On Thu, Jan 31, 2013 at 12:11:16PM -0000, Thomas Gleixner wrote:
> Split cpu_down in separate functions in preparation for state machine
> conversion.
>
> Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Reviewed-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> ---
> 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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