timer.c 41.1 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 <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;

	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);
}

static void __init_timer(struct timer_list *timer);

void init_timer_on_stack(struct timer_list *timer)
{
	debug_object_init_on_stack(timer, &timer_debug_descr);
	__init_timer(timer);
}
EXPORT_SYMBOL_GPL(init_timer_on_stack);

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

static void __init_timer(struct timer_list *timer)
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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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}
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/**
 * init_timer - initialize a timer.
 * @timer: the timer to be initialized
 *
 * init_timer() must be done to a timer prior calling *any* of the
 * other timer functions.
 */
void init_timer(struct timer_list *timer)
{
	debug_timer_init(timer);
	__init_timer(timer);
}
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EXPORT_SYMBOL(init_timer);

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void init_timer_deferrable(struct timer_list *timer)
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{
	init_timer(timer);
	timer_set_deferrable(timer);
}
EXPORT_SYMBOL(init_timer_deferrable);

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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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int __mod_timer(struct timer_list *timer, unsigned long expires)
{
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	struct tvec_base *base, *new_base;
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	unsigned long flags;
	int ret = 0;

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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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	debug_timer_activate(timer);

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	new_base = __get_cpu_var(tvec_bases);
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	if (base != new_base) {
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		/*
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		 * 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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		 */
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		if (likely(base->running_timer != timer)) {
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			/* See the comment in lock_timer_base() */
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			timer_set_base(timer, NULL);
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			spin_unlock(&base->lock);
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			base = new_base;
			spin_lock(&base->lock);
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			timer_set_base(timer, base);
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		}
	}

	timer->expires = expires;
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	internal_add_timer(base, timer);
	spin_unlock_irqrestore(&base->lock, flags);
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	return ret;
}

EXPORT_SYMBOL(__mod_timer);

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/**
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 * 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)
{
648
	struct tvec_base *base = per_cpu(tvec_bases, cpu);
649
	unsigned long flags;
650

651
	timer_stats_timer_set_start_info(timer);
652
	BUG_ON(timer_pending(timer) || !timer->function);
653
	spin_lock_irqsave(&base->lock, flags);
654
	timer_set_base(timer, base);
655
	debug_timer_activate(timer);
L
Linus Torvalds 已提交
656
	internal_add_timer(base, timer);
657 658 659 660 661 662 663 664 665
	/*
	 * 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);
666
	spin_unlock_irqrestore(&base->lock, flags);
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667 668
}

669
/**
L
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670 671
 * mod_timer - modify a timer's timeout
 * @timer: the timer to be modified
672
 * @expires: new timeout in jiffies
L
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673
 *
674
 * 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)
{
	BUG_ON(!timer->function);

693
	timer_stats_timer_set_start_info(timer);
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	/*
	 * 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;

	return __mod_timer(timer, expires);
}

EXPORT_SYMBOL(mod_timer);

707
/**
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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)
{
720
	struct tvec_base *base;
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721
	unsigned long flags;
722
	int ret = 0;
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723

724
	timer_stats_timer_clear_start_info(timer);
725 726 727 728 729 730
	if (timer_pending(timer)) {
		base = lock_timer_base(timer, &flags);
		if (timer_pending(timer)) {
			detach_timer(timer, 1);
			ret = 1;
		}
L
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		spin_unlock_irqrestore(&base->lock, flags);
	}

734
	return ret;
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735 736 737 738 739
}

EXPORT_SYMBOL(del_timer);

#ifdef CONFIG_SMP
740 741 742 743
/**
 * try_to_del_timer_sync - Try to deactivate a timer
 * @timer: timer do del
 *
744 745 746 747 748 749 750
 * 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)
{
751
	struct tvec_base *base;
752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770
	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;
}

771 772
EXPORT_SYMBOL(try_to_del_timer_sync);

773
/**
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774 775 776 777 778 779 780
 * 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.
 *
781
 * Synchronization rules: Callers must prevent restarting of the timer,
L
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782 783
 * otherwise this function is meaningless. It must not be called from
 * interrupt contexts. The caller must not hold locks which would prevent
784 785 786
 * 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
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787 788 789 790 791
 *
 * The function returns whether it has deactivated a pending timer or not.
 */
int del_timer_sync(struct timer_list *timer)
{
792 793 794 795
	for (;;) {
		int ret = try_to_del_timer_sync(timer);
		if (ret >= 0)
			return ret;
796
		cpu_relax();
797
	}
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}

