[PATCH 2/3] Input: alps: drop unlikely before IS_ERR_OR_NULL

[PATCH 2/3] Input: alps: drop unlikely before IS_ERR_OR_NULL

[Geliang Tang]

IS_ERR_OR_NULL already contain an unlikely compiler flag. Drop it.

Signed-off-by: Geliang Tang <geliangtang@163.com>
---
 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,
-- 
2.5.0

Re: [PATCH 2/3] Input: alps: drop unlikely before IS_ERR_OR_NULL

[Pali Rohár]

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@163.com>
> ---
>  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.

-- 
Pali Rohár
pali.rohar@gmail.com
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Re: [PATCH 2/3] Input: alps: drop unlikely before IS_ERR_OR_NULL

[Dmitry Torokhov]

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@163.com>
> > ---
> >  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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