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/*
* linux/kernel/timer.c
*
* Kernel internal timers, basic process system calls
*
* 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/export.h>
#include <linux/interrupt.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/pid_namespace.h>
#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>
#include <linux/delay.h>
#include <linux/tick.h>
#include <linux/kallsyms.h>
#include <linux/irq_work.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/div64.h>
#include <asm/timex.h>
#include <asm/io.h>

#define CREATE_TRACE_POINTS
#include <trace/events/timer.h>

u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;

EXPORT_SYMBOL(jiffies_64);

/*
* 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)
#define MAX_TVAL ((unsigned long)((1ULL << (TVR_BITS + 4*TVN_BITS)) - 1))

struct tvec {
struct list_head vec[TVN_SIZE];
};

struct tvec_root {
struct list_head vec[TVR_SIZE];
};

struct tvec_base {
spinlock_t lock;
struct timer_list *running_timer;
unsigned long timer_jiffies;
unsigned long next_timer;
unsigned long active_timers;
struct tvec_root tv1;
struct tvec tv2;
struct tvec tv3;
struct tvec tv4;
struct tvec tv5;
} ____cacheline_aligned;

struct tvec_base boot_tvec_bases;
EXPORT_SYMBOL(boot_tvec_bases);
static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;

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

static inline unsigned int tbase_get_irqsafe(struct tvec_base *base)
{
return ((unsigned int)(unsigned long)base & TIMER_IRQSAFE);
}

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

static inline void
timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
{
unsigned long flags = (unsigned long)timer->base & TIMER_FLAG_MASK;

timer->base = (struct tvec_base *)((unsigned long)(new_base) | flags);
}

static unsigned long round_jiffies_common(unsigned long j, int cpu,
bool force_up)
{
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.
* But never round down if @force_up is set.
*/
if (rem < HZ/4 && !force_up) /* round down */
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;
}

/**
* __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);
}
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
*
* __round_jiffies_relative() rounds a time delta 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_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, false) - j0;
}
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
*
* 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 return value is the rounded version of the @j parameter.
*/
unsigned long round_jiffies(unsigned long j)
{
return round_jiffies_common(j, raw_smp_processor_id(), false);
}
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
*
* round_jiffies_relative() rounds a time delta 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 return value is the rounded version of the @j parameter.
*/
unsigned long round_jiffies_relative(unsigned long j)
{
return __round_jiffies_relative(j, raw_smp_processor_id());
}
EXPORT_SYMBOL_GPL(round_jiffies_relative);

/**
* __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);

/**
* set_timer_slack - set the allowed slack for a timer
* @timer: the timer to be modified
* @slack_hz: the amount of time (in jiffies) allowed for rounding
*
* Set the amount of time, in jiffies, that a certain timer has
* in terms of slack. By setting this value, the timer subsystem
* will schedule the actual timer somewhere between
* the time mod_timer() asks for, and that time plus the slack.
*
* By setting the slack to -1, a percentage of the delay is used
* instead.
*/
void set_timer_slack(struct timer_list *timer, int slack_hz)
{
timer->slack = slack_hz;
}
EXPORT_SYMBOL_GPL(set_timer_slack);

static void
__internal_add_timer(struct tvec_base *base, struct timer_list *timer)
{
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 MAX_TVAL (on 64-bit
* architectures or with CONFIG_BASE_SMALL=1) then we
* use the maximum timeout.
*/
if (idx > MAX_TVAL) {
idx = MAX_TVAL;
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);
}

static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
{
__internal_add_timer(base, timer);
/*
* Update base->active_timers and base->next_timer
*/
if (!tbase_get_deferrable(timer->base)) {
if (time_before(timer->expires, base->next_timer))
base->next_timer = timer->expires;
base->active_timers++;
}
}

#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;
}

static void timer_stats_account_timer(struct timer_list *timer)
{
unsigned int flag = 0;

if (likely(!timer->start_site))
return;
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) {}
#endif

#ifdef CONFIG_DEBUG_OBJECTS_TIMERS

static struct debug_obj_descr timer_debug_descr;

static void *timer_debug_hint(void *addr)
{
return ((struct timer_list *) addr)->function;
}

/*
* fixup_init is called when:
* - an active object is initialized
*/
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;
}
}

