Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751440AbdH3JOR (ORCPT ); Wed, 30 Aug 2017 05:14:17 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:54239 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298AbdH3JOQ (ORCPT ); Wed, 30 Aug 2017 05:14:16 -0400 Date: Wed, 30 Aug 2017 11:14:09 +0200 From: Peter Zijlstra To: Byungchul Park Cc: mingo@kernel.org, tj@kernel.org, boqun.feng@gmail.com, david@fromorbit.com, johannes@sipsolutions.net, oleg@redhat.com, linux-kernel@vger.kernel.org, kernel-team@lge.com Subject: Re: [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation Message-ID: <20170830091409.y2d4puph3qn2jwxx@hirez.programming.kicks-ass.net> References: <20170823121432.990701317@infradead.org> <20170824021840.GC6772@X58A-UD3R> <20170824140240.t4imrpvussebfimm@hirez.programming.kicks-ass.net> <20170825011114.GA3858@X58A-UD3R> <20170829085939.ggmb6xiohw67micb@hirez.programming.kicks-ass.net> <20170830020953.GE3240@X58A-UD3R> <20170830074117.GG3240@X58A-UD3R> <20170830085333.GM32112@worktop.programming.kicks-ass.net> <004601d3216e$a3702030$ea506090$@lge.com> <20170830091223.xxnh3podtcumlabm@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170830091223.xxnh3podtcumlabm@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 795 Lines: 15 On Wed, Aug 30, 2017 at 11:12:23AM +0200, Peter Zijlstra wrote: > On Wed, Aug 30, 2017 at 06:01:59PM +0900, Byungchul Park wrote: > > My point is that we inevitably lose valuable dependencies by yours. That's > > why I've endlessly asked you 'do you have any reason you try those patches?' > > a ton of times. And you have never answered it. > > The only dependencies that are lost are those between the first work and > the setup of the workqueue thread. > > And there obviously _should_ not be any dependencies between those. A > work should not depend on the setup of the thread. Furthermore, the save/restore can't preserve those dependencies. The moment a work exhausts xhlocks[] they are gone. So by assuming the first work _will_ exhaust the history there is effectively nothing lost.