linux-kernel - RE: [lustre-devel] [PATCH 01/12] staging: lustre: fid: Use !x to check for kzalloc failure

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Date:	Wed, 24 Jun 2015 20:14:04 +0000
From:	"Simmons, James A." <simmonsja@...l.gov>
To:	'Julia Lawall' <julia.lawall@...6.fr>,
	Dan Carpenter <dan.carpenter@...cle.com>
CC:	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	"kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Drokin, Oleg" <oleg.drokin@...el.com>,
	"lustre-devel@...ts.lustre.org" <lustre-devel@...ts.lustre.org>
Subject: RE: [lustre-devel] [PATCH 01/12] staging: lustre: fid: Use !x to
 check for kzalloc failure

>> Yes.  I know Al's thoughts and kernel style.
>>
>> But Alan Cox and Andreas have both said they think (x == NULL) can help
>> you avoid some kind of boolean vs pointer bugs.  I've had co-workers who
>> did massive seds changing !foo to foo == NULL on our code base.  But
>> I've never seen a real life example of a bug this fixes.
>>
>> To be honest, I've never seen a real life proof that (!foo) code is less
>> buggy.  I should look through the kbuild mailbox...  Hm...  But my other
>> idea of setting up code style readability testing website is also a good
>> one.
>>
>> Linux kernel style is based on Joe Perches finding that 80% of the code
>> prefers one way or the other.  That's a valid method for determining
>> code style.  I bet it normally picks the more readable style but it
>> would be interesting to measure it more formally.
>
>On today's linux-next, I find 3218 tests on the result of kmalloc etc
>using NULL and 14429 without, making 82% without.  The complete semantic
>patch is shown below.

Most people doing something a certain way is not a technical argument. Usually
people do what they are taught. From most people's comments their seems to 
be no technical reason to us one over another. I do have one technical reason not
to accept these patches. It is too easy to make a mistake and break things very badly.
I don't think it is worth the risk for a non-hard requirement.

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