#include <linux/init.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/wait.h>
#include <linux/hash.h>

void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *key)
{
	spin_lock_init(&q->lock);
	lockdep_set_class_and_name(&q->lock, key, name);
	INIT_LIST_HEAD(&q->task_list);
}

EXPORT_SYMBOL(__init_waitqueue_head);

void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait)
{
	unsigned long flags;

	wait->flags &= ~WQ_FLAG_EXCLUSIVE;
	spin_lock_irqsave(&q->lock, flags);
	__add_wait_queue(q, wait);
	spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(add_wait_queue);

void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
{
	unsigned long flags;

	wait->flags |= WQ_FLAG_EXCLUSIVE;
	spin_lock_irqsave(&q->lock, flags);
	__add_wait_queue_tail(q, wait);
	spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(add_wait_queue_exclusive);

void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait)
{
	unsigned long flags;

	spin_lock_irqsave(&q->lock, flags);
	__remove_wait_queue(q, wait);
	spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(remove_wait_queue);


void
prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state)
{
	unsigned long flags;

	wait->flags &= ~WQ_FLAG_EXCLUSIVE;
	spin_lock_irqsave(&q->lock, flags);
	if (list_empty(&wait->task_list))
		__add_wait_queue(q, wait);
	set_current_state(state);
	spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(prepare_to_wait);

void
prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state)
{
	unsigned long flags;

	wait->flags |= WQ_FLAG_EXCLUSIVE;
	spin_lock_irqsave(&q->lock, flags);
	if (list_empty(&wait->task_list))
		__add_wait_queue_tail(q, wait);
	set_current_state(state);
	spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(prepare_to_wait_exclusive);

void finish_wait(wait_queue_head_t *q, wait_queue_t *wait)
{
	unsigned long flags;

	__set_current_state(TASK_RUNNING);
	if (!list_empty_careful(&wait->task_list)) {
		spin_lock_irqsave(&q->lock, flags);
		list_del_init(&wait->task_list);
		spin_unlock_irqrestore(&q->lock, flags);
	}
}
EXPORT_SYMBOL(finish_wait);

void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
			unsigned int mode, void *key)
{
	unsigned long flags;

	__set_current_state(TASK_RUNNING);
	spin_lock_irqsave(&q->lock, flags);
	if (!list_empty(&wait->task_list))
		list_del_init(&wait->task_list);
	else if (waitqueue_active(q))
		__wake_up_locked_key(q, mode, key);
	spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(abort_exclusive_wait);

int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key)
{
	int ret = default_wake_function(wait, mode, sync, key);

	if (ret)
		list_del_init(&wait->task_list);
	return ret;
}
EXPORT_SYMBOL(autoremove_wake_function);

int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *arg)
{
	struct wait_bit_key *key = arg;
	struct wait_bit_queue *wait_bit
		= container_of(wait, struct wait_bit_queue, wait);

	if (wait_bit->key.flags != key->flags ||
			wait_bit->key.bit_nr != key->bit_nr ||
			test_bit(key->bit_nr, key->flags))
		return 0;
	else
		return autoremove_wake_function(wait, mode, sync, key);
}
EXPORT_SYMBOL(wake_bit_function);

int __sched
__wait_on_bit(wait_queue_head_t *wq, struct wait_bit_queue *q,
			int (*action)(void *), unsigned mode)
{
	int ret = 0;

	do {
		prepare_to_wait(wq, &q->wait, mode);
		if (test_bit(q->key.bit_nr, q->key.flags))
			ret = (*action)(q->key.flags);
	} while (test_bit(q->key.bit_nr, q->key.flags) && !ret);
	finish_wait(wq, &q->wait);
	return ret;
}
EXPORT_SYMBOL(__wait_on_bit);

int __sched out_of_line_wait_on_bit(void *word, int bit,
					int (*action)(void *), unsigned mode)
{
	wait_queue_head_t *wq = bit_waitqueue(word, bit);
	DEFINE_WAIT_BIT(wait, word, bit);

	return __wait_on_bit(wq, &wait, action, mode);
}
EXPORT_SYMBOL(out_of_line_wait_on_bit);

int __sched
__wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,
			int (*action)(void *), unsigned mode)
{
	do {
		int ret;

		prepare_to_wait_exclusive(wq, &q->wait, mode);
		if (!test_bit(q->key.bit_nr, q->key.flags))
			continue;
		ret = action(q->key.flags);
		if (!ret)
			continue;
		abort_exclusive_wait(wq, &q->wait, mode, &q->key);
		return ret;
	} while (test_and_set_bit(q->key.bit_nr, q->key.flags));
	finish_wait(wq, &q->wait);
	return 0;
}
EXPORT_SYMBOL(__wait_on_bit_lock);

int __sched out_of_line_wait_on_bit_lock(void *word, int bit,
					int (*action)(void *), unsigned mode)
{
	wait_queue_head_t *wq = bit_waitqueue(word, bit);
	DEFINE_WAIT_BIT(wait, word, bit);

	return __wait_on_bit_lock(wq, &wait, action, mode);
}
EXPORT_SYMBOL(out_of_line_wait_on_bit_lock);

void __wake_up_bit(wait_queue_head_t *wq, void *word, int bit)
{
	struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit);
	if (waitqueue_active(wq))
		__wake_up(wq, TASK_NORMAL, 1, &key);
}
EXPORT_SYMBOL(__wake_up_bit);

void wake_up_bit(void *word, int bit)
{
	__wake_up_bit(bit_waitqueue(word, bit), word, bit);
}
EXPORT_SYMBOL(wake_up_bit);

wait_queue_head_t *bit_waitqueue(void *word, int bit)
{
	const int shift = BITS_PER_LONG == 32 ? 5 : 6;
	const struct zone *zone = page_zone(virt_to_page(word));
	unsigned long val = (unsigned long)word << shift | bit;

	return &zone->wait_table[hash_long(val, zone->wait_table_bits)];
}
EXPORT_SYMBOL(bit_waitqueue);