From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751641AbeBZXAq (ORCPT ); Mon, 26 Feb 2018 18:00:46 -0500 Received: from mxf98a.netcup.net ([46.38.249.138]:41109 "EHLO mxf98a.netcup.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751340AbeBZXAp (ORCPT ); Mon, 26 Feb 2018 18:00:45 -0500 Authentication-Results: mxf98a; spf=pass (sender IP is 77.7.26.24) smtp.mailfrom=rabel@robertabel.eu smtp.helo=[192.168.178.21] Subject: Re: [PATCH 3/4] auxdisplay: charlcd: fix x/y address commands To: Miguel Ojeda , Andy Shevchenko Cc: linux-kernel , Willy Tarreau , Geert Uytterhoeven , torvalds@linux-foundation.org, akpm@linux-foundation.org, eldad@fogrefinery.com, me@tobin.cc, corbet@lwn.net, pantelis.antoniou@konsulko.com References: <9ec3c54c-f8fe-22d7-783e-8cf9862405bb@robertabel.eu> <20180225235432.31209-1-rabel@robertabel.eu> <20180225235432.31209-2-rabel@robertabel.eu> <20180225235432.31209-3-rabel@robertabel.eu> <20180225235432.31209-4-rabel@robertabel.eu> From: Robert Abel Message-ID: <1b66ecb1-5951-35f3-3dd2-4448628d3fbc@robertabel.eu> Date: Tue, 27 Feb 2018 00:00:42 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: de-DE Content-Transfer-Encoding: 8bit X-PPP-Message-ID: <20180226230044.11896.51608@mxf98a.netcup.net> X-PPP-Vhost: robertabel.eu Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi @ll, this is a discussion stemming from drivers/auxdisplay about the usage and possible deprecation of simple_strto* set of functions found in lib/vsprintf. I cc'ed everybody who signed off and also everybody who signed/authored/added/removed more than 20% of lib/vsprintf. This has come up, because some auxdisplay functionality was broken by a well-intentioned patch to switch from simple_strtoul to kstrtoul in 129957069e6af42a6e021d90679c56662c95f7e1 (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=129957069e6af42a6e021d90679c56662c95f7e1) and now there is discussion about whether the simple_strto* functions are really obsolete. On 26 Feb 2018 18:26, Miguel Ojeda wrote: > On Mon, Feb 26, 2018 at 6:09 PM, Andy Shevchenko wrote: >> On Mon, Feb 26, 2018 at 6:54 PM, Miguel Ojeda wrote: >>> On Mon, Feb 26, 2018 at 12:44 PM, Andy Shevchenko wrote: >>>> Perhaps instead of dancing around kstrtox() better to switch to >>>> simple_strtoul() ? >>> >>> It seems deprecated: >>> >>> /* Obsolete, do not use. Use kstrto instead */ >>> extern unsigned long simple_strtoul(const char *,char **,unsigned int); >> >> It has been discussed several times. The comment is simple wrong. >> >> Because of the requirement of kstrtox() to have a \0 or \n followed by >> \0 as "end of field". >> simple_strto*() is suitable to be run in place. > > I agree that in-place versions of these kind of string functions are > very useful, don't get me wrong! But unless someone changes the > "official" comment, we shouldn't add new code relying on them. So can we get clarity in form of a patch here, or not? I'm hesitant to move back to simple_kstroul, because to me it seems that general consensus (at least when the comment was put there) was to remove it: > commit 462e471107624fe9bd8b6353ac13e06305c3f3fd > Author: Eldad Zack <> > Date: Mon Dec 17 16:03:05 2012 -0800 > > simple_strto*: annotate function as obsolete > > Update the documentation for simple_strto* to reflect that it has been > obsoleted and advise the usage of kstrto*. > > Signed-off-by: Eldad Zack <> > Cc: J. Bruce Fields <> > Cc: Joe Perches <> > Cc: Randy Dunlap <> > Cc: Alexey Dobriyan <> > Cc: Rob Landley <> > Signed-off-by: Andrew Morton <> > Signed-off-by: Linus Torvalds <> One big advantage simple_kstro* functions have over their kstrto* cousins is that strings don't need to be null-terminated. Instead, they will be parsed as far as they can be and a pointer to the end of the respective number will be returned. Regards, Robert