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-rw-r--r--include/linux/timer.h4
-rw-r--r--kernel/timer.c53
2 files changed, 36 insertions, 21 deletions
diff --git a/include/linux/timer.h b/include/linux/timer.h
index 2e78fedfc06..221f81ac200 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -76,9 +76,11 @@ static inline void add_timer(struct timer_list * timer)
}
#ifdef CONFIG_SMP
+ extern int try_to_del_timer_sync(struct timer_list *timer);
extern int del_timer_sync(struct timer_list *timer);
#else
-# define del_timer_sync(t) del_timer(t)
+# define try_to_del_timer_sync(t) del_timer(t)
+# define del_timer_sync(t) del_timer(t)
#endif
#define del_singleshot_timer_sync(t) del_timer_sync(t)
diff --git a/kernel/timer.c b/kernel/timer.c
index 8aadc62efd6..1f986c16d89 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -365,6 +365,34 @@ int del_timer(struct timer_list *timer)
EXPORT_SYMBOL(del_timer);
#ifdef CONFIG_SMP
+/*
+ * 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)
+{
+ timer_base_t *base;
+ 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;
+}
+
/***
* del_timer_sync - deactivate a timer and wait for the handler to finish.
* @timer: the timer to be deactivated
@@ -384,28 +412,13 @@ EXPORT_SYMBOL(del_timer);
*/
int del_timer_sync(struct timer_list *timer)
{
- timer_base_t *base;
- unsigned long flags;
- int ret = -1;
-
check_timer(timer);
- do {
- base = lock_timer_base(timer, &flags);
-
- if (base->running_timer == timer)
- goto unlock;
-
- ret = 0;
- if (timer_pending(timer)) {
- detach_timer(timer, 1);
- ret = 1;
- }
-unlock:
- spin_unlock_irqrestore(&base->lock, flags);
- } while (ret < 0);
-
- return ret;
+ for (;;) {
+ int ret = try_to_del_timer_sync(timer);
+ if (ret >= 0)
+ return ret;
+ }
}
EXPORT_SYMBOL(del_timer_sync);