On Fri, Nov 07, 2008 at 04:43:25PM +0100, Oleg Nesterov wrote: > On 11/05, Jiri Pirko wrote: > > > > diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c > > index 22016ca..f3bbf49 100644 > > --- a/drivers/input/keyboard/atkbd.c > > +++ b/drivers/input/keyboard/atkbd.c > > @@ -824,7 +824,7 @@ static void atkbd_disconnect(struct serio *serio) > > atkbd_disable(atkbd); > > > > /* make sure we don't have a command in flight */ > > - flush_scheduled_work(); > > + cancel_delayed_work_sync(&atkbd->event_work); > > Ping. Dmitry, could you take a look? > Applied, thank you. > > While we are here, what is the reason for atkbd_schedule_event_work()->wmb() ? > It looks absolutely bogus. Is it for atkbd_event_work() ? In that case it > is not needed, it must see all previous STOREs because both queue_work() and > run_workqueue() take cwq->lock. And in any case, > test_and_set_bit(WORK_STRUCT_PENDING) implies mb(). I wanted to be sure that event_mask is set before we schedule event_work and I don't want to rely on details of queue_delayed_work implementation. If the fact that queue_delayed_work acts as a barrier would be listed part of its published spec I would gladly remove wmb() from atkbd. > If schedule_delayed_work() > fails we can race with the soon-to-be-executed atkbd_event_work(), in that > case that test_and_set_bit() + test_and_clear_bit(->event_mask) save us, > but wmb() can't help again. > > Another question is why do we need ->event_mutex? OK, it can serialize > multiple instances of atkbd_event_work() running on the different CPUs, > but in that case atkbd_reconnect() needs this lock too? It also calls > atkbd_set_repeat_rate/atkbd_set_leds. Probably, I will need to thiknk about it a bit more. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
