From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751190AbaCXEZi (ORCPT ); Mon, 24 Mar 2014 00:25:38 -0400 Received: from smtprelay0139.hostedemail.com ([216.40.44.139]:57457 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750714AbaCXEZh (ORCPT ); Mon, 24 Mar 2014 00:25:37 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::,RULES_HIT:41:355:379:541:599:988:989:1260:1261:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1539:1593:1594:1711:1730:1747:1777:1792:2198:2199:2393:2559:2562:2731:2828:3138:3139:3140:3141:3142:3352:3622:3866:3867:3870:3871:3872:4321:5007:7652:10004:10400:10848:11026:11232:11473:11658:11914:12043:12517:12519:12740:13069:13311:13357,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0 X-HE-Tag: body72_13ac9c3c2e107 X-Filterd-Recvd-Size: 1473 Message-ID: <1395635132.13968.40.camel@joe-AO722> Subject: Re: [PATCH] thermal: Fix KELVIN_TO_CELSIUS macro From: Joe Perches To: Guenter Roeck Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Zhang Rui , Eduardo Valentin Date: Sun, 23 Mar 2014 21:25:32 -0700 In-Reply-To: <1395634496-25040-1-git-send-email-linux@roeck-us.net> References: <1395634496-25040-1-git-send-email-linux@roeck-us.net> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.8.4-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2014-03-23 at 21:14 -0700, Guenter Roeck wrote: > It is always a good idea to use paranthesis around macro parameters > to avoid undesired side effects. > > In this specific case, KELVIN_TO_CELSIUS() is used in > drivers/platform/x86/asus-wmi.c with parameter "value & 0xFFFF", > which due to operator evaluation order causes more or less random > results. Maybe it's better to use a statement expression to avoid multiple calculations of t Maybe; #define KELVIN_TO_CELSIUS(t) \ ({ \ long _t = (long)(t) - 2732; \ _t >= 0 ? (_t + 5) / 10 : (_t - 5) / 10; \ })