sched_rt_global_constraints(void)
{
P
Peter Zijlstra 已提交
8062
	unsigned long flags;
8063
	int i;
8064

8065
	raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
P
Peter Zijlstra 已提交
8066 8067 8068
	for_each_possible_cpu(i) {
		struct rt_rq *rt_rq = &cpu_rq(i)->rt;

8069
		raw_spin_lock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
8070
		rt_rq->rt_runtime = global_rt_runtime();
8071
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
8072
	}
8073
	raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
P
Peter Zijlstra 已提交
8074

8075
	return 0;
8076
}
8077
#endif /* CONFIG_RT_GROUP_SCHED */
8078

8079
static int sched_dl_global_validate(void)
8080
{
8081 8082
	u64 runtime = global_rt_runtime();
	u64 period = global_rt_period();
8083
	u64 new_bw = to_ratio(period, runtime);
8084
	struct dl_bw *dl_b;
8085
	int cpu, ret = 0;
8086
	unsigned long flags;
8087 8088 8089 8090 8091 8092 8093 8094 8095 8096

	/*
	 * 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!
	 */
8097
	for_each_possible_cpu(cpu) {
8098 8099
		rcu_read_lock_sched();
		dl_b = dl_bw_of(cpu);
8100

8101
		raw_spin_lock_irqsave(&dl_b->lock, flags);
8102 8103
		if (new_bw < dl_b->total_bw)
			ret = -EBUSY;
8104
		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
8105

8106 8107
		rcu_read_unlock_sched();

8108 8109
		if (ret)
			break;
8110 8111
	}

8112
	return ret;
8113 8114
}

8115
static void sched_dl_do_global(void)
8116
{
8117
	u64 new_bw = -1;
8118
	struct dl_bw *dl_b;
8119
	int cpu;
8120
	unsigned long flags;
8121

8122 8123 8124 8125 8126 8127 8128 8129 8130 8131
	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) {
8132 8133
		rcu_read_lock_sched();
		dl_b = dl_bw_of(cpu);
8134

8135
		raw_spin_lock_irqsave(&dl_b->lock, flags);
8136
		dl_b->bw = new_bw;
8137
		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
8138 8139

		rcu_read_unlock_sched();
8140
	}
8141 8142 8143 8144 8145 8146 8147
}

static int sched_rt_global_validate(void)
{
	if (sysctl_sched_rt_period <= 0)
		return -EINVAL;

8148 8149
	if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
		(sysctl_sched_rt_runtime > sysctl_sched_rt_period))
8150 8151 8152 8153 8154 8155 8156 8157 8158
		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());
8159 8160
}

8161
int sched_rt_handler(struct ctl_table *table, int write,
8162
		void __user *buffer, size_t *lenp,
8163 8164 8165 8166
		loff_t *ppos)
{
	int old_period, old_runtime;
	static DEFINE_MUTEX(mutex);
8167
	int ret;
8168 8169 8170 8171 8172

	mutex_lock(&mutex);
	old_period = sysctl_sched_rt_period;
	old_runtime = sysctl_sched_rt_runtime;

8173
	ret = proc_dointvec(table, write, buffer, lenp, ppos);
8174 8175

	if (!ret && write) {
8176 8177 8178 8179
		ret = sched_rt_global_validate();
		if (ret)
			goto undo;

8180
		ret = sched_dl_global_validate();
8181 8182 8183
		if (ret)
			goto undo;

8184
		ret = sched_rt_global_constraints();
8185 8186 8187 8188 8189 8190 8191 8192 8193 8194
		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;
8195 8196 8197 8198 8199
	}
	mutex_unlock(&mutex);

	return ret;
}
8200

8201
int sched_rr_handler(struct ctl_table *table, int write,
8202 8203 8204 8205 8206 8207 8208 8209
		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);
8210 8211
	/* make sure that internally we keep jiffies */
	/* also, writing zero resets timeslice to default */
8212
	if (!ret && write) {
8213 8214
		sched_rr_timeslice = sched_rr_timeslice <= 0 ?
			RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
8215 8216 8217 8218 8219
	}
	mutex_unlock(&mutex);
	return ret;
}

