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authorOleg Nesterov <oleg@tv-sign.ru>2007-04-26 18:45:32 -0400
committerDavid S. Miller <davem@davemloft.net>2007-04-26 18:45:32 -0400
commit071b638689464c6b39407025eedd810d5b5e6f5d (patch)
tree702b28d1a7acdd7ea904cd442c4491a24b93c059 /include/linux/workqueue.h
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>
Diffstat (limited to 'include/linux/workqueue.h')
-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 2a7b38d87018..b8abfc74d038 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 *);
191 191
192/* 192/*
193 * Kill off a pending schedule_delayed_work(). Note that the work callback 193 * Kill off a pending schedule_delayed_work(). Note that the work callback
194 * function may still be running on return from cancel_delayed_work(). Run 194 * function may still be running on return from cancel_delayed_work(), unless
195 * flush_scheduled_work() to wait on it. 195 * it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
196 * cancel_work_sync() to wait on it.
196 */ 197 */
197static inline int cancel_delayed_work(struct delayed_work *work) 198static inline int cancel_delayed_work(struct delayed_work *work)
198{ 199{
199 int ret; 200 int ret;
200 201
201 ret = del_timer_sync(&work->timer); 202 ret = del_timer(&work->timer);
202 if (ret) 203 if (ret)
203 work_release(&work->work); 204 work_release(&work->work);
204 return ret; 205 return ret;