There is a problem with the calling cancel_rearming_delayed_work if the
timer was not yet active.
I see this problem when netpoll_cleanup() is called without having done
any work because it had not processed any packets yet. The problem
appears to be a result of the loop check
while(!cancel_delayed_work(dwork)). This endlessly loops because
del_timer_sync() can return 0 or 1 for success which is passed back as a
result to the final invariant check for the loop. In this particular
case zero will always be returned because the timer is not active.
It is possible that the problem exists else where, but I thought I would
ask if this is expected?
#0 del_timer_sync (timer=0xc7ed90f8) at kernel/timer.c:530
#1 0xc012f08e in cancel_rearming_delayed_workqueue (wq=0xc7fee800,
dwork=0xc7ed90e8) at include/linux/workqueue.h:201
#2 0xc012f0af in cancel_rearming_delayed_work (dwork=0x20)
at kernel/workqueue.c:680
#3 0xc0312f78 in netpoll_cleanup (np=0xc880bf40) at net/core/netpoll.c:784
Possible fix.
Signed-off-by: Jason Wessel <[email protected]>
Index: linux-2.6.21/kernel/workqueue.c
===================================================================
--- linux-2.6.21.orig/kernel/workqueue.c
+++ linux-2.6.21/kernel/workqueue.c
@@ -666,7 +666,7 @@ EXPORT_SYMBOL(flush_scheduled_work);
void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
struct delayed_work *dwork)
{
- while (!cancel_delayed_work(dwork))
+ while (cancel_delayed_work(dwork) > 0)
flush_workqueue(wq);
}
EXPORT_SYMBOL(cancel_rearming_delayed_workqueue);
Thanks,
Jason.
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