| Date | Tue, 20 Aug 2019 16:26:59 +0200 | From | Frederic Weisbecker <> | Subject | Re: [patch 04/44] posix-cpu-timers: Fixup stale comment |
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On Mon, Aug 19, 2019 at 04:31:45PM +0200, Thomas Gleixner wrote: > The comment above cleanup_timers() is outdated. The timers are only removed > from the task/process list heads but not modified in any other way. > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > kernel/time/posix-cpu-timers.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > --- a/kernel/time/posix-cpu-timers.c > +++ b/kernel/time/posix-cpu-timers.c > @@ -412,9 +412,10 @@ static void cleanup_timers_list(struct l > } > > /* > - * Clean out CPU timers still ticking when a thread exited. The task > - * pointer is cleared, and the expiry time is replaced with the residual > - * time for later timer_gettime calls to return. > + * Clean out CPU timers which are still armed when a thread exits. The > + * timers are only removed from the list. No other updates are done. The > + * corresponding posix timers are still accessible, but cannot be rearmed. > + * > * This must be called with the siglock held. > */ > static void cleanup_timers(struct list_head *head)
Indeed and I believe we could avoid that step. We remove the sighand at the same time so those can't be accessed anymore anyway.
exit_itimers() takes care of the last call release and could force remove from the list (although it might be taken care of in your series, haven't checked yet):
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 0a426f4e3125..f8f4a07025fd 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -383,11 +383,7 @@ static int posix_cpu_timer_del(struct k_itimer *timer) */ sighand = lock_task_sighand(p, &flags); if (unlikely(sighand == NULL)) { - /* - * We raced with the reaping of the task. - * The deletion should have cleared us off the list. - */ - WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry)); + list_del(&timer->it.cpu.entry); } else { if (timer->it.cpu.firing) ret = TIMER_RETRY;
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
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