timer.c 43.0 KB
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/*
 *  linux/kernel/timer.c
 *
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 *  Kernel internal timers, basic process system calls
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 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-01-28  Modified by Finn Arne Gangstad to make timers scale better.
 *
 *  1997-09-10  Updated NTP code according to technical memorandum Jan '96
 *              "A Kernel Model for Precision Timekeeping" by Dave Mills
 *  1998-12-24  Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
 *              serialize accesses to xtime/lost_ticks).
 *                              Copyright (C) 1998  Andrea Arcangeli
 *  1999-03-10  Improved NTP compatibility by Ulrich Windl
 *  2002-05-31	Move sys_sysinfo here and make its locking sane, Robert Love
 *  2000-10-05  Implemented scalable SMP per-CPU timer handling.
 *                              Copyright (C) 2000, 2001, 2002  Ingo Molnar
 *              Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
 */

#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/swap.h>
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#include <linux/pid_namespace.h>
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#include <linux/notifier.h>
#include <linux/thread_info.h>
#include <linux/time.h>
#include <linux/jiffies.h>
#include <linux/posix-timers.h>
#include <linux/cpu.h>
#include <linux/syscalls.h>
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#include <linux/delay.h>
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#include <linux/tick.h>
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#include <linux/kallsyms.h>
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#include <linux/perf_counter.h>
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#include <linux/sched.h>
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#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/div64.h>
#include <asm/timex.h>
#include <asm/io.h>

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u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;

EXPORT_SYMBOL(jiffies_64);

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/*
 * per-CPU timer vector definitions:
 */
#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
#define TVN_SIZE (1 << TVN_BITS)
#define TVR_SIZE (1 << TVR_BITS)
#define TVN_MASK (TVN_SIZE - 1)
#define TVR_MASK (TVR_SIZE - 1)

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struct tvec {
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	struct list_head vec[TVN_SIZE];
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};
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struct tvec_root {
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	struct list_head vec[TVR_SIZE];
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};
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struct tvec_base {
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	spinlock_t lock;
	struct timer_list *running_timer;
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	unsigned long timer_jiffies;
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	struct tvec_root tv1;
	struct tvec tv2;
	struct tvec tv3;
	struct tvec tv4;
	struct tvec tv5;
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} ____cacheline_aligned;
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struct tvec_base boot_tvec_bases;
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EXPORT_SYMBOL(boot_tvec_bases);
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static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
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/*
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 * Note that all tvec_bases are 2 byte aligned and lower bit of
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 * base in timer_list is guaranteed to be zero. Use the LSB for
 * the new flag to indicate whether the timer is deferrable
 */
#define TBASE_DEFERRABLE_FLAG		(0x1)

/* Functions below help us manage 'deferrable' flag */
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static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
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{
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	return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG);
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}

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static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
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{
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	return ((struct tvec_base *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG));
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}

static inline void timer_set_deferrable(struct timer_list *timer)
{
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	timer->base = ((struct tvec_base *)((unsigned long)(timer->base) |
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				       TBASE_DEFERRABLE_FLAG));
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}

static inline void
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timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
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{
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	timer->base = (struct tvec_base *)((unsigned long)(new_base) |
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				      tbase_get_deferrable(timer->base));
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}

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static unsigned long round_jiffies_common(unsigned long j, int cpu,
		bool force_up)
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{
	int rem;
	unsigned long original = j;

	/*
	 * We don't want all cpus firing their timers at once hitting the
	 * same lock or cachelines, so we skew each extra cpu with an extra
	 * 3 jiffies. This 3 jiffies came originally from the mm/ code which
	 * already did this.
	 * The skew is done by adding 3*cpunr, then round, then subtract this
	 * extra offset again.
	 */
	j += cpu * 3;

	rem = j % HZ;

	/*
	 * If the target jiffie is just after a whole second (which can happen
	 * due to delays of the timer irq, long irq off times etc etc) then
	 * we should round down to the whole second, not up. Use 1/4th second
	 * as cutoff for this rounding as an extreme upper bound for this.
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	 * But never round down if @force_up is set.
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	 */
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	if (rem < HZ/4 && !force_up) /* round down */
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		j = j - rem;
	else /* round up */
		j = j - rem + HZ;

	/* now that we have rounded, subtract the extra skew again */
	j -= cpu * 3;

	if (j <= jiffies) /* rounding ate our timeout entirely; */
		return original;
	return j;
}
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/**
 * __round_jiffies - function to round jiffies to a full second
 * @j: the time in (absolute) jiffies that should be rounded
 * @cpu: the processor number on which the timeout will happen
 *
 * __round_jiffies() rounds an absolute time in the future (in jiffies)
 * up or down to (approximately) full seconds. This is useful for timers
 * for which the exact time they fire does not matter too much, as long as
 * they fire approximately every X seconds.
 *
 * By rounding these timers to whole seconds, all such timers will fire
 * at the same time, rather than at various times spread out. The goal
 * of this is to have the CPU wake up less, which saves power.
 *
 * The exact rounding is skewed for each processor to avoid all
 * processors firing at the exact same time, which could lead
 * to lock contention or spurious cache line bouncing.
 *
 * The return value is the rounded version of the @j parameter.
 */
unsigned long __round_jiffies(unsigned long j, int cpu)
{
	return round_jiffies_common(j, cpu, false);
}
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EXPORT_SYMBOL_GPL(__round_jiffies);

/**
 * __round_jiffies_relative - function to round jiffies to a full second
 * @j: the time in (relative) jiffies that should be rounded
 * @cpu: the processor number on which the timeout will happen
 *
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 * __round_jiffies_relative() rounds a time delta  in the future (in jiffies)
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 * up or down to (approximately) full seconds. This is useful for timers
 * for which the exact time they fire does not matter too much, as long as
 * they fire approximately every X seconds.
 *
 * By rounding these timers to whole seconds, all such timers will fire
 * at the same time, rather than at various times spread out. The goal
 * of this is to have the CPU wake up less, which saves power.
 *
 * The exact rounding is skewed for each processor to avoid all
 * processors firing at the exact same time, which could lead
 * to lock contention or spurious cache line bouncing.
 *
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 * The return value is the rounded version of the @j parameter.
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 */
unsigned long __round_jiffies_relative(unsigned long j, int cpu)
{
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	unsigned long j0 = jiffies;

	/* Use j0 because jiffies might change while we run */
	return round_jiffies_common(j + j0, cpu, false) - j0;
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}
EXPORT_SYMBOL_GPL(__round_jiffies_relative);

