[linux-2.6-block.git] / kernel / cpu.c

/* CPU control.
 * (C) 2001, 2002, 2003, 2004 Rusty Russell
 *
 * This code is licenced under the GPL.
 */
#include <linux/proc_fs.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/notifier.h>
#include <linux/sched.h>
#include <linux/unistd.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/stop_machine.h>
#include <linux/mutex.h>

/*
 * Represents all cpu's present in the system
 * In systems capable of hotplug, this map could dynamically grow
 * as new cpu's are detected in the system via any platform specific
 * method, such as ACPI for e.g.
 */
cpumask_t cpu_present_map __read_mostly;
EXPORT_SYMBOL(cpu_present_map);

#ifndef CONFIG_SMP

/*
 * Represents all cpu's that are currently online.
 */
cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
EXPORT_SYMBOL(cpu_online_map);

cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
EXPORT_SYMBOL(cpu_possible_map);

#else /* CONFIG_SMP */

/* Serializes the updates to cpu_online_map, cpu_present_map */
static DEFINE_MUTEX(cpu_add_remove_lock);

static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);

/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
 * Should always be manipulated under cpu_add_remove_lock
 */
static int cpu_hotplug_disabled;

static struct {
	struct task_struct *active_writer;
	struct mutex lock; /* Synchronizes accesses to refcount, */
	/*
	 * Also blocks the new readers during
	 * an ongoing cpu hotplug operation.
	 */
	int refcount;
} cpu_hotplug;

void __init cpu_hotplug_init(void)
{
	cpu_hotplug.active_writer = NULL;
	mutex_init(&cpu_hotplug.lock);
	cpu_hotplug.refcount = 0;
}

#ifdef CONFIG_HOTPLUG_CPU

void get_online_cpus(void)
{
	might_sleep();
	if (cpu_hotplug.active_writer == current)
		return;
	mutex_lock(&cpu_hotplug.lock);
	cpu_hotplug.refcount++;
	mutex_unlock(&cpu_hotplug.lock);

}
EXPORT_SYMBOL_GPL(get_online_cpus);

void put_online_cpus(void)
{
	if (cpu_hotplug.active_writer == current)
		return;
	mutex_lock(&cpu_hotplug.lock);
	if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
		wake_up_process(cpu_hotplug.active_writer);
	mutex_unlock(&cpu_hotplug.lock);

}
EXPORT_SYMBOL_GPL(put_online_cpus);

#endif	/* CONFIG_HOTPLUG_CPU */

/*
 * The following two API's must be used when attempting
 * to serialize the updates to cpu_online_map, cpu_present_map.
 */
void cpu_maps_update_begin(void)
{
	mutex_lock(&cpu_add_remove_lock);
}

void cpu_maps_update_done(void)
{
	mutex_unlock(&cpu_add_remove_lock);
}

/*
 * This ensures that the hotplug operation can begin only when the
 * refcount goes to zero.
 *
 * Note that during a cpu-hotplug operation, the new readers, if any,
 * will be blocked by the cpu_hotplug.lock
 *
 * Since cpu_hotplug_begin() is always called after invoking
 * cpu_maps_update_begin(), we can be sure that only one writer is active.
 *
 * Note that theoretically, there is a possibility of a livelock:
 * - Refcount goes to zero, last reader wakes up the sleeping
 *   writer.
 * - Last reader unlocks the cpu_hotplug.lock.
 * - A new reader arrives at this moment, bumps up the refcount.
 * - The writer acquires the cpu_hotplug.lock finds the refcount
 *   non zero and goes to sleep again.
 *
 * However, this is very difficult to achieve in practice since
 * get_online_cpus() not an api which is called all that often.
 *
 */
static void cpu_hotplug_begin(void)
{
	cpu_hotplug.active_writer = current;

	for (;;) {
		mutex_lock(&cpu_hotplug.lock);
		if (likely(!cpu_hotplug.refcount))
			break;
		__set_current_state(TASK_UNINTERRUPTIBLE);
		mutex_unlock(&cpu_hotplug.lock);
		schedule();
	}
}

static void cpu_hotplug_done(void)
{
	cpu_hotplug.active_writer = NULL;
	mutex_unlock(&cpu_hotplug.lock);
}
/* Need to know about CPUs going up/down? */
int __ref register_cpu_notifier(struct notifier_block *nb)
{
	int ret;
	cpu_maps_update_begin();
	ret = raw_notifier_chain_register(&cpu_chain, nb);
	cpu_maps_update_done();
	return ret;
}

