linux-kernel - Re: [PATCH next V2] drivers: Use NULL not zero pointer assignments

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Message-ID: <1327649890.12089.20.camel@joe2Laptop>
Date:	Thu, 26 Jan 2012 23:38:10 -0800
From:	Joe Perches <joe@...ches.com>
To:	Ryan Mallon <rmallon@...il.com>
Cc:	Dan Carpenter <dan.carpenter@...cle.com>,
	Jiri Kosina <trivial@...nel.org>,
	kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH next V2] drivers: Use NULL not zero pointer assignments

On Fri, 2012-01-27 at 17:20 +1100, Ryan Mallon wrote:
> On 27/01/12 16:33, Joe Perches wrote:
> > Using NULL pointer assignments is more kernel-style standard.
> > Uncompiled, untested.
> > Done via cocinelle script:
> > @@
> > type T;
> > T *pointer;
> > @@
> > -pointer = 0
> > +pointer = NULL
> Hi Joe,

Hi Ryan.

> I think you can drop a lot of the initialisations completely rather than
> convert them. I've pointed some out below. I'm just scanning through for
> likely candidates and I didn't bother looking at the staging drivers, so
> this list is not comprehensive.

I'll try a more generic solution.
Here's a possible cocci script that looks for declarations with
initializations that are later overwritten.
$ cat multi_set.cocci
@@
type T;
identifier x;
expression y;
expression z;
@@
-T x = y;
+T x;
...
x = z
$

This script has a defect because expression z may
use identifier x.

Anyway, if the script can be tweaked appropriately,
it might be useful to remove these unnecessary
initializations.

cheers, Joe

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