[thirdparty/kernel/stable.git] / kernel / sched / wait_bit.c

/*
 * The implementation of the wait_bit*() and related waiting APIs:
 */
#include "sched.h"

#define WAIT_TABLE_BITS 8
#define WAIT_TABLE_SIZE (1 << WAIT_TABLE_BITS)

static wait_queue_head_t bit_wait_table[WAIT_TABLE_SIZE] __cacheline_aligned;

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

	return bit_wait_table + hash_long(val, WAIT_TABLE_BITS);
}
EXPORT_SYMBOL(bit_waitqueue);

int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *arg)
{
	struct wait_bit_key *key = arg;
	struct wait_bit_queue_entry *wait_bit = container_of(wq_entry, struct wait_bit_queue_entry, wq_entry);

	if (wait_bit->key.flags != key->flags ||
			wait_bit->key.bit_nr != key->bit_nr ||
			test_bit(key->bit_nr, key->flags))
		return 0;

	return autoremove_wake_function(wq_entry, 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
__wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry,
	      wait_bit_action_f *action, unsigned mode)
{
	int ret = 0;

	do {
		prepare_to_wait(wq_head, &wbq_entry->wq_entry, mode);
		if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags))
			ret = (*action)(&wbq_entry->key, mode);
	} while (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags) && !ret);

	finish_wait(wq_head, &wbq_entry->wq_entry);

	return ret;
}
EXPORT_SYMBOL(__wait_on_bit);

int __sched out_of_line_wait_on_bit(void *word, int bit,
				    wait_bit_action_f *action, unsigned mode)
{
	struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
	DEFINE_WAIT_BIT(wq_entry, word, bit);

	return __wait_on_bit(wq_head, &wq_entry, action, mode);
}
EXPORT_SYMBOL(out_of_line_wait_on_bit);

int __sched out_of_line_wait_on_bit_timeout(
	void *word, int bit, wait_bit_action_f *action,
	unsigned mode, unsigned long timeout)
{
	struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
	DEFINE_WAIT_BIT(wq_entry, word, bit);

	wq_entry.key.timeout = jiffies + timeout;

	return __wait_on_bit(wq_head, &wq_entry, action, mode);
}
EXPORT_SYMBOL_GPL(out_of_line_wait_on_bit_timeout);

int __sched
__wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry,
			wait_bit_action_f *action, unsigned mode)
{
	int ret = 0;

	for (;;) {
		prepare_to_wait_exclusive(wq_head, &wbq_entry->wq_entry, mode);
		if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) {
			ret = action(&wbq_entry->key, mode);
			/*
			 * See the comment in prepare_to_wait_event().
			 * finish_wait() does not necessarily takes wwq_head->lock,
			 * but test_and_set_bit() implies mb() which pairs with
			 * smp_mb__after_atomic() before wake_up_page().
			 */
			if (ret)
				finish_wait(wq_head, &wbq_entry->wq_entry);
		}
		if (!test_and_set_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) {
			if (!ret)
				finish_wait(wq_head, &wbq_entry->wq_entry);
			return 0;
		} else if (ret) {
			return ret;
		}
	}
}
EXPORT_SYMBOL(__wait_on_bit_lock);

int __sched out_of_line_wait_on_bit_lock(void *word, int bit,
					 wait_bit_action_f *action, unsigned mode)
{
	struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
	DEFINE_WAIT_BIT(wq_entry, word, bit);

	return __wait_on_bit_lock(wq_head, &wq_entry, action, mode);
}
EXPORT_SYMBOL(out_of_line_wait_on_bit_lock);

void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit)
{
	struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit);

	if (waitqueue_active(wq_head))
		__wake_up(wq_head, TASK_NORMAL, 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_atomic(), 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 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 *__var_waitqueue(void *p)
{
	return bit_wait_table + hash_ptr(p, WAIT_TABLE_BITS);
}
EXPORT_SYMBOL(__var_waitqueue);

static int
var_wake_function(struct wait_queue_entry *wq_entry, unsigned int mode,
		  int sync, void *arg)
{
	struct wait_bit_key *key = arg;
	struct wait_bit_queue_entry *wbq_entry =
		container_of(wq_entry, struct wait_bit_queue_entry, wq_entry);

	if (wbq_entry->key.flags != key->flags ||
	    wbq_entry->key.bit_nr != key->bit_nr)
		return 0;

