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posix-cpu-timers: Stop disabling timers on mt-exec 

The reasons why the extra posix_cpu_timers_exit_group() invocation has been
added are not entirely clear from the commit message.  Today all that
posix_cpu_timers_exit_group() does is stop timers that are tracking the
task from firing.  Every other operation on those timers is still allowed.

The practical implication of this is posix_cpu_timer_del() which could
not get the siglock after the thread group leader has exited (because
sighand == NULL) would be able to run successfully because the timer
was already dequeued.

With that locking issue fixed there is no point in disabling all of the
timers.  So remove this ``tempoary'' hack.

Fixes: e0a7021710 ("posix-cpu-timers: workaround to suppress the problems with mt exec")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87o8tityzs.fsf@x220.int.ebiederm.org
This commit is contained in:
Eric W. Biederman 2020-02-28 11:15:03 -06:00 committed by Thomas Gleixner
parent 55e8c8eb2c
commit b95e31c07c
1 changed files with 1 additions and 10 deletions
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11
kernel/exit.c
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@ -103,17 +103,8 @@ static void __exit_signal(struct task_struct *tsk)
#ifdef CONFIG_POSIX_TIMERS
posix_cpu_timers_exit(tsk);
if (group_dead) {
if (group_dead)
posix_cpu_timers_exit_group(tsk);
} else {
/*
* This can only happen if the caller is de_thread().
* FIXME: this is the temporary hack, we should teach
* posix-cpu-timers to handle this case correctly.
*/
if (unlikely(has_group_leader_pid(tsk)))
posix_cpu_timers_exit_group(tsk);
}
#endif
if (group_dead) {