linux-kernel - Re: [PATCH 05/15] drivers: input: Drop unlikely before IS_ERR(_OR

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Message-ID: <20150802154352.GA28860@amd>
Date:	Sun, 2 Aug 2015 17:43:52 +0200
From:	Pavel Machek <pavel@....cz>
To:	Pali Rohár <pali.rohar@...il.com>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	akpm@...ux-foundation.org, linaro-kernel@...ts.linaro.org,
	linux-kernel@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
	"open list:INPUT (KEYBOARD, MOUSE, JOYSTICK, TOUCHSCREEN)..." 
	<linux-input@...r.kernel.org>, Masaki Ota <masaki.ota@...alps.com>
Subject: Re: [PATCH 05/15] drivers: input: Drop unlikely before
 IS_ERR(_OR_NULL)

On Sat 2015-08-01 13:44:59, Pali Rohár wrote:
> On Saturday 01 August 2015 13:22:51 Viresh Kumar wrote:
> > On 31-07-15, 09:58, Dmitry Torokhov wrote:
> > > On Fri, Jul 31, 2015 at 02:08:25PM +0530, Viresh Kumar wrote:
> > > > IS_ERR(_OR_NULL) already contain an 'unlikely' compiler flag and
> > > > there is no need to do that again from its callers. Drop it.
> > > 
> > > I'd rather keep it as it documents the expected behavior and double
> > > unlikely should work just fine.
> > 
> > TBH, I don't really agree that it is there for documentation. The
> > only purpose of such compiler flags is to try make code more
> > efficient.
> > 
> > Anyway, I got to this series as someone asked me to fix this for one
> > of my patches which used unlikely(IS_ERR_OR_NULL()). And so I
> > thought about fixing all sites that are doing double unlikely (that
> > shouldn't hurt for sure).
> > 
> > I will leave it to you.
> 
> I think that unlikely() macro here make code more readable. Yes, it is 
> also for compiler optimization, but also for me it looks like Clean Code 
> pattern <https://de.wikipedia.org/wiki/Clean_Code> -- is not it?

People know that errors are unlikely, no need to tell them. I'd remove
it.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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