[deliverable/linux.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>
#include <linux/gfp.h>

#ifdef CONFIG_SMP
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);

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

void cpu_maps_update_done(void)
{
	mutex_unlock(&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;

#ifdef CONFIG_HOTPLUG_CPU

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 = {
	.active_writer = NULL,
	.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
	.refcount = 0,
};

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);

/*
 * 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);
}

#else /* #if CONFIG_HOTPLUG_CPU */
static void cpu_hotplug_begin(void) {}
static void cpu_hotplug_done(void) {}
#endif	/* #esle #if CONFIG_HOTPLUG_CPU */

/* 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;
}

static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
			int *nr_calls)
{
	int ret;

	ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
					nr_calls);

	return notifier_to_errno(ret);
}

static int cpu_notify(unsigned long val, void *v)
{
	return __cpu_notify(val, v, -1, NULL);
}

#ifdef CONFIG_HOTPLUG_CPU

static void cpu_notify_nofail(unsigned long val, void *v)
{
	BUG_ON(cpu_notify(val, v));
}

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 && p->state == TASK_RUNNING &&
		    (!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 {
	struct task_struct *caller;
	unsigned long mod;
	void *hcpu;
};

/* Take this CPU down. */
static int __ref take_cpu_down(void *_param)
{
	struct take_cpu_down_param *param = _param;
	unsigned int cpu = (unsigned long)param->hcpu;
	int err;

	/* Ensure this CPU doesn't handle any more interrupts. */
	err = __cpu_disable();
	if (err < 0)
		return err;

	cpu_notify(CPU_DYING | param->mod, param->hcpu);

	if (task_cpu(param->caller) == cpu)
		move_task_off_dead_cpu(cpu, param->caller);
	/* 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;
	void *hcpu = (void *)(long)cpu;
	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
	struct take_cpu_down_param tcd_param = {
		.caller = current,
		.mod = mod,
		.hcpu = hcpu,
	};

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

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

	cpu_hotplug_begin();
	set_cpu_active(cpu, false);
	err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
	if (err) {
		set_cpu_active(cpu, true);

		nr_calls--;
		__cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
		printk("%s: attempt to take down CPU %u failed\n",
				__func__, cpu);
		goto out_release;
	}

	err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
	if (err) {
		set_cpu_active(cpu, true);
		/* CPU didn't die: tell everyone.  Can't complain. */
		cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);

		goto out_release;
	}
	BUG_ON(cpu_online(cpu));

	/* 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. */
	cpu_notify_nofail(CPU_DEAD | mod, hcpu);

	check_for_tasks(cpu);

out_release:
	cpu_hotplug_done();
	if (!err)
		cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
	return err;
}

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

	cpu_maps_update_begin();

	if (cpu_hotplug_disabled) {
		err = -EBUSY;
		goto out;
	}

	err = _cpu_down(cpu, 0);

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

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

	set_cpu_active(cpu, true);

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

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

	return ret;
}

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

#ifdef	CONFIG_MEMORY_HOTPLUG
	int nid;
	pg_data_t	*pgdat;
#endif

	if (!cpu_possible(cpu)) {
		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)
		printk(KERN_ERR "please check additional_cpus= boot "
				"parameter\n");
#endif
		return -EINVAL;
	}

#ifdef	CONFIG_MEMORY_HOTPLUG
	nid = cpu_to_node(cpu);
	if (!node_online(nid)) {
		err = mem_online_node(nid);
		if (err)
			return err;
	}

	pgdat = NODE_DATA(nid);
	if (!pgdat) {
		printk(KERN_ERR
			"Can't online cpu %d due to NULL pgdat\n", cpu);
		return -ENOMEM;
	}

	if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
		mutex_lock(&zonelists_mutex);
		build_all_zonelists(NULL);
		mutex_unlock(&zonelists_mutex);
	}
#endif

	cpu_maps_update_begin();

	if (cpu_hotplug_disabled) {
		err = -EBUSY;
		goto out;
	}

	err = _cpu_up(cpu, 0);

out:
	cpu_maps_update_done();
	return err;
}

#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;

