From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752803AbaILUMw (ORCPT ); Fri, 12 Sep 2014 16:12:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39802 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752125AbaILUMv (ORCPT ); Fri, 12 Sep 2014 16:12:51 -0400 Date: Sat, 13 Sep 2014 05:12:41 +0900 From: Tejun Heo To: Lai Jiangshan , linux-kernel@vger.kernel.org Cc: Gustavo Luiz Duarte , Mike Anderson , Tomas Henzl Subject: Re: [PATCH wq/for-3.18] workqueue: apply __WQ_ORDERED to create_singlethread_workqueue() Message-ID: <20140912201241.GB23756@mtj.dyndns.org> References: <20140912195328.GA23756@mtj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140912195328.GA23756@mtj.dyndns.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 13, 2014 at 04:53:28AM +0900, Tejun Heo wrote: > From e141deffe6a30cfe7dd6ad97f21afa85b80ca3ac Mon Sep 17 00:00:00 2001 > From: Tejun Heo > Date: Sat, 13 Sep 2014 04:14:30 +0900 > > create_singlethread_workqueue() is a compat interface for singled > threaded workqueue which maps to ordered workqueue w/ rescuer in the > current implementation. create_singlethread_workqueue() currently > implemented by invoking alloc_workqueue() w/ appropriate parameters. > > 8719dceae2f9 ("workqueue: reject adjusting max_active or applying > attrs to ordered workqueues") introduced __WQ_ORDERED to protect > ordered workqueues against dynamic attribute changes which can break > ordering guarantees but forgot to apply it to > create_singlethread_workqueue(). While this can be potentially > dangerous, this isn't a problem in practice given the existing uses of > dynamic attribute changes. > > Let's make create_singlethread_workqueue() wrap > alloc_ordered_workqueue() instead so that it inherits __WQ_ORDERED and > can implicitly track future ordered_workqueue changes. Oops, this is the right change but w/ wrong description and branch. W/o __WQ_ORDERED, create_singlethread_workqueue() is broken on NUMA setups. Will respin the patch. Thanks. -- tejun