kernel26-2.6.12-alx-r9/kernel/wait.c

/*
 * Generic waiting primitives.
 *
 * (C) 2004 William Irwin, Oracle
 */
#include <linux/config.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/wait.h>
#include <linux/hash.h>

void fastcall 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 fastcall 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 fastcall 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);


/*
 * Note: we use "set_current_state()" _after_ the wait-queue add,
 * because we need a memory barrier there on SMP, so that any
 * wake-function that tests for the wait-queue being active
 * will be guaranteed to see waitqueue addition _or_ subsequent
 * tests in this thread will see the wakeup having taken place.
 *
 * The spin_unlock() itself is semi-permeable and only protects
 * one way (it only protects stuff inside the critical region and
 * stops them from bleeding out - it would still allow subsequent
 * loads to move into the the critical region).
 */
void fastcall
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);
	/*
	 * don't alter the task state if this is just going to
	 * queue an async wait queue callback
	 */
	if (is_sync_wait(wait))
		set_current_state(state);
	spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(prepare_to_wait);

void fastcall
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);
	/*
	 * don't alter the task state if this is just going to
 	 * queue an async wait queue callback
	 */
	if (is_sync_wait(wait))
		set_current_state(state);
	spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(prepare_to_wait_exclusive);

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

	__set_current_state(TASK_RUNNING);
	/*
	 * We can check for list emptiness outside the lock
	 * IFF:
	 *  - we use the "careful" check that verifies both
	 *    the next and prev pointers, so that there cannot
	 *    be any half-pending updates in progress on other
	 *    CPU's that we haven't seen yet (and that might
	 *    still change the stack area.
	 * and
	 *  - all other users take the lock (ie we can only
	 *    have _one_ other CPU that looks at or modifies
	 *    the list).
	 */
	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);

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);

/*
 * To allow interruptible waiting and asynchronous (i.e. nonblocking)
 * waiting, the actions of __wait_on_bit() and __wait_on_bit_lock() are
 * permitted return codes. Nonzero return codes halt waiting and return.
 */
int __sched fastcall
__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 fastcall 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 fastcall
__wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,
			int (*action)(void *), unsigned mode)
{
	int ret = 0;

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

int __sched fastcall 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 fastcall __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_INTERRUPTIBLE|TASK_UNINTERRUPTIBLE, 1, &key);
}
EXPORT_SYMBOL(__wake_up_bit);

/**
 * wake_up_bit - wake up a waiter on a bit
 * @word: the word being waited on, a kernel virtual address
 * @bit: the bit of the word being waited on
 *
 * There is a standard hashed waitqueue table for generic use. This
 * is the part of the hashtable's accessor API that wakes up waiters
 * on a bit. For instance, if one were to have waiters on a bitflag,
 * one would call wake_up_bit() after clearing the bit.
 *
 * In order for this to function properly, as it uses waitqueue_active()
 * internally, some kind of memory barrier must be done prior to calling
 * this. Typically, this will be smp_mb__after_clear_bit(), but in some
 * cases where bitflags are manipulated non-atomically under a lock, one
 * may need to use a less regular barrier, such fs/inode.c's smp_mb(),
 * because spin_unlock() does not guarantee a memory barrier.
 */
void fastcall wake_up_bit(void *word, int bit)
{
	__wake_up_bit(bit_waitqueue(word, bit), word, bit);
}
EXPORT_SYMBOL(wake_up_bit);

