From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761033AbXGPOFJ (ORCPT ); Mon, 16 Jul 2007 10:05:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765850AbXGPODy (ORCPT ); Mon, 16 Jul 2007 10:03:54 -0400 Received: from qb-out-0506.google.com ([72.14.204.236]:16472 "EHLO qb-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760897AbXGPODv (ORCPT ); Mon, 16 Jul 2007 10:03:51 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:date:from:to:subject:message-id:mail-followup-to:references:mime-version:content-type:content-disposition:in-reply-to:user-agent; b=ZKasPwS93aV2yf/qVRQ1v6bA7XedcJRFl4cjDQFxJgKhJK9Gt2UXeQODzoFm5qAczg+AY5548lWsxlanwR7EStcvOycHxHl7esazwP8osToNP2wBqSGQd4l+AVAYG8eKVZym0Di8bhZsAB/rjyIw2INrUT79hJv7c0DroEYorVQ= Date: Mon, 16 Jul 2007 22:53:47 +0900 From: Akinobu Mita To: linux-kernel@vger.kernel.org, Rusty Russell , Greg Kroah-Hartman , Dmitriy Zavin , "H. Peter Anvin" , Andi Kleen , Ashok Raj Subject: [PATCH 4/10] cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE Message-ID: <20070716135347.GD2040@APFDCB5C> Mail-Followup-To: Akinobu Mita , linux-kernel@vger.kernel.org, Rusty Russell , Greg Kroah-Hartman , Dmitriy Zavin , "H. Peter Anvin" , Andi Kleen , Ashok Raj References: <20070716134855.GA1858@APFDCB5C> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070716134855.GA1858@APFDCB5C> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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(); // bug 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-mm/kernel/cpu.c =================================================================== --- 2.6-mm.orig/kernel/cpu.c +++ 2.6-mm/kernel/cpu.c @@ -138,6 +138,7 @@ 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", @@ -221,6 +222,7 @@ 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;