linux-kernel - Re: [PATCH] posix-timers: Target group sigqueue to current task only if not exiting

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Message-ID: <CACT4Y+YQGLtD0673Oxm2=0mHy9cSx1wTPtVCyxjORSv47M+vUw@mail.gmail.com>
Date: Mon, 25 Nov 2024 10:46:32 +0100
From: Dmitry Vyukov <dvyukov@...gle.com>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Frederic Weisbecker <frederic@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, 
	LKML <linux-kernel@...r.kernel.org>, 
	Anna-Maria Behnsen <anna-maria@...utronix.de>, Anthony Mallet <anthony.mallet@...s.fr>
Subject: Re: [PATCH] posix-timers: Target group sigqueue to current task only
 if not exiting

On Sat, 23 Nov 2024 at 11:13, Oleg Nesterov <oleg@...hat.com> wrote:
>
> On 11/23, Frederic Weisbecker wrote:
> >
> > - * the same thread group as the target process, which avoids
> > - * unnecessarily waking up a potentially idle task.
> > + * the same thread group as the target process and its sighand is
> > + * stable, which avoids unnecessarily waking up a potentially idle task.
> >   */
> >  static inline struct task_struct *posixtimer_get_target(struct k_itimer *tmr)
> >  {
> >       struct task_struct *t = pid_task(tmr->it_pid, tmr->it_pid_type);
> >
> > -     if (t && tmr->it_pid_type != PIDTYPE_PID && same_thread_group(t, current))
> > +     if (t && tmr->it_pid_type != PIDTYPE_PID &&
> > +         same_thread_group(t, current) && !current->exit_state)
> >               t = current;
>
> Thanks!
>
> Acked-by: Oleg Nesterov <oleg@...hat.com>

Can't the group leader be exiting as well? Though, that's still an
improvements. People usually don't do that (exiting from main w/o
killing the process). So thanks for the fix.