On 04/25, Jarek Poplawski wrote:
>
> On Wed, Apr 25, 2007 at 02:20:38PM +0200, Jarek Poplawski wrote:
> > 2 cents more...
> ...
> > On Tue, Apr 24, 2007 at 10:55:37PM +0400, Oleg Nesterov wrote:
> > > + do {
> > > + retry = 1;
>
> Of course this'll be shorter:
>
> retry = 0;
No, this would be wrong. Note the comment about CPU-hotplug below,
we should retry if cwq was changed.
> > > + spin_lock_irq(&cwq->lock);
> > > + /* CPU_DEAD in progress may change cwq */
> > > + if (likely(cwq == get_wq_data(work))) {
> > > + list_del_init(&work->entry);
> > > + __set_bit(WORK_STRUCT_PENDING, work_data_bits(work));
> > > + retry = try_to_del_timer_sync(&dwork->timer) < 0;
> > > + }
> > > + spin_unlock_irq(&cwq->lock);
> > > + } while (unlikely(retry));
> 1. If delayed_work_timer_fn of this work is fired and is waiting
> on the above spin_lock then, after above spin_unlock, the work
> will be queued.
No, in that case try_to_del_timer_sync() returns -1.
> Probably this is also possible without timer i.e.
> with queue_work.
Yes, thanks. While adding cpu-hotplug check I forgot to add ->current_work
check, which is needed to actually implement this
> > Note that cancel_rearming_delayed_work() now can handle the works
> > which re-arm itself via queue_work(), not only queue_delayed_work().
part. I'll resend after fix.
> 2. If this function is fired after setting _PENDING flag in
> queue_delayed_work_on, but before add_timer, this
> try_to_del_timer_sync loop would miss this, too.
same as above, thanks.
Oleg.
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