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Subject[patch 06/40] cpu: hotplug: Split out cpu down functions
Split cpu_down in separate functions in preparation for state machine
conversion.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/cpu.c | 83 +++++++++++++++++++++++++++++++++++++----------------------
1 file changed, 53 insertions(+), 30 deletions(-)

Index: linux-2.6/kernel/cpu.c
===================================================================
--- linux-2.6.orig/kernel/cpu.c
+++ linux-2.6/kernel/cpu.c
@@ -206,11 +206,6 @@ static int bringup_cpu(unsigned int cpu)
}

#ifdef CONFIG_HOTPLUG_CPU
-
-static void cpu_notify_nofail(unsigned long val, unsigned int cpu)
-{
- BUG_ON(cpu_notify(val, cpu));
-}
EXPORT_SYMBOL(register_cpu_notifier);

void __ref unregister_cpu_notifier(struct notifier_block *nb)
@@ -278,6 +273,25 @@ static inline void check_for_tasks(int c
write_unlock_irq(&tasklist_lock);
}

+static void cpu_notify_nofail(unsigned long val, unsigned int cpu)
+{
+ BUG_ON(cpu_notify(val, cpu));
+}
+
+static int notify_down_prepare(unsigned int cpu)
+{
+ int err, nr_calls = 0;
+
+ err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls);
+ if (err) {
+ nr_calls--;
+ __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL);
+ printk("%s: attempt to take down CPU %u failed\n",
+ __func__, cpu);
+ }
+ return err;
+}
+
/* Take this CPU down. */
static int __ref take_cpu_down(void *_param)
{
@@ -294,37 +308,17 @@ static int __ref take_cpu_down(void *_pa
return 0;
}

-/* Requires cpu_add_remove_lock to be held */
-static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
+static int takedown_cpu(unsigned int cpu)
{
- int err, nr_calls = 0;
-
- if (num_online_cpus() == 1)
- return -EBUSY;
-
- if (!cpu_online(cpu))
- return -EINVAL;
-
- cpu_hotplug_begin();
-
- cpuhp_tasks_frozen = tasks_frozen;
+ int err;

- err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls);
- if (err) {
- nr_calls--;
- __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL);
- printk("%s: attempt to take down CPU %u failed\n",
- __func__, cpu);
- goto out_release;
- }
smpboot_park_threads(cpu);
-
err = __stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
if (err) {
/* CPU didn't die: tell everyone. Can't complain. */
smpboot_unpark_threads(cpu);
cpu_notify_nofail(CPU_DOWN_FAILED, cpu);
- goto out_release;
+ return err;
}
BUG_ON(cpu_online(cpu));

@@ -341,10 +335,39 @@ static int __ref _cpu_down(unsigned int
/* This actually kills the CPU. */
__cpu_die(cpu);

- /* CPU is completely dead: tell everyone. Too late to complain. */
- cpu_notify_nofail(CPU_DEAD, cpu);
+ return 0;
+}

+static int notify_dead(unsigned int cpu)
+{
+ cpu_notify_nofail(CPU_DEAD, cpu);
check_for_tasks(cpu);
+ return 0;
+}
+
+/* Requires cpu_add_remove_lock to be held */
+static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
+{
+ int err;
+
+ if (num_online_cpus() == 1)
+ return -EBUSY;
+
+ if (!cpu_online(cpu))
+ return -EINVAL;
+
+ cpu_hotplug_begin();
+
+ cpuhp_tasks_frozen = tasks_frozen;
+
+ err = notify_down_prepare(cpu);
+ if (err)
+ goto out_release;
+ err = takedown_cpu(cpu);
+ if (err)
+ goto out_release;
+
+ notify_dead(cpu);

out_release:
cpu_hotplug_done();



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