linux-kernel - Re: [PATCH v2 2/2] Documentation: dev-tools: Enhance static analysis section with discussion

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Date:   Thu, 31 Mar 2022 11:14:10 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     David Gow <davidgow@...gle.com>
Cc:     Marcelo Schmitt <marcelo.schmitt1@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Daniel Latypov <dlatypov@...gle.com>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        linux-sparse@...r.kernel.org, cocci@...ia.fr,
        smatch@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Shuah Khan <skhan@...uxfoundation.org>, julia.lawall@...ia.fr
Subject: Re: [PATCH v2 2/2] Documentation: dev-tools: Enhance static analysis
 section with discussion

On Wed, Mar 30, 2022 at 10:48:13AM +0800, David Gow wrote:
> > +
> > +Smatch does flow analysis and, if allowed to build the function database, it
> > +also does cross function analysis. Smatch tries to answer questions like where
> > +is this buffer allocated? How big is it? Can this index be controlled by the
> > +user? Is this variable larger than that variable?
> > +
> > +It's generally easier to write checks in Smatch than it is to write checks in
> > +Sparse. Nevertheless, there are some overlaps between Sparse and Smatch checks
> > +because there is no reason for re-implementing Sparse's check in Smatch.
> 
> This last sentence isn't totally clear to me. Should this "because" be "so"?
> 

I stopped reading your email when you wrote "Cheers, David" but I should
have scrolled down.

There is not very much overlap between Sparse and Smatch.  Both have a
warning for if (!x & y).  That is a tiny thing.  The big overlap is when
it comes to the locking checks.  The Smatch check for locking is
honestly way better and more capable.

I always run both Sparse and Smatch on my patches.  I should run
Coccinelle as well, but I'm more familiar with Sparse and Smatch.

regards,
dan carpenter