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

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Message-Id: <201508011344.59372@pali>
Date:	Sat, 1 Aug 2015 13:44:59 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	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 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?

-- 
Pali Rohár
pali.rohar@...il.com

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