From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758115AbcFAMqD (ORCPT ); Wed, 1 Jun 2016 08:46:03 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49592 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750842AbcFAMqA (ORCPT ); Wed, 1 Jun 2016 08:46:00 -0400 Date: Wed, 1 Jun 2016 14:45:41 +0200 From: Peter Zijlstra To: Will Deacon 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: <20160601124541.GS3190@twins.programming.kicks-ass.net> 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> <20160601121333.GC355@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160601121333.GC355@arm.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 01, 2016 at 01:13:33PM +0100, Will Deacon wrote: > On Wed, Jun 01, 2016 at 02:06:54PM +0200, Peter Zijlstra wrote: > > 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? What about say the cmpxchg loops in queued_write_lock_slowpath() ? Would that be something you'd like to use wfe for? Writing those in smp_cond_load_{acquire,relaxed)() is somewhat possible but quite ugleh.