workqueue: trigger WARN if queue_delayed_work() is called with NULL @wq

If queue_delayed_work() gets called with NULL @wq, the kernel will
oops asynchronuosly on timer expiration which isn't too helpful in
tracking down the offender.  This actually happened with smc.

__queue_delayed_work() already does several input sanity checks
synchronously.  Add NULL @wq check.

Reported-by: Dave Jones <davej@codemonkey.org.uk>
Link: http://lkml.kernel.org/r/20170227171439.jshx3qplflyrgcv7@codemonkey.org.uk
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 072cbc9b175dc1efbe95c14858f810f92db12130..c0168b7da1eaf22c216147ca5ebd03ef7311dca8 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1507,6 +1507,7 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
        struct timer_list *timer = &dwork->timer;
        struct work_struct *work = &dwork->work;
 
+       WARN_ON_ONCE(!wq);
        WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
                     timer->data != (unsigned long)dwork);
        WARN_ON_ONCE(timer_pending(timer));