From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751582Ab0CAHf5 (ORCPT ); Mon, 1 Mar 2010 02:35:57 -0500 Received: from terminus.zytor.com ([198.137.202.10]:44738 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751264Ab0CAHf4 (ORCPT ); Mon, 1 Mar 2010 02:35:56 -0500 Message-ID: <4B8B6E43.9030305@zytor.com> Date: Sun, 28 Feb 2010 23:35:31 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc12 Thunderbird/3.0.1 MIME-Version: 1.0 To: Luca Barbieri , Paul Mackerras CC: Ingo Molnar , a.p.zijlstra@chello.nl, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5] x86-32: improve atomic64_t functions (v2) References: <1266600404-16402-1-git-send-email-luca@luca-barbieri.com> <4B845AEE.5080604@zytor.com> <20100226101423.GA25641@elte.hu> In-Reply-To: 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 02/26/2010 03:23 AM, Luca Barbieri wrote: > Sent patches, both to conditionally perform the test and implement the > functions for x86 and x86-64. Yes, and with the test turned on, the kernel crashes immediately on boot on x86-64. Some minor investigation reveals the following: lib/atomic64.c has the wrong return value for atomic64_add_unless(). With "wrong" I mean it is the opposite sense compared to atomic_add_unless(), not just on x86 but on all architectures. Accordingly, I have to conclude that lib/atomic64.c is buggy, and that since your test matches that bug, I will have to conclude that your x86-32 implementation is also buggy. Thus, please send patches to fix your test and your 32-bit implementations (and preferrably lib/atomic64.c too, but I can do that just fine.) Cc: Paul Mackerras who did the generic atomic64_t implementation for verification that this is indeed a bug. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.