linux-kernel - Re: [v4l-dvb-maintainer] [PATCH 3/3] V4L: cinergyT2, remove bad usage of ERESTARTSYS

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Date:	Wed, 10 Oct 2007 20:40:39 +0400
From:	Manu Abraham <abraham.manu@...il.com>
To:	Mauro Carvalho Chehab <mchehab@...radead.org>
CC:	Alan Cox <alan@...hat.com>, video4linux-list@...hat.com,
	Jiri Slaby <jirislaby@...il.com>, daniel@...u.de,
	linux-kernel@...r.kernel.org, holger@...u.de,
	v4l-dvb maintainer list <v4l-dvb-maintainer@...uxtv.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [v4l-dvb-maintainer] [PATCH 3/3] V4L: cinergyT2,	remove bad	usage
 of ERESTARTSYS

Mauro Carvalho Chehab wrote:
> Em Qua, 2007-10-10 Ã s 11:59 -0400, Alan Cox escreveu:
>> On Wed, Oct 10, 2007 at 12:35:41PM -0300, Mauro Carvalho Chehab wrote:
>>> Em Qua, 2007-10-10 Ã s 00:18 -0400, Michael Krufky escreveu:
>>>> Is this illegal as per kernel codingstyle?
>>> Yes, it is. CodingStyle states:
>> <rant>
>> No.. "Illegal" means prohibited by law. Its merely wrong 8)
>> </rant>
> 
> LOL
> 
>>> The proper fix is just to replace the offended code by this:
>>>
>>> err=foo();
>>> if (error)
>>> 	goto error;
>> Lots of code uses
>>
>> 	if ((err = foo()) < 0)
>>
>> so I would'y worry too much. The split one however clearer and also
>> safer.
> 
> Yes, this is not a severe CodingStyle violation. Still, the above code
> is better than the used one.
> 
> Since, on your example, it is clear that the programmer wanted to test
> if the value is less than zero. 
> 
> The code:
> 
> 	if ( (err=foo()) )
> 
> should also indicate an operator mistake of using =, instead of ==.
> 
> Probably, source code analyzers like Coverity will complain about the
> above.
> 
> If not violating CodingStyle, I would rather prefer to code this as:
> 	if ( !(err=foo() ) 
> or, even better, using:
> 	if ( (err=foo()) != 0)
> 
> clearly indicating that it is tested if the value is not zero.
> 
> Even being a quite simple issue, I would prefer if Jiri can fix it.
> 


When you have only some few lines of code you can write

 err = foo()
 if (err) {
  do whatever
 } 

doesn't matter ..

But when you have hell a lot of code, checking error's what you 
mention is insane.

ie,

if ((err = foo()) expr ) is better.

http://lkml.org/lkml/2007/2/4/56

Manu
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