On 04/26, Jarek Poplawski wrote: > > On Wed, Apr 25, 2007 at 04:52:14PM +0400, Oleg Nesterov wrote: > > > > > It seems this > > > change cannot do any harm, but anyway it could change a few > > > things, e.g. with current version of cancel_rearming_delayed_work > > > some flush_workqueue could be done needlessly, before the work > > > is queued from timer. > > > > I don't think so... Could you clarify? > > With a code like: > > if (!cancel_delayed_work(dwork)) > flush_workqueue(wq); > > if cancel_ returns 0, and there is _queue_work in progress, > flush_ will be done once, after this work is queued. > > After the patch, and the same situation flush_ also runs > one time, but maybe without the work in a queue.
First, this is very unlikely event, and the behaviour is correct, do you agree? Even in this case, it is very unlikely that flush_cpu_workqueue() will take cwq->lock before extremely short delayed_work_timer_fn. Even if it does, work->func() likely will be completed when the caller of flush_workqueue() will be woken by run_workquue() and gets CPU. Please also look at http://marc.info/?t=117699337200022&r=1 > > > It's not a big deal here, but if anybody > > > did something like this without loop - it could matter. > > > > > > So, probably a lot of current code should be checked, before > > > applying and I doubt the gain is worth of this. Maybe, for > > > safety, make this with new name as an alternative and > > > deprecate the current version? > > > > This change should not make any visible difference for the callers, > > otherwise it is buggy. > > IMHO, there is the same visible difference, > as between del_timer and del_timer_sync. Jarek, please, could you be more explicite ? del_timer() and del_timer_sync() are different in many ways. What exactly will impact the user of cancel_delaye_work ? Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
