posix-timers: don't switch to ->group_leader if ->it_process dies
posix_timer_event() drops SIGEV_THREAD_ID and switches to ->group_leader
if send_sigqueue() fails.
This is not very useful and doesn't work reliably. send_sigqueue() can
only fail if ->it_process is dead. But it can die before it dequeues the
SI_TIMER signal, in that case the timer stops anyway.
Remove this code. I guess it was needed a long ago to ensure that the
timer is not destroyed when when its creator thread dies.
Q: perhaps it makes sense to change sys_timer_settime() to return an error
if ->it_process is dead?
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index e36d579..3dfd15a 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -298,6 +298,7 @@
int posix_timer_event(struct k_itimer *timr, int si_private)
{
+ int shared, ret;
/*
* FIXME: if ->sigq is queued we can race with
* dequeue_signal()->do_schedule_next_timer().
@@ -316,20 +317,10 @@
timr->sigq->info.si_tid = timr->it_id;
timr->sigq->info.si_value = timr->it_sigev_value;
- if (timr->it_sigev_notify & SIGEV_THREAD_ID) {
- struct task_struct *leader;
- int ret = send_sigqueue(timr->sigq, timr->it_process, 0);
-
- if (likely(ret >= 0))
- return ret;
-
- timr->it_sigev_notify = SIGEV_SIGNAL;
- leader = timr->it_process->group_leader;
- put_task_struct(timr->it_process);
- timr->it_process = leader;
- }
-
- return send_sigqueue(timr->sigq, timr->it_process, 1);
+ shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
+ ret = send_sigqueue(timr->sigq, timr->it_process, shared);
+ /* If we failed to send the signal the timer stops. */
+ return ret > 0;
}
EXPORT_SYMBOL_GPL(posix_timer_event);
