From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756524AbZDWMUA (ORCPT ); Thu, 23 Apr 2009 08:20:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752379AbZDWMTv (ORCPT ); Thu, 23 Apr 2009 08:19:51 -0400 Received: from one.firstfloor.org ([213.235.205.2]:33506 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752897AbZDWMTu (ORCPT ); Thu, 23 Apr 2009 08:19:50 -0400 Date: Thu, 23 Apr 2009 14:23:27 +0200 From: Andi Kleen To: Johannes Weiner Cc: Andi Kleen , arjan@linux.intel.com, linux-kernel@vger.kernel.org, torvalds@osdl.org, akpm@osdl.org Subject: Re: [PATCH] Eliminate thousands of warnings in WARN_ON with gcc 3.2 build Message-ID: <20090423122327.GN13896@one.firstfloor.org> References: <20090422221134.GA1753@basil.nowhere.org> <20090423120219.GA23479@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090423120219.GA23479@cmpxchg.org> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 23, 2009 at 02:02:19PM +0200, Johannes Weiner wrote: > > +{ > > + warn_slowpath_fmt(file, line, ""); > > +} > > +EXPORT_SYMBOL(warn_slowpath_null); > > That should still emit a warning due to passing in a zero-length > format string. Using (const char *){ 0 } as the literal would > suppress it (on gcc 4.3.3 at least) but I'm not sure if it's worth the > uglyness... Hmm, you're right 3.3 generates a warning for that, 3.2 doesn't But at least it's only a single one, not thousands. Your trick would make sense. Updated patch attached. -Andi --- Eliminate thousands of warnings with gcc 3.2 build v2 When building with gcc 3.2 I get thousands of warnings about passing a NULL format string to warn_on_slowpath(). Split this case out into a separate call. This should also shrink the kernel slightly. v2: Avoid warning in warn_slowpath_null on newer gccs too (J.Weiner) Acked-by: Jesper Nilsson Signed-off-by: Andi Kleen --- include/asm-generic/bug.h | 7 ++++--- kernel/panic.c | 12 +++++++++--- 2 files changed, 13 insertions(+), 6 deletions(-) Index: linux-2.6.30-rc2-ak/include/asm-generic/bug.h =================================================================== --- linux-2.6.30-rc2-ak.orig/include/asm-generic/bug.h 2009-01-11 20:20:40.000000000 +0100 +++ linux-2.6.30-rc2-ak/include/asm-generic/bug.h 2009-04-22 23:52:48.000000000 +0200 @@ -58,12 +58,13 @@ */ #ifndef __WARN #ifndef __ASSEMBLY__ -extern void warn_slowpath(const char *file, const int line, +extern void warn_slowpath_fmt(const char *file, const int line, const char *fmt, ...) __attribute__((format(printf, 3, 4))); +extern void warn_slowpath_null(const char *file, const int line); #define WANT_WARN_ON_SLOWPATH #endif -#define __WARN() warn_slowpath(__FILE__, __LINE__, NULL) -#define __WARN_printf(arg...) warn_slowpath(__FILE__, __LINE__, arg) +#define __WARN() warn_slowpath_null(__FILE__, __LINE__) +#define __WARN_printf(arg...) warn_slowpath_fmt(__FILE__, __LINE__, arg) #else #define __WARN_printf(arg...) do { printk(arg); __WARN(); } while (0) #endif Index: linux-2.6.30-rc2-ak/kernel/panic.c =================================================================== --- linux-2.6.30-rc2-ak.orig/kernel/panic.c 2009-04-19 19:29:07.000000000 +0200 +++ linux-2.6.30-rc2-ak/kernel/panic.c 2009-04-23 14:17:34.000000000 +0200 @@ -342,7 +342,7 @@ } #ifdef WANT_WARN_ON_SLOWPATH -void warn_slowpath(const char *file, int line, const char *fmt, ...) +void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) { va_list args; char function[KSYM_SYMBOL_LEN]; @@ -358,7 +358,7 @@ if (board) printk(KERN_WARNING "Hardware name: %s\n", board); - if (fmt) { + if (*fmt) { va_start(args, fmt); vprintk(fmt, args); va_end(args); @@ -369,7 +369,13 @@ print_oops_end_marker(); add_taint(TAINT_WARN); } -EXPORT_SYMBOL(warn_slowpath); +EXPORT_SYMBOL(warn_slowpath_fmt); + +void warn_slowpath_null(const char *file, int line) +{ + warn_slowpath_fmt(file, line, (const char *) { 0 }); +} +EXPORT_SYMBOL(warn_slowpath_null); #endif #ifdef CONFIG_CC_STACKPROTECTOR -- ak@linux.intel.com -- Speaking for myself only.