From: Eduardo Habkost <ehabkost@redhat.com>
Date: Thu, 24 Sep 2009 13:46:28 -0300
Subject: [misc] hotplug: use cpuset hotplug callback to CPU_DYING
Message-id: 1253810790-11195-3-git-send-email-ehabkost@redhat.com
O-Subject: [RHEL-5.5 PATCH 2/4] HOTPLUG: Adapt cpuset hotplug callback to CPU_DYING
Bugzilla: 510814
RH-Acked-by: Juan Quintela <quintela@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=510814

This is a cherry-pick of upstream commit:

commit ac076758b97d9e3d2c1557cfa412911e93cd0919
Author: Avi Kivity <avi@qumranet.com>
Date:   Thu May 24 12:33:15 2007 +0300

    HOTPLUG: Adapt cpuset hotplug callback to CPU_DYING

    CPU_DYING is called in atomic context, so don't try to take any locks.

    Signed-off-by: Avi Kivity <avi@qumranet.com>

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1960d2a..937288b 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2109,6 +2109,9 @@ out:
 static int cpuset_handle_cpuhp(struct notifier_block *nb,
 				unsigned long phase, void *cpu)
 {
+	if (phase == CPU_DYING || phase == CPU_DYING_FROZEN)
+		return NOTIFY_DONE;
+
 	mutex_lock(&manage_mutex);
 	mutex_lock(&callback_mutex);