Re: [patch V5 16/26] signal: Replace resched_timer logic

[Frederic Weisbecker <frederic@kernel.org>]

Le Tue, Oct 29, 2024 at 05:22:17PM +0100, Thomas Gleixner a écrit :
> On Tue, Oct 29 2024 at 16:56, Frederic Weisbecker wrote:
> >> @@ -568,10 +568,10 @@ static void collect_signal(int sig, stru
> >>  		list_del_init(&first->list);
> >>  		copy_siginfo(info, &first->info);
> >>  
> >> -		*resched_timer = (first->flags & SIGQUEUE_PREALLOC) &&
> >> -				 (info->si_code == SI_TIMER);
> >> -
> >> -		__sigqueue_free(first);
> >> +		if (unlikely((first->flags & SIGQUEUE_PREALLOC) && (info->si_code == SI_TIMER)))
> >> +			*timer_sigq = first;
> >> +		else
> >> +			__sigqueue_free(first);
> >
> > So this isn't calling __sigqueue_free() unconditionally anymore. What if
> > the timer has been freed already, what is going to free the sigqueue?
> 
> __sigqueue_free() does not free timers marked with SIGQUEUE_PREALLOC.
> 
> sigqueue_free() takes care of that, which is invoked from
> posixtimer_free_timer(). It clears SIGQUEUE_PREALLOC and if it is queued
> it lets it pending and delivery will free it.

But the delivery freeing used to be done with the __sigqueue_free()
above, which doesn't happen anymore, right?

> 
> That's not any different from before this change.
> 
> Though thinking more about it. As we drop the signal in that case
> anyway, we could remove it from pending in sigqueue_free() directly. Let
> me look into that.

Ok.

Thanks.

> 
> Thanks,
> 
>         tglx