workqueue: add 'flush_delayed_work()' to run and wait for delayed work
It basically turns a delayed work into an immediate work, and then waits
for it to finish.
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 7ef0c7b..cf24c20 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -207,6 +207,7 @@
extern void flush_workqueue(struct workqueue_struct *wq);
extern void flush_scheduled_work(void);
+extern void flush_delayed_work(struct delayed_work *work);
extern int schedule_work(struct work_struct *work);
extern int schedule_work_on(int cpu, struct work_struct *work);