8220
#ifdef CONFIG_CGROUP_SCHED
8221

8222
static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
8223
{
8224
	return css ? container_of(css, struct task_group, css) : NULL;
8225 8226
}

8227 8228
static struct cgroup_subsys_state *
cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
8229
{
8230 8231
	struct task_group *parent = css_tg(parent_css);
	struct task_group *tg;
8232

8233
	if (!parent) {
8234
		/* This is early initialization for the top cgroup */
8235
		return &root_task_group.css;
8236 8237
	}

8238
	tg = sched_create_group(parent);
8239 8240 8241
	if (IS_ERR(tg))
		return ERR_PTR(-ENOMEM);

8242 8243
	sched_online_group(tg, parent);

8244 8245 8246
	return &tg->css;
}

8247
static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
8248
{
8249
	struct task_group *tg = css_tg(css);
8250

8251
	sched_offline_group(tg);
8252 8253
}

8254
static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
8255
{
8256
	struct task_group *tg = css_tg(css);
8257

8258 8259 8260 8261
	/*
	 * Relies on the RCU grace period between css_released() and this.
	 */
	sched_free_group(tg);
8262 8263
}

8264 8265 8266 8267
/*
 * 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.
 */
8268
static void cpu_cgroup_fork(struct task_struct *task)
8269
{
8270 8271 8272 8273 8274 8275 8276 8277
	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);
8278 8279
}

8280
static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
8281
{
8282
	struct task_struct *task;
8283
	struct cgroup_subsys_state *css;
8284
	int ret = 0;
8285

8286
	cgroup_taskset_for_each(task, css, tset) {
8287
#ifdef CONFIG_RT_GROUP_SCHED
8288
		if (!sched_rt_can_attach(css_tg(css), task))
8289
			return -EINVAL;
8290
#else
8291 8292 8293
		/* We don't support RT-tasks being in separate groups */
		if (task->sched_class != &fair_sched_class)
			return -EINVAL;
8294
#endif
8295 8296 8297 8298 8299 8300 8301 8302 8303 8304 8305 8306 8307 8308 8309 8310
		/*
		 * 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;
8311
	}
8312
	return ret;
8313
}
8314

8315
static void cpu_cgroup_attach(struct cgroup_taskset *tset)
8316
{
8317
	struct task_struct *task;
8318
	struct cgroup_subsys_state *css;
8319

8320
	cgroup_taskset_for_each(task, css, tset)
8321
		sched_move_task(task);
8322 8323
}

8324
#ifdef CONFIG_FAIR_GROUP_SCHED
8325 8326
static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
				struct cftype *cftype, u64 shareval)
8327
{
8328
	return sched_group_set_shares(css_tg(css), scale_load(shareval));
8329 8330
}

8331 8332
static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
			       struct cftype *cft)
8333
{
8334
	struct task_group *tg = css_tg(css);
8335

8336
	return (u64) scale_load_down(tg->shares);
8337
}
8338 8339

#ifdef CONFIG_CFS_BANDWIDTH
8340 8341
static DEFINE_MUTEX(cfs_constraints_mutex);

8342 8343 8344
const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */

8345 8346
static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);

8347 8348
static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
{
8349
	int i, ret = 0, runtime_enabled, runtime_was_enabled;
8350
	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8351 8352 8353 8354 8355 8356 8357 8358 8359 8360 8361 8362 8363 8364 8365 8366 8367 8368 8369 8370

	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;

8371 8372 8373 8374 8375
	/*
	 * Prevent race between setting of cfs_rq->runtime_enabled and
	 * unthrottle_offline_cfs_rqs().
	 */
	get_online_cpus();
8376 8377 8378 8379 8380
	mutex_lock(&cfs_constraints_mutex);
	ret = __cfs_schedulable(tg, period, quota);
	if (ret)
		goto out_unlock;

