From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759449AbXGVPpy (ORCPT ); Sun, 22 Jul 2007 11:45:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757366AbXGVPo0 (ORCPT ); Sun, 22 Jul 2007 11:44:26 -0400 Received: from wa-out-1112.google.com ([209.85.146.177]:60825 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753725AbXGVPoZ (ORCPT ); Sun, 22 Jul 2007 11:44:25 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:references:user-agent:date:from:to:cc:subject:content-disposition; b=Oz8OfNRRHhXKG98gd37rerxD4yXfl+ymQyf01DBRkvbIeYjdpRrxkP3pB67n9bTUGr6SdUcy73juywpweYaU1Ou5Qb6OqeDO86Sd7WnkFl5s17xPiL5yrHBONqywcVDVwUqKU+OU8Rax9LHtUPYQSHjfPtVG9DgwKFOb+wkWoX4= Message-Id: <20070722153349.369335694@gmail.com> References: <20070722153312.083951746@gmail.com> User-Agent: quilt/0.46-1 Date: Mon, 23 Jul 2007 00:33:15 +0900 From: Akinobu Mita To: linux-kernel@vger.kernel.org Cc: Rusty Russell , Greg Kroah-Hartman , Dmitriy Zavin , "H. Peter Anvin" , Andi Kleen , Ashok Raj , Akinobu Mita Subject: [patch 3/9] cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE Content-Disposition: inline; filename=cpuhotplug-nr-calls.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Akinobu Mita The functions in a CPU notifier chain is called with CPU_UP_PREPARE event before making the CPU online. If one of the callback returns NOTIFY_BAD, it stops to deliver CPU_UP_PREPARE event, and CPU online operation is canceled. Then CPU_UP_CANCELED event is delivered to the functions in a CPU notifier chain again. This CPU_UP_CANCELED event is delivered to the functions which have been called with CPU_UP_PREPARE, not delivered to the functions which haven't been called with CPU_UP_PREPARE. The problem that makes existing cpu hotplug error handlings complex is that the CPU_UP_CANCELED event is delivered to the function that has returned NOTIFY_BAD, too. Usually we don't expect to call destructor function against the object that has failed to initialize. It is like: err = register_something(); if (err) { unregister_something(); return err; } So it is natural to deliver CPU_UP_CANCELED event only to the functions that have returned NOTIFY_OK with CPU_UP_PREPARE event and not to call the function that have returned NOTIFY_BAD. This is what this patch is doing. Otherwise, every cpu hotplug notifiler has to track whether notifiler event is failed or not for each cpu. (drivers/base/topology.c is doing this with topology_dev_map) Similary this patch makes same thing with CPU_DOWN_PREPARE and CPU_DOWN_FAILED evnets. Cc: Rusty Russell Signed-off-by: Akinobu Mita --- kernel/cpu.c | 2 ++ 1 file changed, 2 insertions(+) Index: 2.6-git/kernel/cpu.c =================================================================== --- 2.6-git.orig/kernel/cpu.c +++ 2.6-git/kernel/cpu.c @@ -150,6 +150,7 @@ static int _cpu_down(unsigned int cpu, i err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls); if (err == NOTIFY_BAD) { + nr_calls--; __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL); printk("%s: attempt to take down CPU %u failed\n", @@ -233,6 +234,7 @@ static int __cpuinit _cpu_up(unsigned in ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls); if (ret == NOTIFY_BAD) { + nr_calls--; printk("%s: attempt to bring up CPU %u failed\n", __FUNCTION__, cpu); ret = -EINVAL; --