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

Browse source 
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: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Oleg Nesterov 2008-12-01 14:18:15 -08:00 committed by Ingo Molnar
parent 27af4245b6
commit 899921025b
1 changed files with 7 additions and 10 deletions
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17
kernel/posix-timers.c
View file

@ -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); idr_remove(&posix_timers_id, tmr->it_id);
spin_unlock_irqrestore(&idr_lock, flags); spin_unlock_irqrestore(&idr_lock, flags);
} }
put_pid(tmr->it_pid);
sigqueue_free(tmr->sigq); sigqueue_free(tmr->sigq);
kmem_cache_free(posix_timers_cache, tmr); kmem_cache_free(posix_timers_cache, tmr);
} }
@ -477,7 +478,6 @@ sys_timer_create(const clockid_t which_clock,
{ {
struct k_itimer *new_timer; struct k_itimer *new_timer;
int error, new_timer_id; int error, new_timer_id;
struct pid *it_pid;
sigevent_t event; sigevent_t event;
int it_id_set = IT_ID_NOT_SET; int it_id_set = IT_ID_NOT_SET;
@ -531,9 +531,9 @@ sys_timer_create(const clockid_t which_clock,
goto out; goto out;
} }
rcu_read_lock(); rcu_read_lock();
it_pid = get_pid(good_sigevent(&event)); new_timer->it_pid = get_pid(good_sigevent(&event));
rcu_read_unlock(); rcu_read_unlock();
if (!it_pid) { if (!new_timer->it_pid) {
error = -EINVAL; error = -EINVAL;
goto out; goto out;
} }
@ -541,7 +541,7 @@ sys_timer_create(const clockid_t which_clock,
event.sigev_notify = SIGEV_SIGNAL; event.sigev_notify = SIGEV_SIGNAL;
event.sigev_signo = SIGALRM; event.sigev_signo = SIGALRM;
event.sigev_value.sival_int = new_timer->it_id; 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; 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; new_timer->sigq->info.si_code = SI_TIMER;
spin_lock_irq(&current->sighand->siglock); spin_lock_irq(&current->sighand->siglock);
new_timer->it_pid = it_pid;
new_timer->it_signal = current->signal; new_timer->it_signal = current->signal;
list_add(&new_timer->list, &current->signal->posix_timers); list_add(&new_timer->list, &current->signal->posix_timers);
spin_unlock_irq(&current->sighand->siglock); 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); timr = idr_find(&posix_timers_id, (int)timer_id);
if (timr) { if (timr) {
spin_lock(&timr->it_lock); spin_lock(&timr->it_lock);
if (timr->it_pid && timr->it_signal == current->signal) { if (timr->it_signal == current->signal) {
spin_unlock(&idr_lock); spin_unlock(&idr_lock);
return timr; return timr;
} }
@ -834,8 +833,7 @@ retry_delete:
* This keeps any tasks waiting on the spin lock from thinking * This keeps any tasks waiting on the spin lock from thinking
* they got something (see the lock code above). * they got something (see the lock code above).
*/ */
put_pid(timer->it_pid); timer->it_signal = NULL;
timer->it_pid = NULL;
unlock_timer(timer, flags); unlock_timer(timer, flags);
release_posix_timer(timer, IT_ID_SET); release_posix_timer(timer, IT_ID_SET);
@ -861,8 +859,7 @@ retry_delete:
* This keeps any tasks waiting on the spin lock from thinking * This keeps any tasks waiting on the spin lock from thinking
* they got something (see the lock code above). * they got something (see the lock code above).
*/ */
put_pid(timer->it_pid); timer->it_signal = NULL;
timer->it_pid = NULL;
unlock_timer(timer, flags); unlock_timer(timer, flags);
release_posix_timer(timer, IT_ID_SET); release_posix_timer(timer, IT_ID_SET);