[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>

/* This protects CPUs going up and down... */
static DEFINE_MUTEX(cpu_add_remove_lock);
static DEFINE_MUTEX(cpu_bitmask_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;

#ifdef CONFIG_HOTPLUG_CPU

/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
static struct task_struct *recursive;
static int recursive_depth;

void lock_cpu_hotplug(void)
{
	struct task_struct *tsk = current;

	if (tsk == recursive) {
		static int warnings = 10;
		if (warnings) {
			printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n");
			WARN_ON(1);
			warnings--;
		}
		recursive_depth++;
		return;
	}
	mutex_lock(&cpu_bitmask_lock);
	recursive = tsk;
}
EXPORT_SYMBOL_GPL(lock_cpu_hotplug);

void unlock_cpu_hotplug(void)
{
	WARN_ON(recursive != current);
	if (recursive_depth) {
		recursive_depth--;
		return;
	}
	recursive = NULL;
	mutex_unlock(&cpu_bitmask_lock);
}
EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);

#endif	/* CONFIG_HOTPLUG_CPU */

/* Need to know about CPUs going up/down? */
int __cpuinit register_cpu_notifier(struct notifier_block *nb)
{
	int ret;
	mutex_lock(&cpu_add_remove_lock);
	ret = raw_notifier_chain_register(&cpu_chain, nb);
	mutex_unlock(&cpu_add_remove_lock);
	return ret;
}

#ifdef CONFIG_HOTPLUG_CPU

EXPORT_SYMBOL(register_cpu_notifier);

void unregister_cpu_notifier(struct notifier_block *nb)
{
	mutex_lock(&cpu_add_remove_lock);
	raw_notifier_chain_unregister(&cpu_chain, nb);
	mutex_unlock(&cpu_add_remove_lock);
}
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 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 _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;

	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
	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",
				__FUNCTION__, cpu);
		err = -EINVAL;
		goto out_release;
	}

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

	mutex_lock(&cpu_bitmask_lock);
	p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
	mutex_unlock(&cpu_bitmask_lock);

	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(current, old_allowed);
out_release:
	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
	return err;
}

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

	mutex_lock(&cpu_add_remove_lock);
	if (cpu_hotplug_disabled)
		err = -EBUSY;
	else
		err = _cpu_down(cpu, 0);

	mutex_unlock(&cpu_add_remove_lock);
	return err;
}
#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;

	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
	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",
				__FUNCTION__, cpu);
		ret = -EINVAL;
		goto out_notify;
	}

	/* Arch-specific enabling code. */
	mutex_lock(&cpu_bitmask_lock);
	ret = __cpu_up(cpu);
	mutex_unlock(&cpu_bitmask_lock);
	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);
	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);

	return ret;
}

int __cpuinit cpu_up(unsigned int cpu)
{
	int err = 0;

	mutex_lock(&cpu_add_remove_lock);
	if (cpu_hotplug_disabled)
		err = -EBUSY;
	else
		err = _cpu_up(cpu, 0);

	mutex_unlock(&cpu_add_remove_lock);
	return err;
}

#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_t frozen_cpus;

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

	mutex_lock(&cpu_add_remove_lock);
	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");
	}
	mutex_unlock(&cpu_add_remove_lock);
	return error;
}

void enable_nonboot_cpus(void)
{
	int cpu, error;