/**
 * round_jiffies - function to round jiffies to a full second
 * @j: the time in (absolute) jiffies that should be rounded
 *
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 * round_jiffies() rounds an absolute time in the future (in jiffies)
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 * up or down to (approximately) full seconds. This is useful for timers
 * for which the exact time they fire does not matter too much, as long as
 * they fire approximately every X seconds.
 *
 * By rounding these timers to whole seconds, all such timers will fire
 * at the same time, rather than at various times spread out. The goal
 * of this is to have the CPU wake up less, which saves power.
 *
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 * The return value is the rounded version of the @j parameter.
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 */
unsigned long round_jiffies(unsigned long j)
{
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	return round_jiffies_common(j, raw_smp_processor_id(), false);
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}
EXPORT_SYMBOL_GPL(round_jiffies);

/**
 * round_jiffies_relative - function to round jiffies to a full second
 * @j: the time in (relative) jiffies that should be rounded
 *
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 * round_jiffies_relative() rounds a time delta  in the future (in jiffies)
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 * up or down to (approximately) full seconds. This is useful for timers
 * for which the exact time they fire does not matter too much, as long as
 * they fire approximately every X seconds.
 *
 * By rounding these timers to whole seconds, all such timers will fire
 * at the same time, rather than at various times spread out. The goal
 * of this is to have the CPU wake up less, which saves power.
 *
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 * The return value is the rounded version of the @j parameter.
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 */
unsigned long round_jiffies_relative(unsigned long j)
{
	return __round_jiffies_relative(j, raw_smp_processor_id());
}
EXPORT_SYMBOL_GPL(round_jiffies_relative);

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/**
 * __round_jiffies_up - function to round jiffies up to a full second
 * @j: the time in (absolute) jiffies that should be rounded
 * @cpu: the processor number on which the timeout will happen
 *
 * This is the same as __round_jiffies() except that it will never
 * round down.  This is useful for timeouts for which the exact time
 * of firing does not matter too much, as long as they don't fire too
 * early.
 */
unsigned long __round_jiffies_up(unsigned long j, int cpu)
{
	return round_jiffies_common(j, cpu, true);
}
EXPORT_SYMBOL_GPL(__round_jiffies_up);

/**
 * __round_jiffies_up_relative - function to round jiffies up to a full second
 * @j: the time in (relative) jiffies that should be rounded
 * @cpu: the processor number on which the timeout will happen
 *
 * This is the same as __round_jiffies_relative() except that it will never
 * round down.  This is useful for timeouts for which the exact time
 * of firing does not matter too much, as long as they don't fire too
 * early.
 */
unsigned long __round_jiffies_up_relative(unsigned long j, int cpu)
{
	unsigned long j0 = jiffies;

	/* Use j0 because jiffies might change while we run */
	return round_jiffies_common(j + j0, cpu, true) - j0;
}
EXPORT_SYMBOL_GPL(__round_jiffies_up_relative);

/**
 * round_jiffies_up - function to round jiffies up to a full second
 * @j: the time in (absolute) jiffies that should be rounded
 *
 * This is the same as round_jiffies() except that it will never
 * round down.  This is useful for timeouts for which the exact time
 * of firing does not matter too much, as long as they don't fire too
 * early.
 */
unsigned long round_jiffies_up(unsigned long j)
{
	return round_jiffies_common(j, raw_smp_processor_id(), true);
}
EXPORT_SYMBOL_GPL(round_jiffies_up);

/**
 * round_jiffies_up_relative - function to round jiffies up to a full second
 * @j: the time in (relative) jiffies that should be rounded
 *
 * This is the same as round_jiffies_relative() except that it will never
 * round down.  This is useful for timeouts for which the exact time
 * of firing does not matter too much, as long as they don't fire too
 * early.
 */
unsigned long round_jiffies_up_relative(unsigned long j)
{
	return __round_jiffies_up_relative(j, raw_smp_processor_id());
}
EXPORT_SYMBOL_GPL(round_jiffies_up_relative);

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static inline void set_running_timer(struct tvec_base *base,
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					struct timer_list *timer)
{
#ifdef CONFIG_SMP
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	base->running_timer = timer;
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#endif
}

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static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
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{
	unsigned long expires = timer->expires;
	unsigned long idx = expires - base->timer_jiffies;
	struct list_head *vec;

	if (idx < TVR_SIZE) {
		int i = expires & TVR_MASK;
		vec = base->tv1.vec + i;
	} else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
		int i = (expires >> TVR_BITS) & TVN_MASK;
		vec = base->tv2.vec + i;
	} else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
		int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
		vec = base->tv3.vec + i;
	} else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
		int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
		vec = base->tv4.vec + i;
	} else if ((signed long) idx < 0) {
		/*
		 * Can happen if you add a timer with expires == jiffies,
		 * or you set a timer to go off in the past
		 */
		vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
	} else {
		int i;
		/* If the timeout is larger than 0xffffffff on 64-bit
		 * architectures then we use the maximum timeout:
		 */
		if (idx > 0xffffffffUL) {
			idx = 0xffffffffUL;
			expires = idx + base->timer_jiffies;
		}
		i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
		vec = base->tv5.vec + i;
	}
	/*
	 * Timers are FIFO:
	 */
	list_add_tail(&timer->entry, vec);
}

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#ifdef CONFIG_TIMER_STATS
void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
{
	if (timer->start_site)
		return;

	timer->start_site = addr;
	memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
	timer->start_pid = current->pid;
}
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static void timer_stats_account_timer(struct timer_list *timer)
{
	unsigned int flag = 0;

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	if (likely(!timer->start_site))
		return;
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	if (unlikely(tbase_get_deferrable(timer->base)))
		flag |= TIMER_STATS_FLAG_DEFERRABLE;

	timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
				 timer->function, timer->start_comm, flag);
}

#else
static void timer_stats_account_timer(struct timer_list *timer) {}
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#endif

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#ifdef CONFIG_DEBUG_OBJECTS_TIMERS

static struct debug_obj_descr timer_debug_descr;

/*
 * fixup_init is called when:
 * - an active object is initialized
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 */
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static int timer_fixup_init(void *addr, enum debug_obj_state state)
{
	struct timer_list *timer = addr;

	switch (state) {
	case ODEBUG_STATE_ACTIVE:
		del_timer_sync(timer);
		debug_object_init(timer, &timer_debug_descr);
		return 1;
	default:
		return 0;
	}
}

