From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031052AbXDYPSp (ORCPT ); Wed, 25 Apr 2007 11:18:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031062AbXDYPSp (ORCPT ); Wed, 25 Apr 2007 11:18:45 -0400 Received: from agminet01.oracle.com ([141.146.126.228]:34880 "EHLO agminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031052AbXDYPSo (ORCPT ); Wed, 25 Apr 2007 11:18:44 -0400 Date: Wed, 25 Apr 2007 08:20:28 -0700 From: Randy Dunlap To: Richard Knutsson Cc: Jiri Bohac , akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH] fix abs() macro to work with types wider than int Message-Id: <20070425082028.8ece3094.randy.dunlap@oracle.com> In-Reply-To: <4628B5B6.90303@student.ltu.se> References: <20070419092339.GA13569@dwarf.suse.cz> <20070419084339.418dbe69.randy.dunlap@oracle.com> <4628B5B6.90303@student.ltu.se> Organization: Oracle Linux Eng. X-Mailer: Sylpheed 2.3.1 (GTK+ 2.8.10; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Whitelist: TRUE X-Whitelist: TRUE X-Brightmail-Tracker: AAAAAQAAAAI= Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Apr 2007 14:44:38 +0200 Richard Knutsson wrote: > Randy Dunlap wrote: > > On Thu, 19 Apr 2007 11:23:39 +0200 Jiri Bohac wrote: > > > > > >> Hi, > >> > >> is there any reason to use an explicit int instead of a typeof in > >> the abs() macro? The current implementation will return bogus > >> results when used with longs. > >> > > > > I think it's like it is just to be consistent with abs() in C, > > which also contains labs() and llabs(). > > > We actually had labs() before (few months ago), but since it was not > used, and if it would it seemed better to just fix abs(), it was > removed. So I think this is the appropriate way to go. Sounds like when someone actually needs labs() or llabs() they can submit a patch for however they would like to use it. > >> How about changing the int to a typeof like this?: > >> > >> > >> > >> Fix the abs() macro to work with wider types than int. > >> > >> Signed-off-by: Jiri Bohac > >> > >> --- linux-2.6.21-rc5.orig/include/linux/kernel.h > >> +++ linux-2.6.21-rc5/include/linux/kernel.h > >> @@ -89,7 +89,7 @@ extern int cond_resched(void); > >> #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) > >> > >> #define abs(x) ({ \ > >> - int __x = (x); \ > >> + typeof(x) __x = (x); \ > >> (__x < 0) ? -__x : __x; \ > >> }) --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***