From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759427AbbFBQZ4 (ORCPT ); Tue, 2 Jun 2015 12:25:56 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:54211 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752625AbbFBQZt (ORCPT ); Tue, 2 Jun 2015 12:25:49 -0400 Date: Tue, 2 Jun 2015 09:25:44 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, laijs@cn.fujitsu.com, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH] rcu: Use WRITE_ONCE in RCU_INIT_POINTER Message-ID: <20150602162544.GI5989@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20150602152648.GT3644@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150602152648.GT3644@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15060216-0013-0000-0000-00000BC5A984 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 02, 2015 at 05:26:48PM +0200, Peter Zijlstra wrote: > > For the paranoid amongst us GCC would be in its right to use byte stores > to write our NULL value, tell it not to do that. > > Signed-off-by: Peter Zijlstra (Intel) Good point, queued for 4.3. Thanx, Paul > --- > include/linux/rcupdate.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > index 33a056bb886f..e173847b6543 100644 > --- a/include/linux/rcupdate.h > +++ b/include/linux/rcupdate.h > @@ -1046,7 +1046,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) > #define RCU_INIT_POINTER(p, v) \ > do { \ > rcu_dereference_sparse(p, __rcu); \ > - p = RCU_INITIALIZER(v); \ > + WRITE_ONCE(p, RCU_INITIALIZER(v)); \ > } while (0) > > /** >