	/* Allow everyone to use the CPU hotplug again */
	mutex_lock(&cpu_add_remove_lock);
	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:
	mutex_unlock(&cpu_add_remove_lock);
}
#endif /* CONFIG_PM_SLEEP_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 LT	17
1da177e4 LT	18	/* This protects CPUs going up and down... */
aa953877 LT	19	static DEFINE_MUTEX(cpu_add_remove_lock);
aa953877 LT	20	static DEFINE_MUTEX(cpu_bitmask_lock);
1da177e4	21
bd5349cf	22	static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
1da177e4	23
e3920fb4 RW	24	/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
	25	* Should always be manipulated under cpu_add_remove_lock
	26	*/
	27	static int cpu_hotplug_disabled;
	28
a9d9baa1	29	#ifdef CONFIG_HOTPLUG_CPU
90d45d17	30
aa953877 LT	31	/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
	32	static struct task_struct *recursive;
	33	static int recursive_depth;
90d45d17	34
a9d9baa1 AR	35	void lock_cpu_hotplug(void)
a9d9baa1 AR	36	{
aa953877 LT	37	struct task_struct *tsk = current;
	38
	39	if (tsk == recursive) {
	40	static int warnings = 10;
	41	if (warnings) {
	42	printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n");
	43	WARN_ON(1);
	44	warnings--;
	45	}
	46	recursive_depth++;
	47	return;
	48	}
	49	mutex_lock(&cpu_bitmask_lock);
	50	recursive = tsk;
a9d9baa1 AR	51	}
a9d9baa1 AR	52	EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
90d45d17	53
a9d9baa1 AR	54	void unlock_cpu_hotplug(void)
a9d9baa1 AR	55	{
aa953877 LT	56	WARN_ON(recursive != current);
	57	if (recursive_depth) {
	58	recursive_depth--;
	59	return;
a9d9baa1	60	}
aa953877	61	recursive = NULL;
4b96b1a1	62	mutex_unlock(&cpu_bitmask_lock);
a9d9baa1 AR	63	}
	64	EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
	65
a9d9baa1	66	#endif /* CONFIG_HOTPLUG_CPU */
90d45d17	67
1da177e4	68	/* Need to know about CPUs going up/down? */
65edc68c	69	int __cpuinit register_cpu_notifier(struct notifier_block *nb)
1da177e4	70	{
bd5349cf NB	71	int ret;
	72	mutex_lock(&cpu_add_remove_lock);
	73	ret = raw_notifier_chain_register(&cpu_chain, nb);
	74	mutex_unlock(&cpu_add_remove_lock);
	75	return ret;
1da177e4	76	}
65edc68c CS	77
	78	#ifdef CONFIG_HOTPLUG_CPU
	79
1da177e4 LT	80	EXPORT_SYMBOL(register_cpu_notifier);
	81
	82	void unregister_cpu_notifier(struct notifier_block *nb)
	83	{
bd5349cf NB	84	mutex_lock(&cpu_add_remove_lock);
	85	raw_notifier_chain_unregister(&cpu_chain, nb);
	86	mutex_unlock(&cpu_add_remove_lock);
1da177e4 LT	87	}
	88	EXPORT_SYMBOL(unregister_cpu_notifier);
	89
1da177e4 LT	90	static inline void check_for_tasks(int cpu)
	91	{
	92	struct task_struct *p;
	93
	94	write_lock_irq(&tasklist_lock);
	95	for_each_process(p) {
	96	if (task_cpu(p) == cpu &&
	97	(!cputime_eq(p->utime, cputime_zero) \|\|
	98	!cputime_eq(p->stime, cputime_zero)))
	99	printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
e7407dcc	100	(state = %ld, flags = %x) \n",
ba25f9dc PE	101	p->comm, task_pid_nr(p), cpu,
ba25f9dc PE	102	p->state, p->flags);
1da177e4 LT	103	}
	104	write_unlock_irq(&tasklist_lock);
	105	}
	106
db912f96 AK	107	struct take_cpu_down_param {
	108	unsigned long mod;
	109	void *hcpu;
	110	};
	111
1da177e4	112	/* Take this CPU down. */
db912f96	113	static int take_cpu_down(void *_param)
1da177e4	114	{
db912f96	115	struct take_cpu_down_param *param = _param;
1da177e4 LT	116	int err;
1da177e4 LT	117
db912f96 AK	118	raw_notifier_call_chain(&cpu_chain, CPU_DYING \| param->mod,
db912f96 AK	119	param->hcpu);
1da177e4 LT	120	/* Ensure this CPU doesn't handle any more interrupts. */