800
EXPORT_SYMBOL(del_timer_sync);
L
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801 802
#endif

803
static int cascade(struct tvec_base *base, struct tvec *tv, int index)
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804 805
{
	/* cascade all the timers from tv up one level */
806 807 808 809
	struct timer_list *timer, *tmp;
	struct list_head tv_list;

	list_replace_init(tv->vec + index, &tv_list);
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810 811

	/*
812 813
	 * We are removing _all_ timers from the list, so we
	 * don't have to detach them individually.
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814
	 */
815
	list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
816
		BUG_ON(tbase_get_base(timer->base) != base);
817
		internal_add_timer(base, timer);
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818 819 820 821 822
	}

	return index;
}

823 824 825
#define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)

/**
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Linus Torvalds 已提交
826 827 828 829 830 831
 * __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.
 */
832
static inline void __run_timers(struct tvec_base *base)
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833 834 835
{
	struct timer_list *timer;

836
	spin_lock_irq(&base->lock);
L
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837
	while (time_after_eq(jiffies, base->timer_jiffies)) {
838
		struct list_head work_list;
L
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839
		struct list_head *head = &work_list;
840
		int index = base->timer_jiffies & TVR_MASK;
841

L
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842 843 844 845 846 847 848 849
		/*
		 * 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));
850 851
		++base->timer_jiffies;
		list_replace_init(base->tv1.vec + index, &work_list);
852
		while (!list_empty(head)) {
L
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853 854 855
			void (*fn)(unsigned long);
			unsigned long data;

856
			timer = list_first_entry(head, struct timer_list,entry);
857 858
			fn = timer->function;
			data = timer->data;
L
Linus Torvalds 已提交
859

860 861
			timer_stats_account_timer(timer);

L
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862
			set_running_timer(base, timer);
863
			detach_timer(timer, 1);
864
			spin_unlock_irq(&base->lock);
L
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865
			{
866
				int preempt_count = preempt_count();
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867 868
				fn(data);
				if (preempt_count != preempt_count()) {
P
Pavel Machek 已提交
869
					printk(KERN_ERR "huh, entered %p "
870 871 872 873
					       "with preempt_count %08x, exited"
					       " with %08x?\n",
					       fn, preempt_count,
					       preempt_count());
L
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874 875 876
					BUG();
				}
			}
877
			spin_lock_irq(&base->lock);
L
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878 879 880
		}
	}
	set_running_timer(base, NULL);
881
	spin_unlock_irq(&base->lock);
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882 883
}

884
#ifdef CONFIG_NO_HZ
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/*
 * 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.
 */
890
static unsigned long __next_timer_interrupt(struct tvec_base *base)
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891
{
892
	unsigned long timer_jiffies = base->timer_jiffies;
893
	unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;
894
	int index, slot, array, found = 0;
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895
	struct timer_list *nte;
896
	struct tvec *varray[4];
L
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897 898

	/* Look for timer events in tv1. */
899
	index = slot = timer_jiffies & TVR_MASK;
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900
	do {
901
		list_for_each_entry(nte, base->tv1.vec + slot, entry) {
902 903
			if (tbase_get_deferrable(nte->base))
				continue;
904

905
			found = 1;
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906
			expires = nte->expires;
907 908 909 910
			/* Look at the cascade bucket(s)? */
			if (!index || slot < index)
				goto cascade;
			return expires;
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911
		}
912 913 914 915 916 917 918 919
		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;
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920 921 922 923 924 925

	/* Check tv2-tv5. */
	varray[0] = &base->tv2;
	varray[1] = &base->tv3;
	varray[2] = &base->tv4;
	varray[3] = &base->tv5;
926 927

	for (array = 0; array < 4; array++) {
928
		struct tvec *varp = varray[array];
929 930

		index = slot = timer_jiffies & TVN_MASK;
L
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931
		do {
932 933
			list_for_each_entry(nte, varp->vec + slot, entry) {
				found = 1;
L
Linus Torvalds 已提交
934 935
				if (time_before(nte->expires, expires))
					expires = nte->expires;
936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952
			}
			/*
			 * 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
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953
	}
954 955
	return expires;
}
956