#ifdef CONFIG_HOTPLUG_CPU

EXPORT_SYMBOL(register_cpu_notifier);

void __ref unregister_cpu_notifier(struct notifier_block *nb)
{
	cpu_maps_update_begin();
	raw_notifier_chain_unregister(&cpu_chain, nb);
	cpu_maps_update_done();
}
EXPORT_SYMBOL(unregister_cpu_notifier);

static inline void check_for_tasks(int cpu)
{
	struct task_struct *p;

	write_lock_irq(&tasklist_lock);
	for_each_process(p) {
		if (task_cpu(p) == cpu &&
		    (!cputime_eq(p->utime, cputime_zero) ||
		     !cputime_eq(p->stime, cputime_zero)))
			printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
				(state = %ld, flags = %x) \n",
				 p->comm, task_pid_nr(p), cpu,
				 p->state, p->flags);
	}
	write_unlock_irq(&tasklist_lock);
}

struct take_cpu_down_param {
	unsigned long mod;
	void *hcpu;
};

/* Take this CPU down. */
static int __ref take_cpu_down(void *_param)
{
	struct take_cpu_down_param *param = _param;
	int err;

	raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
				param->hcpu);
	/* Ensure this CPU doesn't handle any more interrupts. */
	err = __cpu_disable();
	if (err < 0)
		return err;

	/* Force idle task to run as soon as we yield: it should
	   immediately notice cpu is offline and die quickly. */
	sched_idle_next();
	return 0;
}

/* Requires cpu_add_remove_lock to be held */
static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
{
	int err, nr_calls = 0;
	struct task_struct *p;
	cpumask_t old_allowed, tmp;
	void *hcpu = (void *)(long)cpu;
	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
	struct take_cpu_down_param tcd_param = {
		.mod = mod,
		.hcpu = hcpu,
	};

	if (num_online_cpus() == 1)
		return -EBUSY;

	if (!cpu_online(cpu))
		return -EINVAL;

	cpu_hotplug_begin();
	err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
					hcpu, -1, &nr_calls);
	if (err == NOTIFY_BAD) {
		nr_calls--;
		__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
					  hcpu, nr_calls, NULL);
		printk("%s: attempt to take down CPU %u failed\n",
				__func__, cpu);
		err = -EINVAL;
		goto out_release;
	}

	/* Ensure that we are not runnable on dying cpu */
	old_allowed = current->cpus_allowed;
	cpus_setall(tmp);
	cpu_clear(cpu, tmp);
	set_cpus_allowed_ptr(current, &tmp);

	p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);

	if (IS_ERR(p) || cpu_online(cpu)) {
		/* CPU didn't die: tell everyone.  Can't complain. */
		if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
					    hcpu) == NOTIFY_BAD)
			BUG();

		if (IS_ERR(p)) {
			err = PTR_ERR(p);
			goto out_allowed;
		}
		goto out_thread;
	}

	/* Wait for it to sleep (leaving idle task). */
	while (!idle_cpu(cpu))
		yield();

	/* This actually kills the CPU. */
	__cpu_die(cpu);

	/* CPU is completely dead: tell everyone.  Too late to complain. */
	if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod,
				    hcpu) == NOTIFY_BAD)
		BUG();

	check_for_tasks(cpu);

out_thread:
	err = kthread_stop(p);
out_allowed:
	set_cpus_allowed_ptr(current, &old_allowed);
out_release:
	cpu_hotplug_done();
	return err;
}

int __ref cpu_down(unsigned int cpu)
{
	int err = 0;

	cpu_maps_update_begin();
	if (cpu_hotplug_disabled)
		err = -EBUSY;
	else
		err = _cpu_down(cpu, 0);

	cpu_maps_update_done();
	return err;
}
EXPORT_SYMBOL(cpu_down);
#endif /*CONFIG_HOTPLUG_CPU*/

/* Requires cpu_add_remove_lock to be held */
static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
{
	int ret, nr_calls = 0;
	void *hcpu = (void *)(long)cpu;
	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;

	if (cpu_online(cpu) || !cpu_present(cpu))
		return -EINVAL;

	cpu_hotplug_begin();
	ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu,
							-1, &nr_calls);
	if (ret == NOTIFY_BAD) {
		nr_calls--;
		printk("%s: attempt to bring up CPU %u failed\n",
				__func__, cpu);
		ret = -EINVAL;
		goto out_notify;
	}

