[PATCH v2] kthread_worker: Check all delayed works when destroy kthread worker

[Zqiang]

This commit add a check for delayed works, when destroy kthread worker
if there are still some pending delayed works will trigger warnning,
this remind caller should clear all pending delayed works before destroy
kthread worker.

Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
---
 v1->v2:
 Only add WARN_ON() and function description

 kernel/kthread.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index f97fd01a2932..7e6751b29101 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -1382,6 +1382,10 @@ EXPORT_SYMBOL_GPL(kthread_flush_worker);
  * Flush and destroy @worker.  The simple flush is enough because the kthread
  * worker API is used only in trivial scenarios.  There are no multi-step state
  * machines needed.
+ *
+ * Note that this function is not responsible for handling delayed work, so
+ * caller should be responsible for queuing or canceling all delayed work items
+ * before invoke this function.
  */
 void kthread_destroy_worker(struct kthread_worker *worker)
 {
@@ -1393,6 +1397,7 @@ void kthread_destroy_worker(struct kthread_worker *worker)
 
 	kthread_flush_worker(worker);
 	kthread_stop(task);
+	WARN_ON(!list_empty(&worker->delayed_work_list));
 	WARN_ON(!list_empty(&worker->work_list));
 	kfree(worker);
 }
-- 
2.25.1