fastcall 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);
1	/*
2	* Generic waiting primitives.
3	*
4	* (C) 2004 William Irwin, Oracle
5	*/
6	#include <linux/config.h>
7	#include <linux/init.h>
8	#include <linux/module.h>
9	#include <linux/sched.h>
10	#include <linux/mm.h>
11	#include <linux/wait.h>
12	#include <linux/hash.h>
13
14	void fastcall add_wait_queue(wait_queue_head_t q, wait_queue_t wait)
15	{
16	unsigned long flags;
17
18	wait->flags &= ~WQ_FLAG_EXCLUSIVE;
19	spin_lock_irqsave(&q->lock, flags);
20	__add_wait_queue(q, wait);
21	spin_unlock_irqrestore(&q->lock, flags);
22	}
23	EXPORT_SYMBOL(add_wait_queue);
24
25	void fastcall add_wait_queue_exclusive(wait_queue_head_t q, wait_queue_t wait)
26	{
27	unsigned long flags;
28
29	wait->flags \|= WQ_FLAG_EXCLUSIVE;
30	spin_lock_irqsave(&q->lock, flags);
31	__add_wait_queue_tail(q, wait);
32	spin_unlock_irqrestore(&q->lock, flags);
33	}
34	EXPORT_SYMBOL(add_wait_queue_exclusive);
35
36	void fastcall remove_wait_queue(wait_queue_head_t q, wait_queue_t wait)
37	{
38	unsigned long flags;
39
40	spin_lock_irqsave(&q->lock, flags);
41	__remove_wait_queue(q, wait);
42	spin_unlock_irqrestore(&q->lock, flags);
43	}
44	EXPORT_SYMBOL(remove_wait_queue);
45
46
47	/*
48	* Note: we use "set_current_state()" _after_ the wait-queue add,
49	* because we need a memory barrier there on SMP, so that any
50	* wake-function that tests for the wait-queue being active
51	* will be guaranteed to see waitqueue addition _or_ subsequent
52	* tests in this thread will see the wakeup having taken place.
53	*
54	* The spin_unlock() itself is semi-permeable and only protects
55	* one way (it only protects stuff inside the critical region and
56	* stops them from bleeding out - it would still allow subsequent
57	* loads to move into the the critical region).
58	*/
59	void fastcall
60	prepare_to_wait(wait_queue_head_t q, wait_queue_t wait, int state)
61	{
62	unsigned long flags;
63
64	wait->flags &= ~WQ_FLAG_EXCLUSIVE;
65	spin_lock_irqsave(&q->lock, flags);
66	if (list_empty(&wait->task_list))
67	__add_wait_queue(q, wait);
68	/*
69	* don't alter the task state if this is just going to
70	* queue an async wait queue callback
71	*/
72	if (is_sync_wait(wait))
73	set_current_state(state);
74	spin_unlock_irqrestore(&q->lock, flags);
75	}
76	EXPORT_SYMBOL(prepare_to_wait);
77
78	void fastcall
79	prepare_to_wait_exclusive(wait_queue_head_t q, wait_queue_t wait, int state)
80	{
81	unsigned long flags;
82
83	wait->flags \|= WQ_FLAG_EXCLUSIVE;
84	spin_lock_irqsave(&q->lock, flags);
85	if (list_empty(&wait->task_list))
86	__add_wait_queue_tail(q, wait);
87	/*
88	* don't alter the task state if this is just going to
89	* queue an async wait queue callback
90	*/
91	if (is_sync_wait(wait))
92	set_current_state(state);
93	spin_unlock_irqrestore(&q->lock, flags);
94	}
95	EXPORT_SYMBOL(prepare_to_wait_exclusive);
96
97	void fastcall finish_wait(wait_queue_head_t q, wait_queue_t wait)
98	{
99	unsigned long flags;
100
101	__set_current_state(TASK_RUNNING);
102	/*
103	* We can check for list emptiness outside the lock
104	* IFF:
105	* - we use the "careful" check that verifies both
106	* the next and prev pointers, so that there cannot
107	* be any half-pending updates in progress on other
108	* CPU's that we haven't seen yet (and that might
109	* still change the stack area.
110	* and
111	* - all other users take the lock (ie we can only
112	* have _one_ other CPU that looks at or modifies
113	* the list).
114	*/
115	if (!list_empty_careful(&wait->task_list)) {
116	spin_lock_irqsave(&q->lock, flags);
117	list_del_init(&wait->task_list);
118	spin_unlock_irqrestore(&q->lock, flags);
119	}
120	}
121	EXPORT_SYMBOL(finish_wait);
122
123	int autoremove_wake_function(wait_queue_t wait, unsigned mode, int sync, void key)
124	{
125	int ret = default_wake_function(wait, mode, sync, key);
126
127	if (ret)
128	list_del_init(&wait->task_list);
129	return ret;
130	}
131	EXPORT_SYMBOL(autoremove_wake_function);
132
