linux-kernel - Re: [PATCH v6] coccinelle: api: add kvfree script

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Message-ID: <alpine.DEB.2.22.394.2008031410490.27678@hadrien>
Date:   Mon, 3 Aug 2020 14:12:46 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     Denis Efremov <efremov@...ux.com>
cc:     cocci@...teme.lip6.fr, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6] coccinelle: api: add kvfree script



On Mon, 3 Aug 2020, Denis Efremov wrote:

> Is there a difference from cocci point of view between:
>
> ... when != !is_vmalloc_addr(E)

This will only reject cases where the ! is present.  Coccinelle doesn't
apply isomorphisms to the C source code, so it doesn't detect that eg

if (A)
  B
else C

could be rewritten as

if (!A)
  C
ese B

So when != !A would only match when the code is in the second form.
>
> and
>
> ... when != is_vmalloc_addr(E)
>
> Should the latter one be used in most cases?

This matches both a call to is_vmalloc_addr and a negated call, so it is
more general.

julia