[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, p->pid, 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) {
		__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) {
		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_SUSPEND_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
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",
1da177e4 LT	101	p->comm, p->pid, cpu, p->state, p->flags);
	102	}
	103	write_unlock_irq(&tasklist_lock);
	104	}
	105
db912f96 AK	106	struct take_cpu_down_param {
	107	unsigned long mod;
	108	void *hcpu;
	109	};
	110
1da177e4	111	/* Take this CPU down. */
db912f96	112	static int take_cpu_down(void *_param)
1da177e4	113	{
db912f96	114	struct take_cpu_down_param *param = _param;
1da177e4 LT	115	int err;
1da177e4 LT	116
db912f96 AK	117	raw_notifier_call_chain(&cpu_chain, CPU_DYING \| param->mod,
db912f96 AK	118	param->hcpu);
1da177e4 LT	119	/* Ensure this CPU doesn't handle any more interrupts. */
	120	err = __cpu_disable();
	121	if (err < 0)
f3705136	122	return err;
1da177e4	123
f3705136 ZM	124	/* Force idle task to run as soon as we yield: it should
	125	immediately notice cpu is offline and die quickly. */
	126	sched_idle_next();
	127	return 0;
1da177e4 LT	128	}
1da177e4 LT	129
e3920fb4	130	/* Requires cpu_add_remove_lock to be held */
8bb78442	131	static int _cpu_down(unsigned int cpu, int tasks_frozen)
1da177e4	132	{
e7407dcc	133	int err, nr_calls = 0;
1da177e4 LT	134	struct task_struct *p;
1da177e4 LT	135	cpumask_t old_allowed, tmp;
e7407dcc	136	void hcpu = (void )(long)cpu;
8bb78442	137	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
db912f96 AK	138	struct take_cpu_down_param tcd_param = {
	139	.mod = mod,
	140	.hcpu = hcpu,
	141	};
1da177e4	142
e3920fb4 RW	143	if (num_online_cpus() == 1)
e3920fb4 RW	144	return -EBUSY;
1da177e4	145
e3920fb4 RW	146	if (!cpu_online(cpu))
e3920fb4 RW	147	return -EINVAL;
1da177e4	148
e7407dcc	149	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
8bb78442	150	err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE \| mod,
e7407dcc	151	hcpu, -1, &nr_calls);
1da177e4	152	if (err == NOTIFY_BAD) {
8bb78442 RW	153	__raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED \| mod,
8bb78442 RW	154	hcpu, nr_calls, NULL);
1da177e4 LT	155	printk("%s: attempt to take down CPU %u failed\n",
1da177e4 LT	156	__FUNCTION__, cpu);
baaca49f GS	157	err = -EINVAL;
baaca49f GS	158	goto out_release;
1da177e4 LT	159	}
	160
	161	/* Ensure that we are not runnable on dying cpu */
	162	old_allowed = current->cpus_allowed;
	163	tmp = CPU_MASK_ALL;
	164	cpu_clear(cpu, tmp);
	165	set_cpus_allowed(current, tmp);
	166
aa953877	167	mutex_lock(&cpu_bitmask_lock);
db912f96	168	p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
aa953877 LT	169	mutex_unlock(&cpu_bitmask_lock);
aa953877 LT	170
8fa1d7d3	171	if (IS_ERR(p) \|\| cpu_online(cpu)) {
1da177e4	172	/* CPU didn't die: tell everyone. Can't complain. */
8bb78442	173	if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED \| mod,
e7407dcc	174	hcpu) == NOTIFY_BAD)
1da177e4 LT	175	BUG();
1da177e4 LT	176
8fa1d7d3 ST	177	if (IS_ERR(p)) {
	178	err = PTR_ERR(p);
	179	goto out_allowed;
	180	}
1da177e4	181	goto out_thread;
8fa1d7d3	182	}
1da177e4 LT	183
	184	/* Wait for it to sleep (leaving idle task). */
	185	while (!idle_cpu(cpu))
	186	yield();
	187
	188	/* This actually kills the CPU. */
	189	__cpu_die(cpu);
	190
1da177e4	191	/* CPU is completely dead: tell everyone. Too late to complain. */
8bb78442 RW	192	if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD \| mod,
8bb78442 RW	193	hcpu) == NOTIFY_BAD)
1da177e4 LT	194	BUG();
	195
	196	check_for_tasks(cpu);
	197
	198	out_thread:
	199	err = kthread_stop(p);
	200	out_allowed:
	201	set_cpus_allowed(current, old_allowed);
baaca49f	202	out_release:
8bb78442	203	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
e3920fb4 RW	204	return err;
	205	}
	206
	207	int cpu_down(unsigned int cpu)
	208	{
	209	int err = 0;