	/* Arch-specific enabling code. */
	ret = __cpu_up(cpu);
	if (ret != 0)
		goto out_notify;
	BUG_ON(!cpu_online(cpu));

	/* Now call notifier in preparation. */
	raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu);

out_notify:
	if (ret != 0)
		__raw_notifier_call_chain(&cpu_chain,
				CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
	cpu_hotplug_done();

	return ret;
}

int __cpuinit cpu_up(unsigned int cpu)
{
	int err = 0;
	if (!cpu_isset(cpu, cpu_possible_map)) {
		printk(KERN_ERR "can't online cpu %d because it is not "
			"configured as may-hotadd at boot time\n", cpu);
#if defined(CONFIG_IA64) || defined(CONFIG_X86_64) || defined(CONFIG_S390)
		printk(KERN_ERR "please check additional_cpus= boot "
				"parameter\n");
#endif
		return -EINVAL;
	}

	cpu_maps_update_begin();
	if (cpu_hotplug_disabled)
		err = -EBUSY;
	else
		err = _cpu_up(cpu, 0);

	cpu_maps_update_done();
	return err;
}

#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_t frozen_cpus;

int disable_nonboot_cpus(void)
{
	int cpu, first_cpu, error = 0;

	cpu_maps_update_begin();
	first_cpu = first_cpu(cpu_online_map);
	/* We take down all of the non-boot CPUs in one shot to avoid races
	 * with the userspace trying to use the CPU hotplug at the same time
	 */
	cpus_clear(frozen_cpus);
	printk("Disabling non-boot CPUs ...\n");
	for_each_online_cpu(cpu) {
		if (cpu == first_cpu)
			continue;
		error = _cpu_down(cpu, 1);
		if (!error) {
			cpu_set(cpu, frozen_cpus);
			printk("CPU%d is down\n", cpu);
		} else {
			printk(KERN_ERR "Error taking CPU%d down: %d\n",
				cpu, error);
			break;
		}
	}
	if (!error) {
		BUG_ON(num_online_cpus() > 1);
		/* Make sure the CPUs won't be enabled by someone else */
		cpu_hotplug_disabled = 1;
	} else {
		printk(KERN_ERR "Non-boot CPUs are not disabled\n");
	}
	cpu_maps_update_done();
	return error;
}

void __ref enable_nonboot_cpus(void)
{
	int cpu, error;

	/* Allow everyone to use the CPU hotplug again */
	cpu_maps_update_begin();
	cpu_hotplug_disabled = 0;
	if (cpus_empty(frozen_cpus))
		goto out;

	printk("Enabling non-boot CPUs ...\n");
	for_each_cpu_mask(cpu, frozen_cpus) {
		error = _cpu_up(cpu, 1);
		if (!error) {
			printk("CPU%d is up\n", cpu);
			continue;
		}
		printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
	}
	cpus_clear(frozen_cpus);
out:
	cpu_maps_update_done();
}
#endif /* CONFIG_PM_SLEEP_SMP */