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

	cpu_maps_update_begin();
	first_cpu = cpumask_first(cpu_online_mask);
	/*
	 * 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
	 */
	cpumask_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)
			cpumask_set_cpu(cpu, frozen_cpus);
		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 __weak arch_enable_nonboot_cpus_begin(void)
{
}

void __weak arch_enable_nonboot_cpus_end(void)
{
}

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 (cpumask_empty(frozen_cpus))
		goto out;

	printk("Enabling non-boot CPUs ...\n");

	arch_enable_nonboot_cpus_begin();

	for_each_cpu(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);
	}

	arch_enable_nonboot_cpus_end();

	cpumask_clear(frozen_cpus);
out:
	cpu_maps_update_done();
}

static int alloc_frozen_cpus(void)
{
	if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
		return -ENOMEM;
	return 0;
}
core_initcall(alloc_frozen_cpus);
#endif /* CONFIG_PM_SLEEP_SMP */

/**
 * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
 * @cpu: cpu that just started
 *
 * This function calls the cpu_chain notifiers with CPU_STARTING.
 * It must be called by the arch code on the new cpu, before the new cpu
 * enables interrupts and before the "boot" cpu returns from __cpu_up().
 */
void __cpuinit notify_cpu_starting(unsigned int cpu)
{
	unsigned long val = CPU_STARTING;

#ifdef CONFIG_PM_SLEEP_SMP
	if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
		val = CPU_STARTING_FROZEN;
#endif /* CONFIG_PM_SLEEP_SMP */
	cpu_notify(val, (void *)(long)cpu);
}

#endif /* CONFIG_SMP */

/*
 * cpu_bit_bitmap[] is a special, "compressed" data structure that
 * represents all NR_CPUS bits binary values of 1<<nr.
 *
 * It is used by cpumask_of() to get a constant address to a CPU
 * mask value that has a single bit set only.
 */

/* cpu_bit_bitmap[0] is empty - so we can back into it */
#define MASK_DECLARE_1(x)	[x+1][0] = 1UL << (x)
#define MASK_DECLARE_2(x)	MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
#define MASK_DECLARE_4(x)	MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
#define MASK_DECLARE_8(x)	MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)

const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {

	MASK_DECLARE_8(0),	MASK_DECLARE_8(8),
	MASK_DECLARE_8(16),	MASK_DECLARE_8(24),
#if BITS_PER_LONG > 32
	MASK_DECLARE_8(32),	MASK_DECLARE_8(40),
	MASK_DECLARE_8(48),	MASK_DECLARE_8(56),
#endif
};
EXPORT_SYMBOL_GPL(cpu_bit_bitmap);

const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
EXPORT_SYMBOL(cpu_all_bits);

#ifdef CONFIG_INIT_ALL_POSSIBLE
static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
	= CPU_BITS_ALL;
#else
static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
#endif
const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
EXPORT_SYMBOL(cpu_possible_mask);

static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
EXPORT_SYMBOL(cpu_online_mask);

static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
EXPORT_SYMBOL(cpu_present_mask);

static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
EXPORT_SYMBOL(cpu_active_mask);

void set_cpu_possible(unsigned int cpu, bool possible)
{
	if (possible)
		cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
	else
		cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
}

void set_cpu_present(unsigned int cpu, bool present)
{
	if (present)
		cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
	else
		cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
}

void set_cpu_online(unsigned int cpu, bool online)
{
	if (online)
		cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
	else
		cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
}

void set_cpu_active(unsigned int cpu, bool active)
{
	if (active)
		cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
	else
		cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
}

void init_cpu_present(const struct cpumask *src)
{
	cpumask_copy(to_cpumask(cpu_present_bits), src);
}

