linux-kernel - Re: [PATCH v5] Coccinelle: semantic code search for missing put

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Date:   Fri, 15 Feb 2019 14:02:05 +0100 (CET)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Markus Elfring <Markus.Elfring@....de>
cc:     Wen Yang <wen.yang99@....com.cn>,
        Gilles Muller <Gilles.Muller@...6.fr>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Michal Marek <michal.lkml@...kovi.net>,
        Yi Wang <wang.yi59@....com.cn>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Wen Yang <yellowriver2010@...mail.com>,
        Cheng Shengyu <cheng.shengyu@....com.cn>,
        cocci@...teme.lip6.fr, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v5] Coccinelle: semantic code search for missing
 put_device()



On Fri, 15 Feb 2019, Markus Elfring wrote:

> > +@...rch exists@
> > +local idexpression id;
> > +expression x,e,e1;
> > +position p1,p2;
> > +type T,T1,T2,T3;
> > +@@
> > +
> > +id = of_find_device_by_node@p1(x)
> > +... when != e = id
> > +if (id == NULL || ...) { ... return ...; }
> > +... when != put_device(&id->dev)
> …
> > +    when != if (id) { ... put_device(&id->dev) ... }
> …
>
> I would interpret this SmPL code in the way that the if statement
> for the pointer check is “optional” in this line.
> Is it an extra and redundant SmPL specification when the reference
> release function could eventually be found just anywhere within
> an implementation?

The proposed when code is correct.  It is not redundant, because it checks
for a particular control-flow pattern.

julia

>
>
> Will a need evolve to develop a similar source code search approach
> for safer resource management with other function combinations?
>
> Regards,
> Markus
>