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Commit f972be33 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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[PATCH] posix-timers: use try_to_del_timer_sync() 



sys_timer_settime/sys_timer_delete needs to delete k_itimer->real.timer
synchronously while holding ->it_lock, which is also locked in
posix_timer_fn.

This patch removes timer_active/set_timer_inactive which plays with
timer_list's internals in favour of using try_to_del_timer_sync(), which
was introduced in the previous patch.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent fd450b73

kernel/posix-timers.c

+7 −27
Original line number Diff line number Diff line
@@ -88,23 +88,6 @@ static kmem_cache_t *posix_timers_cache; 
static struct idr posix_timers_id;

static DEFINE_SPINLOCK(idr_lock);



/*

 * Just because the timer is not in the timer list does NOT mean it is

 * inactive.  It could be in the "fire" routine getting a new expire time.

 */

#define TIMER_INACTIVE 1



#ifdef CONFIG_SMP

# define timer_active(tmr) \

		((tmr)->it.real.timer.entry.prev != (void *)TIMER_INACTIVE)

# define set_timer_inactive(tmr) \

		do { \

			(tmr)->it.real.timer.entry.prev = (void *)TIMER_INACTIVE; \

		} while (0)

#else

# define timer_active(tmr) BARFY	// error to use outside of SMP

# define set_timer_inactive(tmr) do { } while (0)

#endif

/*

 * we assume that the new SIGEV_THREAD_ID shares no bits with the other

 * SIGEV values.  Here we put out an error if this assumption fails.
@@ -226,7 +209,6 @@ static inline int common_timer_create(struct k_itimer *new_timer) 
	init_timer(&new_timer->it.real.timer);

	new_timer->it.real.timer.data = (unsigned long) new_timer;

	new_timer->it.real.timer.function = posix_timer_fn;

	set_timer_inactive(new_timer);

	return 0;

}
@@ -480,7 +462,6 @@ static void posix_timer_fn(unsigned long __data) 
	int do_notify = 1;



	spin_lock_irqsave(&timr->it_lock, flags);

 	set_timer_inactive(timr);

	if (!list_empty(&timr->it.real.abs_timer_entry)) {

		spin_lock(&abs_list.lock);

		do {
@@ -983,8 +964,8 @@ common_timer_set(struct k_itimer *timr, int flags, 
	 * careful here.  If smp we could be in the "fire" routine which will

	 * be spinning as we hold the lock.  But this is ONLY an SMP issue.

	 */

	if (try_to_del_timer_sync(&timr->it.real.timer) < 0) {

#ifdef CONFIG_SMP

	if (timer_active(timr) && !del_timer(&timr->it.real.timer))

		/*

		 * It can only be active if on an other cpu.  Since

		 * we have cleared the interval stuff above, it should
@@ -994,11 +975,9 @@ common_timer_set(struct k_itimer *timr, int flags, 
		 * a "retry" exit status.

		 */

		return TIMER_RETRY;



	set_timer_inactive(timr);

#else

	del_timer(&timr->it.real.timer);

#endif

	}



	remove_from_abslist(timr);



	timr->it_requeue_pending = (timr->it_requeue_pending + 2) &
@@ -1083,8 +1062,9 @@ retry: 
static inline int common_timer_del(struct k_itimer *timer)

{

	timer->it.real.incr = 0;



	if (try_to_del_timer_sync(&timer->it.real.timer) < 0) {

#ifdef CONFIG_SMP

	if (timer_active(timer) && !del_timer(&timer->it.real.timer))

		/*

		 * It can only be active if on an other cpu.  Since

		 * we have cleared the interval stuff above, it should
@@ -1094,9 +1074,9 @@ static inline int common_timer_del(struct k_itimer *timer) 
		 * a "retry" exit status.

		 */

		return TIMER_RETRY;

#else

	del_timer(&timer->it.real.timer);

#endif

	}



	remove_from_abslist(timer);



	return 0;