void init_cpu_possible(const struct cpumask *src)
{
	cpumask_copy(to_cpumask(cpu_possible_bits), src);
}

void init_cpu_online(const struct cpumask *src)
{
	cpumask_copy(to_cpumask(cpu_online_bits), src);
}
Commit	Line	Data
	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>
	16	#include <linux/mutex.h>
	17	#include <linux/gfp.h>
	18
	19	#ifdef CONFIG_SMP
	20	/* Serializes the updates to cpu_online_mask, cpu_present_mask */
	21	static DEFINE_MUTEX(cpu_add_remove_lock);
	22
	23	/*
	24	* The following two API's must be used when attempting
	25	* to serialize the updates to cpu_online_mask, cpu_present_mask.
	26	*/
	27	void cpu_maps_update_begin(void)
	28	{
	29	mutex_lock(&cpu_add_remove_lock);
	30	}
	31
	32	void cpu_maps_update_done(void)
	33	{
	34	mutex_unlock(&cpu_add_remove_lock);
	35	}
	36
	37	static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
	38
	39	/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
	40	* Should always be manipulated under cpu_add_remove_lock
	41	*/
	42	static int cpu_hotplug_disabled;
	43
	44	#ifdef CONFIG_HOTPLUG_CPU
	45
	46	static struct {
	47	struct task_struct *active_writer;
	48	struct mutex lock; /* Synchronizes accesses to refcount, */
	49	/*
	50	* Also blocks the new readers during
	51	* an ongoing cpu hotplug operation.
	52	*/
	53	int refcount;
	54	} cpu_hotplug = {
	55	.active_writer = NULL,
	56	.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
	57	.refcount = 0,
	58	};
	59
	60	void get_online_cpus(void)
	61	{
	62	might_sleep();
	63	if (cpu_hotplug.active_writer == current)
	64	return;
	65	mutex_lock(&cpu_hotplug.lock);
	66	cpu_hotplug.refcount++;
	67	mutex_unlock(&cpu_hotplug.lock);
	68
	69	}
	70	EXPORT_SYMBOL_GPL(get_online_cpus);
	71
	72	void put_online_cpus(void)
	73	{
	74	if (cpu_hotplug.active_writer == current)
	75	return;
	76	mutex_lock(&cpu_hotplug.lock);
	77	if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
	78	wake_up_process(cpu_hotplug.active_writer);
	79	mutex_unlock(&cpu_hotplug.lock);
	80
	81	}
	82	EXPORT_SYMBOL_GPL(put_online_cpus);
	83
	84	/*
	85	* This ensures that the hotplug operation can begin only when the
	86	* refcount goes to zero.
	87	*
	88	* Note that during a cpu-hotplug operation, the new readers, if any,
	89	* will be blocked by the cpu_hotplug.lock
	90	*
	91	* Since cpu_hotplug_begin() is always called after invoking
	92	* cpu_maps_update_begin(), we can be sure that only one writer is active.
	93	*
	94	* Note that theoretically, there is a possibility of a livelock:
	95	* - Refcount goes to zero, last reader wakes up the sleeping
	96	* writer.
	97	* - Last reader unlocks the cpu_hotplug.lock.
	98	* - A new reader arrives at this moment, bumps up the refcount.
	99	* - The writer acquires the cpu_hotplug.lock finds the refcount
	100	* non zero and goes to sleep again.
	101	*
	102	* However, this is very difficult to achieve in practice since
	103	* get_online_cpus() not an api which is called all that often.
	104	*
	105	*/
	106	static void cpu_hotplug_begin(void)
	107	{
	108	cpu_hotplug.active_writer = current;
	109
	110	for (;;) {
	111	mutex_lock(&cpu_hotplug.lock);
	112	if (likely(!cpu_hotplug.refcount))
	113	break;
	114	__set_current_state(TASK_UNINTERRUPTIBLE);