	121	err = __cpu_disable();
	122	if (err < 0)
f3705136	123	return err;
1da177e4	124
f3705136 ZM	125	/* Force idle task to run as soon as we yield: it should
	126	immediately notice cpu is offline and die quickly. */
	127	sched_idle_next();
	128	return 0;
1da177e4 LT	129	}
1da177e4 LT	130
e3920fb4	131	/* Requires cpu_add_remove_lock to be held */
8bb78442	132	static int _cpu_down(unsigned int cpu, int tasks_frozen)
1da177e4	133	{
e7407dcc	134	int err, nr_calls = 0;
1da177e4 LT	135	struct task_struct *p;
1da177e4 LT	136	cpumask_t old_allowed, tmp;
e7407dcc	137	void hcpu = (void )(long)cpu;
8bb78442	138	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
db912f96 AK	139	struct take_cpu_down_param tcd_param = {
	140	.mod = mod,
	141	.hcpu = hcpu,
	142	};
1da177e4	143
e3920fb4 RW	144	if (num_online_cpus() == 1)
e3920fb4 RW	145	return -EBUSY;
1da177e4	146
e3920fb4 RW	147	if (!cpu_online(cpu))
e3920fb4 RW	148	return -EINVAL;
1da177e4	149
e7407dcc	150	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
8bb78442	151	err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE \| mod,
e7407dcc	152	hcpu, -1, &nr_calls);
1da177e4	153	if (err == NOTIFY_BAD) {
a0d8cdb6	154	nr_calls--;
8bb78442 RW	155	__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED \| mod,
8bb78442 RW	156	hcpu, nr_calls, NULL);
1da177e4 LT	157	printk("%s: attempt to take down CPU %u failed\n",
1da177e4 LT	158	__FUNCTION__, cpu);
baaca49f GS	159	err = -EINVAL;
baaca49f GS	160	goto out_release;
1da177e4 LT	161	}
	162
	163	/* Ensure that we are not runnable on dying cpu */
	164	old_allowed = current->cpus_allowed;
	165	tmp = CPU_MASK_ALL;
	166	cpu_clear(cpu, tmp);
	167	set_cpus_allowed(current, tmp);
	168
aa953877	169	mutex_lock(&cpu_bitmask_lock);
db912f96	170	p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
aa953877 LT	171	mutex_unlock(&cpu_bitmask_lock);
aa953877 LT	172
8fa1d7d3	173	if (IS_ERR(p) \|\| cpu_online(cpu)) {
1da177e4	174	/* CPU didn't die: tell everyone. Can't complain. */
8bb78442	175	if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED \| mod,
e7407dcc	176	hcpu) == NOTIFY_BAD)
1da177e4 LT	177	BUG();
1da177e4 LT	178
8fa1d7d3 ST	179	if (IS_ERR(p)) {
	180	err = PTR_ERR(p);
	181	goto out_allowed;
	182	}
1da177e4	183	goto out_thread;
8fa1d7d3	184	}
1da177e4 LT	185
	186	/* Wait for it to sleep (leaving idle task). */
	187	while (!idle_cpu(cpu))
	188	yield();
	189
	190	/* This actually kills the CPU. */
	191	__cpu_die(cpu);
	192
1da177e4	193	/* CPU is completely dead: tell everyone. Too late to complain. */
8bb78442 RW	194	if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD \| mod,
8bb78442 RW	195	hcpu) == NOTIFY_BAD)
1da177e4 LT	196	BUG();
	197
	198	check_for_tasks(cpu);
	199
	200	out_thread:
	201	err = kthread_stop(p);
	202	out_allowed:
	203	set_cpus_allowed(current, old_allowed);
baaca49f	204	out_release:
8bb78442	205	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
e3920fb4 RW	206	return err;
	207	}
	208
	209	int cpu_down(unsigned int cpu)
	210	{
	211	int err = 0;
	212
	213	mutex_lock(&cpu_add_remove_lock);
	214	if (cpu_hotplug_disabled)
	215	err = -EBUSY;
	216	else
8bb78442	217	err = _cpu_down(cpu, 0);
e3920fb4	218
aa953877	219	mutex_unlock(&cpu_add_remove_lock);
1da177e4 LT	220	return err;
	221	}
	222	#endif /CONFIG_HOTPLUG_CPU/
	223
e3920fb4	224	/* Requires cpu_add_remove_lock to be held */
8bb78442	225	static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
1da177e4	226	{
baaca49f	227	int ret, nr_calls = 0;
1da177e4	228	void hcpu = (void )(long)cpu;