/* Stub timer callback for improperly used timers. */
static void stub_timer(unsigned long data)
{
WARN_ON(1);
}

/*
* 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 {
setup_timer(timer, stub_timer, 0);
return 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;
}
}

/*
* fixup_assert_init is called when:
* - an untracked/uninit-ed object is found
*/
static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)
{
struct timer_list *timer = addr;

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

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

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 inline void debug_timer_assert_init(struct timer_list *timer)
{
debug_object_assert_init(timer, &timer_debug_descr);
}

static void do_init_timer(struct timer_list *timer, unsigned int flags,
const char *name, struct lock_class_key *key);

void init_timer_on_stack_key(struct timer_list *timer, unsigned int flags,
const char *name, struct lock_class_key *key)
{
debug_object_init_on_stack(timer, &timer_debug_descr);
do_init_timer(timer, flags, name, key);
}
EXPORT_SYMBOL_GPL(init_timer_on_stack_key);

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) { }
static inline void debug_timer_assert_init(struct timer_list *timer) { }
#endif

static inline void debug_init(struct timer_list *timer)
{
debug_timer_init(timer);
trace_timer_init(timer);
}

static inline void
debug_activate(struct timer_list *timer, unsigned long expires)
{
debug_timer_activate(timer);
trace_timer_start(timer, expires);
}

static inline void debug_deactivate(struct timer_list *timer)
{
debug_timer_deactivate(timer);
trace_timer_cancel(timer);
}

static inline void debug_assert_init(struct timer_list *timer)
{
debug_timer_assert_init(timer);
}

static void do_init_timer(struct timer_list *timer, unsigned int flags,
const char *name, struct lock_class_key *key)
{
struct tvec_base *base = __raw_get_cpu_var(tvec_bases);

timer->entry.next = NULL;
timer->base = (void *)((unsigned long)base | flags);
timer->slack = -1;
#ifdef CONFIG_TIMER_STATS
timer->start_site = NULL;
timer->start_pid = -1;
memset(timer->start_comm, 0, TASK_COMM_LEN);
#endif
lockdep_init_map(&timer->lockdep_map, name, key, 0);
}

/**
* init_timer_key - initialize a timer
* @timer: the timer to be initialized
* @flags: timer flags
* @name: name of the timer
* @key: lockdep class key of the fake lock used for tracking timer
* sync lock dependencies
*
* init_timer_key() must be done to a timer prior calling *any* of the
* other timer functions.
*/
void init_timer_key(struct timer_list *timer, unsigned int flags,
const char *name, struct lock_class_key *key)
{
debug_init(timer);
do_init_timer(timer, flags, name, key);
}
EXPORT_SYMBOL(init_timer_key);

static inline void detach_timer(struct timer_list *timer, bool clear_pending)
{
struct list_head *entry = &timer->entry;

debug_deactivate(timer);

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

static inline void
detach_expired_timer(struct timer_list *timer, struct tvec_base *base)
{
detach_timer(timer, true);
if (!tbase_get_deferrable(timer->base))
base->active_timers--;
}

static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
bool clear_pending)
{
if (!timer_pending(timer))
return 0;

detach_timer(timer, clear_pending);
if (!tbase_get_deferrable(timer->base)) {
base->active_timers--;
if (timer->expires == base->next_timer)
base->next_timer = base->timer_jiffies;
}
return 1;
}

/*
* We are using hashed locking: holding per_cpu(tvec_bases).lock
* 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.
*/
static struct tvec_base *lock_timer_base(struct timer_list *timer,
unsigned long *flags)
__acquires(timer->base->lock)
{
struct tvec_base *base;

for (;;) {
struct tvec_base *prelock_base = timer->base;
base = tbase_get_base(prelock_base);
if (likely(base != NULL)) {
spin_lock_irqsave(&base->lock, *flags);
if (likely(prelock_base == timer->base))
return base;
/* The timer has migrated to another CPU */
spin_unlock_irqrestore(&base->lock, *flags);
}
cpu_relax();
}
}

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

timer_stats_timer_set_start_info(timer);
BUG_ON(!timer->function);

base = lock_timer_base(timer, &flags);

ret = detach_if_pending(timer, base, false);
if (!ret && pending_only)
goto out_unlock;

debug_activate(timer, expires);

cpu = smp_processor_id();

