From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751963AbbFXJbY (ORCPT ); Wed, 24 Jun 2015 05:31:24 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:48766 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbbFXJbS (ORCPT ); Wed, 24 Jun 2015 05:31:18 -0400 Date: Wed, 24 Jun 2015 11:31:02 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Oleg Nesterov , tj@kernel.org, mingo@redhat.com, linux-kernel@vger.kernel.org, der.herr@hofr.at, dave@stgolabs.net, riel@redhat.com, viro@ZenIV.linux.org.uk, torvalds@linux-foundation.org Subject: Re: [RFC][PATCH 12/13] stop_machine: Remove lglock Message-ID: <20150624093102.GI18673@twins.programming.kicks-ass.net> References: <20150623100932.GB3644@twins.programming.kicks-ass.net> <20150623105548.GE18673@twins.programming.kicks-ass.net> <20150623112041.GF18673@twins.programming.kicks-ass.net> <20150623130826.GG18673@twins.programming.kicks-ass.net> <20150623173038.GJ3892@linux.vnet.ibm.com> <20150623180411.GF3644@twins.programming.kicks-ass.net> <20150623182626.GO3892@linux.vnet.ibm.com> <20150623190506.GA7731@linux.vnet.ibm.com> <20150624022332.GA16620@linux.vnet.ibm.com> <20150624083257.GI3644@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150624083257.GI3644@twins.programming.kicks-ass.net> 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 24, 2015 at 10:32:57AM +0200, Peter Zijlstra wrote: > + s = atomic_long_read(&rsp->expedited_done); > + if (ULONG_CMP_GE((ulong)s, (ulong)snap)) { > + /* ensure test happens before caller kfree */ > + smp_mb__before_atomic(); /* ^^^ */ FWIW isn't that guaranteed by the control dep? > + atomic_long_inc(&rsp->expedited_workdone1); > + goto unlock; > + }