Re: [PATCH 05/15] drivers: input: Drop unlikely before IS_ERR(_OR_NULL)

From: Pavel Machek
Date: Sun Aug 02 2015 - 11:44:04 EST


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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/