From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: linux-next: build failure after merge of the rcu tree Date: Fri, 11 Aug 2017 07:39:17 -0700 Message-ID: <20170811143917.GD3730@linux.vnet.ibm.com> References: <20170811144352.585085e2@canb.auug.org.au> <20170811045453.GB3730@linux.vnet.ibm.com> <20170811091434.h6mkuuw3zcgkzg26@hirez.programming.kicks-ass.net> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49596 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753183AbdHKOjh (ORCPT ); Fri, 11 Aug 2017 10:39:37 -0400 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7BEdaH1009288 for ; Fri, 11 Aug 2017 10:39:37 -0400 Received: from e18.ny.us.ibm.com (e18.ny.us.ibm.com [129.33.205.208]) by mx0a-001b2d01.pphosted.com with ESMTP id 2c9bk19xtq-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 11 Aug 2017 10:39:37 -0400 Received: from localhost by e18.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 11 Aug 2017 10:39:19 -0400 Content-Disposition: inline In-Reply-To: <20170811091434.h6mkuuw3zcgkzg26@hirez.programming.kicks-ass.net> Sender: linux-next-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: Stephen Rothwell , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Linux-Next Mailing List , Linux Kernel Mailing List On Fri, Aug 11, 2017 at 11:14:34AM +0200, Peter Zijlstra wrote: > On Thu, Aug 10, 2017 at 09:54:53PM -0700, Paul E. McKenney wrote: > > On Fri, Aug 11, 2017 at 02:43:52PM +1000, Stephen Rothwell wrote: > > > > Looks like I need to rebase my patch on top of a9668cd6ee28, and > > than put an smp_mb__after_spinlock() between the lock and the unlock. > > > > Peter, any objections to that approach? Other suggestions? > > Hurm.. I'll have to try and understand that comment there again it > seems. My reasoning is as follows: 1. The critical section is empty, so any prior references would be ordered only against later critical sections. 2. A full barrier within the critical section will order those prior references against later critical sections just as easily as would one prior to the critical section. Does that make sense, I should I have stayed away from the keyboard at this early hour? ;-) Thanx, Paul