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Commit 98458172 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

cpu/hotplug: Split out cpu down functions 



Split cpu_down in separate functions in preparation for state machine
conversion.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182340.511796562@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent ba997462

kernel/cpu.c

+53 −30
Original line number Diff line number Diff line
@@ -266,11 +266,6 @@ 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);

EXPORT_SYMBOL(__register_cpu_notifier);
@@ -353,6 +348,25 @@ static inline void check_for_tasks(int dead_cpu) 
	read_unlock(&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);

		pr_warn("%s: attempt to take down CPU %u failed\n",

				__func__, cpu);

	}

	return err;

}



/* Take this CPU down. */

static int take_cpu_down(void *_param)

{
@@ -371,29 +385,9 @@ static int take_cpu_down(void *_param) 
	return 0;

}



/* Requires cpu_add_remove_lock to be held */

static int _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;



	err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls);

	if (err) {

		nr_calls--;

		__cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL);

		pr_warn("%s: attempt to take down CPU %u failed\n",

			__func__, cpu);

		goto out_release;

	}

	int err;



	/*

	 * By now we've cleared cpu_active_mask, wait for all preempt-disabled
@@ -426,7 +420,7 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) 
		/* CPU didn't die: tell everyone.  Can't complain. */

		cpu_notify_nofail(CPU_DOWN_FAILED, cpu);

		irq_unlock_sparse();

		goto out_release;

		return err;

	}

	BUG_ON(cpu_online(cpu));
@@ -449,11 +443,40 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) 
	/* This actually kills the CPU. */

	__cpu_die(cpu);



	/* CPU is completely dead: tell everyone.  Too late to complain. */

	tick_cleanup_dead_cpu(cpu);

	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();