#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu))
cpu = get_nohz_timer_target();
#endif
new_base = per_cpu(tvec_bases, cpu);

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

timer->expires = expires;
internal_add_timer(base, timer);

out_unlock:
spin_unlock_irqrestore(&base->lock, flags);

return ret;
}

/**
* mod_timer_pending - modify a pending timer's timeout
* @timer: the pending timer to be modified
* @expires: new timeout in jiffies
*
* 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.
*/
int mod_timer_pending(struct timer_list *timer, unsigned long expires)
{
return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
}
EXPORT_SYMBOL(mod_timer_pending);

/*
* Decide where to put the timer while taking the slack into account
*
* Algorithm:
* 1) calculate the maximum (absolute) time
* 2) calculate the highest bit where the expires and new max are different
* 3) use this bit to make a mask
* 4) use the bitmask to round down the maximum time, so that all last
* bits are zeros
*/
static inline
unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
{
unsigned long expires_limit, mask;
int bit;

if (timer->slack >= 0) {
expires_limit = expires + timer->slack;
} else {
long delta = expires - jiffies;

if (delta < 256)
return expires;

expires_limit = expires + delta / 256;
}
mask = expires ^ expires_limit;
if (mask == 0)
return expires;

bit = find_last_bit(&mask, BITS_PER_LONG);

mask = (1 << bit) - 1;

expires_limit = expires_limit & ~(mask);

return expires_limit;
}

/**
* mod_timer - modify a timer's timeout
* @timer: the timer to be modified
* @expires: new timeout in jiffies
*
* mod_timer() is a more efficient way to update the expire field of an
* 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)
{
expires = apply_slack(timer, 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_pending(timer) && timer->expires == expires)
return 1;

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

/**
* 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 to ensure that the timer is scheduled on the current CPU.
*
* Note that this does not prevent the timer from being migrated
* when the current CPU goes offline. If this is a problem for
* you, use CPU-hotplug notifiers to handle it correctly, for
* example, cancelling the timer when the corresponding CPU goes
* offline.
*
* 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);

/**
* 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_activate(timer, timer->expires);
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);
}
EXPORT_SYMBOL_GPL(add_timer_on);

/**
* 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)
{
struct tvec_base *base;
unsigned long flags;
int ret = 0;

debug_assert_init(timer);

timer_stats_timer_clear_start_info(timer);
if (timer_pending(timer)) {
base = lock_timer_base(timer, &flags);
ret = detach_if_pending(timer, base, true);
spin_unlock_irqrestore(&base->lock, flags);
}

return ret;
}
EXPORT_SYMBOL(del_timer);

/**
* try_to_del_timer_sync - Try to deactivate a timer
* @timer: timer do del
*
* 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.
*/
int try_to_del_timer_sync(struct timer_list *timer)
{
struct tvec_base *base;
unsigned long flags;
int ret = -1;

debug_assert_init(timer);

base = lock_timer_base(timer, &flags);

if (base->running_timer != timer) {
timer_stats_timer_clear_start_info(timer);
ret = detach_if_pending(timer, base, true);
}
spin_unlock_irqrestore(&base->lock, flags);

return ret;
}
EXPORT_SYMBOL(try_to_del_timer_sync);

#ifdef CONFIG_SMP
/**
* 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.
*
* Synchronization rules: Callers must prevent restarting of the timer,
* otherwise this function is meaningless. It must not be called from
* interrupt contexts unless the timer is an irqsafe one. The caller must
* not hold locks which would prevent 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.
*
* Note: For !irqsafe timers, you must not hold locks that are held in
* interrupt context while calling this function. Even if the lock has
* nothing to do with the timer in question. Here's why:
*
* CPU0 CPU1
* ---- ----
* <SOFTIRQ>
* call_timer_fn();
* base->running_timer = mytimer;
* spin_lock_irq(somelock);
* <IRQ>
* spin_lock(somelock);
* del_timer_sync(mytimer);
* while (base->running_timer == mytimer);
*
* Now del_timer_sync() will never return and never release somelock.
* The interrupt on the other CPU is waiting to grab somelock but
* it has interrupted the softirq that CPU0 is waiting to finish.
*
* The function returns whether it has deactivated a pending timer or not.
*/
int del_timer_sync(struct timer_list *timer)
{
#ifdef CONFIG_LOCKDEP
unsigned long flags;

