Commit 1caf7d50 authored Jul 24, 2019 by Joel Fernandes (Google) Committed by Christian Brauner Jul 29, 2019

pidfd: Add warning if exit_state is 0 during notification

Previously a condition got missed where the pidfd waiters are awakened
before the exit_state gets set. This can result in a missed notification
[1] and the polling thread waiting forever.

It is fixed now, however it would be nice to avoid this kind of issue
going unnoticed in the future. So just add a warning to catch it in the
future.

/* References */
[1]: https://lore.kernel.org/lkml/20190717172100.261204-1-joel@joelfernandes.org/



Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Link: https://lore.kernel.org/r/20190724164816.201099-1-joel@joelfernandes.org


Signed-off-by: Christian Brauner <christian@brauner.io>

parent 3884ae44

kernel/signal.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1885,6 +1885,7 @@ static void do_notify_pidfd(struct task_struct *task)
		{
		struct pid *pid;

		WARN_ON(task->exit_state == 0);
		pid = task_pid(task);
		wake_up_all(&pid->wait_pidfd);
		}

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