/*
 * fixup_activate is called when:
 * - an active object is activated
 * - an unknown object is activated (might be a statically initialized object)
 */
static int timer_fixup_activate(void *addr, enum debug_obj_state state)
{
	struct timer_list *timer = addr;

	switch (state) {

	case ODEBUG_STATE_NOTAVAILABLE:
		/*
		 * This is not really a fixup. The timer was
		 * statically initialized. We just make sure that it
		 * is tracked in the object tracker.
		 */
		if (timer->entry.next == NULL &&
		    timer->entry.prev == TIMER_ENTRY_STATIC) {
			debug_object_init(timer, &timer_debug_descr);
			debug_object_activate(timer, &timer_debug_descr);
			return 0;
		} else {
			WARN_ON_ONCE(1);
		}
		return 0;

	case ODEBUG_STATE_ACTIVE:
		WARN_ON(1);

	default:
		return 0;
	}
}

/*
 * fixup_free is called when:
 * - an active object is freed
 */
static int timer_fixup_free(void *addr, enum debug_obj_state state)
{
	struct timer_list *timer = addr;

	switch (state) {
	case ODEBUG_STATE_ACTIVE:
		del_timer_sync(timer);
		debug_object_free(timer, &timer_debug_descr);
		return 1;
	default:
		return 0;
	}
}

static struct debug_obj_descr timer_debug_descr = {
	.name		= "timer_list",
	.fixup_init	= timer_fixup_init,
	.fixup_activate	= timer_fixup_activate,
	.fixup_free	= timer_fixup_free,
};

static inline void debug_timer_init(struct timer_list *timer)
{
	debug_object_init(timer, &timer_debug_descr);
}

static inline void debug_timer_activate(struct timer_list *timer)
{
	debug_object_activate(timer, &timer_debug_descr);
}

static inline void debug_timer_deactivate(struct timer_list *timer)
{
	debug_object_deactivate(timer, &timer_debug_descr);
}

static inline void debug_timer_free(struct timer_list *timer)
{
	debug_object_free(timer, &timer_debug_descr);
}

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static void __init_timer(struct timer_list *timer,
			 const char *name,
			 struct lock_class_key *key);
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void init_timer_on_stack_key(struct timer_list *timer,
			     const char *name,
			     struct lock_class_key *key)
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{
	debug_object_init_on_stack(timer, &timer_debug_descr);
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	__init_timer(timer, name, key);
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}
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EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
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void destroy_timer_on_stack(struct timer_list *timer)
{
	debug_object_free(timer, &timer_debug_descr);
}
EXPORT_SYMBOL_GPL(destroy_timer_on_stack);

#else
static inline void debug_timer_init(struct timer_list *timer) { }
static inline void debug_timer_activate(struct timer_list *timer) { }
static inline void debug_timer_deactivate(struct timer_list *timer) { }
#endif

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static void __init_timer(struct timer_list *timer,
			 const char *name,
			 struct lock_class_key *key)
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{
	timer->entry.next = NULL;
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	timer->base = __raw_get_cpu_var(tvec_bases);
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#ifdef CONFIG_TIMER_STATS
	timer->start_site = NULL;
	timer->start_pid = -1;
	memset(timer->start_comm, 0, TASK_COMM_LEN);
#endif
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	lockdep_init_map(&timer->lockdep_map, name, key, 0);
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}
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/**
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 * init_timer_key - initialize a timer
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 * @timer: the timer to be initialized
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 * @name: name of the timer
 * @key: lockdep class key of the fake lock used for tracking timer
 *       sync lock dependencies
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 *
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 * init_timer_key() must be done to a timer prior calling *any* of the
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 * other timer functions.
 */
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void init_timer_key(struct timer_list *timer,
		    const char *name,
		    struct lock_class_key *key)
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{
	debug_timer_init(timer);
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	__init_timer(timer, name, key);
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}
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EXPORT_SYMBOL(init_timer_key);
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void init_timer_deferrable_key(struct timer_list *timer,
			       const char *name,
			       struct lock_class_key *key)
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{
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	init_timer_key(timer, name, key);
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	timer_set_deferrable(timer);
}
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EXPORT_SYMBOL(init_timer_deferrable_key);
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static inline void detach_timer(struct timer_list *timer,
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				int clear_pending)
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{
	struct list_head *entry = &timer->entry;

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	debug_timer_deactivate(timer);

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	__list_del(entry->prev, entry->next);
	if (clear_pending)
		entry->next = NULL;
	entry->prev = LIST_POISON2;
}

/*
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 * We are using hashed locking: holding per_cpu(tvec_bases).lock
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 * means that all timers which are tied to this base via timer->base are
 * locked, and the base itself is locked too.
 *
 * So __run_timers/migrate_timers can safely modify all timers which could
 * be found on ->tvX lists.
 *
 * When the timer's base is locked, and the timer removed from list, it is
 * possible to set timer->base = NULL and drop the lock: the timer remains
 * locked.
 */
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static struct tvec_base *lock_timer_base(struct timer_list *timer,
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					unsigned long *flags)
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	__acquires(timer->base->lock)
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{
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	struct tvec_base *base;
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	for (;;) {
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		struct tvec_base *prelock_base = timer->base;
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		base = tbase_get_base(prelock_base);
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		if (likely(base != NULL)) {
			spin_lock_irqsave(&base->lock, *flags);
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			if (likely(prelock_base == timer->base))
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				return base;
			/* The timer has migrated to another CPU */
			spin_unlock_irqrestore(&base->lock, *flags);
		}
		cpu_relax();
	}
}

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static inline int
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__mod_timer(struct timer_list *timer, unsigned long expires,
						bool pending_only, int pinned)
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{
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	struct tvec_base *base, *new_base;
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	unsigned long flags;
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	int ret = 0 , cpu;
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	timer_stats_timer_set_start_info(timer);
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	BUG_ON(!timer->function);

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	base = lock_timer_base(timer, &flags);

	if (timer_pending(timer)) {
		detach_timer(timer, 0);
		ret = 1;
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	} else {
		if (pending_only)
			goto out_unlock;
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	}

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	debug_timer_activate(timer);

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	new_base = __get_cpu_var(tvec_bases);
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	cpu = smp_processor_id();

#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
	if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) {
		int preferred_cpu = get_nohz_load_balancer();

		if (preferred_cpu >= 0)
			cpu = preferred_cpu;
	}
#endif
	new_base = per_cpu(tvec_bases, cpu);

647
	if (base != new_base) {
L
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648
		/*
649 650 651 652 653
		 * We are trying to schedule the timer on the local CPU.
		 * However we can't change timer's base while it is running,
		 * otherwise del_timer_sync() can't detect that the timer's
		 * handler yet has not finished. This also guarantees that
		 * the timer is serialized wrt itself.
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		 */
655
		if (likely(base->running_timer != timer)) {
656
			/* See the comment in lock_timer_base() */
657
			timer_set_base(timer, NULL);
658
			spin_unlock(&base->lock);
659 660
			base = new_base;
			spin_lock(&base->lock);
661
			timer_set_base(timer, base);
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662 663 664 665
		}
	}

	timer->expires = expires;
666
	internal_add_timer(base, timer);
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Ingo Molnar 已提交
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out_unlock:
669
	spin_unlock_irqrestore(&base->lock, flags);
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670 671 672 673

	return ret;
}

674
/**
I
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675 676 677
 * mod_timer_pending - modify a pending timer's timeout
 * @timer: the pending timer to be modified
 * @expires: new timeout in jiffies
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 *
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 * mod_timer_pending() is the same for pending timers as mod_timer(),
 * but will not re-activate and modify already deleted timers.
 *
 * It is useful for unserialized use of timers.
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 */
I
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int mod_timer_pending(struct timer_list *timer, unsigned long expires)
L
Linus Torvalds 已提交
685
{
686
	return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
L
Linus Torvalds 已提交
687
}
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688
EXPORT_SYMBOL(mod_timer_pending);
L
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689

