Re: [PATCH] signals: work around random wakeups in sigsuspend()
From: Oleg Nesterov
Date: Mon Jan 25 2016 - 14:09:31 EST
On 01/25, Sasha Levin wrote:
>
> A random wakeup can get us out of sigsuspend() without TIF_SIGPENDING
> being set.
and TIF_RESTORE_SIGMASK is just wrong in this case. I'd say this is the
bugfix, not work-around ;)
> Avoid that by making sure we were signaled, like sys_pause() does.
>
> Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Thanks Sasha.
> ---
> kernel/signal.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 5da9180..3256c7e 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -3528,8 +3528,10 @@ static int sigsuspend(sigset_t *set)
> current->saved_sigmask = current->blocked;
> set_current_blocked(set);
>
> - __set_current_state(TASK_INTERRUPTIBLE);
> - schedule();
> + while (!signal_pending(current)) {
> + __set_current_state(TASK_INTERRUPTIBLE);
> + schedule();
> + }
> set_restore_sigmask();
> return -ERESTARTNOHAND;
> }
> --
> 1.7.10.4
>