提交 fd450b73 编写于 作者: O Oleg Nesterov 提交者: Linus Torvalds

[PATCH] timers: introduce try_to_del_timer_sync()

This patch splits del_timer_sync() into 2 functions.  The new one,
try_to_del_timer_sync(), returns -1 when it hits executing timer.

It can be used in interrupt context, or when the caller hold locks which
can prevent completion of the timer's handler.

NOTE.  Currently it can't be used in interrupt context in UP case, because
->running_timer is used only with CONFIG_SMP.

Should the need arise, it is possible to kill #ifdef CONFIG_SMP in
set_running_timer(), it is cheap.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
上级 55c888d6
...@@ -76,9 +76,11 @@ static inline void add_timer(struct timer_list * timer) ...@@ -76,9 +76,11 @@ static inline void add_timer(struct timer_list * timer)
} }
#ifdef CONFIG_SMP #ifdef CONFIG_SMP
extern int try_to_del_timer_sync(struct timer_list *timer);
extern int del_timer_sync(struct timer_list *timer); extern int del_timer_sync(struct timer_list *timer);
#else #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 #endif
#define del_singleshot_timer_sync(t) del_timer_sync(t) #define del_singleshot_timer_sync(t) del_timer_sync(t)
......
...@@ -365,6 +365,34 @@ int del_timer(struct timer_list *timer) ...@@ -365,6 +365,34 @@ int del_timer(struct timer_list *timer)
EXPORT_SYMBOL(del_timer); EXPORT_SYMBOL(del_timer);
#ifdef CONFIG_SMP #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. * del_timer_sync - deactivate a timer and wait for the handler to finish.
* @timer: the timer to be deactivated * @timer: the timer to be deactivated
...@@ -384,28 +412,13 @@ EXPORT_SYMBOL(del_timer); ...@@ -384,28 +412,13 @@ EXPORT_SYMBOL(del_timer);
*/ */
int del_timer_sync(struct timer_list *timer) int del_timer_sync(struct timer_list *timer)
{ {
timer_base_t *base;
unsigned long flags;
int ret = -1;
check_timer(timer); check_timer(timer);
do { for (;;) {
base = lock_timer_base(timer, &flags); int ret = try_to_del_timer_sync(timer);
if (ret >= 0)
if (base->running_timer == timer) return ret;
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;
} }
EXPORT_SYMBOL(del_timer_sync); EXPORT_SYMBOL(del_timer_sync);
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册