From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757142AbbHZSfd (ORCPT ); Wed, 26 Aug 2015 14:35:33 -0400 Received: from smtprelay0145.hostedemail.com ([216.40.44.145]:39002 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751751AbbHZSf3 (ORCPT ); Wed, 26 Aug 2015 14:35:29 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::,RULES_HIT:41:355:379:541:599:966:973:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2196:2199:2393:2553:2559:2562:2828:3138:3139:3140:3141:3142:3353:3622:3865:3866:3867:3868:3870:3871:3874:4321:4385:4605:5007:6119:6261:7808:7903:8603:8660:10004:10400:10450:10455:10848:11026:11232:11473:11658:11914:12043:12296:12438:12517:12519:12555:12740:13069:13148:13161:13229:13230:13255:13311:13357:19904:19999:21080:21088,0,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: fan06_1271da9303319 X-Filterd-Recvd-Size: 2662 Message-ID: <1440614125.2780.33.camel@perches.com> Subject: Re: [PATCH] thinkpad_acpi: Remove side effects from vdbg_printk -> no_printk macro From: Joe Perches To: Henrique de Moraes Holschuh Cc: Darren Hart , ibm-acpi-devel@lists.sourceforge.net, platform-driver-x86@vger.kernel.org, linux-kernel Date: Wed, 26 Aug 2015 11:35:25 -0700 In-Reply-To: <1440613632.3433387.366841089.60E02F29@webmail.messagingengine.com> References: <1440612818.2780.24.camel@perches.com> <1440613632.3433387.366841089.60E02F29@webmail.messagingengine.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.12.11-0ubuntu3 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 Wed, 2015-08-26 at 15:27 -0300, Henrique de Moraes Holschuh wrote: > On Wed, Aug 26, 2015, at 15:13, Joe Perches wrote: > > vdbg_printk when not using CONFIG_THINKPAD_ACPI_DEBUG uses > > no_printk which produces no logging output but always > > evaluates arguments. > > > > Change the macro to surround the no_printk call with > > do { if (0) no_printk(...); } while (0) > > to avoid the unnecessary argument evaluations. > > > > $ size drivers/platform/x86/thinkpad_acpi.o* > > text data bss dec hex filename > > 60918 6184 824 67926 10956 > > drivers/platform/x86/thinkpad_acpi.o.new > > 60927 6184 824 67935 1095f > > drivers/platform/x86/thinkpad_acpi.o.old > > The code size savings of this change are really small... yup. This is just an on-the-way patch to get all the no_printk uses in a state that can be converted more simply to a side-effect free mechanism. > > --- a/drivers/platform/x86/thinkpad_acpi.c > > +++ b/drivers/platform/x86/thinkpad_acpi.c > > @@ -402,7 +402,7 @@ static const char *str_supported(int is_supported); > > #else > > static inline const char *str_supported(int is_supported) { return ""; } > > #define vdbg_printk(a_dbg_level, format, arg...) \ > > - no_printk(format, ##arg) > > + do { if (0) no_printk(format, ##arg); } while (0) > > #endif > > And won't this change disable compile-time checking of 'format ## arg' > for issues? No. The call is still there so the compiler checks the format/argument matches, but eliminates the call and any side-effect calls from the object file.