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posix-timers: Rework cancel retry loops

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As a preparatory step for adding the PREEMPT RT specific synchronization
mechanism to wait for a running timer callback, rework the timer cancel
retry loops so they call a common function. This allows trivial
substitution in one place.

Originally-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190730223828.874901027@linutronix.de
This commit is contained in:
Thomas Gleixner 2019-07-31 00:33:53 +02:00
parent 21670ee44f
commit 6945e5c2ab
1 changed files with 23 additions and 6 deletions
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29
kernel/time/posix-timers.c
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@ -805,6 +805,17 @@ static int common_hrtimer_try_to_cancel(struct k_itimer *timr)
return hrtimer_try_to_cancel(&timr->it.real.timer);
}
static struct k_itimer *timer_wait_running(struct k_itimer *timer,
unsigned long *flags)
{
timer_t timer_id = READ_ONCE(timer->it_id);
unlock_timer(timer, *flags);
cpu_relax();
/* Relock the timer. It might be not longer hashed. */
return lock_timer(timer_id, flags);
}
/* Set a POSIX.1b interval timer. */
int common_timer_set(struct k_itimer *timr, int flags,
struct itimerspec64 *new_setting,
@ -859,8 +870,9 @@ static int do_timer_settime(timer_t timer_id, int tmr_flags,
if (old_spec64)
memset(old_spec64, 0, sizeof(*old_spec64));
retry:
timr = lock_timer(timer_id, &flags);
retry:
if (!timr)
return -EINVAL;
@ -870,11 +882,14 @@ retry:
else
error = kc->timer_set(timr, tmr_flags, new_spec64, old_spec64);
unlock_timer(timr, flags);
if (error == TIMER_RETRY) {
old_spec64 = NULL; // We already got the old time...
// We already got the old time...
old_spec64 = NULL;
/* Unlocks and relocks the timer if it still exists */
timr = timer_wait_running(timr, &flags);
goto retry;
}
unlock_timer(timr, flags);
return error;
}
@ -951,13 +966,15 @@ SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
struct k_itimer *timer;
unsigned long flags;
retry_delete:
timer = lock_timer(timer_id, &flags);
retry_delete:
if (!timer)
return -EINVAL;
if (timer_delete_hook(timer) == TIMER_RETRY) {
unlock_timer(timer, flags);
if (unlikely(timer_delete_hook(timer) == TIMER_RETRY)) {
/* Unlocks and relocks the timer if it still exists */
timer = timer_wait_running(timer, &flags);
goto retry_delete;
}