Re: [patch v6.1 17/20] signal: Queue ignored posixtimers on ignore list

From: Thomas Gleixner
Date: Mon Nov 04 2024 - 10:22:17 EST


On Mon, Nov 04 2024 at 12:42, Frederic Weisbecker wrote:
> But there is something more problematic against the delete() path:
>
> Thread within Signal target Timer target
> signal target group
> -------------------- ------------- -------------
> timr->it_status = POSIX_TIMER_REQUEUE_PENDING
> posixtimer_send_sigqueue();
> do_exit();
> timer_delete()
> posix_cpu_timer_del()
> // return NULL
> cpu_timer_task_rcu()
> // timer->it_status NOT set
> // to POSIX_TIMER_DISARMED
> hlist_del(&timer->list);
> posix_timer_cleanup_ignored()
>
>
> do_sigaction(SIG_IGN...)
> flush_sigqueue_mask()
> sigqueue_free_ignored()
> posixtimer_sig_ignore()
> // Observe POSIX_TIMER_REQUEUE_PENDING
> hlist_add_head(...ignored_posix_timers)
> do_exit()
> exit_itimers()
> if (hlist_empty(&tsk->signal->posix_timers))
> return;
> // leaked timer queued to migrate list
>

Duh. Let me stare at that some more.