690
/**
L
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691 692
 * mod_timer - modify a timer's timeout
 * @timer: the timer to be modified
693
 * @expires: new timeout in jiffies
L
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694
 *
695
 * mod_timer() is a more efficient way to update the expire field of an
L
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 * active timer (if the timer is inactive it will be activated)
 *
 * mod_timer(timer, expires) is equivalent to:
 *
 *     del_timer(timer); timer->expires = expires; add_timer(timer);
 *
 * Note that if there are multiple unserialized concurrent users of the
 * same timer, then mod_timer() is the only safe way to modify the timeout,
 * since add_timer() cannot modify an already running timer.
 *
 * The function returns whether it has modified a pending timer or not.
 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
 * active timer returns 1.)
 */
int mod_timer(struct timer_list *timer, unsigned long expires)
{
	/*
	 * This is a common optimization triggered by the
	 * networking code - if the timer is re-modified
	 * to be the same thing then just return:
	 */
	if (timer->expires == expires && timer_pending(timer))
		return 1;

720
	return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);
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}
EXPORT_SYMBOL(mod_timer);

724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745
/**
 * mod_timer_pinned - modify a timer's timeout
 * @timer: the timer to be modified
 * @expires: new timeout in jiffies
 *
 * mod_timer_pinned() is a way to update the expire field of an
 * active timer (if the timer is inactive it will be activated)
 * and not allow the timer to be migrated to a different CPU.
 *
 * mod_timer_pinned(timer, expires) is equivalent to:
 *
 *     del_timer(timer); timer->expires = expires; add_timer(timer);
 */
int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
{
	if (timer->expires == expires && timer_pending(timer))
		return 1;

	return __mod_timer(timer, expires, false, TIMER_PINNED);
}
EXPORT_SYMBOL(mod_timer_pinned);

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746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795
/**
 * add_timer - start a timer
 * @timer: the timer to be added
 *
 * The kernel will do a ->function(->data) callback from the
 * timer interrupt at the ->expires point in the future. The
 * current time is 'jiffies'.
 *
 * The timer's ->expires, ->function (and if the handler uses it, ->data)
 * fields must be set prior calling this function.
 *
 * Timers with an ->expires field in the past will be executed in the next
 * timer tick.
 */
void add_timer(struct timer_list *timer)
{
	BUG_ON(timer_pending(timer));
	mod_timer(timer, timer->expires);
}
EXPORT_SYMBOL(add_timer);

/**
 * add_timer_on - start a timer on a particular CPU
 * @timer: the timer to be added
 * @cpu: the CPU to start it on
 *
 * This is not very scalable on SMP. Double adds are not possible.
 */
void add_timer_on(struct timer_list *timer, int cpu)
{
	struct tvec_base *base = per_cpu(tvec_bases, cpu);
	unsigned long flags;

	timer_stats_timer_set_start_info(timer);
	BUG_ON(timer_pending(timer) || !timer->function);
	spin_lock_irqsave(&base->lock, flags);
	timer_set_base(timer, base);
	debug_timer_activate(timer);
	internal_add_timer(base, timer);
	/*
	 * Check whether the other CPU is idle and needs to be
	 * triggered to reevaluate the timer wheel when nohz is
	 * active. We are protected against the other CPU fiddling
	 * with the timer by holding the timer base lock. This also
	 * makes sure that a CPU on the way to idle can not evaluate
	 * the timer wheel.
	 */
	wake_up_idle_cpu(cpu);
	spin_unlock_irqrestore(&base->lock, flags);
}
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796
EXPORT_SYMBOL_GPL(add_timer_on);
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797

798
/**
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 * del_timer - deactive a timer.
 * @timer: the timer to be deactivated
 *
 * del_timer() deactivates a timer - this works on both active and inactive
 * timers.
 *
 * The function returns whether it has deactivated a pending timer or not.
 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
 * active timer returns 1.)
 */
int del_timer(struct timer_list *timer)
{
811
	struct tvec_base *base;
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812
	unsigned long flags;
813
	int ret = 0;
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814

815
	timer_stats_timer_clear_start_info(timer);
816 817 818 819 820 821
	if (timer_pending(timer)) {
		base = lock_timer_base(timer, &flags);
		if (timer_pending(timer)) {
			detach_timer(timer, 1);
			ret = 1;
		}
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822 823 824
		spin_unlock_irqrestore(&base->lock, flags);
	}

825
	return ret;
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826 827 828 829
}
EXPORT_SYMBOL(del_timer);

#ifdef CONFIG_SMP
830 831 832 833
/**
 * try_to_del_timer_sync - Try to deactivate a timer
 * @timer: timer do del
 *
834 835 836 837 838 839 840
 * This function tries to deactivate a timer. Upon successful (ret >= 0)
 * exit the timer is not queued and the handler is not running on any CPU.
 *
 * It must not be called from interrupt contexts.
 */
int try_to_del_timer_sync(struct timer_list *timer)
{
841
	struct tvec_base *base;
842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859
	unsigned long flags;
	int ret = -1;

	base = lock_timer_base(timer, &flags);

	if (base->running_timer == timer)
		goto out;

	ret = 0;
	if (timer_pending(timer)) {
		detach_timer(timer, 1);
		ret = 1;
	}
out:
	spin_unlock_irqrestore(&base->lock, flags);

	return ret;
}
860 861
EXPORT_SYMBOL(try_to_del_timer_sync);

862
/**
L
Linus Torvalds 已提交
863 864 865 866 867 868 869
 * del_timer_sync - deactivate a timer and wait for the handler to finish.
 * @timer: the timer to be deactivated
 *
 * This function only differs from del_timer() on SMP: besides deactivating
 * the timer it also makes sure the handler has finished executing on other
 * CPUs.
 *
870
 * Synchronization rules: Callers must prevent restarting of the timer,
L
Linus Torvalds 已提交
871 872
 * otherwise this function is meaningless. It must not be called from
 * interrupt contexts. The caller must not hold locks which would prevent
873 874 875
 * completion of the timer's handler. The timer's handler must not call
 * add_timer_on(). Upon exit the timer is not queued and the handler is
 * not running on any CPU.
L
Linus Torvalds 已提交
876 877 878 879 880
 *
 * The function returns whether it has deactivated a pending timer or not.
 */
int del_timer_sync(struct timer_list *timer)
{
881 882 883 884 885 886 887 888 889
#ifdef CONFIG_LOCKDEP
	unsigned long flags;

	local_irq_save(flags);
	lock_map_acquire(&timer->lockdep_map);
	lock_map_release(&timer->lockdep_map);
	local_irq_restore(flags);
#endif