#endif /* CONFIG_SMP */
Commit	Line	Data
1da177e4 LT	1	/* CPU control.
	2	* (C) 2001, 2002, 2003, 2004 Rusty Russell
	3	*
	4	* This code is licenced under the GPL.
	5	*/
	6	#include <linux/proc_fs.h>
	7	#include <linux/smp.h>
	8	#include <linux/init.h>
	9	#include <linux/notifier.h>
	10	#include <linux/sched.h>
	11	#include <linux/unistd.h>
	12	#include <linux/cpu.h>
	13	#include <linux/module.h>
	14	#include <linux/kthread.h>
	15	#include <linux/stop_machine.h>
81615b62	16	#include <linux/mutex.h>
1da177e4	17
68f4f1ec MK	18	/*
	19	* Represents all cpu's present in the system
	20	* In systems capable of hotplug, this map could dynamically grow
	21	* as new cpu's are detected in the system via any platform specific
	22	* method, such as ACPI for e.g.
	23	*/
	24	cpumask_t cpu_present_map __read_mostly;
	25	EXPORT_SYMBOL(cpu_present_map);
	26
	27	#ifndef CONFIG_SMP
	28
	29	/*
	30	* Represents all cpu's that are currently online.
	31	*/
	32	cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
	33	EXPORT_SYMBOL(cpu_online_map);
	34
	35	cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
	36	EXPORT_SYMBOL(cpu_possible_map);
	37
	38	#else /* CONFIG_SMP */
	39
d221938c	40	/* Serializes the updates to cpu_online_map, cpu_present_map */
aa953877	41	static DEFINE_MUTEX(cpu_add_remove_lock);
1da177e4	42
bd5349cf	43	static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
1da177e4	44
e3920fb4 RW	45	/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
	46	* Should always be manipulated under cpu_add_remove_lock
	47	*/
	48	static int cpu_hotplug_disabled;
	49
d221938c GS	50	static struct {
	51	struct task_struct *active_writer;
	52	struct mutex lock; /* Synchronizes accesses to refcount, */
	53	/*
	54	* Also blocks the new readers during
	55	* an ongoing cpu hotplug operation.
	56	*/
	57	int refcount;
d221938c	58	} cpu_hotplug;
90d45d17	59
d221938c GS	60	void __init cpu_hotplug_init(void)
	61	{
	62	cpu_hotplug.active_writer = NULL;
	63	mutex_init(&cpu_hotplug.lock);
	64	cpu_hotplug.refcount = 0;
d221938c GS	65	}
	66
	67	#ifdef CONFIG_HOTPLUG_CPU
90d45d17	68
86ef5c9a	69	void get_online_cpus(void)
a9d9baa1	70	{
d221938c GS	71	might_sleep();
d221938c GS	72	if (cpu_hotplug.active_writer == current)
aa953877	73	return;
d221938c GS	74	mutex_lock(&cpu_hotplug.lock);
	75	cpu_hotplug.refcount++;
	76	mutex_unlock(&cpu_hotplug.lock);
	77
a9d9baa1	78	}
86ef5c9a	79	EXPORT_SYMBOL_GPL(get_online_cpus);
90d45d17	80
86ef5c9a	81	void put_online_cpus(void)
a9d9baa1	82	{
d221938c	83	if (cpu_hotplug.active_writer == current)
aa953877	84	return;
d221938c	85	mutex_lock(&cpu_hotplug.lock);
d2ba7e2a ON	86	if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
d2ba7e2a ON	87	wake_up_process(cpu_hotplug.active_writer);
d221938c GS	88	mutex_unlock(&cpu_hotplug.lock);
d221938c GS	89
a9d9baa1	90	}
86ef5c9a	91	EXPORT_SYMBOL_GPL(put_online_cpus);
a9d9baa1	92
a9d9baa1	93	#endif /* CONFIG_HOTPLUG_CPU */
90d45d17	94
d221938c GS	95	/*
	96	* The following two API's must be used when attempting
	97	* to serialize the updates to cpu_online_map, cpu_present_map.
	98	*/
	99	void cpu_maps_update_begin(void)
	100	{
	101	mutex_lock(&cpu_add_remove_lock);
	102	}
	103
	104	void cpu_maps_update_done(void)
	105	{
	106	mutex_unlock(&cpu_add_remove_lock);
	107	}
	108
	109	/*
	110	* This ensures that the hotplug operation can begin only when the
	111	* refcount goes to zero.
	112	*
	113	* Note that during a cpu-hotplug operation, the new readers, if any,
