From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-yw1-f68.google.com ([209.85.161.68]:43743 "EHLO mail-yw1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726615AbeHUUsR (ORCPT ); Tue, 21 Aug 2018 16:48:17 -0400 Date: Tue, 21 Aug 2018 10:27:11 -0700 From: Tejun Heo To: Johannes Berg Cc: Lai Jiangshan , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org Subject: Re: [PATCH 1/2] workqueue: skip lockdep wq dependency in cancel_work_sync() Message-ID: <20180821172711.GR3978217@devbig004.ftw2.facebook.com> (sfid-20180821_192725_761527_55888B0B) References: <20180821120317.4115-1-johannes@sipsolutions.net> <20180821120317.4115-2-johannes@sipsolutions.net> <20180821160814.GP3978217@devbig004.ftw2.facebook.com> <1534871894.25523.34.camel@sipsolutions.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1534871894.25523.34.camel@sipsolutions.net> Sender: linux-wireless-owner@vger.kernel.org List-ID: Hello, Johannes. On Tue, Aug 21, 2018 at 07:18:14PM +0200, Johannes Berg wrote: > > But this can lead to a deadlock. I'd much rather err on the side of > > discouraging complex lock dancing around ordered workqueues, no? > > What can lead to a deadlock? Oh not this particular case, but I was wondering whether we'd be missing legitimate possible deadlock cases by skipping lockdep for all cancel_work_sync()'s as they can actually flush. Thanks. -- tejun