890 891 892 893
	for (;;) {
		int ret = try_to_del_timer_sync(timer);
		if (ret >= 0)
			return ret;
894
		cpu_relax();
895
	}
L
Linus Torvalds 已提交
896
}
897
EXPORT_SYMBOL(del_timer_sync);
L
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898 899
#endif

900
static int cascade(struct tvec_base *base, struct tvec *tv, int index)
L
Linus Torvalds 已提交
901 902
{
	/* cascade all the timers from tv up one level */
903 904 905 906
	struct timer_list *timer, *tmp;
	struct list_head tv_list;

	list_replace_init(tv->vec + index, &tv_list);
L
Linus Torvalds 已提交
907 908

	/*
909 910
	 * We are removing _all_ timers from the list, so we
	 * don't have to detach them individually.
L
Linus Torvalds 已提交
911
	 */
912
	list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
913
		BUG_ON(tbase_get_base(timer->base) != base);
914
		internal_add_timer(base, timer);
L
Linus Torvalds 已提交
915 916 917 918 919
	}

	return index;
}

920 921 922
#define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)

/**
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Linus Torvalds 已提交
923 924 925 926 927 928
 * __run_timers - run all expired timers (if any) on this CPU.
 * @base: the timer vector to be processed.
 *
 * This function cascades all vectors and executes all expired timer
 * vectors.
 */
929
static inline void __run_timers(struct tvec_base *base)
L
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930 931 932
{
	struct timer_list *timer;

933
	spin_lock_irq(&base->lock);
L
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934
	while (time_after_eq(jiffies, base->timer_jiffies)) {
935
		struct list_head work_list;
L
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936
		struct list_head *head = &work_list;
937
		int index = base->timer_jiffies & TVR_MASK;
938

L
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939 940 941 942 943 944 945 946
		/*
		 * Cascade timers:
		 */
		if (!index &&
			(!cascade(base, &base->tv2, INDEX(0))) &&
				(!cascade(base, &base->tv3, INDEX(1))) &&
					!cascade(base, &base->tv4, INDEX(2)))
			cascade(base, &base->tv5, INDEX(3));
947 948
		++base->timer_jiffies;
		list_replace_init(base->tv1.vec + index, &work_list);
949
		while (!list_empty(head)) {
L
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950 951 952
			void (*fn)(unsigned long);
			unsigned long data;

953
			timer = list_first_entry(head, struct timer_list,entry);
954 955
			fn = timer->function;
			data = timer->data;
L
Linus Torvalds 已提交
956

957 958
			timer_stats_account_timer(timer);

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959
			set_running_timer(base, timer);
960
			detach_timer(timer, 1);
961

962
			spin_unlock_irq(&base->lock);
L
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963
			{
964
				int preempt_count = preempt_count();
965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986

#ifdef CONFIG_LOCKDEP
				/*
				 * It is permissible to free the timer from
				 * inside the function that is called from
				 * it, this we need to take into account for
				 * lockdep too. To avoid bogus "held lock
				 * freed" warnings as well as problems when
				 * looking into timer->lockdep_map, make a
				 * copy and use that here.
				 */
				struct lockdep_map lockdep_map =
					timer->lockdep_map;
#endif
				/*
				 * Couple the lock chain with the lock chain at
				 * del_timer_sync() by acquiring the lock_map
				 * around the fn() call here and in
				 * del_timer_sync().
				 */
				lock_map_acquire(&lockdep_map);

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987
				fn(data);
988 989 990

				lock_map_release(&lockdep_map);

L
Linus Torvalds 已提交
991
				if (preempt_count != preempt_count()) {
P
Pavel Machek 已提交
992
					printk(KERN_ERR "huh, entered %p "
993 994 995 996
					       "with preempt_count %08x, exited"
					       " with %08x?\n",
					       fn, preempt_count,
					       preempt_count());
L
Linus Torvalds 已提交
997 998 999
					BUG();
				}
			}
1000
			spin_lock_irq(&base->lock);
L
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1001 1002 1003
		}
	}
	set_running_timer(base, NULL);
1004
	spin_unlock_irq(&base->lock);
L
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1005 1006
}

1007
#ifdef CONFIG_NO_HZ
L
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1008 1009 1010 1011 1012
/*
 * Find out when the next timer event is due to happen. This
 * is used on S/390 to stop all activity when a cpus is idle.
 * This functions needs to be called disabled.
 */
1013
static unsigned long __next_timer_interrupt(struct tvec_base *base)
L
Linus Torvalds 已提交
1014
{
1015
	unsigned long timer_jiffies = base->timer_jiffies;
1016
	unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;
1017
	int index, slot, array, found = 0;
L
Linus Torvalds 已提交
1018
	struct timer_list *nte;
1019
	struct tvec *varray[4];
L
Linus Torvalds 已提交
1020 1021

	/* Look for timer events in tv1. */
1022
	index = slot = timer_jiffies & TVR_MASK;
L
Linus Torvalds 已提交
1023
	do {
1024
		list_for_each_entry(nte, base->tv1.vec + slot, entry) {
1025 1026
			if (tbase_get_deferrable(nte->base))
				continue;
1027

1028
			found = 1;
L
Linus Torvalds 已提交
1029
			expires = nte->expires;
1030 1031 1032 1033
			/* Look at the cascade bucket(s)? */
			if (!index || slot < index)
				goto cascade;
			return expires;
L
Linus Torvalds 已提交
1034
		}
1035 1036 1037 1038 1039 1040 1041 1042
		slot = (slot + 1) & TVR_MASK;
	} while (slot != index);

cascade:
	/* Calculate the next cascade event */
	if (index)
		timer_jiffies += TVR_SIZE - index;
	timer_jiffies >>= TVR_BITS;
L
Linus Torvalds 已提交
1043 1044 1045 1046 1047 1048

	/* Check tv2-tv5. */
	varray[0] = &base->tv2;
	varray[1] = &base->tv3;
	varray[2] = &base->tv4;
	varray[3] = &base->tv5;
1049 1050

	for (array = 0; array < 4; array++) {
1051
		struct tvec *varp = varray[array];
1052 1053

		index = slot = timer_jiffies & TVN_MASK;
L
Linus Torvalds 已提交
1054
		do {
1055
			list_for_each_entry(nte, varp->vec + slot, entry) {
1056 1057 1058
				if (tbase_get_deferrable(nte->base))
					continue;

