From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759120AbZBDXqZ (ORCPT ); Wed, 4 Feb 2009 18:46:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757376AbZBDXpy (ORCPT ); Wed, 4 Feb 2009 18:45:54 -0500 Received: from ozlabs.org ([203.10.76.45]:58899 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756125AbZBDXpx (ORCPT ); Wed, 4 Feb 2009 18:45:53 -0500 From: Rusty Russell To: Andrew Morton Subject: Re: [PATCH 2/3] work_on_cpu: Use our own workqueue. Date: Thu, 5 Feb 2009 10:15:46 +1030 User-Agent: KMail/1.11.0 (Linux/2.6.27-11-generic; KDE/4.2.0; i686; ; ) Cc: Ingo Molnar , travis@sgi.com, mingo@redhat.com, davej@redhat.com, cpufreq@vger.kernel.org, linux-kernel@vger.kernel.org References: <20090116191108.135927000@polaris-admin.engr.sgi.com> <20090204213519.GR22608@elte.hu> <20090204134823.8eefa728.akpm@linux-foundation.org> In-Reply-To: <20090204134823.8eefa728.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200902051015.47360.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 05 February 2009 08:18:23 Andrew Morton wrote: > I expect that the same argument applies to most of the set_cpus_allowed() > callsites - they're run by root-only code. Sure, root can (with > careful timing) move root's own thread onto the wrong CPU in the middle > of microcode loading. In which case root gets to own both pieces. Sorry, I don't accept this at all. It's completely reasonable for me to write a tool which clears all tasks off a cpu. We wrote an API to do it, now we're going to say don't use it? Yes, it's a pain to fix. Yes, we should never have been doing it this way in the first place. But let's not blame the users. Rusty.