8bb78442	229	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
1da177e4	230
e3920fb4 RW	231	if (cpu_online(cpu) \|\| !cpu_present(cpu))
e3920fb4 RW	232	return -EINVAL;
90d45d17	233
baaca49f	234	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
8bb78442	235	ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE \| mod, hcpu,
baaca49f	236	-1, &nr_calls);
1da177e4	237	if (ret == NOTIFY_BAD) {
a0d8cdb6	238	nr_calls--;
1da177e4 LT	239	printk("%s: attempt to bring up CPU %u failed\n",
	240	__FUNCTION__, cpu);
	241	ret = -EINVAL;
	242	goto out_notify;
	243	}
	244
	245	/* Arch-specific enabling code. */
aa953877	246	mutex_lock(&cpu_bitmask_lock);
1da177e4	247	ret = __cpu_up(cpu);
aa953877	248	mutex_unlock(&cpu_bitmask_lock);
1da177e4 LT	249	if (ret != 0)
1da177e4 LT	250	goto out_notify;
6978c705	251	BUG_ON(!cpu_online(cpu));
1da177e4 LT	252
1da177e4 LT	253	/* Now call notifier in preparation. */
8bb78442	254	raw_notifier_call_chain(&cpu_chain, CPU_ONLINE \| mod, hcpu);
1da177e4 LT	255
	256	out_notify:
	257	if (ret != 0)
baaca49f	258	__raw_notifier_call_chain(&cpu_chain,
8bb78442	259	CPU_UP_CANCELED \| mod, hcpu, nr_calls, NULL);
baaca49f	260	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
e3920fb4 RW	261
	262	return ret;
	263	}
	264
b282b6f8	265	int __cpuinit cpu_up(unsigned int cpu)
e3920fb4 RW	266	{
	267	int err = 0;
	268
	269	mutex_lock(&cpu_add_remove_lock);
	270	if (cpu_hotplug_disabled)
	271	err = -EBUSY;
	272	else
8bb78442	273	err = _cpu_up(cpu, 0);
e3920fb4 RW	274
	275	mutex_unlock(&cpu_add_remove_lock);
	276	return err;
	277	}
	278
f3de4be9	279	#ifdef CONFIG_PM_SLEEP_SMP
e3920fb4 RW	280	static cpumask_t frozen_cpus;
	281
	282	int disable_nonboot_cpus(void)
	283	{
e1d9fd2e	284	int cpu, first_cpu, error = 0;
e3920fb4 RW	285
e3920fb4 RW	286	mutex_lock(&cpu_add_remove_lock);
1d64b9cb	287	first_cpu = first_cpu(cpu_online_map);
e3920fb4 RW	288	/* We take down all of the non-boot CPUs in one shot to avoid races
	289	* with the userspace trying to use the CPU hotplug at the same time
	290	*/
	291	cpus_clear(frozen_cpus);
	292	printk("Disabling non-boot CPUs ...\n");
	293	for_each_online_cpu(cpu) {
	294	if (cpu == first_cpu)
	295	continue;
8bb78442	296	error = _cpu_down(cpu, 1);
e3920fb4 RW	297	if (!error) {
	298	cpu_set(cpu, frozen_cpus);
	299	printk("CPU%d is down\n", cpu);
	300	} else {
	301	printk(KERN_ERR "Error taking CPU%d down: %d\n",
	302	cpu, error);
	303	break;
	304	}
	305	}
	306	if (!error) {
	307	BUG_ON(num_online_cpus() > 1);
	308	/* Make sure the CPUs won't be enabled by someone else */
	309	cpu_hotplug_disabled = 1;
	310	} else {
e1d9fd2e	311	printk(KERN_ERR "Non-boot CPUs are not disabled\n");
e3920fb4	312	}
aa953877	313	mutex_unlock(&cpu_add_remove_lock);
e3920fb4 RW	314	return error;
	315	}
	316
	317	void enable_nonboot_cpus(void)
	318	{
	319	int cpu, error;
	320
	321	/* Allow everyone to use the CPU hotplug again */
	322	mutex_lock(&cpu_add_remove_lock);
	323	cpu_hotplug_disabled = 0;
ed746e3b	324	if (cpus_empty(frozen_cpus))
1d64b9cb	325	goto out;
e3920fb4 RW	326
	327	printk("Enabling non-boot CPUs ...\n");
	328	for_each_cpu_mask(cpu, frozen_cpus) {
8bb78442	329	error = _cpu_up(cpu, 1);
e3920fb4 RW	330	if (!error) {
	331	printk("CPU%d is up\n", cpu);
	332	continue;
	333	}
1d64b9cb	334	printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
e3920fb4 RW	335	}
e3920fb4 RW	336	cpus_clear(frozen_cpus);
1d64b9cb RW	337	out:
1d64b9cb RW	338	mutex_unlock(&cpu_add_remove_lock);
1da177e4	339	}
f3de4be9	340	#endif /* CONFIG_PM_SLEEP_SMP */