1059
				found = 1;
L
Linus Torvalds 已提交
1060 1061
				if (time_before(nte->expires, expires))
					expires = nte->expires;
1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078
			}
			/*
			 * Do we still search for the first timer or are
			 * we looking up the cascade buckets ?
			 */
			if (found) {
				/* Look at the cascade bucket(s)? */
				if (!index || slot < index)
					break;
				return expires;
			}
			slot = (slot + 1) & TVN_MASK;
		} while (slot != index);

		if (index)
			timer_jiffies += TVN_SIZE - index;
		timer_jiffies >>= TVN_BITS;
L
Linus Torvalds 已提交
1079
	}
1080 1081
	return expires;
}
1082

1083 1084 1085 1086 1087 1088 1089 1090 1091
/*
 * Check, if the next hrtimer event is before the next timer wheel
 * event:
 */
static unsigned long cmp_next_hrtimer_event(unsigned long now,
					    unsigned long expires)
{
	ktime_t hr_delta = hrtimer_get_next_event();
	struct timespec tsdelta;
1092
	unsigned long delta;
1093 1094 1095

	if (hr_delta.tv64 == KTIME_MAX)
		return expires;
1096

1097 1098 1099 1100 1101
	/*
	 * Expired timer available, let it expire in the next tick
	 */
	if (hr_delta.tv64 <= 0)
		return now + 1;
1102

1103
	tsdelta = ktime_to_timespec(hr_delta);
1104
	delta = timespec_to_jiffies(&tsdelta);
1105 1106 1107 1108 1109 1110 1111 1112

	/*
	 * Limit the delta to the max value, which is checked in
	 * tick_nohz_stop_sched_tick():
	 */
	if (delta > NEXT_TIMER_MAX_DELTA)
		delta = NEXT_TIMER_MAX_DELTA;

1113 1114 1115 1116 1117 1118 1119 1120 1121
	/*
	 * Take rounding errors in to account and make sure, that it
	 * expires in the next tick. Otherwise we go into an endless
	 * ping pong due to tick_nohz_stop_sched_tick() retriggering
	 * the timer softirq
	 */
	if (delta < 1)
		delta = 1;
	now += delta;
1122 1123
	if (time_before(now, expires))
		return now;
L
Linus Torvalds 已提交
1124 1125
	return expires;
}
1126 1127

/**
1128
 * get_next_timer_interrupt - return the jiffy of the next pending timer
1129
 * @now: current time (in jiffies)
1130
 */
1131
unsigned long get_next_timer_interrupt(unsigned long now)
1132
{
1133
	struct tvec_base *base = __get_cpu_var(tvec_bases);
1134
	unsigned long expires;
1135 1136 1137 1138 1139 1140 1141 1142 1143 1144

	spin_lock(&base->lock);
	expires = __next_timer_interrupt(base);
	spin_unlock(&base->lock);

	if (time_before_eq(expires, now))
		return now;

	return cmp_next_hrtimer_event(now, expires);
}
L
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1145 1146 1147
#endif

/*
D
Daniel Walker 已提交
1148
 * Called from the timer interrupt handler to charge one tick to the current
L
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1149 1150 1151 1152 1153 1154 1155 1156
 * process.  user_tick is 1 if the tick is user time, 0 for system.
 */
void update_process_times(int user_tick)
{
	struct task_struct *p = current;
	int cpu = smp_processor_id();

	/* Note: this timer irq context must be accounted for as well. */
1157
	account_process_tick(p, user_tick);
L
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1158 1159 1160
	run_local_timers();
	if (rcu_pending(cpu))
		rcu_check_callbacks(cpu, user_tick);
P
Peter Zijlstra 已提交
1161
	printk_tick();
L
Linus Torvalds 已提交
1162
	scheduler_tick();
1163
	run_posix_cpu_timers(p);
L
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1164 1165 1166 1167 1168 1169 1170
}

/*
 * This function runs timers and the timer-tq in bottom half context.
 */
static void run_timer_softirq(struct softirq_action *h)
{
1171
	struct tvec_base *base = __get_cpu_var(tvec_bases);
L
Linus Torvalds 已提交
1172

1173 1174
	perf_counter_do_pending();

1175
	hrtimer_run_pending();
1176

L
Linus Torvalds 已提交
1177 1178 1179 1180 1181 1182 1183 1184 1185
	if (time_after_eq(jiffies, base->timer_jiffies))
		__run_timers(base);
}

/*
 * Called by the local, per-CPU timer interrupt on SMP.
 */
void run_local_timers(void)
{
1186
	hrtimer_run_queues();
L
Linus Torvalds 已提交
1187
	raise_softirq(TIMER_SOFTIRQ);
1188
	softlockup_tick();
L
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1189 1190 1191 1192 1193 1194 1195 1196
}

/*
 * The 64-bit jiffies value is not atomic - you MUST NOT read it
 * without sampling the sequence number in xtime_lock.
 * jiffies is defined in the linker script...
 */

1197
void do_timer(unsigned long ticks)
L
Linus Torvalds 已提交
1198
{
1199
	jiffies_64 += ticks;
1200 1201
	update_wall_time();
	calc_global_load();
L
Linus Torvalds 已提交
1202 1203 1204 1205 1206 1207 1208 1209
}

#ifdef __ARCH_WANT_SYS_ALARM

/*
 * For backwards compatibility?  This can be done in libc so Alpha
 * and all newer ports shouldn't need it.
 */
1210
SYSCALL_DEFINE1(alarm, unsigned int, seconds)
L
Linus Torvalds 已提交
1211
{
1212
	return alarm_setitimer(seconds);
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}

#endif

#ifndef __alpha__

/*
 * The Alpha uses getxpid, getxuid, and getxgid instead.  Maybe this
 * should be moved into arch/i386 instead?
 */

/**
 * sys_getpid - return the thread group id of the current process
 *
 * Note, despite the name, this returns the tgid not the pid.  The tgid and
 * the pid are identical unless CLONE_THREAD was specified on clone() in
 * which case the tgid is the same in all threads of the same group.
 *
 * This is SMP safe as current->tgid does not change.
 */
1233
SYSCALL_DEFINE0(getpid)
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{
1235
	return task_tgid_vnr(current);
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1236 1237 1238
}

/*
1239 1240 1241 1242
 * Accessing ->real_parent is not SMP-safe, it could
 * change from under us. However, we can use a stale
 * value of ->real_parent under rcu_read_lock(), see
 * release_task()->call_rcu(delayed_put_task_struct).
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 */
1244
SYSCALL_DEFINE0(getppid)
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{
	int pid;

1248
	rcu_read_lock();
1249
	pid = task_tgid_vnr(current->real_parent);
1250
	rcu_read_unlock();
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	return pid;
}

1255
SYSCALL_DEFINE0(getuid)
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{
	/* Only we change this so SMP safe */
1258
	return current_uid();
L
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1259 1260
}