	114	* will be blocked by the cpu_hotplug.lock
	115	*
d2ba7e2a ON	116	* Since cpu_hotplug_begin() is always called after invoking
d2ba7e2a ON	117	* cpu_maps_update_begin(), we can be sure that only one writer is active.
d221938c GS	118	*
	119	* Note that theoretically, there is a possibility of a livelock:
	120	* - Refcount goes to zero, last reader wakes up the sleeping
	121	* writer.
	122	* - Last reader unlocks the cpu_hotplug.lock.
	123	* - A new reader arrives at this moment, bumps up the refcount.
	124	* - The writer acquires the cpu_hotplug.lock finds the refcount
	125	* non zero and goes to sleep again.
	126	*
	127	* However, this is very difficult to achieve in practice since
86ef5c9a	128	* get_online_cpus() not an api which is called all that often.
d221938c GS	129	*
	130	*/
	131	static void cpu_hotplug_begin(void)
	132	{
d221938c	133	cpu_hotplug.active_writer = current;
d2ba7e2a ON	134
	135	for (;;) {
	136	mutex_lock(&cpu_hotplug.lock);
	137	if (likely(!cpu_hotplug.refcount))
	138	break;
	139	__set_current_state(TASK_UNINTERRUPTIBLE);
d221938c GS	140	mutex_unlock(&cpu_hotplug.lock);
d221938c GS	141	schedule();
d221938c	142	}
d221938c GS	143	}
	144
	145	static void cpu_hotplug_done(void)
	146	{
	147	cpu_hotplug.active_writer = NULL;
	148	mutex_unlock(&cpu_hotplug.lock);
	149	}
1da177e4	150	/* Need to know about CPUs going up/down? */
f7b16c10	151	int __ref register_cpu_notifier(struct notifier_block *nb)
1da177e4	152	{
bd5349cf	153	int ret;
d221938c	154	cpu_maps_update_begin();
bd5349cf	155	ret = raw_notifier_chain_register(&cpu_chain, nb);
d221938c	156	cpu_maps_update_done();
bd5349cf	157	return ret;
1da177e4	158	}
65edc68c CS	159
	160	#ifdef CONFIG_HOTPLUG_CPU
	161
1da177e4 LT	162	EXPORT_SYMBOL(register_cpu_notifier);
1da177e4 LT	163
9647155f	164	void __ref unregister_cpu_notifier(struct notifier_block *nb)
1da177e4	165	{
d221938c	166	cpu_maps_update_begin();
bd5349cf	167	raw_notifier_chain_unregister(&cpu_chain, nb);
d221938c	168	cpu_maps_update_done();
1da177e4 LT	169	}
	170	EXPORT_SYMBOL(unregister_cpu_notifier);
	171
1da177e4 LT	172	static inline void check_for_tasks(int cpu)
	173	{
	174	struct task_struct *p;
	175
	176	write_lock_irq(&tasklist_lock);
	177	for_each_process(p) {
	178	if (task_cpu(p) == cpu &&
	179	(!cputime_eq(p->utime, cputime_zero) \|\|
	180	!cputime_eq(p->stime, cputime_zero)))
	181	printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
e7407dcc	182	(state = %ld, flags = %x) \n",
ba25f9dc PE	183	p->comm, task_pid_nr(p), cpu,
ba25f9dc PE	184	p->state, p->flags);
1da177e4 LT	185	}
	186	write_unlock_irq(&tasklist_lock);
	187	}
	188
db912f96 AK	189	struct take_cpu_down_param {
	190	unsigned long mod;
	191	void *hcpu;
	192	};
	193
1da177e4	194	/* Take this CPU down. */
514a20a5	195	static int __ref take_cpu_down(void *_param)
1da177e4	196	{
db912f96	197	struct take_cpu_down_param *param = _param;
1da177e4 LT	198	int err;
1da177e4 LT	199
db912f96 AK	200	raw_notifier_call_chain(&cpu_chain, CPU_DYING \| param->mod,
db912f96 AK	201	param->hcpu);
1da177e4 LT	202	/* Ensure this CPU doesn't handle any more interrupts. */
	203	err = __cpu_disable();
	204	if (err < 0)
f3705136	205	return err;
1da177e4	206
f3705136 ZM	207	/* Force idle task to run as soon as we yield: it should
	208	immediately notice cpu is offline and die quickly. */
	209	sched_idle_next();
	210	return 0;
1da177e4 LT	211	}
1da177e4 LT	212
e3920fb4	213	/* Requires cpu_add_remove_lock to be held */
