Re: [PATCH] cancel_delayed_work: use del_timer() instead of del_timer_sync()

From: Jarek Poplawski
Date: Fri Apr 27 2007 - 02:09:30 EST

On Thu, Apr 26, 2007 at 07:29:53PM +0400, Oleg Nesterov wrote:
> On 04/26, Jarek Poplawski wrote:
> > > 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 ?

OK, I changed my mind. Now, I think it's very probable
this should matter...

According to workqueue.h:
> /*
> * 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_workqueue() or cancel_work_sync() to wait on it.
> */
> static inline int cancel_delayed_work(struct delayed_work *work)

So, we can do something like this:


And this is enough to work with not rearming work.

But no more after this patch...

So, I think, your proposal should be alternative version,
and current version should stay, so we have a choice.
Just like del_timer and del_timer_sync.

Jarek P.
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