On Thu, Oct 01, 2015 at 09:30:19AM +0200, Pali Rohár wrote:
> On Thursday 01 October 2015 10:55:30 Geliang Tang wrote:
> > IS_ERR_OR_NULL already contain an unlikely compiler flag. Drop it.
> >
> > Signed-off-by: Geliang Tang <geliangtang@xxxxxxx>
> > ---
> > drivers/input/mouse/alps.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
> > index 4d24686..b4f146a 100644
> > --- a/drivers/input/mouse/alps.c
> > +++ b/drivers/input/mouse/alps.c
> > @@ -1367,7 +1367,7 @@ static void alps_report_bare_ps2_packet(struct psmouse *psmouse,
> > /* On V2 devices the DualPoint Stick reports bare packets */
> > dev = priv->dev2;
> > dev2 = psmouse->dev;
> > - } else if (unlikely(IS_ERR_OR_NULL(priv->dev3))) {
> > + } else if (IS_ERR_OR_NULL(priv->dev3)) {
> > /* Register dev3 mouse if we received PS/2 packet first time */
> > if (!IS_ERR(priv->dev3))
> > psmouse_queue_work(psmouse, &priv->dev3_register_work,
>
> Hm... I do not like this change. If I read code
>
> if (unlikely(IS_ERR_OR_NULL(priv->dev3)))
>
> then I know that it is really unlikely that condition will be truth and
> so this is some case of error/exception or something that normally does
> not happen too much.
>
> But if I read code
>
> if (IS_ERR_OR_NULL(priv->dev3))
>
> I know nothing about chance that this condition will be truth. Explicit
> unlikely in previous example give me more information.
Yes, given that this is in packet processing path I prefer having
explicit unlikely there.
Thanks.
--
Dmitry
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