514a20a5	214	static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
1da177e4	215	{
e7407dcc	216	int err, nr_calls = 0;
1da177e4 LT	217	struct task_struct *p;
1da177e4 LT	218	cpumask_t old_allowed, tmp;
e7407dcc	219	void hcpu = (void )(long)cpu;
8bb78442	220	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
db912f96 AK	221	struct take_cpu_down_param tcd_param = {
	222	.mod = mod,
	223	.hcpu = hcpu,
	224	};
1da177e4	225
e3920fb4 RW	226	if (num_online_cpus() == 1)
e3920fb4 RW	227	return -EBUSY;
1da177e4	228
e3920fb4 RW	229	if (!cpu_online(cpu))
e3920fb4 RW	230	return -EINVAL;
1da177e4	231
d221938c	232	cpu_hotplug_begin();
8bb78442	233	err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE \| mod,
e7407dcc	234	hcpu, -1, &nr_calls);
1da177e4	235	if (err == NOTIFY_BAD) {
a0d8cdb6	236	nr_calls--;
8bb78442 RW	237	__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED \| mod,
8bb78442 RW	238	hcpu, nr_calls, NULL);
1da177e4	239	printk("%s: attempt to take down CPU %u failed\n",
af1f16d0	240	__func__, cpu);
baaca49f GS	241	err = -EINVAL;
baaca49f GS	242	goto out_release;
1da177e4 LT	243	}
	244
	245	/* Ensure that we are not runnable on dying cpu */
	246	old_allowed = current->cpus_allowed;
f70316da	247	cpus_setall(tmp);
1da177e4	248	cpu_clear(cpu, tmp);
f70316da	249	set_cpus_allowed_ptr(current, &tmp);
1da177e4	250
db912f96	251	p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
aa953877	252
8fa1d7d3	253	if (IS_ERR(p) \|\| cpu_online(cpu)) {
1da177e4	254	/* CPU didn't die: tell everyone. Can't complain. */
8bb78442	255	if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED \| mod,
e7407dcc	256	hcpu) == NOTIFY_BAD)
1da177e4 LT	257	BUG();
1da177e4 LT	258
8fa1d7d3 ST	259	if (IS_ERR(p)) {
	260	err = PTR_ERR(p);
	261	goto out_allowed;
	262	}
1da177e4	263	goto out_thread;
8fa1d7d3	264	}
1da177e4 LT	265
	266	/* Wait for it to sleep (leaving idle task). */
	267	while (!idle_cpu(cpu))
	268	yield();
	269
	270	/* This actually kills the CPU. */
	271	__cpu_die(cpu);
	272
1da177e4	273	/* CPU is completely dead: tell everyone. Too late to complain. */
8bb78442 RW	274	if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD \| mod,
8bb78442 RW	275	hcpu) == NOTIFY_BAD)
1da177e4 LT	276	BUG();
	277
	278	check_for_tasks(cpu);
	279
	280	out_thread:
	281	err = kthread_stop(p);
	282	out_allowed:
f70316da	283	set_cpus_allowed_ptr(current, &old_allowed);
baaca49f	284	out_release:
d221938c	285	cpu_hotplug_done();
e3920fb4 RW	286	return err;
	287	}
	288
514a20a5	289	int __ref cpu_down(unsigned int cpu)
e3920fb4 RW	290	{
	291	int err = 0;
	292
d221938c	293	cpu_maps_update_begin();
e3920fb4 RW	294	if (cpu_hotplug_disabled)
	295	err = -EBUSY;
	296	else
8bb78442	297	err = _cpu_down(cpu, 0);
e3920fb4	298
d221938c	299	cpu_maps_update_done();
1da177e4 LT	300	return err;
1da177e4 LT	301	}
b62b8ef9	302	EXPORT_SYMBOL(cpu_down);
1da177e4 LT	303	#endif /CONFIG_HOTPLUG_CPU/
1da177e4 LT	304
e3920fb4	305	/* Requires cpu_add_remove_lock to be held */
8bb78442	306	static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
1da177e4	307	{
baaca49f	308	int ret, nr_calls = 0;
1da177e4	309	void hcpu = (void )(long)cpu;
8bb78442	310	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
1da177e4	311
e3920fb4 RW	312	if (cpu_online(cpu) \|\| !cpu_present(cpu))
e3920fb4 RW	313	return -EINVAL;
90d45d17	314
d221938c	315	cpu_hotplug_begin();
8bb78442	316	ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE \| mod, hcpu,
baaca49f	317	-1, &nr_calls);
