From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757338AbdJKMVL (ORCPT ); Wed, 11 Oct 2017 08:21:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57218 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752033AbdJKMVI (ORCPT ); Wed, 11 Oct 2017 08:21:08 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 4AA1EA797 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=dhowells@redhat.com Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20171010001951.GA6476@linux.vnet.ibm.com> References: <20171010001951.GA6476@linux.vnet.ibm.com> To: paulmck@linux.vnet.ibm.com Cc: dhowells@redhat.com, linux-kernel@vger.kernel.org, mark.rutland@arm.com, linux-arch@vger.kernel.org, viro@zeniv.linux.org.uk, tj@kernel.org, cl@linux.com, davem@davemloft.net, peterz@infradead.org, mingo@redhat.com, rostedt@goodmis.org, akpm@linux-foundation.org, corbet@lwn.net, james.l.morris@oracle.com, torvalds@linux-foundation.org Subject: Re: [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <26478.1507724463.1@warthog.procyon.org.uk> Date: Wed, 11 Oct 2017 13:21:03 +0100 Message-ID: <26479.1507724463@warthog.procyon.org.uk> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 11 Oct 2017 12:21:08 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paul E. McKenney wrote: > Will Deacon has proposed adding smp_read_barrier_depends() to READ_ONCE(), > which would mean that quite a few instances of smp_read_barrier_depends() > would become redundant. It's not clear from you description where the barrier is added in relation to the read: before, after or both? David