linux-kernel - Re: [Cocci] [PATCH] crypto: cavium: zip: Remove unnecessary parentheses

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Date:   Sat, 31 Mar 2018 08:17:34 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Joe Perches <joe@...ches.com>
cc:     Varsha Rao <rvarsha016@...il.com>, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, cocci <cocci@...teme.lip6.fr>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [Cocci] [PATCH] crypto: cavium: zip: Remove unnecessary
 parentheses



On Fri, 30 Mar 2018, Joe Perches wrote:

> On Thu, 2018-03-29 at 21:03 +0530, Varsha Rao wrote:
> > On Wed, Mar 28, 2018 at 11:41 PM, Joe Perches wrote:
> > >
> > > On Wed, 2018-03-28 at 23:27, Varsha Rao wrote:
> > > > This patch fixes the clang warning of extraneous parentheses, with the
> > > > following coccinelle script.
> > > >
> > > > @@
> > > > identifier i;
> > > > constant c;
> > > > @@
> > > > (
> > > > -((i == c))
> > > > +i == c
> > > > >
> > > >
> > > > -((i <= c))
> > > > +i <= c
> > >
> > > Why just the "==" and "<=" cases?
> > > Why not "<", ">" and ">=" too?
> > >
> > > Why not expression instead of constant?
> >
> > Initially I had the other cases too and used expression instead of
> > constant. But the results included only "==" and "<=" cases with
> > constant. Along with one false positive case.
> hmm
> Perhaps you should use something like this?
> @@
> identifier i;
> constant c;
> @@
>
> -(
> \(i == c\|i <= c\|i < c\|i >= c\|i > c\)
> -)

This is not safe with respect to !.  The following seems to address this
problem:

@@
identifier i;
constant c;
expression e;
@@

(
!(e)
|
-(
\(i == c\|i <= c\|i < c\|i >= c\|i > c\)
-)
)

julia