	115	mutex_unlock(&cpu_hotplug.lock);
	116	schedule();
	117	}
	118	}
	119
	120	static void cpu_hotplug_done(void)
	121	{
	122	cpu_hotplug.active_writer = NULL;
	123	mutex_unlock(&cpu_hotplug.lock);
	124	}
	125
	126	#else /* #if CONFIG_HOTPLUG_CPU */
	127	static void cpu_hotplug_begin(void) {}
	128	static void cpu_hotplug_done(void) {}
	129	#endif /* #esle #if CONFIG_HOTPLUG_CPU */
	130
	131	/* Need to know about CPUs going up/down? */
	132	int __ref register_cpu_notifier(struct notifier_block *nb)
	133	{
	134	int ret;
	135	cpu_maps_update_begin();
	136	ret = raw_notifier_chain_register(&cpu_chain, nb);
	137	cpu_maps_update_done();
	138	return ret;
	139	}
	140
	141	static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
	142	int *nr_calls)
	143	{
	144	int ret;
	145
	146	ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,
	147	nr_calls);
	148
	149	return notifier_to_errno(ret);
	150	}
	151
	152	static int cpu_notify(unsigned long val, void *v)
	153	{
	154	return __cpu_notify(val, v, -1, NULL);
	155	}
	156
	157	#ifdef CONFIG_HOTPLUG_CPU
	158
	159	static void cpu_notify_nofail(unsigned long val, void *v)
	160	{
	161	BUG_ON(cpu_notify(val, v));
	162	}
	163
	164	EXPORT_SYMBOL(register_cpu_notifier);
	165
	166	void __ref unregister_cpu_notifier(struct notifier_block *nb)
	167	{
	168	cpu_maps_update_begin();
	169	raw_notifier_chain_unregister(&cpu_chain, nb);
	170	cpu_maps_update_done();
	171	}
	172	EXPORT_SYMBOL(unregister_cpu_notifier);
	173
	174	static inline void check_for_tasks(int cpu)
	175	{
	176	struct task_struct *p;
	177
	178	write_lock_irq(&tasklist_lock);
	179	for_each_process(p) {
	180	if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
	181	(!cputime_eq(p->utime, cputime_zero) \|\|
	182	!cputime_eq(p->stime, cputime_zero)))
	183	printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
	184	"(state = %ld, flags = %x)\n",
	185	p->comm, task_pid_nr(p), cpu,
	186	p->state, p->flags);
	187	}
	188	write_unlock_irq(&tasklist_lock);
	189	}
	190
	191	struct take_cpu_down_param {
	192	struct task_struct *caller;
	193	unsigned long mod;
	194	void *hcpu;
	195	};
	196
	197	/* Take this CPU down. */
	198	static int __ref take_cpu_down(void *_param)
	199	{
	200	struct take_cpu_down_param *param = _param;
	201	unsigned int cpu = (unsigned long)param->hcpu;
	202	int err;
	203
	204	/* Ensure this CPU doesn't handle any more interrupts. */
	205	err = __cpu_disable();
	206	if (err < 0)
	207	return err;
	208
	209	cpu_notify(CPU_DYING \| param->mod, param->hcpu);
	210
	211	if (task_cpu(param->caller) == cpu)
	212	move_task_off_dead_cpu(cpu, param->caller);
	213	/* Force idle task to run as soon as we yield: it should
	214	immediately notice cpu is offline and die quickly. */
	215	sched_idle_next();
	216	return 0;
	217	}
	218
	219	/* Requires cpu_add_remove_lock to be held */
	220	static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
	221	{
	222	int err, nr_calls = 0;
	223	void hcpu = (void )(long)cpu;
	224	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
	225	struct take_cpu_down_param tcd_param = {
	226	.caller = current,
	227	.mod = mod,
	228	.hcpu = hcpu,
	229	};
	230
	231	if (num_online_cpus() == 1)
	232	return -EBUSY;
	233
	234	if (!cpu_online(cpu))
