Messages in this thread | | | Date | Thu, 3 Feb 2011 08:45:49 -0800 | From | Dmitry Torokhov <> | Subject | Re: [PATCH 4/4] workqueue: Remove now superfluous cancel_delayed_work() calls |
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On Thu, Feb 03, 2011 at 05:19:06PM +0100, Tejun Heo wrote: > Hello, Peter. > > On Thu, Feb 03, 2011 at 03:09:44PM +0100, Peter Zijlstra wrote: > > Since queue_delayed_work() can now deal with existing timers, we don't > > need to explicitly call cancel_delayed_work() anymore. > > This is nice but there's small complication with the way > queue_delayed_work() behaves. If a delayed work item is already > pending, another queue_delayed_work() doesn't modify the delay whether > the new delay is longer or shorter than the current one. The previous > patch doesn't really change the behavior as the whole thing is gated > with WORK_STRUCT_PENDING_BIT. > > So, cancel_delayed_work() followed by queue_delayed_work() schedules > the work to be executed at the specified time regardless of the > current pending state while queue_delayed_work() takes effect iff > currently the work item is not pending. > > The current behavior is weird and it often is easier to use explicit > timer + work item if the timer needs to be modified, but it has been > that way from the beginning so I don't think changing it would be a > good idea. We can introduce a new interface (mod_delayed_work() > maybe) for this tho. >
I agree. If we were to change queue_delayed_work() we'd have to verify that all users that do not presently use cancel_delayed_work() in reschedule would be OK with the new behavior.
Thanks.
-- Dmitry
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