/*
* If lockdep gives a backtrace here, please reference
* the synchronization rules above.
*/
local_irq_save(flags);
lock_map_acquire(&timer->lockdep_map);
lock_map_release(&timer->lockdep_map);
local_irq_restore(flags);
#endif
/*
* don't use it in hardirq context, because it
* could lead to deadlock.
*/
WARN_ON(in_irq() && !tbase_get_irqsafe(timer->base));
for (;;) {
int ret = try_to_del_timer_sync(timer);
if (ret >= 0)
return ret;
cpu_relax();
}
}
EXPORT_SYMBOL(del_timer_sync);
#endif

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

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

/*
* We are removing _all_ timers from the list, so we
* don't have to detach them individually.
*/
list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
BUG_ON(tbase_get_base(timer->base) != base);
/* No accounting, while moving them */
__internal_add_timer(base, timer);
}

return index;
}

static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
unsigned long data)
{
int preempt_count = preempt_count();

#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;

lockdep_copy_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);

trace_timer_expire_entry(timer);
fn(data);
trace_timer_expire_exit(timer);

lock_map_release(&lockdep_map);

if (preempt_count != preempt_count()) {
WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
fn, preempt_count, preempt_count());
/*
* Restore the preempt count. That gives us a decent
* chance to survive and extract information. If the
* callback kept a lock held, bad luck, but not worse
* than the BUG() we had.
*/
preempt_count() = preempt_count;
}
}

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

/**
* __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.
*/
static inline void __run_timers(struct tvec_base *base)
{
struct timer_list *timer;

spin_lock_irq(&base->lock);
while (time_after_eq(jiffies, base->timer_jiffies)) {
struct list_head work_list;
struct list_head *head = &work_list;
int index = base->timer_jiffies & TVR_MASK;

/*
* 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));
++base->timer_jiffies;
list_replace_init(base->tv1.vec + index, &work_list);
while (!list_empty(head)) {
void (*fn)(unsigned long);
unsigned long data;
bool irqsafe;

timer = list_first_entry(head, struct timer_list,entry);
fn = timer->function;
data = timer->data;
irqsafe = tbase_get_irqsafe(timer->base);

timer_stats_account_timer(timer);

base->running_timer = timer;
detach_expired_timer(timer, base);

if (irqsafe) {
spin_unlock(&base->lock);
call_timer_fn(timer, fn, data);
spin_lock(&base->lock);
} else {
spin_unlock_irq(&base->lock);
call_timer_fn(timer, fn, data);
spin_lock_irq(&base->lock);
}
}
}
base->running_timer = NULL;
spin_unlock_irq(&base->lock);
}

#ifdef CONFIG_NO_HZ
/*
* Find out when the next timer event is due to happen. This
* is used on S/390 to stop all activity when a CPU is idle.
* This function needs to be called with interrupts disabled.
*/
static unsigned long __next_timer_interrupt(struct tvec_base *base)
{
unsigned long timer_jiffies = base->timer_jiffies;
unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;
int index, slot, array, found = 0;
struct timer_list *nte;
struct tvec *varray[4];

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

found = 1;
expires = nte->expires;
/* Look at the cascade bucket(s)? */
if (!index || slot < index)
goto cascade;
return expires;
}
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;

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

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

index = slot = timer_jiffies & TVN_MASK;
do {
list_for_each_entry(nte, varp->vec + slot, entry) {
if (tbase_get_deferrable(nte->base))
continue;

found = 1;
if (time_before(nte->expires, expires))
expires = nte->expires;
}
/*
* 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;
}
return expires;
}

/*
* 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;
unsigned long delta;

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

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

tsdelta = ktime_to_timespec(hr_delta);
delta = timespec_to_jiffies(&tsdelta);

/*
* 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;

/*
* 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;
if (time_before(now, expires))
return now;
return expires;
}

/**
* get_next_timer_interrupt - return the jiffy of the next pending timer
* @now: current time (in jiffies)
*/
unsigned long get_next_timer_interrupt(unsigned long now)
{
struct tvec_base *base = __this_cpu_read(tvec_bases);
unsigned long expires = now + NEXT_TIMER_MAX_DELTA;

