linux-kernel - Re: [v2] coccinelle: semantic patch to check for inappropriate do

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Message-ID: <alpine.DEB.2.21.2001091315560.10786@hadrien>
Date:   Thu, 9 Jan 2020 13:17:44 +0100 (CET)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     Markus Elfring <Markus.Elfring@....de>
cc:     Wen Yang <wenyang@...ux.alibaba.com>, cocci@...teme.lip6.fr,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        Gilles Muller <Gilles.Muller@...6.fr>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Matthias Männich <maennich@...gle.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [v2] coccinelle: semantic patch to check for inappropriate
 do_div() calls



On Thu, 9 Jan 2020, Markus Elfring wrote:

> >> Does the Coccinelle software ensure that a variable like “r.ul” contains
> >> really useful data even if the expected branch of the SmPL disjunction
> >> was occasionally not matched?
> >
> > The python code will only be executed if it does.
>
> The Python scripts will be executed if the SmPL rule “r” found something.
> I suggest to take a closer look at the involved data types for
> really safe case distinctions.
> Does the dependency management around the application of SmPL disjunctions
> need any further clarification?

I already clarified it.  The python code will only be executed if the
variables that it references have values.  The criterion is not just
whether the rule r was matched.

To see that this is the case, all or you have to do is try it.  Or read
the Coccinelle source code.

julia