957 958 959 960 961 962 963 964 965
/*
 * 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;
966
	unsigned long delta;
967 968 969

	if (hr_delta.tv64 == KTIME_MAX)
		return expires;
970

971 972 973 974 975
	/*
	 * Expired timer available, let it expire in the next tick
	 */
	if (hr_delta.tv64 <= 0)
		return now + 1;
976

977
	tsdelta = ktime_to_timespec(hr_delta);
978
	delta = timespec_to_jiffies(&tsdelta);
979 980 981 982 983 984 985 986

	/*
	 * 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;

987 988 989 990 991 992 993 994 995
	/*
	 * 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;
996 997
	if (time_before(now, expires))
		return now;
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998 999
	return expires;
}
1000 1001

/**
1002
 * get_next_timer_interrupt - return the jiffy of the next pending timer
1003
 * @now: current time (in jiffies)
1004
 */
1005
unsigned long get_next_timer_interrupt(unsigned long now)
1006
{
1007
	struct tvec_base *base = __get_cpu_var(tvec_bases);
1008
	unsigned long expires;
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018

	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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1019 1020 1021
#endif

/*
D
Daniel Walker 已提交
1022
 * Called from the timer interrupt handler to charge one tick to the current
L
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1023 1024 1025 1026 1027 1028 1029 1030
 * 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. */
1031
	account_process_tick(p, user_tick);
L
Linus Torvalds 已提交
1032 1033 1034
	run_local_timers();
	if (rcu_pending(cpu))
		rcu_check_callbacks(cpu, user_tick);
P
Peter Zijlstra 已提交
1035
	printk_tick();
L
Linus Torvalds 已提交
1036
	scheduler_tick();
1037
	run_posix_cpu_timers(p);
L
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1038 1039 1040 1041 1042 1043 1044
}

/*
 * Nr of active tasks - counted in fixed-point numbers
 */
static unsigned long count_active_tasks(void)
{
1045
	return nr_active() * FIXED_1;
L
Linus Torvalds 已提交
1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068
}

/*
 * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 * imply that avenrun[] is the standard name for this kind of thing.
 * Nothing else seems to be standardized: the fractional size etc
 * all seem to differ on different machines.
 *
 * Requires xtime_lock to access.
 */
unsigned long avenrun[3];

EXPORT_SYMBOL(avenrun);

/*
 * calc_load - given tick count, update the avenrun load estimates.
 * This is called while holding a write_lock on xtime_lock.
 */
static inline void calc_load(unsigned long ticks)
{
	unsigned long active_tasks; /* fixed-point */
	static int count = LOAD_FREQ;

E
Eric Dumazet 已提交
1069 1070 1071 1072 1073 1074 1075 1076 1077
	count -= ticks;
	if (unlikely(count < 0)) {
		active_tasks = count_active_tasks();
		do {
			CALC_LOAD(avenrun[0], EXP_1, active_tasks);
			CALC_LOAD(avenrun[1], EXP_5, active_tasks);
			CALC_LOAD(avenrun[2], EXP_15, active_tasks);
			count += LOAD_FREQ;
		} while (count < 0);
L
Linus Torvalds 已提交
1078 1079 1080 1081 1082 1083 1084 1085
	}
}

/*
 * This function runs timers and the timer-tq in bottom half context.
 */
static void run_timer_softirq(struct softirq_action *h)
{
1086
	struct tvec_base *base = __get_cpu_var(tvec_bases);
L
Linus Torvalds 已提交
1087

1088
	hrtimer_run_pending();
1089

L
Linus Torvalds 已提交
1090 1091 1092 1093 1094 1095 1096 1097 1098
	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)
{
1099
	hrtimer_run_queues();
L
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1100
	raise_softirq(TIMER_SOFTIRQ);
1101
	softlockup_tick();
L
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1102 1103 1104 1105 1106 1107
}

