From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934426AbZKYItS (ORCPT ); Wed, 25 Nov 2009 03:49:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933784AbZKYItS (ORCPT ); Wed, 25 Nov 2009 03:49:18 -0500 Received: from one.firstfloor.org ([213.235.205.2]:43857 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933733AbZKYItR (ORCPT ); Wed, 25 Nov 2009 03:49:17 -0500 To: David Miller Cc: npiggin@suse.de, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org Subject: Re: [rfc] "fair" rw spinlocks From: Andi Kleen References: <20091123145409.GA29627@wotan.suse.de> <20091124.121959.35689494.davem@davemloft.net> Date: Wed, 25 Nov 2009 09:49:23 +0100 In-Reply-To: <20091124.121959.35689494.davem@davemloft.net> (David Miller's message of "Tue, 24 Nov 2009 12:19:59 -0800 (PST)") Message-ID: <87638zvvjg.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/22.3 (gnu/linux) 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 David Miller writes: > > I think nobody would notice if you changed tasklist_lock into > a spinlock_t, and this would solve the DoS because at least on > x86 you'd end up with the ticket spinlocks. iirc tasklist_lock was one of them who could be potentially nested. So just turning it into a spinlock might deadlock. -Andi -- ak@linux.intel.com -- Speaking for myself only.