1da177e4	318	if (ret == NOTIFY_BAD) {
a0d8cdb6	319	nr_calls--;
1da177e4	320	printk("%s: attempt to bring up CPU %u failed\n",
af1f16d0	321	__func__, cpu);
1da177e4 LT	322	ret = -EINVAL;
	323	goto out_notify;
	324	}
	325
	326	/* Arch-specific enabling code. */
	327	ret = __cpu_up(cpu);
	328	if (ret != 0)
	329	goto out_notify;
6978c705	330	BUG_ON(!cpu_online(cpu));
1da177e4 LT	331
1da177e4 LT	332	/* Now call notifier in preparation. */
8bb78442	333	raw_notifier_call_chain(&cpu_chain, CPU_ONLINE \| mod, hcpu);
1da177e4 LT	334
	335	out_notify:
	336	if (ret != 0)
baaca49f	337	__raw_notifier_call_chain(&cpu_chain,
8bb78442	338	CPU_UP_CANCELED \| mod, hcpu, nr_calls, NULL);
d221938c	339	cpu_hotplug_done();
e3920fb4 RW	340
	341	return ret;
	342	}
	343
b282b6f8	344	int __cpuinit cpu_up(unsigned int cpu)
e3920fb4 RW	345	{
e3920fb4 RW	346	int err = 0;
73e753a5 KH	347	if (!cpu_isset(cpu, cpu_possible_map)) {
	348	printk(KERN_ERR "can't online cpu %d because it is not "
	349	"configured as may-hotadd at boot time\n", cpu);
	350	#if defined(CONFIG_IA64) \|\| defined(CONFIG_X86_64) \|\| defined(CONFIG_S390)
	351	printk(KERN_ERR "please check additional_cpus= boot "
	352	"parameter\n");
	353	#endif
	354	return -EINVAL;
	355	}
e3920fb4	356
d221938c	357	cpu_maps_update_begin();
e3920fb4 RW	358	if (cpu_hotplug_disabled)
	359	err = -EBUSY;
	360	else
8bb78442	361	err = _cpu_up(cpu, 0);
e3920fb4	362
d221938c	363	cpu_maps_update_done();
e3920fb4 RW	364	return err;
	365	}
	366
f3de4be9	367	#ifdef CONFIG_PM_SLEEP_SMP
e3920fb4 RW	368	static cpumask_t frozen_cpus;
	369
	370	int disable_nonboot_cpus(void)
	371	{
e1d9fd2e	372	int cpu, first_cpu, error = 0;
e3920fb4	373
d221938c	374	cpu_maps_update_begin();
1d64b9cb	375	first_cpu = first_cpu(cpu_online_map);
e3920fb4 RW	376	/* We take down all of the non-boot CPUs in one shot to avoid races
	377	* with the userspace trying to use the CPU hotplug at the same time
	378	*/
	379	cpus_clear(frozen_cpus);
	380	printk("Disabling non-boot CPUs ...\n");
	381	for_each_online_cpu(cpu) {
	382	if (cpu == first_cpu)
	383	continue;
8bb78442	384	error = _cpu_down(cpu, 1);
e3920fb4 RW	385	if (!error) {
	386	cpu_set(cpu, frozen_cpus);
	387	printk("CPU%d is down\n", cpu);
	388	} else {
	389	printk(KERN_ERR "Error taking CPU%d down: %d\n",
	390	cpu, error);
	391	break;
	392	}
	393	}
	394	if (!error) {
	395	BUG_ON(num_online_cpus() > 1);
	396	/* Make sure the CPUs won't be enabled by someone else */
	397	cpu_hotplug_disabled = 1;
	398	} else {
e1d9fd2e	399	printk(KERN_ERR "Non-boot CPUs are not disabled\n");
e3920fb4	400	}
d221938c	401	cpu_maps_update_done();
e3920fb4 RW	402	return error;
	403	}
	404
fa7303e2	405	void __ref enable_nonboot_cpus(void)
e3920fb4 RW	406	{
	407	int cpu, error;
	408
	409	/* Allow everyone to use the CPU hotplug again */
d221938c	410	cpu_maps_update_begin();
e3920fb4	411	cpu_hotplug_disabled = 0;
ed746e3b	412	if (cpus_empty(frozen_cpus))
1d64b9cb	413	goto out;
e3920fb4 RW	414
	415	printk("Enabling non-boot CPUs ...\n");
	416	for_each_cpu_mask(cpu, frozen_cpus) {
8bb78442	417	error = _cpu_up(cpu, 1);
e3920fb4 RW	418	if (!error) {
	419	printk("CPU%d is up\n", cpu);
	420	continue;
	421	}
1d64b9cb	422	printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
e3920fb4 RW	423	}
e3920fb4 RW	424	cpus_clear(frozen_cpus);
1d64b9cb	425	out:
d221938c	426	cpu_maps_update_done();
1da177e4	427	}
f3de4be9	428	#endif /* CONFIG_PM_SLEEP_SMP */
68f4f1ec MK	429
68f4f1ec MK	430	#endif /* CONFIG_SMP */