/*
 * Called by the timer interrupt. xtime_lock must already be taken
 * by the timer IRQ!
 */
1108
static inline void update_times(unsigned long ticks)
L
Linus Torvalds 已提交
1109
{
1110
	update_wall_time();
L
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1111 1112
	calc_load(ticks);
}
1113

L
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1114 1115 1116 1117 1118 1119
/*
 * 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...
 */

1120
void do_timer(unsigned long ticks)
L
Linus Torvalds 已提交
1121
{
1122 1123
	jiffies_64 += ticks;
	update_times(ticks);
L
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1124 1125 1126 1127 1128 1129 1130 1131
}

#ifdef __ARCH_WANT_SYS_ALARM

/*
 * For backwards compatibility?  This can be done in libc so Alpha
 * and all newer ports shouldn't need it.
 */
1132
SYSCALL_DEFINE1(alarm, unsigned int, seconds)
L
Linus Torvalds 已提交
1133
{
1134
	return alarm_setitimer(seconds);
L
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1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154
}

#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.
 */
1155
SYSCALL_DEFINE0(getpid)
L
Linus Torvalds 已提交
1156
{
1157
	return task_tgid_vnr(current);
L
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1158 1159 1160
}

/*
1161 1162 1163 1164
 * 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).
L
Linus Torvalds 已提交
1165
 */
1166
SYSCALL_DEFINE0(getppid)
L
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1167 1168 1169
{
	int pid;

1170
	rcu_read_lock();
1171
	pid = task_tgid_vnr(current->real_parent);
1172
	rcu_read_unlock();
L
Linus Torvalds 已提交
1173 1174 1175 1176

	return pid;
}

1177
SYSCALL_DEFINE0(getuid)
L
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1178 1179
{
	/* Only we change this so SMP safe */
1180
	return current_uid();
L
Linus Torvalds 已提交
1181 1182
}

1183
SYSCALL_DEFINE0(geteuid)
L
Linus Torvalds 已提交
1184 1185
{
	/* Only we change this so SMP safe */
1186
	return current_euid();
L
Linus Torvalds 已提交
1187 1188
}

1189
SYSCALL_DEFINE0(getgid)
L
Linus Torvalds 已提交
1190 1191
{
	/* Only we change this so SMP safe */
1192
	return current_gid();
L
Linus Torvalds 已提交
1193 1194
}

1195
SYSCALL_DEFINE0(getegid)
L
Linus Torvalds 已提交
1196 1197
{
	/* Only we change this so SMP safe */
1198
	return  current_egid();
L
Linus Torvalds 已提交
1199 1200 1201 1202 1203 1204
}

#endif

static void process_timeout(unsigned long __data)
{
1205
	wake_up_process((struct task_struct *)__data);
L
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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.
 */
1234
signed long __sched schedule_timeout(signed long timeout)
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1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258
{
	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.
		 */
1259
		if (timeout < 0) {
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1260
			printk(KERN_ERR "schedule_timeout: wrong timeout "
1261 1262
				"value %lx\n", timeout);
			dump_stack();
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1263 1264 1265 1266 1267 1268 1269
			current->state = TASK_RUNNING;
			goto out;
		}
	}

	expire = timeout + jiffies;

1270
	setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
1271
	__mod_timer(&timer, expire);
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	schedule();
	del_singleshot_timer_sync(&timer);

1275 1276 1277
	/* 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);

1285 1286 1287 1288
/*
 * We can use __set_current_state() here because schedule_timeout() calls
 * schedule() unconditionally.
 */
1289 1290
signed long __sched schedule_timeout_interruptible(signed long timeout)
{
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	__set_current_state(TASK_INTERRUPTIBLE);
	return schedule_timeout(timeout);
1293 1294 1295
}
EXPORT_SYMBOL(schedule_timeout_interruptible);

M
Matthew Wilcox 已提交
1296 1297 1298 1299 1300 1301 1302
signed long __sched schedule_timeout_killable(signed long timeout)
{
	__set_current_state(TASK_KILLABLE);
	return schedule_timeout(timeout);
}
EXPORT_SYMBOL(schedule_timeout_killable);

