workqueue: make cancel_rearming_delayed_workqueue() work on idle dwork
cancel_rearming_delayed_workqueue(dwork) will hang forever if dwork was not
scheduled, because in that case cancel_delayed_work()->del_timer_sync() never
returns true.
I don't know if there are any callers which may have problems, but this is not
so convenient, and the fix is very simple.
Q: looks like we don't need "struct workqueue_struct *wq" parameter. If the
timer was aborted successfully, get_wq_data() == wq. Is it worth to add the
new function?
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 74f3f78..ce72d45 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -569,6 +569,10 @@
void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
struct delayed_work *dwork)
{
+ /* Was it ever queued ? */
+ if (!get_wq_data(&dwork->work))
+ return;
+
while (!cancel_delayed_work(dwork))
flush_workqueue(wq);
}