1261
SYSCALL_DEFINE0(geteuid)
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1262 1263
{
	/* Only we change this so SMP safe */
1264
	return current_euid();
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}

1267
SYSCALL_DEFINE0(getgid)
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1268 1269
{
	/* Only we change this so SMP safe */
1270
	return current_gid();
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1271 1272
}

1273
SYSCALL_DEFINE0(getegid)
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{
	/* Only we change this so SMP safe */
1276
	return  current_egid();
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}

#endif

static void process_timeout(unsigned long __data)
{
1283
	wake_up_process((struct task_struct *)__data);
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}

/**
 * schedule_timeout - sleep until timeout
 * @timeout: timeout value in jiffies
 *
 * Make the current task sleep until @timeout jiffies have
 * elapsed. The routine will return immediately unless
 * the current task state has been set (see set_current_state()).
 *
 * You can set the task state as follows -
 *
 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
 * pass before the routine returns. The routine will return 0
 *
 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
 * delivered to the current task. In this case the remaining time
 * in jiffies will be returned, or 0 if the timer expired in time
 *
 * The current task state is guaranteed to be TASK_RUNNING when this
 * routine returns.
 *
 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
 * the CPU away without a bound on the timeout. In this case the return
 * value will be %MAX_SCHEDULE_TIMEOUT.
 *
 * In all cases the return value is guaranteed to be non-negative.
 */
1312
signed long __sched schedule_timeout(signed long timeout)
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{
	struct timer_list timer;
	unsigned long expire;

	switch (timeout)
	{
	case MAX_SCHEDULE_TIMEOUT:
		/*
		 * These two special cases are useful to be comfortable
		 * in the caller. Nothing more. We could take
		 * MAX_SCHEDULE_TIMEOUT from one of the negative value
		 * but I' d like to return a valid offset (>=0) to allow
		 * the caller to do everything it want with the retval.
		 */
		schedule();
		goto out;
	default:
		/*
		 * Another bit of PARANOID. Note that the retval will be
		 * 0 since no piece of kernel is supposed to do a check
		 * for a negative retval of schedule_timeout() (since it
		 * should never happens anyway). You just have the printk()
		 * that will tell you if something is gone wrong and where.
		 */
1337
		if (timeout < 0) {
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			printk(KERN_ERR "schedule_timeout: wrong timeout "
1339 1340
				"value %lx\n", timeout);
			dump_stack();
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			current->state = TASK_RUNNING;
			goto out;
		}
	}

	expire = timeout + jiffies;

1348
	setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
1349
	__mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
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	schedule();
	del_singleshot_timer_sync(&timer);

1353 1354 1355
	/* Remove the timer from the object tracker */
	destroy_timer_on_stack(&timer);

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	timeout = expire - jiffies;

 out:
	return timeout < 0 ? 0 : timeout;
}
EXPORT_SYMBOL(schedule_timeout);

1363 1364 1365 1366
/*
 * We can use __set_current_state() here because schedule_timeout() calls
 * schedule() unconditionally.
 */
1367 1368
signed long __sched schedule_timeout_interruptible(signed long timeout)
{
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	__set_current_state(TASK_INTERRUPTIBLE);
	return schedule_timeout(timeout);
1371 1372 1373
}
EXPORT_SYMBOL(schedule_timeout_interruptible);

M
Matthew Wilcox 已提交
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signed long __sched schedule_timeout_killable(signed long timeout)
{
	__set_current_state(TASK_KILLABLE);
	return schedule_timeout(timeout);
}
EXPORT_SYMBOL(schedule_timeout_killable);

1381 1382
signed long __sched schedule_timeout_uninterruptible(signed long timeout)
{
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	__set_current_state(TASK_UNINTERRUPTIBLE);
	return schedule_timeout(timeout);
1385 1386 1387
}
EXPORT_SYMBOL(schedule_timeout_uninterruptible);

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/* Thread ID - the internal kernel "pid" */
1389
SYSCALL_DEFINE0(gettid)
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1390
{
1391
	return task_pid_vnr(current);
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}

1394
/**
1395
 * do_sysinfo - fill in sysinfo struct
1396
 * @info: pointer to buffer to fill
1397
 */
1398
int do_sysinfo(struct sysinfo *info)
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{
	unsigned long mem_total, sav_total;
	unsigned int mem_unit, bitcount;
1402
	struct timespec tp;
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1404
	memset(info, 0, sizeof(struct sysinfo));
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1406 1407 1408
	ktime_get_ts(&tp);
	monotonic_to_bootbased(&tp);
	info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
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1410
	get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);
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1411

1412
	info->procs = nr_threads;
L
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1413

1414 1415
	si_meminfo(info);
	si_swapinfo(info);
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	/*
	 * If the sum of all the available memory (i.e. ram + swap)
	 * is less than can be stored in a 32 bit unsigned long then
	 * we can be binary compatible with 2.2.x kernels.  If not,
	 * well, in that case 2.2.x was broken anyways...
	 *
	 *  -Erik Andersen <andersee@debian.org>
	 */

1426 1427
	mem_total = info->totalram + info->totalswap;
	if (mem_total < info->totalram || mem_total < info->totalswap)
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1428 1429
		goto out;
	bitcount = 0;
1430
	mem_unit = info->mem_unit;
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	while (mem_unit > 1) {
		bitcount++;
		mem_unit >>= 1;
		sav_total = mem_total;
		mem_total <<= 1;
		if (mem_total < sav_total)
			goto out;
	}

	/*
	 * If mem_total did not overflow, multiply all memory values by
1442
	 * info->mem_unit and set it to 1.  This leaves things compatible
L
Linus Torvalds 已提交
1443 1444 1445 1446
	 * with 2.2.x, and also retains compatibility with earlier 2.4.x
	 * kernels...
	 */

1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460
	info->mem_unit = 1;
	info->totalram <<= bitcount;
	info->freeram <<= bitcount;
	info->sharedram <<= bitcount;
	info->bufferram <<= bitcount;
	info->totalswap <<= bitcount;
	info->freeswap <<= bitcount;
	info->totalhigh <<= bitcount;
	info->freehigh <<= bitcount;

out:
	return 0;
}

1461
SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
1462 1463 1464 1465
{
	struct sysinfo val;

	do_sysinfo(&val);
L
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1466 1467 1468 1469 1470 1471 1472

	if (copy_to_user(info, &val, sizeof(struct sysinfo)))
		return -EFAULT;

	return 0;
}

A
Adrian Bunk 已提交
1473
static int __cpuinit init_timers_cpu(int cpu)
L
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1474 1475
{
	int j;
1476
	struct tvec_base *base;
A
Adrian Bunk 已提交
1477
	static char __cpuinitdata tvec_base_done[NR_CPUS];
1478