/*
* Pretend that there is no timer pending if the cpu is offline.
* Possible pending timers will be migrated later to an active cpu.
*/
if (cpu_is_offline(smp_processor_id()))
return expires;

spin_lock(&base->lock);
if (base->active_timers) {
if (time_before_eq(base->next_timer, base->timer_jiffies))
base->next_timer = __next_timer_interrupt(base);
expires = base->next_timer;
}
spin_unlock(&base->lock);

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

return cmp_next_hrtimer_event(now, expires);
}
#endif

/*
* Called from the timer interrupt handler to charge one tick to the current
* 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. */
account_process_tick(p, user_tick);
run_local_timers();
rcu_check_callbacks(cpu, user_tick);
printk_tick();
#ifdef CONFIG_IRQ_WORK
if (in_irq())
irq_work_run();
#endif
scheduler_tick();
run_posix_cpu_timers(p);
}

/*
* This function runs timers and the timer-tq in bottom half context.
*/
static void run_timer_softirq(struct softirq_action *h)
{
struct tvec_base *base = __this_cpu_read(tvec_bases);

hrtimer_run_pending();

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)
{
hrtimer_run_queues();
raise_softirq(TIMER_SOFTIRQ);
}

#ifdef __ARCH_WANT_SYS_ALARM

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

#endif

/**
* 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.
*/
SYSCALL_DEFINE0(getpid)
{
return task_tgid_vnr(current);
}

/*
* 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).
*/
SYSCALL_DEFINE0(getppid)
{
int pid;

rcu_read_lock();
pid = task_tgid_vnr(rcu_dereference(current->real_parent));
rcu_read_unlock();

return pid;
}

SYSCALL_DEFINE0(getuid)
{
/* Only we change this so SMP safe */
return from_kuid_munged(current_user_ns(), current_uid());
}

SYSCALL_DEFINE0(geteuid)
{
/* Only we change this so SMP safe */
return from_kuid_munged(current_user_ns(), current_euid());
}

SYSCALL_DEFINE0(getgid)
{
/* Only we change this so SMP safe */
return from_kgid_munged(current_user_ns(), current_gid());
}

SYSCALL_DEFINE0(getegid)
{
/* Only we change this so SMP safe */
return from_kgid_munged(current_user_ns(), current_egid());
}

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

/**
* 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.
*/
signed long __sched schedule_timeout(signed long timeout)
{
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.
*/
if (timeout < 0) {
printk(KERN_ERR "schedule_timeout: wrong timeout "
"value %lx\n", timeout);
dump_stack();
current->state = TASK_RUNNING;
goto out;
}
}

expire = timeout + jiffies;

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

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

timeout = expire - jiffies;

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

/*
* We can use __set_current_state() here because schedule_timeout() calls
* schedule() unconditionally.
*/
signed long __sched schedule_timeout_interruptible(signed long timeout)
{
__set_current_state(TASK_INTERRUPTIBLE);
return schedule_timeout(timeout);
}
EXPORT_SYMBOL(schedule_timeout_interruptible);

signed long __sched schedule_timeout_killable(signed long timeout)
{
__set_current_state(TASK_KILLABLE);
return schedule_timeout(timeout);
}
EXPORT_SYMBOL(schedule_timeout_killable);

signed long __sched schedule_timeout_uninterruptible(signed long timeout)
{
__set_current_state(TASK_UNINTERRUPTIBLE);
return schedule_timeout(timeout);
}
EXPORT_SYMBOL(schedule_timeout_uninterruptible);

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

/**
* do_sysinfo - fill in sysinfo struct
* @info: pointer to buffer to fill
*/
int do_sysinfo(struct sysinfo *info)
{
unsigned long mem_total, sav_total;
unsigned int mem_unit, bitcount;
struct timespec tp;

memset(info, 0, sizeof(struct sysinfo));

ktime_get_ts(&tp);
monotonic_to_bootbased(&tp);
info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);

get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);

info->procs = nr_threads;

si_meminfo(info);
si_swapinfo(info);

/*
* 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>
*/

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

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;
}

SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
{
struct sysinfo val;

do_sysinfo(&val);

