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Diffstat (limited to 'kernel/timer.c')
-rw-r--r--kernel/timer.c110
1 files changed, 61 insertions, 49 deletions
diff --git a/kernel/timer.c b/kernel/timer.c
index 6ec7e7e0db4..a61c09374eb 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -77,6 +77,7 @@ struct tvec_base {
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;
@@ -330,7 +331,8 @@ void set_timer_slack(struct timer_list *timer, int slack_hz)
}
EXPORT_SYMBOL_GPL(set_timer_slack);
-static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
+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;
@@ -372,6 +374,19 @@ static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
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)
{
@@ -654,8 +669,7 @@ void init_timer_deferrable_key(struct timer_list *timer,
}
EXPORT_SYMBOL(init_timer_deferrable_key);
-static inline void detach_timer(struct timer_list *timer,
- int clear_pending)
+static inline void detach_timer(struct timer_list *timer, bool clear_pending)
{
struct list_head *entry = &timer->entry;
@@ -667,6 +681,29 @@ static inline void detach_timer(struct timer_list *timer,
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))
+ timer->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)) {
+ timer->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
@@ -712,16 +749,9 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
base = lock_timer_base(timer, &flags);
- if (timer_pending(timer)) {
- detach_timer(timer, 0);
- if (timer->expires == base->next_timer &&
- !tbase_get_deferrable(timer->base))
- base->next_timer = base->timer_jiffies;
- ret = 1;
- } else {
- if (pending_only)
- goto out_unlock;
- }
+ ret = detach_if_pending(timer, base, false);
+ if (!ret && pending_only)
+ goto out_unlock;
debug_activate(timer, expires);
@@ -752,9 +782,6 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
}
timer->expires = expires;
- if (time_before(timer->expires, base->next_timer) &&
- !tbase_get_deferrable(timer->base))
- base->next_timer = timer->expires;
internal_add_timer(base, timer);
out_unlock:
@@ -920,9 +947,6 @@ void add_timer_on(struct timer_list *timer, int cpu)
spin_lock_irqsave(&base->lock, flags);
timer_set_base(timer, base);
debug_activate(timer, timer->expires);
- if (time_before(timer->expires, base->next_timer) &&
- !tbase_get_deferrable(timer->base))
- base->next_timer = timer->expires;
internal_add_timer(base, timer);
/*
* Check whether the other CPU is idle and needs to be
@@ -959,13 +983,7 @@ int del_timer(struct timer_list *timer)
timer_stats_timer_clear_start_info(timer);
if (timer_pending(timer)) {
base = lock_timer_base(timer, &flags);
- if (timer_pending(timer)) {
- detach_timer(timer, 1);
- if (timer->expires == base->next_timer &&
- !tbase_get_deferrable(timer->base))
- base->next_timer = base->timer_jiffies;
- ret = 1;
- }
+ ret = detach_if_pending(timer, base, true);
spin_unlock_irqrestore(&base->lock, flags);
}
@@ -990,19 +1008,10 @@ int try_to_del_timer_sync(struct timer_list *timer)
base = lock_timer_base(timer, &flags);
- if (base->running_timer == timer)
- goto out;
-
- timer_stats_timer_clear_start_info(timer);
- ret = 0;
- if (timer_pending(timer)) {
- detach_timer(timer, 1);
- if (timer->expires == base->next_timer &&
- !tbase_get_deferrable(timer->base))
- base->next_timer = base->timer_jiffies;
- ret = 1;
+ if (base->running_timer != timer) {
+ timer_stats_timer_clear_start_info(timer);
+ ret = detach_if_pending(timer, base, true);
}
-out:
spin_unlock_irqrestore(&base->lock, flags);
return ret;
@@ -1089,7 +1098,8 @@ static int cascade(struct tvec_base *base, struct tvec *tv, int index)
*/
list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
BUG_ON(tbase_get_base(timer->base) != base);
- internal_add_timer(base, timer);
+ /* No accounting, while moving them */
+ __internal_add_timer(base, timer);
}
return index;
@@ -1178,7 +1188,7 @@ static inline void __run_timers(struct tvec_base *base)
timer_stats_account_timer(timer);
base->running_timer = timer;
- detach_timer(timer, 1);
+ detach_expired_timer(timer, base);
spin_unlock_irq(&base->lock);
call_timer_fn(timer, fn, data);
@@ -1316,18 +1326,21 @@ static unsigned long cmp_next_hrtimer_event(unsigned long now,
unsigned long get_next_timer_interrupt(unsigned long now)
{
struct tvec_base *base = __this_cpu_read(tvec_bases);
- unsigned long expires;
+ 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 now + NEXT_TIMER_MAX_DELTA;
+ return expires;
+
spin_lock(&base->lock);
- if (time_before_eq(base->next_timer, base->timer_jiffies))
- base->next_timer = __next_timer_interrupt(base);
- expires = base->next_timer;
+ 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))
@@ -1704,6 +1717,7 @@ static int __cpuinit init_timers_cpu(int cpu)
base->timer_jiffies = jiffies;
base->next_timer = base->timer_jiffies;
+ base->active_timers = 0;
return 0;
}
@@ -1714,11 +1728,9 @@ static void migrate_timer_list(struct tvec_base *new_base, struct list_head *hea
while (!list_empty(head)) {
timer = list_first_entry(head, struct timer_list, entry);
- detach_timer(timer, 0);
+ /* We ignore the accounting on the dying cpu */
+ detach_timer(timer, false);
timer_set_base(timer, new_base);
- if (time_before(timer->expires, new_base->next_timer) &&
- !tbase_get_deferrable(timer->base))
- new_base->next_timer = timer->expires;
internal_add_timer(new_base, timer);
}
}