Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756037AbXKDSGi (ORCPT ); Sun, 4 Nov 2007 13:06:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753358AbXKDSGb (ORCPT ); Sun, 4 Nov 2007 13:06:31 -0500 Received: from nf-out-0910.google.com ([64.233.182.186]:6243 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752582AbXKDSGa (ORCPT ); Sun, 4 Nov 2007 13:06:30 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=n36poz6Ryut4I8sf+bQ0ePRDfuXnsdPTOV4BCctq4xheYutQR7iKiWxFNJvVW0FtupxQjzUldmuHV7m0v9l/rxtwBo1Od2W0TjMzJGXuqG92imjqh4l7RhSwQ0e7XN9h9qcLFFMDIFsEcxvoQx2s23UI+es+z9OFxeYe46Xe7IY= Message-ID: Date: Sun, 4 Nov 2007 19:06:28 +0100 From: "Bart Van Assche" To: "Linus Torvalds" Subject: Re: Is gcc thread-unsafe? Cc: "Andrew Haley" , "Linux Kernel Mailing List" , "Tomash Brechko" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <18210.2314.57767.962503@zebedee.pink> <18215.1394.294830.944162@zebedee.pink> <18219.17505.443550.620503@zebedee.pink> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1577 Lines: 35 On 11/4/07, Linus Torvalds wrote: > > On Sun, 4 Nov 2007, Bart Van Assche wrote: > > > > Has it already been decided who will do this audit, and when this > > audit will happen ? Has a target date been set when this audit should > > be complete, or is the completion of this audit a requirement for the > > release of a specific gcc version ? > > I am told that the gcc people realized that was indeed a bug (people were > able to show problems even in non-threaded environments with mprotect()), > and have now fixed it in the current gcc sources. That still leaves the > old versions with potential problems, but I think it makes it much less > interesting to audit for these things. > > Linus What I understood from the gcc mailing list is that a patch has been applied to the gcc sources that solves the issue with speculative stores that was already discussed here on the LKML (http://gcc.gnu.org/ml/gcc/2007-10/msg00554.html). But the issue I am referring to is a different issue: namely that a compiler optimization called register promotion can introduce data races. Hans J. Boehm has a clear explanation of this -- see also paragraph 4.3 in http://www.hpl.hp.com/techreports/2004/HPL-2004-209.pdf or http://portal.acm.org/citation.cfm?id=1064978.1065042 . Bart Van Assche. - 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/