From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752959AbcFAMNW (ORCPT ); Wed, 1 Jun 2016 08:13:22 -0400 Received: from foss.arm.com ([217.140.101.70]:37430 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750697AbcFAMNU (ORCPT ); Wed, 1 Jun 2016 08:13:20 -0400 Date: Wed, 1 Jun 2016 13:13:33 +0100 From: Will Deacon To: Peter Zijlstra Cc: Waiman Long , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, manfred@colorfullife.com, dave@stgolabs.net, paulmck@linux.vnet.ibm.com, boqun.feng@gmail.com, tj@kernel.org, pablo@netfilter.org, kaber@trash.net, davem@davemloft.net, oleg@redhat.com, netfilter-devel@vger.kernel.org, sasha.levin@oracle.com, hofrat@osadl.org Subject: Re: [PATCH -v3 7/8] locking: Move smp_cond_load_acquire() and friends into asm-generic/barrier.h Message-ID: <20160601121333.GC355@arm.com> References: <20160531094134.606249808@infradead.org> <20160531094844.282806055@infradead.org> <574DED82.9080200@hpe.com> <20160601093158.GN3190@twins.programming.kicks-ass.net> <20160601120009.GB355@arm.com> <20160601120654.GR3190@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160601120654.GR3190@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 01, 2016 at 02:06:54PM +0200, Peter Zijlstra wrote: > On Wed, Jun 01, 2016 at 01:00:10PM +0100, Will Deacon wrote: > > On Wed, Jun 01, 2016 at 11:31:58AM +0200, Peter Zijlstra wrote: > > > Will, since ARM64 seems to want to use this, does the below make sense > > > to you? > > > > Not especially -- I was going to override smp_cond_load_acquire anyway > > because I want to build it using cmpwait_acquire and get rid of the > > smp_acquire__after_ctrl_dep trick, which is likely slower on arm64. > > > > So I'd be happier nuking cmpwait from the generic interfaces and using > > smp_cond_load_acquire everywhere, if that's possible. > > Works for me; but that would loose using cmpwait() for > !smp_cond_load_acquire() spins, you fine with that? > > The two conversions in the patch were both !acquire spins. Maybe we could go the whole hog and add smp_cond_load_relaxed? Will