	235	return -EINVAL;
	236
	237	cpu_hotplug_begin();
	238	set_cpu_active(cpu, false);
	239	err = __cpu_notify(CPU_DOWN_PREPARE \| mod, hcpu, -1, &nr_calls);
	240	if (err) {
	241	set_cpu_active(cpu, true);
	242
	243	nr_calls--;
	244	__cpu_notify(CPU_DOWN_FAILED \| mod, hcpu, nr_calls, NULL);
	245	printk("%s: attempt to take down CPU %u failed\n",
	246	__func__, cpu);
	247	goto out_release;
	248	}
	249
	250	err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
	251	if (err) {
	252	set_cpu_active(cpu, true);
	253	/* CPU didn't die: tell everyone. Can't complain. */
	254	cpu_notify_nofail(CPU_DOWN_FAILED \| mod, hcpu);
	255
	256	goto out_release;
	257	}
	258	BUG_ON(cpu_online(cpu));
	259
	260	/* Wait for it to sleep (leaving idle task). */
	261	while (!idle_cpu(cpu))
	262	yield();
	263
	264	/* This actually kills the CPU. */
	265	__cpu_die(cpu);
	266
	267	/* CPU is completely dead: tell everyone. Too late to complain. */
	268	cpu_notify_nofail(CPU_DEAD \| mod, hcpu);
	269
	270	check_for_tasks(cpu);
	271
	272	out_release:
	273	cpu_hotplug_done();
	274	if (!err)
	275	cpu_notify_nofail(CPU_POST_DEAD \| mod, hcpu);
	276	return err;
	277	}
	278
	279	int __ref cpu_down(unsigned int cpu)
	280	{
	281	int err;
	282
	283	cpu_maps_update_begin();
	284
	285	if (cpu_hotplug_disabled) {
	286	err = -EBUSY;
	287	goto out;
	288	}
	289
	290	err = _cpu_down(cpu, 0);
	291
	292	out:
	293	cpu_maps_update_done();
	294	return err;
	295	}
	296	EXPORT_SYMBOL(cpu_down);
	297	#endif /CONFIG_HOTPLUG_CPU/
	298
	299	/* Requires cpu_add_remove_lock to be held */
	300	static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
	301	{
	302	int ret, nr_calls = 0;
	303	void hcpu = (void )(long)cpu;
	304	unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
	305
	306	if (cpu_online(cpu) \|\| !cpu_present(cpu))
	307	return -EINVAL;
	308
	309	cpu_hotplug_begin();
	310	ret = __cpu_notify(CPU_UP_PREPARE \| mod, hcpu, -1, &nr_calls);
	311	if (ret) {
	312	nr_calls--;
	313	printk("%s: attempt to bring up CPU %u failed\n",
	314	__func__, cpu);
	315	goto out_notify;
	316	}
	317
	318	/* Arch-specific enabling code. */
	319	ret = __cpu_up(cpu);
	320	if (ret != 0)
	321	goto out_notify;
	322	BUG_ON(!cpu_online(cpu));
	323
	324	set_cpu_active(cpu, true);
	325
	326	/* Now call notifier in preparation. */
	327	cpu_notify(CPU_ONLINE \| mod, hcpu);
	328
	329	out_notify:
	330	if (ret != 0)
	331	__cpu_notify(CPU_UP_CANCELED \| mod, hcpu, nr_calls, NULL);
	332	cpu_hotplug_done();
	333
	334	return ret;
	335	}
	336
	337	int __cpuinit cpu_up(unsigned int cpu)
	338	{
	339	int err = 0;
	340
	341	#ifdef CONFIG_MEMORY_HOTPLUG
	342	int nid;
	343	pg_data_t *pgdat;
	344	#endif
	345
	346	if (!cpu_possible(cpu)) {
	347	printk(KERN_ERR "can't online cpu %d because it is not "
	348	"configured as may-hotadd at boot time\n", cpu);
	349	#if defined(CONFIG_IA64)
	350	printk(KERN_ERR "please check additional_cpus= boot "
	351	"parameter\n");
	352	#endif
	353	return -EINVAL;
	354	}
	355
	356	#ifdef CONFIG_MEMORY_HOTPLUG
	357	nid = cpu_to_node(cpu);
	358	if (!node_online(nid)) {
	359	err = mem_online_node(nid);
	360	if (err)
	361	return err;
	362	}
	363
	364	pgdat = NODE_DATA(nid);
	365	if (!pgdat) {
	366	printk(KERN_ERR
