linux-kernel - Re: [Cocci] [PATCH V3] scripts/coccinelle/free: Delete NULL test before freeing functions?

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Date:	Sat, 28 Jun 2014 23:28:42 +0200 (CEST)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	SF Markus Elfring <elfring@...rs.sourceforge.net>
cc:	Fabian Frederick <fabf@...net.be>, Joe Perches <joe@...ches.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Coccinelle <cocci@...teme.lip6.fr>
Subject: Re: [Cocci] [PATCH V3] scripts/coccinelle/free: Delete NULL test
 before freeing functions?

On Sat, 28 Jun 2014, SF Markus Elfring wrote:

> > Sorry but I'm not working on coccinelle ; just did a small script for kernel tree.
> 
> I would appreciate a more constructive feedback for my update suggestions around
> the topic "Deletion of unnecessary checks before specific function calls".
> - Did you look at the concrete patches?
> - How do you think about the general approach?
> 
> Examples:
> https://systeme.lip6.fr/pipermail/cocci/2014-March/000676.html
> http://marc.info/?l=kernel-janitors&m=139405971927100&w=2

Regular expressions do not allow taking advantage of the optimizations 
provided by Coccinelle and are not easy for a reader to understand.

> https://systeme.lip6.fr/pipermail/cocci/2014-March/000677.html
> http://marc.info/?l=kernel-janitors&m=139405983727148&w=2

This is not safe due to the use of when any.  You have no guarantee that 
there is not a dereference of input in the matched region, or that the 
value of input is still the argument value at the point of the test.

julia
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