1303 1304
signed long __sched schedule_timeout_uninterruptible(signed long timeout)
{
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	__set_current_state(TASK_UNINTERRUPTIBLE);
	return schedule_timeout(timeout);
1307 1308 1309
}
EXPORT_SYMBOL(schedule_timeout_uninterruptible);

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1310
/* Thread ID - the internal kernel "pid" */
1311
SYSCALL_DEFINE0(gettid)
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{
1313
	return task_pid_vnr(current);
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}

1316
/**
1317
 * do_sysinfo - fill in sysinfo struct
1318
 * @info: pointer to buffer to fill
1319
 */
1320
int do_sysinfo(struct sysinfo *info)
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{
	unsigned long mem_total, sav_total;
	unsigned int mem_unit, bitcount;
	unsigned long seq;

1326
	memset(info, 0, sizeof(struct sysinfo));
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	do {
		struct timespec tp;
		seq = read_seqbegin(&xtime_lock);

		/*
		 * This is annoying.  The below is the same thing
		 * posix_get_clock_monotonic() does, but it wants to
		 * take the lock which we want to cover the loads stuff
		 * too.
		 */

		getnstimeofday(&tp);
		tp.tv_sec += wall_to_monotonic.tv_sec;
		tp.tv_nsec += wall_to_monotonic.tv_nsec;
1342
		monotonic_to_bootbased(&tp);
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		if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
			tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
			tp.tv_sec++;
		}
1347
		info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
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1349 1350 1351
		info->loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
		info->loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
		info->loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
L
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1352

1353
		info->procs = nr_threads;
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	} while (read_seqretry(&xtime_lock, seq));

1356 1357
	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>
	 */

1368 1369
	mem_total = info->totalram + info->totalswap;
	if (mem_total < info->totalram || mem_total < info->totalswap)
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		goto out;
	bitcount = 0;
1372
	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
1384
	 * info->mem_unit and set it to 1.  This leaves things compatible
L
Linus Torvalds 已提交
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	 * with 2.2.x, and also retains compatibility with earlier 2.4.x
	 * kernels...
	 */

1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402
	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;
}

1403
SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
1404 1405 1406 1407
{
	struct sysinfo val;

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

	return 0;
}

A
Adrian Bunk 已提交
1415
static int __cpuinit init_timers_cpu(int cpu)
L
Linus Torvalds 已提交
1416 1417
{
	int j;
1418
	struct tvec_base *base;
A
Adrian Bunk 已提交
1419
	static char __cpuinitdata tvec_base_done[NR_CPUS];
1420

A
Andrew Morton 已提交
1421
	if (!tvec_base_done[cpu]) {
1422 1423 1424
		static char boot_done;

		if (boot_done) {
A
Andrew Morton 已提交
1425 1426 1427
			/*
			 * The APs use this path later in boot
			 */
1428 1429
			base = kmalloc_node(sizeof(*base),
						GFP_KERNEL | __GFP_ZERO,
1430 1431 1432
						cpu_to_node(cpu));
			if (!base)
				return -ENOMEM;
1433 1434 1435 1436 1437 1438 1439

			/* 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
1440
			per_cpu(tvec_bases, cpu) = base;
1441
		} else {
A
Andrew Morton 已提交
1442 1443 1444 1445 1446 1447
			/*
			 * 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.
			 */
1448
			boot_done = 1;
A
Andrew Morton 已提交
1449
			base = &boot_tvec_bases;
1450
		}
A
Andrew Morton 已提交
1451 1452 1453
		tvec_base_done[cpu] = 1;
	} else {
		base = per_cpu(tvec_bases, cpu);
1454
	}
A
Andrew Morton 已提交
1455

1456
	spin_lock_init(&base->lock);
1457

L
Linus Torvalds 已提交
1458 1459 1460 1461 1462 1463 1464 1465 1466 1467
	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;
1468
	return 0;
L
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1469 1470 1471
}

