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Commit 89992102 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
Browse files

posix-timers: check ->it_signal instead of ->it_pid to validate the timer 



Impact: clean up, speed up

->it_pid (was ->it_process) has also a special meaning: if it is NULL,
the timer is under deletion or it wasn't initialized yet. We can check
->it_signal != NULL instead, this way we can

	- simplify sys_timer_create() a bit

	- remove yet another check from lock_timer()

	- move put_pid(->it_pid) into release_posix_timer() which
	  runs outside of ->it_lock

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 27af4245

kernel/posix-timers.c

+7 −10
Original line number Diff line number Diff line
@@ -464,6 +464,7 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set) 
		idr_remove(&posix_timers_id, tmr->it_id);

		spin_unlock_irqrestore(&idr_lock, flags);

	}

	put_pid(tmr->it_pid);

	sigqueue_free(tmr->sigq);

	kmem_cache_free(posix_timers_cache, tmr);

}
@@ -477,7 +478,6 @@ sys_timer_create(const clockid_t which_clock, 
{

	struct k_itimer *new_timer;

	int error, new_timer_id;

	struct pid *it_pid;

	sigevent_t event;

	int it_id_set = IT_ID_NOT_SET;
@@ -531,9 +531,9 @@ sys_timer_create(const clockid_t which_clock, 
			goto out;

		}

		rcu_read_lock();

		it_pid = get_pid(good_sigevent(&event));

		new_timer->it_pid = get_pid(good_sigevent(&event));

		rcu_read_unlock();

		if (!it_pid) {

		if (!new_timer->it_pid) {

			error = -EINVAL;

			goto out;

		}
@@ -541,7 +541,7 @@ sys_timer_create(const clockid_t which_clock, 
		event.sigev_notify = SIGEV_SIGNAL;

		event.sigev_signo = SIGALRM;

		event.sigev_value.sival_int = new_timer->it_id;

		it_pid = get_pid(task_tgid(current));

		new_timer->it_pid = get_pid(task_tgid(current));

	}



	new_timer->it_sigev_notify     = event.sigev_notify;
@@ -551,7 +551,6 @@ sys_timer_create(const clockid_t which_clock, 
	new_timer->sigq->info.si_code  = SI_TIMER;



	spin_lock_irq(&current->sighand->siglock);

	new_timer->it_pid = it_pid;

	new_timer->it_signal = current->signal;

	list_add(&new_timer->list, &current->signal->posix_timers);

	spin_unlock_irq(&current->sighand->siglock);
@@ -587,7 +586,7 @@ static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags) 
	timr = idr_find(&posix_timers_id, (int)timer_id);

	if (timr) {

		spin_lock(&timr->it_lock);

		if (timr->it_pid && timr->it_signal == current->signal) {

		if (timr->it_signal == current->signal) {

			spin_unlock(&idr_lock);

			return timr;

		}
@@ -834,8 +833,7 @@ sys_timer_delete(timer_t timer_id) 
	 * This keeps any tasks waiting on the spin lock from thinking

	 * they got something (see the lock code above).

	 */

	put_pid(timer->it_pid);

	timer->it_pid = NULL;

	timer->it_signal = NULL;



	unlock_timer(timer, flags);

	release_posix_timer(timer, IT_ID_SET);
@@ -861,8 +859,7 @@ static void itimer_delete(struct k_itimer *timer) 
	 * This keeps any tasks waiting on the spin lock from thinking

	 * they got something (see the lock code above).

	 */

	put_pid(timer->it_pid);

	timer->it_pid = NULL;

	timer->it_signal = NULL;



	unlock_timer(timer, flags);

	release_posix_timer(timer, IT_ID_SET);