8381
	runtime_enabled = quota != RUNTIME_INF;
8382
	runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
8383 8384 8385 8386 8387 8388
	/*
	 * 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();
8389 8390 8391
	raw_spin_lock_irq(&cfs_b->lock);
	cfs_b->period = ns_to_ktime(period);
	cfs_b->quota = quota;
8392

P
Paul Turner 已提交
8393
	__refill_cfs_bandwidth_runtime(cfs_b);
8394
	/* restart the period timer (if active) to handle new period expiry */
P
Peter Zijlstra 已提交
8395 8396
	if (runtime_enabled)
		start_cfs_bandwidth(cfs_b);
8397 8398
	raw_spin_unlock_irq(&cfs_b->lock);

8399
	for_each_online_cpu(i) {
8400
		struct cfs_rq *cfs_rq = tg->cfs_rq[i];
8401
		struct rq *rq = cfs_rq->rq;
8402 8403

		raw_spin_lock_irq(&rq->lock);
8404
		cfs_rq->runtime_enabled = runtime_enabled;
8405
		cfs_rq->runtime_remaining = 0;
8406

8407
		if (cfs_rq->throttled)
8408
			unthrottle_cfs_rq(cfs_rq);
8409 8410
		raw_spin_unlock_irq(&rq->lock);
	}
8411 8412
	if (runtime_was_enabled && !runtime_enabled)
		cfs_bandwidth_usage_dec();
8413 8414
out_unlock:
	mutex_unlock(&cfs_constraints_mutex);
8415
	put_online_cpus();
8416

8417
	return ret;
8418 8419 8420 8421 8422 8423
}

int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
{
	u64 quota, period;

8424
	period = ktime_to_ns(tg->cfs_bandwidth.period);
8425 8426 8427 8428 8429 8430 8431 8432 8433 8434 8435 8436
	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;

8437
	if (tg->cfs_bandwidth.quota == RUNTIME_INF)
8438 8439
		return -1;

8440
	quota_us = tg->cfs_bandwidth.quota;
8441 8442 8443 8444 8445 8446 8447 8448 8449 8450
	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;
8451
	quota = tg->cfs_bandwidth.quota;
8452 8453 8454 8455 8456 8457 8458 8459

	return tg_set_cfs_bandwidth(tg, period, quota);
}

long tg_get_cfs_period(struct task_group *tg)
{
	u64 cfs_period_us;

8460
	cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
8461 8462 8463 8464 8465
	do_div(cfs_period_us, NSEC_PER_USEC);

	return cfs_period_us;
}

8466 8467
static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
				  struct cftype *cft)
8468
{
8469
	return tg_get_cfs_quota(css_tg(css));
8470 8471
}

8472 8473
static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
				   struct cftype *cftype, s64 cfs_quota_us)
8474
{
8475
	return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
8476 8477
}

8478 8479
static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
				   struct cftype *cft)
8480
{
8481
	return tg_get_cfs_period(css_tg(css));
8482 8483
}

8484 8485
static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
				    struct cftype *cftype, u64 cfs_period_us)
8486
{
8487
	return tg_set_cfs_period(css_tg(css), cfs_period_us);
8488 8489
}

8490 8491 8492 8493 8494 8495 8496 8497 8498 8499 8500 8501 8502 8503 8504 8505 8506 8507 8508 8509 8510 8511 8512 8513 8514 8515 8516 8517 8518 8519 8520 8521
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;
8522
	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8523 8524 8525 8526 8527
	s64 quota = 0, parent_quota = -1;

	if (!tg->parent) {
		quota = RUNTIME_INF;
	} else {
8528
		struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
8529 8530

		quota = normalize_cfs_quota(tg, d);
8531
		parent_quota = parent_b->hierarchical_quota;
8532 8533 8534 8535 8536 8537 8538 8539 8540 8541

