Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755514AbXJ0TFR (ORCPT ); Sat, 27 Oct 2007 15:05:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752557AbXJ0TFD (ORCPT ); Sat, 27 Oct 2007 15:05:03 -0400 Received: from mx2.suse.de ([195.135.220.15]:33135 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751800AbXJ0TFB (ORCPT ); Sat, 27 Oct 2007 15:05:01 -0400 To: Mathieu Desnoyers Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] Fix x86_64 TIF_SYSCALL_TRACE race in entry.S From: Andi Kleen References: <20071026193738.GA1591@Krystal> <20071027180837.GA18134@Krystal> Date: Sat, 27 Oct 2007 21:04:57 +0200 In-Reply-To: <20071027180837.GA18134@Krystal> (Mathieu Desnoyers's message of "Sat\, 27 Oct 2007 14\:08\:37 -0400") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 648 Lines: 18 Mathieu Desnoyers writes: > We make sure that the thread flag read is coherent between our new test and the ALLWORK_MASK test by first saving it in a register used for both comparisons. > That doesn't make sense. If someone is setting those asynchronously you can always race. You should really just stop the process like ptrace does before changing such things. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/