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posix-timers: Handle the timer_[re]arm() return value

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The [re]arm callbacks will return true when the timer was queued and false
if it was already expired at enqueue time.

In both cases the call sites can trivially queue the signal right there,
when the timer was already expired. That avoids a full round trip through
the hrtimer interrupt.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260408114952.198028466@kernel.org
This commit is contained in:
Thomas Gleixner 2026-04-08 13:54:01 +02:00
parent 6fdb2677a5
commit cfb7fe3fdd
1 changed files with 17 additions and 5 deletions
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22
kernel/time/posix-timers.c
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@ -299,6 +299,8 @@ static bool common_hrtimer_rearm(struct k_itimer *timr)
static bool __posixtimer_deliver_signal(struct kernel_siginfo *info, struct k_itimer *timr)
{
bool queued;
guard(spinlock)(&timr->it_lock);
/*
@ -312,12 +314,18 @@ static bool __posixtimer_deliver_signal(struct kernel_siginfo *info, struct k_it
if (!timr->it_interval || WARN_ON_ONCE(timr->it_status != POSIX_TIMER_REQUEUE_PENDING))
return true;
timr->kclock->timer_rearm(timr);
timr->it_status = POSIX_TIMER_ARMED;
/* timer_rearm() updates timr::it_overrun */
queued = timr->kclock->timer_rearm(timr);
timr->it_overrun_last = timr->it_overrun;
timr->it_overrun = -1LL;
++timr->it_signal_seq;
info->si_overrun = timer_overrun_to_int(timr);
if (queued)
timr->it_status = POSIX_TIMER_ARMED;
else
posix_timer_queue_signal(timr);
return true;
}
@ -905,9 +913,13 @@ int common_timer_set(struct k_itimer *timr, int flags,
expires = timens_ktime_to_host(timr->it_clock, expires);
sigev_none = timr->it_sigev_notify == SIGEV_NONE;
kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none);
if (!sigev_none)
timr->it_status = POSIX_TIMER_ARMED;
if (kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none)) {
if (!sigev_none)
timr->it_status = POSIX_TIMER_ARMED;
} else {
/* Timer was already expired, queue the signal */
posix_timer_queue_signal(timr);
}
return 0;
}