From: Eduardo Habkost <ehabkost@redhat.com>
Date: Thu, 24 Sep 2009 13:46:29 -0300
Subject: [misc] hotplug: adapt thermal throttle to CPU_DYING
Message-id: 1253810790-11195-4-git-send-email-ehabkost@redhat.com
O-Subject: [RHEL-5.5 PATCH 3/4] HOTPLUG: Adapt thermal throttle 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 38ef6d195fb794e61a687ef8f5a37daf6044d576
Author: Avi Kivity <avi@qumranet.com>
Date:   Thu May 24 12:37:34 2007 +0300

    HOTPLUG: Adapt thermal throttle to CPU_DYING

    CPU_DYING is notified in atomic context, so no taking mutexes here.

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

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

diff --git a/arch/i386/kernel/cpu/mcheck/therm_throt.c b/arch/i386/kernel/cpu/mcheck/therm_throt.c
index 7ba7c3a..1203dc5 100644
--- a/arch/i386/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/i386/kernel/cpu/mcheck/therm_throt.c
@@ -134,19 +134,21 @@ static __cpuinit int thermal_throttle_cpu_callback(struct notifier_block *nfb,
 	int err;
 
 	sys_dev = get_cpu_sysdev(cpu);
-	mutex_lock(&therm_cpu_lock);
 	switch (action) {
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
+		mutex_lock(&therm_cpu_lock);
 		err = thermal_throttle_add_dev(sys_dev);
+		mutex_unlock(&therm_cpu_lock);
 		WARN_ON(err);
 		break;
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
+		mutex_lock(&therm_cpu_lock);
 		thermal_throttle_remove_dev(sys_dev);
+		mutex_unlock(&therm_cpu_lock);
 		break;
 	}
-	mutex_unlock(&therm_cpu_lock);
 	return NOTIFY_OK;
 }