Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752854AbZI2VTG (ORCPT ); Tue, 29 Sep 2009 17:19:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752144AbZI2VTG (ORCPT ); Tue, 29 Sep 2009 17:19:06 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:52223 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752096AbZI2VTF (ORCPT ); Tue, 29 Sep 2009 17:19:05 -0400 Date: Tue, 29 Sep 2009 14:17:58 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Eric Dumazet cc: Martin Schwidefsky , Thomas Gleixner , John Stultz , Linux Kernel Mailing List , Peter Zijlstra , Ingo Molnar , Arjan van de Ven Subject: Re: Linux 2.6.32-rc1 In-Reply-To: <4AC2712C.4080901@gmail.com> Message-ID: References: <4AC060AE.1090401@gmail.com> <20090928191506.40b61793@mschwide.boeblingen.de.ibm.com> <4AC10365.7090802@gmail.com> <4AC2712C.4080901@gmail.com> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1172 Lines: 32 On Tue, 29 Sep 2009, Eric Dumazet wrote: > > Checking this commit, I believe problem comes from cmpxchg(), which doesnt > handle 64 bit on X86_32 (no compilation error, and null operation :( ) Wow. That's broken. Very nasty silent failure. > 1) Use cmpxchg64() Clearly better than what we have now, although cmpxchg64 does result is some really disgusting code. We will use a bare CMPXCHG64 only if you compile for PAE right now - so even if you tell Kconfig that you want to compile for a modern CPU, we won't be doing that whole cmpxchg64b thing directly, we'll inline some really disgusting code. So we really need to fix that up before it would be acceptable to use cmpxchg64(). And regardless, we should fix the silent cmpxchg failure, even if it's just a link-time failure or something. 64-bit things in the kernel used to be rare and special, but they aren't any more. Ingo, Peter, comments? 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/