Re: [PATCH] checkpatch giving bogus advice (was staging: goldfish: Fix minor coding style)

[Jeremiah Mahler]

On Mon, Dec 15, 2014 at 11:44:21AM +0000, One Thousand Gnomes wrote:
> On Sat, 13 Dec 2014 11:46:47 -0800
> Jeremiah Mahler <jmmahler@xxxxxxxxx> wrote:
> 
> > LoÃc,
> > 
> > On Sat, Dec 13, 2014 at 07:22:38PM +0100, Loic Pefferkorn wrote:
> > > > Whose convention is this?  I can't find any mention in
> > > > Documention/CodingStyle. checkpatch.pl doesn't complain about them.
> > > > And there are almost three thousand examples in staging which don't
> > > > use this convention.
> > > > 
> > > >   linux-next$ grep -r "== NULL" drivers/staging/* | wc -l
> > > >   2844
> > > 
> > > Hi Jeremiah,
> > > 
> > > Thanks for your feedback.
> > > 
> > > I have used checkpatch.pl with the --strict flag:
> 
> checkpatch.pl is a bit dubious at the best of times - you can't automate
> taste without an AI ;). With --strict it's a positive hazard.
> 
> Those kind of small cleanups really only make sense if you are doing big
> changes to the code itself anyway and are doing testing and all the rest.
> 
> In this case I'd say checkpatch.pl is actually wrong because in the
> general case it's better to compare with NULL in C
> 
> If you write
> 
>           if (!x)
> 
> and accidentally use a non-pointer type you don't get a warning. If you
> try and compare a non pointer type to NULL you usually do. So the NULL
> comparison avoids accidents.
> 
> The historical reason for it being done in C was I think to avoid the
> 
>           if (x = NULL) 
> 
> bug, but gcc will shout at you for that these days.
> 

Or another way mentioned in K&R that produces a compile error

            if (NULL = x) 

> Alan
> 
> 
> 

-- 
- Jeremiah Mahler
--
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/