rt-patches/0105-hotplug-Use-migrate-disable-on-unplug.patch

From 6e58d6c97bc8a170f5f3fb35954a765623f3817c Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 17 Jul 2011 19:35:29 +0200
Subject: [PATCH 105/366] hotplug: Use migrate disable on unplug

Migration needs to be disabled accross the unplug handling to make
sure that the unplug thread is off the unplugged cpu.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/cpu.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 04df252..494b606 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -457,14 +457,13 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen)
 	cpumask_andnot(cpumask, cpu_online_mask, cpumask_of(cpu));
 	set_cpus_allowed_ptr(current, cpumask);
 	free_cpumask_var(cpumask);
-	preempt_disable();
+	migrate_disable();
 	mycpu = smp_processor_id();
 	if (mycpu == cpu) {
 		printk(KERN_ERR "Yuck! Still on unplug CPU\n!");
-		preempt_enable();
+		migrate_enable();
 		return -EBUSY;
 	}
-	preempt_enable();
 
 	cpu_hotplug_begin();
 	err = cpu_unplug_begin(cpu);
@@ -546,6 +545,7 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen)
 out_release:
 	cpu_unplug_done(cpu);
 out_cancel:
+	migrate_enable();
 	cpu_hotplug_done();
 	trace_sched_cpu_hotplug(cpu, err, 0);
 	if (!err)
-- 
1.9.1