Commit b95e31c0 authored Feb 28, 2020 by Eric W. Biederman Committed by Thomas Gleixner Mar 04, 2020

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: e0a70217 ("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

parent 55e8c8eb

kernel/exit.c

+1 −10

Original line number	Diff line number	Diff line
		@@ -103,17 +103,8 @@ static void __exit_signal(struct task_struct *tsk)

		#ifdef CONFIG_POSIX_TIMERS
		posix_cpu_timers_exit(tsk);
		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)))
		if (group_dead)
		posix_cpu_timers_exit_group(tsk);
		}
		#endif

		if (group_dead) {

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