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authorOleg Nesterov <oleg@tv-sign.ru>2007-04-26 15:45:32 -0700
committerDavid S. Miller <davem@davemloft.net>2007-04-26 15:45:32 -0700
commit071b638689464c6b39407025eedd810d5b5e6f5d (patch)
tree702b28d1a7acdd7ea904cd442c4491a24b93c059
parent566ec03448052c096dc3982fbe573522dc0ba479 (diff)
[WORKQUEUE]: cancel_delayed_work: use del_timer() instead of del_timer_sync()
del_timer_sync() buys nothing for cancel_delayed_work(), but it is less efficient since it locks the timer unconditionally, and may wait for the completion of the delayed_work_timer_fn(). cancel_delayed_work() == 0 means: before this patch: work->func may still be running or queued after this patch: work->func may still be running or queued, or delayed_work_timer_fn->__queue_work() in progress. The latter doesn't differ from the caller's POV, delayed_work_timer_fn() is called with _PENDING bit set. cancel_delayed_work() == 1 with this patch adds a new possibility: delayed_work->work was cancelled, but delayed_work_timer_fn is still running (this is only possible for the re-arming works on single-threaded workqueue). In this case the timer was re-started by work->func(), nobody else can do this. This in turn means that delayed_work_timer_fn has already passed __queue_work() (and wont't touch delayed_work) because nobody else can queue delayed_work->work. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/workqueue.h7
1 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 2a7b38d8701..b8abfc74d03 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -191,14 +191,15 @@ int execute_in_process_context(work_func_t fn, struct execute_work *);
/*
* Kill off a pending schedule_delayed_work(). Note that the work callback
- * function may still be running on return from cancel_delayed_work(). Run
- * flush_scheduled_work() to wait on it.
+ * function may still be running on return from cancel_delayed_work(), unless
+ * it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
+ * cancel_work_sync() to wait on it.
*/
static inline int cancel_delayed_work(struct delayed_work *work)
{
int ret;
- ret = del_timer_sync(&work->timer);
+ ret = del_timer(&work->timer);
if (ret)
work_release(&work->work);
return ret;