Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755414AbdIGPVV (ORCPT ); Thu, 7 Sep 2017 11:21:21 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:42427 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753715AbdIGPVU (ORCPT ); Thu, 7 Sep 2017 11:21:20 -0400 Date: Thu, 7 Sep 2017 17:21:07 +0200 From: Peter Zijlstra To: Byungchul Park Cc: Byungchul Park , Tejun Heo , johannes.berg@intel.com, Ingo Molnar , Thomas Gleixner , oleg@redhat.com, david@fromorbit.com, "linux-kernel@vger.kernel.org" , kernel-team@lge.com Subject: Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush Message-ID: <20170907152107.v4wbvzi2zxlaelms@hirez.programming.kicks-ass.net> References: <1504744396-4182-1-git-send-email-byungchul.park@lge.com> <20170907094109.t5qzs3glfx32l327@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: 1072 Lines: 22 On Thu, Sep 07, 2017 at 08:37:08PM +0900, Byungchul Park wrote: > On Thu, Sep 7, 2017 at 6:41 PM, Peter Zijlstra wrote: > > On Thu, Sep 07, 2017 at 09:33:16AM +0900, Byungchul Park wrote: > >> Workqueue added manual acquisitions to catch deadlock cases. Now > >> crossrelease was introduced, some of those are redundant because > >> crossrelease-enabled wait_for_completeion() also does it. Removed it. > > > > This does not explain how it doesn't become the regular timing dependent > > stuff cross-release normally is. > > Yes, I will add more explanation for it at the next spin. > > But, let me explain it a bit here to help you get it, since it's very > simple. This has nothing to do with 'might' thing I introduced > previously. For 'might' thing, I will start it after getting your response. > > Here, I just removed acquire() because wait_for_completion() > already includes the acquire() by LOCKDEP_COMPLETIONS. > That's all. Ah I see, but it does so using some fairly nasty completion init stuff. The old code was far easier to read.