1 files changed, 13 insertions, 12 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 14d32588cccd..42bd331ee0ab 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -80,6 +80,10 @@ void put_online_cpus(void)
         if (cpu_hotplug.active_writer == current)
                 return;
         mutex_lock(&cpu_hotplug.lock);
+
+        if (WARN_ON(!cpu_hotplug.refcount))
+                cpu_hotplug.refcount++; /* try to fix things up */
+
         if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
                 wake_up_process(cpu_hotplug.active_writer);
         mutex_unlock(&cpu_hotplug.lock);
@@ -280,12 +284,13 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
                                 __func__, cpu);
                 goto out_release;
         }
+        smpboot_park_threads(cpu);
 
         err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
         if (err) {
                 /* CPU didn't die: tell everyone.  Can't complain. */
+                smpboot_unpark_threads(cpu);
                 cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
-
                 goto out_release;
         }
         BUG_ON(cpu_online(cpu));
@@ -354,6 +359,10 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
                 goto out;
         }
 
+        ret = smpboot_create_threads(cpu);
+        if (ret)
+                goto out;
+
         ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
         if (ret) {
                 nr_calls--;
@@ -368,6 +377,9 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
                 goto out_notify;
         BUG_ON(!cpu_online(cpu));
 
+        /* Wake the per cpu threads */
+        smpboot_unpark_threads(cpu);
+
         /* Now call notifier in preparation. */
         cpu_notify(CPU_ONLINE | mod, hcpu);
 
@@ -439,14 +451,6 @@ EXPORT_SYMBOL_GPL(cpu_up);
 #ifdef CONFIG_PM_SLEEP_SMP
 static cpumask_var_t frozen_cpus;
 
-void __weak arch_disable_nonboot_cpus_begin(void)
-{
-}
-
-void __weak arch_disable_nonboot_cpus_end(void)
-{
-}
-
 int disable_nonboot_cpus(void)
 {
         int cpu, first_cpu, error = 0;
@@ -458,7 +462,6 @@ int disable_nonboot_cpus(void)
          * with the userspace trying to use the CPU hotplug at the same time
          */
         cpumask_clear(frozen_cpus);
-        arch_disable_nonboot_cpus_begin();
 
         printk("Disabling non-boot CPUs ...\n");
         for_each_online_cpu(cpu) {
@@ -474,8 +477,6 @@ int disable_nonboot_cpus(void)
                 }
         }
 
-        arch_disable_nonboot_cpus_end();
-
         if (!error) {
                 BUG_ON(num_online_cpus() > 1);
                 /* Make sure the CPUs won't be enabled by someone else */