Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751516AbaLONDv (ORCPT ); Mon, 15 Dec 2014 08:03:51 -0500 Received: from mail-pa0-f52.google.com ([209.85.220.52]:43317 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751270AbaLONDu (ORCPT ); Mon, 15 Dec 2014 08:03:50 -0500 Date: Mon, 15 Dec 2014 05:03:46 -0800 From: Jeremiah Mahler To: One Thousand Gnomes Cc: Loic Pefferkorn , gregkh@linuxfoundation.org, alan@linux.intel.com, jun.j.tian@intel.com, octavian.purdila@intel.com, nnk@google.com, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, apw@canonical.com, joe@perches.com Subject: Re: [PATCH] checkpatch giving bogus advice (was staging: goldfish: Fix minor coding style) Message-ID: <20141215130346.GB18251@hudson.localdomain> Mail-Followup-To: Jeremiah Mahler , One Thousand Gnomes , Loic Pefferkorn , gregkh@linuxfoundation.org, alan@linux.intel.com, jun.j.tian@intel.com, octavian.purdila@intel.com, nnk@google.com, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, apw@canonical.com, joe@perches.com References: <20141213175518.GA28616@hudson.localdomain> <20141213182238.GA6979@iron> <20141213194647.GA30065@hudson.localdomain> <20141215114421.7389d32a@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20141215114421.7389d32a@lxorguk.ukuu.org.uk> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 15, 2014 at 11:44:21AM +0000, One Thousand Gnomes wrote: > On Sat, 13 Dec 2014 11:46:47 -0800 > Jeremiah Mahler wrote: > > > Loïc, > > > > On Sat, Dec 13, 2014 at 07:22:38PM +0100, Loic Pefferkorn wrote: > > > > Whose convention is this? I can't find any mention in > > > > Documention/CodingStyle. checkpatch.pl doesn't complain about them. > > > > And there are almost three thousand examples in staging which don't > > > > use this convention. > > > > > > > > linux-next$ grep -r "== NULL" drivers/staging/* | wc -l > > > > 2844 > > > > > > Hi Jeremiah, > > > > > > Thanks for your feedback. > > > > > > I have used checkpatch.pl with the --strict flag: > > checkpatch.pl is a bit dubious at the best of times - you can't automate > taste without an AI ;). With --strict it's a positive hazard. > > Those kind of small cleanups really only make sense if you are doing big > changes to the code itself anyway and are doing testing and all the rest. > > In this case I'd say checkpatch.pl is actually wrong because in the > general case it's better to compare with NULL in C > > If you write > > if (!x) > > and accidentally use a non-pointer type you don't get a warning. If you > try and compare a non pointer type to NULL you usually do. So the NULL > comparison avoids accidents. > > The historical reason for it being done in C was I think to avoid the > > if (x = NULL) > > bug, but gcc will shout at you for that these days. > Or another way mentioned in K&R that produces a compile error if (NULL = x) > Alan > > > -- - Jeremiah Mahler -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/