From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932099Ab3KWEAV (ORCPT ); Fri, 22 Nov 2013 23:00:21 -0500 Received: from relay4-d.mail.gandi.net ([217.70.183.196]:44102 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755311Ab3KWEAS (ORCPT ); Fri, 22 Nov 2013 23:00:18 -0500 X-Originating-IP: 50.43.14.201 Date: Fri, 22 Nov 2013 20:00:05 -0800 From: Josh Triplett To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu Subject: Re: [PATCH v3 tip/core/locking 0/3] Memory-barrier documentation updates Message-ID: <20131123040005.GA2090@leaf> References: <20131122192657.GA11924@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131122192657.GA11924@linux.vnet.ibm.com> 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 Fri, Nov 22, 2013 at 11:26:57AM -0800, Paul E. McKenney wrote: > Hello! > > This series applies some long-needed updates to memory-barriers.txt: > > 1. Add ACCESS_ONCE() calls where needed to ensure their inclusion > in code copy-and-pasted from this file. > > 2. Add long atomic examples alongside the existing atomics. > > 3. Prohibit architectures supporting the Linux kernel from > speculating stores. > > Changes from v2: > > o Update examples so that that load against which the subsequent > store is to be ordered is part of the "if" condition. > > o Add an example showing how the compiler can remove "if" > conditions and how to prevent it from doing so. > > o Add ACCESS_ONCE() to the compiler-barrier section. > > o Add a sentence noting that transitivity requires smp_mb(). > > Changes from v1: > > o Combined with Peter Zijlstra's speculative-store-prohibition patch. > > o Added more pitfalls to avoid when prohibiting speculative > stores, along with how to avoid them. > > o Applied Josh Triplett's review comments. For v3, all three patches: Reviewed-by: Josh Triplett