From: Dan Carpenter <dan.carpenter@oracle.com>
To: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
kernel-janitors@vger.kernel.org,
Gilles Muller <Gilles.Muller@lip6.fr>,
Nicolas Palix <nicolas.palix@imag.fr>,
Michal Marek <michal.lkml@markovi.net>,
cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] scripts/coccinelle/misc/shift.cocci: detect < or > that should be a shift
Date: Thu, 8 Feb 2018 16:53:50 +0300 [thread overview]
Message-ID: <20180208135350.e4yljburdpq7f5ny@mwanda> (raw)
In-Reply-To: <1518094434-12852-1-git-send-email-Julia.Lawall@lip6.fr>
On Thu, Feb 08, 2018 at 01:53:54PM +0100, Julia Lawall wrote:
> This checks for a comparison using < or > between two constants,
> considering both explicit constants (1, 2, etc) and macros defined
> with #define. False positives are possible in the latter case, when
> a macro may have multiple possible definitions and it is indeed
> necessary to check the value. There are currently two such false
> positives, in drivers/net/ethernet/chelsio/cxgb3/sge.c:
>
> q->fl[0].use_pages = FL0_PG_CHUNK_SIZE > 0;
> q->fl[1].use_pages = FL1_PG_CHUNK_SIZE > 0;
>
We could eliminate both these false postives by ignoring >> vs >. Did
searching for > actually find any bugs? I think you were right that
right shifting a constant is way less common than left shifting and I
have some smatch scripts where I ignore right shifting bugs.
On the other hand, two false positives are not a big deal.
regards,
dan carpenter
next prev parent reply other threads:[~2018-02-08 13:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 12:53 Julia Lawall
2018-02-08 13:53 ` Dan Carpenter [this message]
2018-02-08 13:58 ` Julia Lawall
2018-02-08 14:04 ` Dan Carpenter
2018-02-09 14:10 ` scripts/coccinelle/misc/shift.cocci: Refactoring? SF Markus Elfring
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