From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754591AbbAIGmK (ORCPT ); Fri, 9 Jan 2015 01:42:10 -0500 Received: from smtp2.provo.novell.com ([137.65.250.81]:40015 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751108AbbAIGmJ (ORCPT ); Fri, 9 Jan 2015 01:42:09 -0500 Message-ID: <1420785714.25454.1.camel@stgolabs.net> Subject: Re: [PATCH tip/core/rcu 01/14] rcu: Protect rcu_boost() lockless accesses with ACCESS_ONCE() From: Davidlohr Bueso To: paulmck@linux.vnet.ibm.com Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Date: Thu, 08 Jan 2015 22:41:54 -0800 In-Reply-To: <20150108152230.GL5280@linux.vnet.ibm.com> References: <20150107173215.GA897@linux.vnet.ibm.com> <1420651953-2651-1-git-send-email-paulmck@linux.vnet.ibm.com> <20150108094102.GD29390@twins.programming.kicks-ass.net> <20150108152230.GL5280@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2015-01-08 at 07:22 -0800, Paul E. McKenney wrote: > > Didn't we just obsolete ACCESS_ONCE with that {READ,WRITE}_ONCE stuff? > > Indeed we did! But that was after I did this commit back on October 29th. > > I am planning a bulk change to READ_ONCE() and ASSIGN_ONCE() either as > the last patch for 3.20 or as the first one for 3.21. Probably as the > first for 3.21 to minimize rebasing hassles with any needed 3.20 fixes. That reminds me, I think the new conversion for stores will most likely introduce silly arg bugs: - ACCESS_ONCE(a) = b; + ASSIGN_ONCE(b, a); Thanks, Davidlohr