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

return 0;
}

static int __cpuinit init_timers_cpu(int cpu)
{
int j;
struct tvec_base *base;
static char __cpuinitdata tvec_base_done[NR_CPUS];

if (!tvec_base_done[cpu]) {
static char boot_done;

if (boot_done) {
/*
* The APs use this path later in boot
*/
base = kmalloc_node(sizeof(*base),
GFP_KERNEL | __GFP_ZERO,
cpu_to_node(cpu));
if (!base)
return -ENOMEM;

/* Make sure that tvec_base is 2 byte aligned */
if (tbase_get_deferrable(base)) {
WARN_ON(1);
kfree(base);
return -ENOMEM;
}
per_cpu(tvec_bases, cpu) = base;
} else {
/*
* 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.
*/
boot_done = 1;
base = &boot_tvec_bases;
}
tvec_base_done[cpu] = 1;
} else {
base = per_cpu(tvec_bases, cpu);
}

spin_lock_init(&base->lock);

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;
base->next_timer = base->timer_jiffies;
base->active_timers = 0;
return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
static void migrate_timer_list(struct tvec_base *new_base, struct list_head *head)
{
struct timer_list *timer;

while (!list_empty(head)) {
timer = list_first_entry(head, struct timer_list, entry);
/* We ignore the accounting on the dying cpu */
detach_timer(timer, false);
timer_set_base(timer, new_base);
internal_add_timer(new_base, timer);
}
}

static void __cpuinit migrate_timers(int cpu)
{
struct tvec_base *old_base;
struct tvec_base *new_base;
int i;

BUG_ON(cpu_online(cpu));
old_base = per_cpu(tvec_bases, cpu);
new_base = get_cpu_var(tvec_bases);
/*
* The caller is globally serialized and nobody else
* takes two locks at once, deadlock is not possible.
*/
spin_lock_irq(&new_base->lock);
spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);

BUG_ON(old_base->running_timer);

for (i = 0; i < TVR_SIZE; i++)
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);
}

spin_unlock(&old_base->lock);
spin_unlock_irq(&new_base->lock);
put_cpu_var(tvec_bases);
}
#endif /* CONFIG_HOTPLUG_CPU */

static int __cpuinit timer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
int err;

switch(action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
err = init_timers_cpu(cpu);
if (err < 0)
return notifier_from_errno(err);
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DEAD:
case CPU_DEAD_FROZEN:
migrate_timers(cpu);
break;
#endif
default:
break;
}
return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata timers_nb = {
.notifier_call = timer_cpu_notify,
};


void __init init_timers(void)
{
int err;

/* ensure there are enough low bits for flags in timer->base pointer */
BUILD_BUG_ON(__alignof__(struct tvec_base) & TIMER_FLAG_MASK);

err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
(void *)(long)smp_processor_id());
init_timer_stats();

BUG_ON(err != NOTIFY_OK);
register_cpu_notifier(&timers_nb);
open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
}

/**
* 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;

while (timeout)
timeout = schedule_timeout_uninterruptible(timeout);
}

EXPORT_SYMBOL(msleep);

/**
* msleep_interruptible - sleep waiting for signals
* @msecs: Time in milliseconds to sleep for
*/
unsigned long msleep_interruptible(unsigned int msecs)
{
unsigned long timeout = msecs_to_jiffies(msecs) + 1;

while (timeout && !signal_pending(current))
timeout = schedule_timeout_interruptible(timeout);
return jiffies_to_msecs(timeout);
}

EXPORT_SYMBOL(msleep_interruptible);

static int __sched do_usleep_range(unsigned long min, unsigned long max)
{
ktime_t kmin;
unsigned long delta;

kmin = ktime_set(0, min * NSEC_PER_USEC);
delta = (max - min) * NSEC_PER_USEC;
return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
}

/**
* usleep_range - Drop in replacement for udelay where wakeup is flexible
* @min: Minimum time in usecs to sleep
* @max: Maximum time in usecs to sleep
*/
void usleep_range(unsigned long min, unsigned long max)
{
__set_current_state(TASK_UNINTERRUPTIBLE);
do_usleep_range(min, max);
}
EXPORT_SYMBOL(usleep_range);
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