		/*
		 * 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;
	}
8542
	cfs_b->hierarchical_quota = quota;
8543 8544 8545 8546 8547 8548

	return 0;
}

static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
{
8549
	int ret;
8550 8551 8552 8553 8554 8555 8556 8557 8558 8559 8560
	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);
	}

8561 8562 8563 8564 8565
	rcu_read_lock();
	ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
	rcu_read_unlock();

	return ret;
8566
}
8567

8568
static int cpu_stats_show(struct seq_file *sf, void *v)
8569
{
8570
	struct task_group *tg = css_tg(seq_css(sf));
8571
	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8572

8573 8574 8575
	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);
8576 8577 8578

	return 0;
}
8579
#endif /* CONFIG_CFS_BANDWIDTH */
8580
#endif /* CONFIG_FAIR_GROUP_SCHED */
8581

8582
#ifdef CONFIG_RT_GROUP_SCHED
8583 8584
static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
				struct cftype *cft, s64 val)
P
Peter Zijlstra 已提交
8585
{
8586
	return sched_group_set_rt_runtime(css_tg(css), val);
P
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8587 8588
}

8589 8590
static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
			       struct cftype *cft)
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Peter Zijlstra 已提交
8591
{
8592
	return sched_group_rt_runtime(css_tg(css));
P
Peter Zijlstra 已提交
8593
}
8594

8595 8596
static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
				    struct cftype *cftype, u64 rt_period_us)
8597
{
8598
	return sched_group_set_rt_period(css_tg(css), rt_period_us);
8599 8600
}

8601 8602
static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
				   struct cftype *cft)
8603
{
8604
	return sched_group_rt_period(css_tg(css));
8605
}
8606
#endif /* CONFIG_RT_GROUP_SCHED */
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8607

8608
static struct cftype cpu_files[] = {
8609
#ifdef CONFIG_FAIR_GROUP_SCHED
8610 8611
	{
		.name = "shares",
8612 8613
		.read_u64 = cpu_shares_read_u64,
		.write_u64 = cpu_shares_write_u64,
8614
	},
8615
#endif
8616 8617 8618 8619 8620 8621 8622 8623 8624 8625 8626
#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,
	},
8627 8628
	{
		.name = "stat",
8629
		.seq_show = cpu_stats_show,
8630
	},
8631
#endif
8632
#ifdef CONFIG_RT_GROUP_SCHED
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8633
	{
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8634
		.name = "rt_runtime_us",
8635 8636
		.read_s64 = cpu_rt_runtime_read,
		.write_s64 = cpu_rt_runtime_write,
P
Peter Zijlstra 已提交
8637
	},
8638 8639
	{
		.name = "rt_period_us",
8640 8641
		.read_u64 = cpu_rt_period_read_uint,
		.write_u64 = cpu_rt_period_write_uint,
8642
	},
8643
#endif
8644
	{ }	/* terminate */
8645 8646
};

8647
struct cgroup_subsys cpu_cgrp_subsys = {
8648
	.css_alloc	= cpu_cgroup_css_alloc,
8649
	.css_released	= cpu_cgroup_css_released,
8650
	.css_free	= cpu_cgroup_css_free,
8651
	.fork		= cpu_cgroup_fork,
8652 8653
	.can_attach	= cpu_cgroup_can_attach,
	.attach		= cpu_cgroup_attach,
8654
	.legacy_cftypes	= cpu_files,
8655
	.early_init	= true,
8656 8657
};

8658
#endif	/* CONFIG_CGROUP_SCHED */
8659

8660 8661 8662 8663 8664
void dump_cpu_task(int cpu)
{
	pr_info("Task dump for CPU %d:\n", cpu);
	sched_show_task(cpu_curr(cpu));
}
8665 8666 8667 8668 8669 8670 8671 8672 8673 8674 8675 8676 8677 8678 8679 8680 8681 8682 8683 8684 8685 8686 8687 8688 8689 8690 8691 8692 8693 8694 8695 8696 8697 8698 8699 8700 8701 8702 8703 8704 8705

/*
 * 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,
};