Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936703AbXHLSMf (ORCPT ); Sun, 12 Aug 2007 14:12:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756762AbXHLSMX (ORCPT ); Sun, 12 Aug 2007 14:12:23 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:38942 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752603AbXHLSMV (ORCPT ); Sun, 12 Aug 2007 14:12:21 -0400 Date: Sun, 12 Aug 2007 11:11:25 -0700 (PDT) From: Linus Torvalds To: Segher Boessenkool cc: schwidefsky@de.ibm.com, wjiang@resilience.com, wensong@linux-vs.org, heiko.carstens@de.ibm.com, linux-kernel@vger.kernel.org, ak@suse.de, cfriesen@nortel.com, netdev@vger.kernel.org, horms@verge.net.au, akpm@linux-foundation.org, Chuck Ebbert , davem@davemloft.net, zlynx@acm.org, Chris Snook Subject: Re: [PATCH] make atomic_t volatile on all architectures In-Reply-To: <74868f39491f8691afc5540f72679129@kernel.crashing.org> Message-ID: References: <20070808230733.GA17270@shell.boston.redhat.com> <46BAC2BE.1090106@redhat.com> <46BB508B.7050601@redhat.com> <1186683646.9669.20.camel@localhost> <1186912098.3852.11.camel@localhost> <74868f39491f8691afc5540f72679129@kernel.crashing.org> 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: 982 Lines: 23 On Sun, 12 Aug 2007, Segher Boessenkool wrote: > > Yeah. Compiler errors are more annoying though I dare say ;-) Actually, compile-time errors are fine, and easy to work around. *Much* more annoying is when gcc actively generates subtly bad code. We've had use-after-free issues due to incorrect gcc liveness calculations etc, and inline asm has beeen one of the more common causes - exactly because the kernel is one of the few users (along with glibc) that uses it at all. Now *those* are hard to find - the code works most of the time, but the compiler has inserted a really subtle race condition into the code (deallocated a local stack entry before last use). We had that with our semaphore code at some point. Linus - 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/