From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753260AbZLHIlH (ORCPT ); Tue, 8 Dec 2009 03:41:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751465AbZLHIlF (ORCPT ); Tue, 8 Dec 2009 03:41:05 -0500 Received: from hera.kernel.org ([140.211.167.34]:39021 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750842AbZLHIlD (ORCPT ); Tue, 8 Dec 2009 03:41:03 -0500 Message-ID: <4B1E1130.9050108@kernel.org> Date: Tue, 08 Dec 2009 17:41:20 +0900 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20090915 SUSE/3.0b4-3.6 Thunderbird/3.0b4 MIME-Version: 1.0 To: Peter Zijlstra CC: tglx@linutronix.de, mingo@elte.hu, avi@redhat.com, efault@gmx.de, rusty@rustcorp.com.au, linux-kernel@vger.kernel.org, Gautham R Shenoy , Linus Torvalds Subject: Re: [PATCH 4/7] sched: implement force_cpus_allowed() References: <1259726212-30259-1-git-send-email-tj@kernel.org> <1259726212-30259-5-git-send-email-tj@kernel.org> <1259923259.3977.1928.camel@laptop> <1259923381.3977.1934.camel@laptop> <4B1C85D3.3080401@kernel.org> <1260174900.8223.1159.camel@laptop> <4B1CDA1C.3000802@kernel.org> <1260183278.8223.1500.camel@laptop> <4B1CE1E8.2070803@kernel.org> In-Reply-To: <4B1CE1E8.2070803@kernel.org> X-Enigmail-Version: 0.97a Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On 12/07/2009 08:07 PM, Tejun Heo wrote: > On 12/07/2009 07:54 PM, Peter Zijlstra wrote: >> So we seem to do cleanup_workqueue_thread() from CPU_POST_DEAD, but at >> that time any thread that might still be around will most certainly not >> be running on the offlined cpu anymore. >> >> If you really want to ensure you remain on the cpu, you have to complete >> from CPU_DOWN_PREPARE. >> >> We're not running things from offline CPUs. > > Oh, no, we're not doing that. We can't do that. What we're doing is > to continue to process works which were queued on the now offline cpu > unless it has been flushed/cancled from one of the cpu down > notifications and the reason why we need to be able to fork after > active is clear is to guarantee those flush/cancels don't deadlock. Does my explanation justify the patch? Thanks. -- tejun