From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752414AbZHZR2W (ORCPT ); Wed, 26 Aug 2009 13:28:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752378AbZHZR2W (ORCPT ); Wed, 26 Aug 2009 13:28:22 -0400 Received: from terminus.zytor.com ([198.137.202.10]:51371 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752370AbZHZR2V (ORCPT ); Wed, 26 Aug 2009 13:28:21 -0400 Message-ID: <4A957073.10302@zytor.com> Date: Wed, 26 Aug 2009 10:27:15 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Thunderbird/3.0b2 MIME-Version: 1.0 To: Ingo Molnar CC: Jiri Slaby , jeremy@xensource.com, chrisw@sous-sol.org, virtualization@lists.osdl.org, xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] XEN: enlighten, use uninitialized_var(cx) References: <1251234044-6943-1-git-send-email-jirislaby@gmail.com> <20090826060925.GA6194@elte.hu> In-Reply-To: <20090826060925.GA6194@elte.hu> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/25/2009 11:09 PM, Ingo Molnar wrote: >> >> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c >> index e90540a..5ab75e2 100644 >> --- a/arch/x86/xen/enlighten.c >> +++ b/arch/x86/xen/enlighten.c >> @@ -202,7 +202,7 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx, >> >> static __init void xen_init_cpuid_mask(void) >> { >> - unsigned int ax, bx, cx, dx; >> + unsigned int ax, bx, uninitialized_var(cx), dx; > > Please dont use uninitialized_var(), it's an unreliable facility: if > this variable ever grows a real used-without-initialization bug in > the future, the compiler warning is turned off permanently. It's > rare but might happen. We are better off with initializing it to > zero. > I hadn't seen this thread, but I pushed a patch to x86/urgent to do exactly that while I was committing the Xen crash patch last night. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.