From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751904AbaCVQhp (ORCPT ); Sat, 22 Mar 2014 12:37:45 -0400 Received: from mail-pa0-f51.google.com ([209.85.220.51]:37347 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751512AbaCVQhk (ORCPT ); Sat, 22 Mar 2014 12:37:40 -0400 Message-ID: <532DBC50.9040505@converseincode.com> Date: Sat, 22 Mar 2014 09:37:36 -0700 From: Behan Webster User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: James Bottomley CC: arnd@arndb.de, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, dwmw2@infradead.org, pageexec@freemail.hu, Mark Charlebois Subject: Re: [PATCH v2] LLVMLinux: Remove warning about returning an uninitialized variable References: <201403221101.16961.arnd@arndb.de> <1395503299-15203-1-git-send-email-behanw@converseincode.com> <1395505786.2143.14.camel@dabdike.int.hansenpartnership.com> In-Reply-To: <1395505786.2143.14.camel@dabdike.int.hansenpartnership.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/22/14 09:29, James Bottomley wrote: > On Sat, 2014-03-22 at 08:48 -0700, behanw@converseincode.com wrote: >> From: Behan Webster >> >> Fix uninitialized return code in default case in cmpxchg-local.h >> >> This patch fixes the code to prevent an uninitialized return value that is detected >> when compiling with clang. The bug produces numerous warnings when compiling the >> Linux kernel with clang. >> >> Signed-off-by: Behan Webster >> Signed-off-by: Mark Charlebois >> --- >> include/asm-generic/cmpxchg-local.h | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h >> index d8d4c89..9112111 100644 >> --- a/include/asm-generic/cmpxchg-local.h >> +++ b/include/asm-generic/cmpxchg-local.h >> @@ -41,6 +41,7 @@ static inline unsigned long __cmpxchg_local_generic(volatile void *ptr, >> break; >> default: >> wrong_size_cmpxchg(ptr); >> + __builtin_unreachable(); > No, that's got to be unreachable() so that it works in all compilers, > (__builtin_unreachable is a gcc-4 ism). It is also supported by clang. > Got to say this still looks wrong. If wrong_size_cmpxchg() cannot > return, the function should be annotated as such with __noreturn (like > panic()) so the unreachable() should be superfluous. Okay. I can try that instead. Thanks, Behan -- Behan Webster behanw@converseincode.com