From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934149AbbEMMvR (ORCPT ); Wed, 13 May 2015 08:51:17 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:51052 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754626AbbEMMvN (ORCPT ); Wed, 13 May 2015 08:51:13 -0400 Date: Wed, 13 May 2015 05:51:06 -0700 From: "Paul E. McKenney" To: Borislav Petkov 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, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, linux-edac@vger.kernel.org, Tony Luck Subject: Re: [PATCH tip/core/rcu 1/4] mce: Stop using array-index-based RCU primitives Message-ID: <20150513125106.GV6776@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20150512211814.GA31939@linux.vnet.ibm.com> <1431465524-32246-1-git-send-email-paulmck@linux.vnet.ibm.com> <20150513103157.GF1517@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150513103157.GF1517@pd.tnic> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15051312-0005-0000-0000-00000AC296A4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 13, 2015 at 12:31:57PM +0200, Borislav Petkov wrote: > On Tue, May 12, 2015 at 02:18:41PM -0700, Paul E. McKenney wrote: > > From: "Paul E. McKenney" > > > > Because mce is arch-specific x86 code, there is little or no > > performance benefit of using rcu_dereference_index_check() over using > > smp_load_acquire(). It also turns out that mce is the only place that > > array-index-based RCU is used, and it would be convenient to drop > > this portion of the RCU API. > > > > This patch therefore changes rcu_dereference_index_check() uses to > > smp_load_acquire(), but keeping the lockdep diagnostics, and also > > changes rcu_access_index() uses to READ_ONCE(). > > > > Signed-off-by: Paul E. McKenney > > Cc: linux-edac@vger.kernel.org > > Cc: Tony Luck > > Cc: Borislav Petkov > > Looks good to me. > > If it is easier for you carrying it in your tree: > > Acked-by: Borislav Petkov > > Otherwise, let me know. Thank you, I have applied your Acked-by. Probably easier for me to carry this change, given that it needs to be applied before the later patches that remove array-index support from RCU. Thanx, Paul