#ifdef CONFIG_HOTPLUG_CPU
1472
static void migrate_timer_list(struct tvec_base *new_base, struct list_head *head)
L
Linus Torvalds 已提交
1473 1474 1475 1476
{
	struct timer_list *timer;

	while (!list_empty(head)) {
1477
		timer = list_first_entry(head, struct timer_list, entry);
1478
		detach_timer(timer, 0);
1479
		timer_set_base(timer, new_base);
L
Linus Torvalds 已提交
1480 1481 1482 1483
		internal_add_timer(new_base, timer);
	}
}

R
Randy Dunlap 已提交
1484
static void __cpuinit migrate_timers(int cpu)
L
Linus Torvalds 已提交
1485
{
1486 1487
	struct tvec_base *old_base;
	struct tvec_base *new_base;
L
Linus Torvalds 已提交
1488 1489 1490
	int i;

	BUG_ON(cpu_online(cpu));
1491 1492
	old_base = per_cpu(tvec_bases, cpu);
	new_base = get_cpu_var(tvec_bases);
1493 1494 1495 1496 1497
	/*
	 * The caller is globally serialized and nobody else
	 * takes two locks at once, deadlock is not possible.
	 */
	spin_lock_irq(&new_base->lock);
1498
	spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1499 1500

	BUG_ON(old_base->running_timer);
L
Linus Torvalds 已提交
1501 1502

	for (i = 0; i < TVR_SIZE; i++)
1503 1504 1505 1506 1507 1508 1509 1510
		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);
	}

1511
	spin_unlock(&old_base->lock);
1512
	spin_unlock_irq(&new_base->lock);
L
Linus Torvalds 已提交
1513 1514 1515 1516
	put_cpu_var(tvec_bases);
}
#endif /* CONFIG_HOTPLUG_CPU */

1517
static int __cpuinit timer_cpu_notify(struct notifier_block *self,
L
Linus Torvalds 已提交
1518 1519 1520 1521 1522
				unsigned long action, void *hcpu)
{
	long cpu = (long)hcpu;
	switch(action) {
	case CPU_UP_PREPARE:
1523
	case CPU_UP_PREPARE_FROZEN:
1524 1525
		if (init_timers_cpu(cpu) < 0)
			return NOTIFY_BAD;
L
Linus Torvalds 已提交
1526 1527 1528
		break;
#ifdef CONFIG_HOTPLUG_CPU
	case CPU_DEAD:
1529
	case CPU_DEAD_FROZEN:
L
Linus Torvalds 已提交
1530 1531 1532 1533 1534 1535 1536 1537 1538
		migrate_timers(cpu);
		break;
#endif
	default:
		break;
	}
	return NOTIFY_OK;
}

1539
static struct notifier_block __cpuinitdata timers_nb = {
L
Linus Torvalds 已提交
1540 1541 1542 1543 1544 1545
	.notifier_call	= timer_cpu_notify,
};


void __init init_timers(void)
{
1546
	int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
L
Linus Torvalds 已提交
1547
				(void *)(long)smp_processor_id());
1548

1549 1550
	init_timer_stats();

1551
	BUG_ON(err == NOTIFY_BAD);
L
Linus Torvalds 已提交
1552
	register_cpu_notifier(&timers_nb);
1553
	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
L
Linus Torvalds 已提交
1554 1555 1556 1557 1558 1559 1560 1561 1562 1563
}

/**
 * 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;

1564 1565
	while (timeout)
		timeout = schedule_timeout_uninterruptible(timeout);
L
Linus Torvalds 已提交
1566 1567 1568 1569 1570
}

EXPORT_SYMBOL(msleep);

/**
1571
 * msleep_interruptible - sleep waiting for signals
L
Linus Torvalds 已提交
1572 1573 1574 1575 1576 1577
 * @msecs: Time in milliseconds to sleep for
 */
unsigned long msleep_interruptible(unsigned int msecs)
{
	unsigned long timeout = msecs_to_jiffies(msecs) + 1;

1578 1579
	while (timeout && !signal_pending(current))
		timeout = schedule_timeout_interruptible(timeout);
L
Linus Torvalds 已提交
1580 1581 1582 1583
	return jiffies_to_msecs(timeout);
}

EXPORT_SYMBOL(msleep_interruptible);