From: Joel Fernandes (Google) Date: Wed, 24 Jul 2019 16:48:16 +0000 (-0400) Subject: pidfd: Add warning if exit_state is 0 during notification X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=1caf7d50f46bd0388e38e653b146aa81700e8eb8;p=openwrt%2Fstaging%2Fblogic.git 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) Link: https://lore.kernel.org/r/20190724164816.201099-1-joel@joelfernandes.org Signed-off-by: Christian Brauner --- diff --git a/kernel/signal.c b/kernel/signal.c index 91b789dd6e72..349f5a67f100 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -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); }