133	int wake_bit_function(wait_queue_t wait, unsigned mode, int sync, void arg)
134	{
135	struct wait_bit_key *key = arg;
136	struct wait_bit_queue *wait_bit
137	= container_of(wait, struct wait_bit_queue, wait);
138
139	if (wait_bit->key.flags != key->flags \|\|
140	wait_bit->key.bit_nr != key->bit_nr \|\|
141	test_bit(key->bit_nr, key->flags))
142	return 0;
143	else
144	return autoremove_wake_function(wait, mode, sync, key);
145	}
146	EXPORT_SYMBOL(wake_bit_function);
147
148	/*
149	* To allow interruptible waiting and asynchronous (i.e. nonblocking)
150	* waiting, the actions of __wait_on_bit() and __wait_on_bit_lock() are
151	* permitted return codes. Nonzero return codes halt waiting and return.
152	*/
153	int __sched fastcall
154	__wait_on_bit(wait_queue_head_t wq, struct wait_bit_queue q,
155	int (action)(void ), unsigned mode)
156	{
157	int ret = 0;
158
159	do {
160	prepare_to_wait(wq, &q->wait, mode);
161	if (test_bit(q->key.bit_nr, q->key.flags))
162	ret = (*action)(q->key.flags);
163	} while (test_bit(q->key.bit_nr, q->key.flags) && !ret);
164	finish_wait(wq, &q->wait);
165	return ret;
166	}
167	EXPORT_SYMBOL(__wait_on_bit);
168
169	int __sched fastcall out_of_line_wait_on_bit(void *word, int bit,
170	int (action)(void ), unsigned mode)
171	{
172	wait_queue_head_t *wq = bit_waitqueue(word, bit);
173	DEFINE_WAIT_BIT(wait, word, bit);
174
175	return __wait_on_bit(wq, &wait, action, mode);
176	}
177	EXPORT_SYMBOL(out_of_line_wait_on_bit);
178
179	int __sched fastcall
180	__wait_on_bit_lock(wait_queue_head_t wq, struct wait_bit_queue q,
181	int (action)(void ), unsigned mode)
182	{
183	int ret = 0;
184
185	do {
186	prepare_to_wait_exclusive(wq, &q->wait, mode);
187	if (test_bit(q->key.bit_nr, q->key.flags)) {
188	if ((ret = (*action)(q->key.flags)))
189	break;
190	}
191	} while (test_and_set_bit(q->key.bit_nr, q->key.flags));
192	finish_wait(wq, &q->wait);
193	return ret;
194	}
195	EXPORT_SYMBOL(__wait_on_bit_lock);
196
197	int __sched fastcall out_of_line_wait_on_bit_lock(void *word, int bit,
198	int (action)(void ), unsigned mode)
199	{
200	wait_queue_head_t *wq = bit_waitqueue(word, bit);
201	DEFINE_WAIT_BIT(wait, word, bit);
202
203	return __wait_on_bit_lock(wq, &wait, action, mode);
204	}
205	EXPORT_SYMBOL(out_of_line_wait_on_bit_lock);
206
207	void fastcall __wake_up_bit(wait_queue_head_t wq, void word, int bit)
208	{
209	struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit);
210	if (waitqueue_active(wq))
211	__wake_up(wq, TASK_INTERRUPTIBLE\|TASK_UNINTERRUPTIBLE, 1, &key);
212	}
213	EXPORT_SYMBOL(__wake_up_bit);
214
215	/**
216	* wake_up_bit - wake up a waiter on a bit
217	* @word: the word being waited on, a kernel virtual address
218	* @bit: the bit of the word being waited on
219	*
220	* There is a standard hashed waitqueue table for generic use. This
221	* is the part of the hashtable's accessor API that wakes up waiters
222	* on a bit. For instance, if one were to have waiters on a bitflag,
223	* one would call wake_up_bit() after clearing the bit.
224	*
225	* In order for this to function properly, as it uses waitqueue_active()
226	* internally, some kind of memory barrier must be done prior to calling
227	* this. Typically, this will be smp_mb__after_clear_bit(), but in some
228	* cases where bitflags are manipulated non-atomically under a lock, one
229	* may need to use a less regular barrier, such fs/inode.c's smp_mb(),
230	* because spin_unlock() does not guarantee a memory barrier.
231	*/
232	void fastcall wake_up_bit(void *word, int bit)
233	{
234	__wake_up_bit(bit_waitqueue(word, bit), word, bit);
235	}
236	EXPORT_SYMBOL(wake_up_bit);
237
238	fastcall wait_queue_head_t bit_waitqueue(void word, int bit)
239	{
240	const int shift = BITS_PER_LONG == 32 ? 5 : 6;
241	const struct zone *zone = page_zone(virt_to_page(word));
242	unsigned long val = (unsigned long)word << shift \| bit;
243
244	return &zone->wait_table[hash_long(val, zone->wait_table_bits)];
245	}
246	EXPORT_SYMBOL(bit_waitqueue);