From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932538AbcFAQXO (ORCPT ); Wed, 1 Jun 2016 12:23:14 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:40361 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750828AbcFAQXN (ORCPT ); Wed, 1 Jun 2016 12:23:13 -0400 Date: Wed, 1 Jun 2016 18:22:55 +0200 From: Peter Zijlstra To: Boqun Feng Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, manfred@colorfullife.com, dave@stgolabs.net, paulmck@linux.vnet.ibm.com, will.deacon@arm.com, Waiman.Long@hpe.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 3/8] locking: Introduce smp_acquire__after_ctrl_dep Message-ID: <20160601162255.GT3190@twins.programming.kicks-ass.net> References: <20160531094134.606249808@infradead.org> <20160531094844.037298593@infradead.org> <20160601135214.GC30064@insomnia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160601135214.GC30064@insomnia> 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 09:52:14PM +0800, Boqun Feng wrote: > On Tue, May 31, 2016 at 11:41:37AM +0200, Peter Zijlstra wrote: > > @@ -292,7 +282,7 @@ static void sem_wait_array(struct sem_ar > > sem = sma->sem_base + i; > > spin_unlock_wait(&sem->lock); > > } > > - ipc_smp_acquire__after_spin_is_unlocked(); > > + smp_acquire__after_ctrl_dep(); > > I wonder whether we can kill this barrier after updating > spin_unlock_wait() to ACQUIRE? See patch 5 doing that :-)