From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751550AbaCVQ3u (ORCPT ); Sat, 22 Mar 2014 12:29:50 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:48309 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750948AbaCVQ3s (ORCPT ); Sat, 22 Mar 2014 12:29:48 -0400 Message-ID: <1395505786.2143.14.camel@dabdike.int.hansenpartnership.com> Subject: Re: [PATCH v2] LLVMLinux: Remove warning about returning an uninitialized variable From: James Bottomley To: behanw@converseincode.com Cc: arnd@arndb.de, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, dwmw2@infradead.org, pageexec@freemail.hu, Mark Charlebois Date: Sat, 22 Mar 2014 09:29:46 -0700 In-Reply-To: <1395503299-15203-1-git-send-email-behanw@converseincode.com> References: <201403221101.16961.arnd@arndb.de> <1395503299-15203-1-git-send-email-behanw@converseincode.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.10.2 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 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). 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. James