	367	"Can't online cpu %d due to NULL pgdat\n", cpu);
	368	return -ENOMEM;
	369	}
	370
	371	if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
	372	mutex_lock(&zonelists_mutex);
	373	build_all_zonelists(NULL);
	374	mutex_unlock(&zonelists_mutex);
	375	}
	376	#endif
	377
	378	cpu_maps_update_begin();
	379
	380	if (cpu_hotplug_disabled) {
	381	err = -EBUSY;
	382	goto out;
	383	}
	384
	385	err = _cpu_up(cpu, 0);
	386
	387	out:
	388	cpu_maps_update_done();
	389	return err;
	390	}
	391
	392	#ifdef CONFIG_PM_SLEEP_SMP
	393	static cpumask_var_t frozen_cpus;
	394
	395	int disable_nonboot_cpus(void)
	396	{
	397	int cpu, first_cpu, error;
	398
	399	cpu_maps_update_begin();
	400	first_cpu = cpumask_first(cpu_online_mask);
	401	/*
	402	* We take down all of the non-boot CPUs in one shot to avoid races
	403	* with the userspace trying to use the CPU hotplug at the same time
	404	*/
	405	cpumask_clear(frozen_cpus);
	406
	407	printk("Disabling non-boot CPUs ...\n");
	408	for_each_online_cpu(cpu) {
	409	if (cpu == first_cpu)
	410	continue;
	411	error = _cpu_down(cpu, 1);
	412	if (!error)
	413	cpumask_set_cpu(cpu, frozen_cpus);
	414	else {
	415	printk(KERN_ERR "Error taking CPU%d down: %d\n",
	416	cpu, error);
	417	break;
	418	}
	419	}
	420
	421	if (!error) {
	422	BUG_ON(num_online_cpus() > 1);
	423	/* Make sure the CPUs won't be enabled by someone else */
	424	cpu_hotplug_disabled = 1;
	425	} else {
	426	printk(KERN_ERR "Non-boot CPUs are not disabled\n");
	427	}
	428	cpu_maps_update_done();
	429	return error;
	430	}
	431
	432	void __weak arch_enable_nonboot_cpus_begin(void)
	433	{
	434	}
	435
	436	void __weak arch_enable_nonboot_cpus_end(void)
	437	{
	438	}
	439
	440	void __ref enable_nonboot_cpus(void)
	441	{
	442	int cpu, error;
	443
	444	/* Allow everyone to use the CPU hotplug again */
	445	cpu_maps_update_begin();
	446	cpu_hotplug_disabled = 0;
	447	if (cpumask_empty(frozen_cpus))
	448	goto out;
	449
	450	printk("Enabling non-boot CPUs ...\n");
	451
	452	arch_enable_nonboot_cpus_begin();
	453
	454	for_each_cpu(cpu, frozen_cpus) {
	455	error = _cpu_up(cpu, 1);
	456	if (!error) {
	457	printk("CPU%d is up\n", cpu);
	458	continue;
	459	}
	460	printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
	461	}
	462
	463	arch_enable_nonboot_cpus_end();
	464
	465	cpumask_clear(frozen_cpus);
	466	out:
	467	cpu_maps_update_done();
	468	}
	469
	470	static int alloc_frozen_cpus(void)
	471	{
	472	if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL\|__GFP_ZERO))
	473	return -ENOMEM;
	474	return 0;
	475	}
	476	core_initcall(alloc_frozen_cpus);
	477	#endif /* CONFIG_PM_SLEEP_SMP */
	478
	479	/**
	480	* notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
	481	* @cpu: cpu that just started
	482	*
	483	* This function calls the cpu_chain notifiers with CPU_STARTING.
	484	* It must be called by the arch code on the new cpu, before the new cpu
	485	* enables interrupts and before the "boot" cpu returns from __cpu_up().
	486	*/
	487	void __cpuinit notify_cpu_starting(unsigned int cpu)
	488	{
	489	unsigned long val = CPU_STARTING;
	490
	491	#ifdef CONFIG_PM_SLEEP_SMP
	492	if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
	493	val = CPU_STARTING_FROZEN;
	494	#endif /* CONFIG_PM_SLEEP_SMP */
