From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752312Ab3FYJcX (ORCPT ); Tue, 25 Jun 2013 05:32:23 -0400 Received: from intranet.asianux.com ([58.214.24.6]:1351 "EHLO intranet.asianux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751250Ab3FYJcU (ORCPT ); Tue, 25 Jun 2013 05:32:20 -0400 X-Spam-Score: -100.8 Message-ID: <51C9636F.1050709@asianux.com> Date: Tue, 25 Jun 2013 17:31:27 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Heiko Carstens CC: Martin Schwidefsky , linux390@de.ibm.com, cornelia.huck@de.ibm.com, mtosatti@redhat.com, Thomas Gleixner , linux-s390@vger.kernel.org, "linux-kernel@vger.kernel.org" , Linux-Arch Subject: Re: [PATCH] arch: s390: kernel: reset 'c->hotpluggable' when failure occurs References: <51C8F685.6000209@asianux.com> <20130625064832.GA4999@osiris> <51C94599.1020707@asianux.com> <20130625090928.GA8981@osiris> In-Reply-To: <20130625090928.GA8981@osiris> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/25/2013 05:09 PM, Heiko Carstens wrote: > On Tue, Jun 25, 2013 at 03:24:09PM +0800, Chen Gang wrote: >> On 06/25/2013 02:48 PM, Heiko Carstens wrote: >>> On Tue, Jun 25, 2013 at 09:46:45AM +0800, Chen Gang wrote: >>>>> When smp_add_present_cpu() fails, it has reset all things excluding >>>>> 'c->hotpluggable', so need reset it as original state completely. >>>>> >>>>> + c->hotpluggable = 0; >>>>> return rc; >>> No, that doesn't make sense. All cpus on s390 are always hotplugable. >>> It really doesn't matter if the value of this field is 0 or 1 after >>> an error. >>> >> >> If so, is it better to set 'c->hotpluggable' for all cpus on s390 during >> initializing ? > > No, just leave the code as it is. > Currently we have 3 possible states for 'struct cpu': initialized, and set hotplugable. unitialized, and set hotplugable. unitialized, and unset hotplugable. Either 2nd or 3rd is inconsistent. The cpu_is_hotplugable() will be used in kernel/rcutorture.c. I do not know whether it will cause issue or not, but it seems dangerous when __smp_rescan_cpus() has already called, and has some unsucessfull call of smp_add_present_cpu(). Please help check. Thanks. -- Chen Gang Asianux Corporation