	210
	211	mutex_lock(&cpu_add_remove_lock);
	212	if (cpu_hotplug_disabled)
	213	err = -EBUSY;
	214	else
8bb78442	215	err = _cpu_down(cpu, 0);
e3920fb4	216
aa953877	217	mutex_unlock(&cpu_add_remove_lock);
1da177e4 LT	218	return err;
	219	}
	220	#endif /CONFIG_HOTPLUG_CPU/
	221
e3920fb4	222	/* Requires cpu_add_remove_lock to be held */
8bb78442	223	static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
1da177e4	224	{
baaca49f	225	int ret, nr_calls = 0;
1da177e4	226	void hcpu = (void )(long)cpu;
8bb78442	227	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
1da177e4	228
e3920fb4 RW	229	if (cpu_online(cpu) \|\| !cpu_present(cpu))
e3920fb4 RW	230	return -EINVAL;
90d45d17	231
baaca49f	232	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
8bb78442	233	ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE \| mod, hcpu,
baaca49f	234	-1, &nr_calls);
1da177e4 LT	235	if (ret == NOTIFY_BAD) {
	236	printk("%s: attempt to bring up CPU %u failed\n",
	237	__FUNCTION__, cpu);
	238	ret = -EINVAL;
	239	goto out_notify;
	240	}
	241
	242	/* Arch-specific enabling code. */
aa953877	243	mutex_lock(&cpu_bitmask_lock);
1da177e4	244	ret = __cpu_up(cpu);
aa953877	245	mutex_unlock(&cpu_bitmask_lock);
1da177e4 LT	246	if (ret != 0)
1da177e4 LT	247	goto out_notify;
6978c705	248	BUG_ON(!cpu_online(cpu));
1da177e4 LT	249
1da177e4 LT	250	/* Now call notifier in preparation. */
8bb78442	251	raw_notifier_call_chain(&cpu_chain, CPU_ONLINE \| mod, hcpu);
1da177e4 LT	252
	253	out_notify:
	254	if (ret != 0)
baaca49f	255	__raw_notifier_call_chain(&cpu_chain,
8bb78442	256	CPU_UP_CANCELED \| mod, hcpu, nr_calls, NULL);
baaca49f	257	raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
e3920fb4 RW	258
	259	return ret;
	260	}
	261
b282b6f8	262	int __cpuinit cpu_up(unsigned int cpu)
e3920fb4 RW	263	{
	264	int err = 0;
	265
	266	mutex_lock(&cpu_add_remove_lock);
	267	if (cpu_hotplug_disabled)
	268	err = -EBUSY;
	269	else
8bb78442	270	err = _cpu_up(cpu, 0);
e3920fb4 RW	271
	272	mutex_unlock(&cpu_add_remove_lock);
	273	return err;
	274	}
	275
	276	#ifdef CONFIG_SUSPEND_SMP
	277	static cpumask_t frozen_cpus;
	278
	279	int disable_nonboot_cpus(void)
	280	{
e1d9fd2e	281	int cpu, first_cpu, error = 0;
e3920fb4 RW	282
e3920fb4 RW	283	mutex_lock(&cpu_add_remove_lock);
1d64b9cb	284	first_cpu = first_cpu(cpu_online_map);
e3920fb4 RW	285	/* We take down all of the non-boot CPUs in one shot to avoid races
	286	* with the userspace trying to use the CPU hotplug at the same time
	287	*/
	288	cpus_clear(frozen_cpus);
	289	printk("Disabling non-boot CPUs ...\n");
	290	for_each_online_cpu(cpu) {
	291	if (cpu == first_cpu)
	292	continue;
8bb78442	293	error = _cpu_down(cpu, 1);
e3920fb4 RW	294	if (!error) {
	295	cpu_set(cpu, frozen_cpus);
	296	printk("CPU%d is down\n", cpu);
	297	} else {
	298	printk(KERN_ERR "Error taking CPU%d down: %d\n",
	299	cpu, error);
	300	break;
	301	}
	302	}
	303	if (!error) {
	304	BUG_ON(num_online_cpus() > 1);
	305	/* Make sure the CPUs won't be enabled by someone else */
	306	cpu_hotplug_disabled = 1;
	307	} else {
e1d9fd2e	308	printk(KERN_ERR "Non-boot CPUs are not disabled\n");
e3920fb4	309	}
aa953877	310	mutex_unlock(&cpu_add_remove_lock);
e3920fb4 RW	311	return error;
	312	}
	313
	314	void enable_nonboot_cpus(void)
	315	{
	316	int cpu, error;
	317
	318	/* Allow everyone to use the CPU hotplug again */
	319	mutex_lock(&cpu_add_remove_lock);
	320	cpu_hotplug_disabled = 0;
ed746e3b	321	if (cpus_empty(frozen_cpus))
1d64b9cb	322	goto out;
e3920fb4 RW	323
	324	printk("Enabling non-boot CPUs ...\n");
	325	for_each_cpu_mask(cpu, frozen_cpus) {
8bb78442	326	error = _cpu_up(cpu, 1);
e3920fb4 RW	327	if (!error) {
	328	printk("CPU%d is up\n", cpu);
	329	continue;
	330	}
1d64b9cb	331	printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
e3920fb4 RW	332	}
e3920fb4 RW	333	cpus_clear(frozen_cpus);
1d64b9cb RW	334	out:
1d64b9cb RW	335	mutex_unlock(&cpu_add_remove_lock);
1da177e4	336	}
e3920fb4	337	#endif