Commit fc4b514f authored Dec 04, 2012 by Tejun Heo

workqueue: convert BUG_ON()s in __queue_delayed_work() to WARN_ON_ONCE()s



8852aac2 ("workqueue: mod_delayed_work_on() shouldn't queue timer on
0 delay") unexpectedly uncovered a very nasty abuse of delayed_work in
megaraid - it allocated work_struct, casted it to delayed_work and
then pass that into queue_delayed_work().

Previously, this was okay because 0 @delay short-circuited to
queue_work() before doing anything with delayed_work.  8852aac2
moved 0 @delay test into __queue_delayed_work() after sanity check on
delayed_work making megaraid trigger BUG_ON().

Although megaraid is already fixed by c1d390d8 ("megaraid: fix
BUG_ON() from incorrect use of delayed work"), this patch converts
BUG_ON()s in __queue_delayed_work() to WARN_ON_ONCE()s so that such
abusers, if there are more, trigger warning but don't crash the
machine.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Xiaotian Feng <xtfeng@gmail.com>

parent c1d390d8

kernel/workqueue.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1361,8 +1361,8 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,

		WARN_ON_ONCE(timer->function != delayed_work_timer_fn \|\|
		timer->data != (unsigned long)dwork);
		BUG_ON(timer_pending(timer));
		BUG_ON(!list_empty(&work->entry));
		WARN_ON_ONCE(timer_pending(timer));
		WARN_ON_ONCE(!list_empty(&work->entry));

		/*
		* If @delay is 0, queue @dwork->work immediately. This is for

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