From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757254AbdJKQHN (ORCPT ); Wed, 11 Oct 2017 12:07:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48766 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752250AbdJKQHJ (ORCPT ); Wed, 11 Oct 2017 12:07:09 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 3FFB082109 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.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: <20171011155948.GE3521@linux.vnet.ibm.com> References: <20171011155948.GE3521@linux.vnet.ibm.com> <20171011122217.GD11106@arm.com> <20171010155042.GD3521@linux.vnet.ibm.com> <1507594969-8347-12-git-send-email-paulmck@linux.vnet.ibm.com> <20171010001951.GA6476@linux.vnet.ibm.com> <8079.1507628146@warthog.procyon.org.uk> <26455.1507724399@warthog.procyon.org.uk> <6309.1507735045@warthog.procyon.org.uk> To: paulmck@linux.vnet.ibm.com Cc: dhowells@redhat.com, Will Deacon , linux-kernel@vger.kernel.org, mingo@kernel.org, torvalds@linux-foundation.org, mark.rutland@arm.com, linux-arch@vger.kernel.org, peterz@infradead.org, Jonathan Corbet , Alexander Kuleshov , dvyukov@google.com Subject: Re: [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends() MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <7483.1507738025.1@warthog.procyon.org.uk> Date: Wed, 11 Oct 2017 17:07:05 +0100 Message-ID: <7484.1507738025@warthog.procyon.org.uk> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 11 Oct 2017 16:07:09 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paul E. McKenney wrote: > It does not. In most cases, the barriered version would be > smp_store_release(). Ummm... Is that good enough? Is: WRITE_ONCE(x, 1); WRITE_ONCE(x, 2); equivalent to: smp_store_release(x, 1); smp_store_release(x, 2); if CONFIG_SMP=n? (Consider what happens if an interrupt messes with x). If it is good enough, should we be using smp_load_acquire() rather than READ_ONCE()? David