[no subject]

From: Tejun Heo
Date: Tue Dec 04 2012 - 10:40:39 EST

8852aac25e ("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, used container_of() to cast 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. 8852aac25e
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 c1d390d8e6 ("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

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Xiaotian Feng <xtfeng@xxxxxxxxx>
kernel/workqueue.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 084aa47..1dae900 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -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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