From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751296AbcGFFfV (ORCPT ); Wed, 6 Jul 2016 01:35:21 -0400 Received: from LGEAMRELO11.lge.com ([156.147.23.51]:52402 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750879AbcGFFfR (ORCPT ); Wed, 6 Jul 2016 01:35:17 -0400 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Wed, 6 Jul 2016 14:33:29 +0900 From: Byungchul Park To: Boqun Feng Cc: Peter Zijlstra , mingo@kernel.org, linux-kernel@vger.kernel.org, walken@google.com Subject: Re: [PATCH] lockdep: Add a document describing crossrelease feature Message-ID: <20160706053328.GB2279@X58A-UD3R> References: <1466398527-1122-1-git-send-email-byungchul.park@lge.com> <1467346538-1579-1-git-send-email-byungchul.park@lge.com> <20160701104521.GG30154@twins.programming.kicks-ass.net> <20160704064259.GX2279@X58A-UD3R> <20160706004943.GA20366@insomnia> <20160706021710.GA2279@X58A-UD3R> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160706021710.GA2279@X58A-UD3R> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 06, 2016 at 11:17:10AM +0900, Byungchul Park wrote: > > lock(A) > wait_for(B) > ~~~~~~~~~~~~~~~~~~~~~~~~ <- serialized by atomic operation > lock(A) > unlock(A) > wake(B) > unlock(A) By the way, I have a question. Is there anyone who could answer it? I want to serialize between two context's lock operations, for example, context A context B -------------- -------------- lock A lock B ... lock C atomic_inc_return ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <- serialization atomic_read lock D ... lock E lock F so that we can see these in the order like A -> B -> C -> D -> E -> F. atomic_inc_return() is used after lock C in context A, and atomic_read() is used before lock D in context B. And I want to make it serialized when the atomic_read() can see the increased value. Can I use smp_mb__after_atomic() just after atomic_read() or should I use smp_mb()? I think anyway I have to choose one of them for that ordering. Thank you, Byungchul