A
Andrew Morton 已提交
1479
	if (!tvec_base_done[cpu]) {
1480 1481 1482
		static char boot_done;

		if (boot_done) {
A
Andrew Morton 已提交
1483 1484 1485
			/*
			 * The APs use this path later in boot
			 */
1486 1487
			base = kmalloc_node(sizeof(*base),
						GFP_KERNEL | __GFP_ZERO,
1488 1489 1490
						cpu_to_node(cpu));
			if (!base)
				return -ENOMEM;
1491 1492 1493 1494 1495 1496 1497

			/* Make sure that tvec_base is 2 byte aligned */
			if (tbase_get_deferrable(base)) {
				WARN_ON(1);
				kfree(base);
				return -ENOMEM;
			}
A
Andrew Morton 已提交
1498
			per_cpu(tvec_bases, cpu) = base;
1499
		} else {
A
Andrew Morton 已提交
1500 1501 1502 1503 1504 1505
			/*
			 * This is for the boot CPU - we use compile-time
			 * static initialisation because per-cpu memory isn't
			 * ready yet and because the memory allocators are not
			 * initialised either.
			 */
1506
			boot_done = 1;
A
Andrew Morton 已提交
1507
			base = &boot_tvec_bases;
1508
		}
A
Andrew Morton 已提交
1509 1510 1511
		tvec_base_done[cpu] = 1;
	} else {
		base = per_cpu(tvec_bases, cpu);
1512
	}
A
Andrew Morton 已提交
1513

1514
	spin_lock_init(&base->lock);
1515

L
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1516 1517 1518 1519 1520 1521 1522 1523 1524 1525
	for (j = 0; j < TVN_SIZE; j++) {
		INIT_LIST_HEAD(base->tv5.vec + j);
		INIT_LIST_HEAD(base->tv4.vec + j);
		INIT_LIST_HEAD(base->tv3.vec + j);
		INIT_LIST_HEAD(base->tv2.vec + j);
	}
	for (j = 0; j < TVR_SIZE; j++)
		INIT_LIST_HEAD(base->tv1.vec + j);

	base->timer_jiffies = jiffies;
1526
	return 0;
L
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1527 1528 1529
}

#ifdef CONFIG_HOTPLUG_CPU
1530
static void migrate_timer_list(struct tvec_base *new_base, struct list_head *head)
L
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1531 1532 1533 1534
{
	struct timer_list *timer;

	while (!list_empty(head)) {
1535
		timer = list_first_entry(head, struct timer_list, entry);
1536
		detach_timer(timer, 0);
1537
		timer_set_base(timer, new_base);
L
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1538 1539 1540 1541
		internal_add_timer(new_base, timer);
	}
}

R
Randy Dunlap 已提交
1542
static void __cpuinit migrate_timers(int cpu)
L
Linus Torvalds 已提交
1543
{
1544 1545
	struct tvec_base *old_base;
	struct tvec_base *new_base;
L
Linus Torvalds 已提交
1546 1547 1548
	int i;

	BUG_ON(cpu_online(cpu));
1549 1550
	old_base = per_cpu(tvec_bases, cpu);
	new_base = get_cpu_var(tvec_bases);
1551 1552 1553 1554 1555
	/*
	 * The caller is globally serialized and nobody else
	 * takes two locks at once, deadlock is not possible.
	 */
	spin_lock_irq(&new_base->lock);
1556
	spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1557 1558

	BUG_ON(old_base->running_timer);
L
Linus Torvalds 已提交
1559 1560

	for (i = 0; i < TVR_SIZE; i++)
1561 1562 1563 1564 1565 1566 1567 1568
		migrate_timer_list(new_base, old_base->tv1.vec + i);
	for (i = 0; i < TVN_SIZE; i++) {
		migrate_timer_list(new_base, old_base->tv2.vec + i);
		migrate_timer_list(new_base, old_base->tv3.vec + i);
		migrate_timer_list(new_base, old_base->tv4.vec + i);
		migrate_timer_list(new_base, old_base->tv5.vec + i);
	}

1569
	spin_unlock(&old_base->lock);
1570
	spin_unlock_irq(&new_base->lock);
L
Linus Torvalds 已提交
1571 1572 1573 1574
	put_cpu_var(tvec_bases);
}
#endif /* CONFIG_HOTPLUG_CPU */

1575
static int __cpuinit timer_cpu_notify(struct notifier_block *self,
L
Linus Torvalds 已提交
1576 1577 1578 1579 1580
				unsigned long action, void *hcpu)
{
	long cpu = (long)hcpu;
	switch(action) {
	case CPU_UP_PREPARE:
1581
	case CPU_UP_PREPARE_FROZEN:
1582 1583
		if (init_timers_cpu(cpu) < 0)
			return NOTIFY_BAD;
L
Linus Torvalds 已提交
1584 1585 1586
		break;
#ifdef CONFIG_HOTPLUG_CPU
	case CPU_DEAD:
1587
	case CPU_DEAD_FROZEN:
L
Linus Torvalds 已提交
1588 1589 1590 1591 1592 1593 1594 1595 1596
		migrate_timers(cpu);
		break;
#endif
	default:
		break;
	}
	return NOTIFY_OK;
}

1597
static struct notifier_block __cpuinitdata timers_nb = {
L
Linus Torvalds 已提交
1598 1599 1600 1601 1602 1603
	.notifier_call	= timer_cpu_notify,
};


void __init init_timers(void)
{
1604
	int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
L
Linus Torvalds 已提交
1605
				(void *)(long)smp_processor_id());
1606

1607 1608
	init_timer_stats();

1609
	BUG_ON(err == NOTIFY_BAD);
L
Linus Torvalds 已提交
1610
	register_cpu_notifier(&timers_nb);
1611
	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
L
Linus Torvalds 已提交
1612 1613 1614 1615 1616 1617 1618 1619 1620 1621
}

/**
 * msleep - sleep safely even with waitqueue interruptions
 * @msecs: Time in milliseconds to sleep for
 */
void msleep(unsigned int msecs)
{
	unsigned long timeout = msecs_to_jiffies(msecs) + 1;

1622 1623
	while (timeout)
		timeout = schedule_timeout_uninterruptible(timeout);
L
Linus Torvalds 已提交
1624 1625 1626 1627 1628
}

EXPORT_SYMBOL(msleep);

/**
1629
 * msleep_interruptible - sleep waiting for signals
L
Linus Torvalds 已提交
1630 1631 1632 1633 1634 1635
 * @msecs: Time in milliseconds to sleep for
 */
unsigned long msleep_interruptible(unsigned int msecs)
{
	unsigned long timeout = msecs_to_jiffies(msecs) + 1;

1636 1637
	while (timeout && !signal_pending(current))
		timeout = schedule_timeout_interruptible(timeout);
L
Linus Torvalds 已提交
1638 1639 1640 1641
	return jiffies_to_msecs(timeout);
}

EXPORT_SYMBOL(msleep_interruptible);