Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753589AbYJGKXq (ORCPT ); Tue, 7 Oct 2008 06:23:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752474AbYJGKXh (ORCPT ); Tue, 7 Oct 2008 06:23:37 -0400 Received: from one.firstfloor.org ([213.235.205.2]:35827 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751185AbYJGKXg (ORCPT ); Tue, 7 Oct 2008 06:23:36 -0400 Date: Tue, 7 Oct 2008 12:29:42 +0200 From: Andi Kleen To: Hisashi Hifumi Cc: Andi Kleen , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RESEND] [PATCH] VFS: make file->f_pos access atomic on 32bit arch Message-ID: <20081007102942.GE20740@one.firstfloor.org> References: <6.0.0.20.2.20081007140438.0580f110@172.19.0.2> <87hc7onbvo.fsf@basil.nowhere.org> <6.0.0.20.2.20081007183452.0f052210@172.19.0.2> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6.0.0.20.2.20081007183452.0f052210@172.19.0.2> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 746 Lines: 20 > Maybe cmpxchg8b is good for i486 or later x86, but i386 or other architectures > that do not have similar instruction needs some locking primitive. I think lazy We have a cmpxchg emulation on 386. That works because only UP 386s are supported, so it can be done in software. > seqlock is one option for making file->f_pos access atomic. The question is if it's the right option. At least all the common operations on fds (read/write) are all writers, not readers. -Andi -- ak@linux.intel.com -- 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/