From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751907AbaETKZw (ORCPT ); Tue, 20 May 2014 06:25:52 -0400 Received: from casper.infradead.org ([85.118.1.10]:33144 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750745AbaETKZv (ORCPT ); Tue, 20 May 2014 06:25:51 -0400 Date: Tue, 20 May 2014 12:25:42 +0200 From: Peter Zijlstra To: "Srivatsa S. Bhat" Cc: Oleg Nesterov , Tejun Heo , akpm@linux-foundation.org, fweisbec@gmail.com, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, mingo@kernel.org, rusty@rustcorp.com.au, hch@infradead.org, mgorman@suse.de, riel@redhat.com, bp@suse.de, rostedt@goodmis.org, mgalbraith@suse.de, ego@linux.vnet.ibm.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 UPDATEDv3 3/3] CPU hotplug, smp: Flush any pending IPI callbacks before CPU offline Message-ID: <20140520102542.GW2485@laptop.programming.kicks-ass.net> References: <20140515191938.GB21306@htj.dyndns.org> <537514D3.4060308@linux.vnet.ibm.com> <20140515193656.GM4570@linux.vnet.ibm.com> <537518D6.6030006@linux.vnet.ibm.com> <5379F6BD.1090809@linux.vnet.ibm.com> <20140519161836.GA30387@redhat.com> <537A6060.7070406@linux.vnet.ibm.com> <537A6811.50808@linux.vnet.ibm.com> <20140520094203.GU2485@laptop.programming.kicks-ass.net> <537B29F7.6060104@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <537B29F7.6060104@linux.vnet.ibm.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 Tue, May 20, 2014 at 03:39:59PM +0530, Srivatsa S. Bhat wrote: > > The multi_cpu_stop() path isn't exclusive to hotplug, so your changelog > > is wrong or the patch is. > > > > Yes, I know that multi_cpu_stop() isn't exclusive to hotplug. That's why > I have explicitly referred to CPU hotplug in the comment as well as the > changelog. > > But I totally agree that code-wise this is not the best way to do it since > this affects (although harmlessly) usecases other than hotplug as well. > > Do you have any other suggestions? How about making a kernel/smp.c hotplug notifier and stuffing it in the CPU_DYING list? That's typically after we've already torn down the interrupts for that cpu, so no chance of any new ones coming in. Or is that too late?