	495	cpu_notify(val, (void *)(long)cpu);
	496	}
	497
	498	#endif /* CONFIG_SMP */
	499
	500	/*
	501	* cpu_bit_bitmap[] is a special, "compressed" data structure that
	502	* represents all NR_CPUS bits binary values of 1<<nr.
	503	*
	504	* It is used by cpumask_of() to get a constant address to a CPU
	505	* mask value that has a single bit set only.
	506	*/
	507
	508	/* cpu_bit_bitmap[0] is empty - so we can back into it */
	509	#define MASK_DECLARE_1(x) [x+1][0] = 1UL << (x)
	510	#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
	511	#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
	512	#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
	513
	514	const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
	515
	516	MASK_DECLARE_8(0), MASK_DECLARE_8(8),
	517	MASK_DECLARE_8(16), MASK_DECLARE_8(24),
	518	#if BITS_PER_LONG > 32
	519	MASK_DECLARE_8(32), MASK_DECLARE_8(40),
	520	MASK_DECLARE_8(48), MASK_DECLARE_8(56),
	521	#endif
	522	};
	523	EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
	524
	525	const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
	526	EXPORT_SYMBOL(cpu_all_bits);
	527
	528	#ifdef CONFIG_INIT_ALL_POSSIBLE
	529	static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
	530	= CPU_BITS_ALL;
	531	#else
	532	static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
	533	#endif
	534	const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
	535	EXPORT_SYMBOL(cpu_possible_mask);
	536
	537	static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
	538	const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
	539	EXPORT_SYMBOL(cpu_online_mask);
	540
	541	static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
	542	const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
	543	EXPORT_SYMBOL(cpu_present_mask);
	544
	545	static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
	546	const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
	547	EXPORT_SYMBOL(cpu_active_mask);
	548
	549	void set_cpu_possible(unsigned int cpu, bool possible)
	550	{
	551	if (possible)
	552	cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
	553	else
	554	cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
	555	}
	556
	557	void set_cpu_present(unsigned int cpu, bool present)
	558	{
	559	if (present)
	560	cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
	561	else
	562	cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
	563	}
	564
	565	void set_cpu_online(unsigned int cpu, bool online)
	566	{
	567	if (online)
	568	cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
	569	else
	570	cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
	571	}
	572
	573	void set_cpu_active(unsigned int cpu, bool active)
	574	{
	575	if (active)
	576	cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
	577	else
	578	cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
	579	}
	580
	581	void init_cpu_present(const struct cpumask *src)
	582	{
	583	cpumask_copy(to_cpumask(cpu_present_bits), src);
	584	}
	585
	586	void init_cpu_possible(const struct cpumask *src)
	587	{
	588	cpumask_copy(to_cpumask(cpu_possible_bits), src);
	589	}
	590
	591	void init_cpu_online(const struct cpumask *src)
	592	{
	593	cpumask_copy(to_cpumask(cpu_online_bits), src);
	594	}