[PATCH] workqueue: dump workqueue state on sanity check failures in destroy_workqueue()

[Tejun Heo]

destroy_workqueue() performs a number of sanity checks to ensure that
the workqueue is empty before proceeding with destruction.  However,
it's not always easy to tell what's going on just from the warning
message.  Let's dump workqueue state after sanity check failures to
help debugging.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/CACT4Y+Zs6vkjHo9qHb4TrEiz3S4+quvvVQ9VWvj2Mx6pETGb9Q@xxxxxxxxxxxxxx
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
---
 kernel/workqueue.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index ef071ca..4eaec8b8 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4021,6 +4021,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
 		for (i = 0; i < WORK_NR_COLORS; i++) {
 			if (WARN_ON(pwq->nr_in_flight[i])) {
 				mutex_unlock(&wq->mutex);
+				show_workqueue_state();
 				return;
 			}
 		}
@@ -4029,6 +4030,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
 		    WARN_ON(pwq->nr_active) ||
 		    WARN_ON(!list_empty(&pwq->delayed_works))) {
 			mutex_unlock(&wq->mutex);
+			show_workqueue_state();
 			return;
 		}
 	}
-- 
2.7.4