Messages in this thread | | | Date | Wed, 16 Jun 2021 13:33:42 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 4/6] posix-cpu-timers: Force next_expiration recalc after timer reset |
| |
On Wed, Jun 16, 2021 at 01:21:11PM +0200, Frederic Weisbecker wrote: > On Wed, Jun 16, 2021 at 11:23:33AM +0200, Peter Zijlstra wrote: > > On Fri, Jun 04, 2021 at 01:31:57PM +0200, Frederic Weisbecker wrote: > > > > > @@ -647,8 +651,6 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, > > > if (unlikely(timer->it.cpu.firing)) { > > > timer->it.cpu.firing = -1; > > > ret = TIMER_RETRY; > > > - } else { > > > - cpu_timer_dequeue(ctmr); > > > } > > > > > > /* > > > @@ -713,9 +715,13 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, > > > * For a timer with no notification action, we don't actually > > > * arm the timer (we'll just fake it for timer_gettime). > > > */ > > > - cpu_timer_setexpires(ctmr, new_expires); > > > - if (new_expires != 0 && val < new_expires) { > > > - arm_timer(timer, p); > > > + if (new_expires != 0) { > > > + cpu_timer_dequeue(ctmr); > > > + cpu_timer_setexpires(ctmr, new_expires); > > > + if (val < new_expires) > > > + arm_timer(timer, p); > > > + } else { > > > + disarm_timer(timer, p); > > > } > > > > > > unlock_task_sighand(p, &flags); > > > > AFAICT there's an error path in between where you've removed > > cpu_timer_dequeue() and added it back. This error path will now leave > > the timer enqueued. > > Ah that's the case where the timer is firing. In this case it can't be queued > anyway. Also it's a retry path so we'll eventually dequeue it in any case > (should it be concurrently requeued after firing).
Urgh, I see.. this code is a maze :-(
| |