Re: [PATCH] checkpatch: Test for kmalloc/memset(0) pairs

From: Steven Rostedt
Date: Thu Mar 17 2011 - 23:33:04 EST

On Thu, 2011-03-17 at 21:15 -0600, Jonathan Corbet wrote:
> On Thu, 17 Mar 2011 22:52:24 -0400
> Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> > The use of kzalloc() is preferred over kmalloc/memset(0) pairs.
> >
> > When a match is made with "memset(p, 0, s);" a search back through the
> > patch hunk is made looking for "p = kmalloc(s,". If that is found, then
> > a warning is given, suggesting to use kzalloc() instead.
> The Coccinelle stuff already has a lot of this kind of test. See, for
> example, scripts/coccinelle/api/alloc/kzalloc-simple.cocci. Suppose
> there is some way all this nice analysis infrastructure could be
> integrated instead of duplicated? Or am I just a crazy dreamer?

Hmm, to me Coccinelle is sorta the big hammer approach to this. It can
be used to analyze the kernel code that exists. checkpatch is made to
stop developers from adding new crap.

That said, I wonder if there is a way to make one use information from
the other. Perhaps we can make checkpatch read the Concinelle rules.
Honestly, I've never used Concinelle and have no idea how to use it.
Looking at their web site there's a PDF on how to use something called
"spatch" but it seems more complex than checkpatch.

But if we can teach checkpatch to read the rule files, then maybe that
would be beneficial.

-- Steve

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