	return autoremove_wake_function(wq_entry, mode, sync, key);
}

void init_wait_var_entry(struct wait_bit_queue_entry *wbq_entry, void *var, int flags)
{
	*wbq_entry = (struct wait_bit_queue_entry){
		.key = {
			.flags	= (var),
			.bit_nr = -1,
		},
		.wq_entry = {
			.private = current,
			.func	 = var_wake_function,
			.entry	 = LIST_HEAD_INIT(wbq_entry->wq_entry.entry),
		},
	};
}
EXPORT_SYMBOL(init_wait_var_entry);

void wake_up_var(void *var)
{
	__wake_up_bit(__var_waitqueue(var), var, -1);
}
EXPORT_SYMBOL(wake_up_var);

__sched int bit_wait(struct wait_bit_key *word, int mode)
{
	schedule();
	if (signal_pending_state(mode, current))
		return -EINTR;

	return 0;
}
EXPORT_SYMBOL(bit_wait);

__sched int bit_wait_io(struct wait_bit_key *word, int mode)
{
	io_schedule();
	if (signal_pending_state(mode, current))
		return -EINTR;

	return 0;
}
EXPORT_SYMBOL(bit_wait_io);

__sched int bit_wait_timeout(struct wait_bit_key *word, int mode)
{
	unsigned long now = READ_ONCE(jiffies);

	if (time_after_eq(now, word->timeout))
		return -EAGAIN;
	schedule_timeout(word->timeout - now);
	if (signal_pending_state(mode, current))
		return -EINTR;

	return 0;
}
EXPORT_SYMBOL_GPL(bit_wait_timeout);

__sched int bit_wait_io_timeout(struct wait_bit_key *word, int mode)
{
	unsigned long now = READ_ONCE(jiffies);

	if (time_after_eq(now, word->timeout))
		return -EAGAIN;
	io_schedule_timeout(word->timeout - now);
	if (signal_pending_state(mode, current))
		return -EINTR;

	return 0;
}
EXPORT_SYMBOL_GPL(bit_wait_io_timeout);

void __init wait_bit_init(void)
{
	int i;

	for (i = 0; i < WAIT_TABLE_SIZE; i++)
		init_waitqueue_head(bit_wait_table + i);
}
Commit	Line	Data
5dd43ce2 IM	1	/*
	2	* The implementation of the wait_bit*() and related waiting APIs:
	3	*/
325ea10c	4	#include "sched.h"
5822a454 IM	5
	6	#define WAIT_TABLE_BITS 8
	7	#define WAIT_TABLE_SIZE (1 << WAIT_TABLE_BITS)
	8
	9	static wait_queue_head_t bit_wait_table[WAIT_TABLE_SIZE] __cacheline_aligned;
	10
	11	wait_queue_head_t bit_waitqueue(void word, int bit)
	12	{
	13	const int shift = BITS_PER_LONG == 32 ? 5 : 6;
	14	unsigned long val = (unsigned long)word << shift \| bit;
	15
	16	return bit_wait_table + hash_long(val, WAIT_TABLE_BITS);
	17	}
	18	EXPORT_SYMBOL(bit_waitqueue);
5dd43ce2 IM	19
	20	int wake_bit_function(struct wait_queue_entry wq_entry, unsigned mode, int sync, void arg)
	21	{
	22	struct wait_bit_key *key = arg;
	23	struct wait_bit_queue_entry *wait_bit = container_of(wq_entry, struct wait_bit_queue_entry, wq_entry);
	24
	25	if (wait_bit->key.flags != key->flags \|\|
	26	wait_bit->key.bit_nr != key->bit_nr \|\|
	27	test_bit(key->bit_nr, key->flags))
	28	return 0;
97fb7a0a IM	29
97fb7a0a IM	30	return autoremove_wake_function(wq_entry, mode, sync, key);
5dd43ce2 IM	31	}
	32	EXPORT_SYMBOL(wake_bit_function);
	33
	34	/*
	35	* To allow interruptible waiting and asynchronous (i.e. nonblocking)
	36	* waiting, the actions of __wait_on_bit() and __wait_on_bit_lock() are
	37	* permitted return codes. Nonzero return codes halt waiting and return.
	38	*/
	39	int __sched
	40	__wait_on_bit(struct wait_queue_head wq_head, struct wait_bit_queue_entry wbq_entry,
	41	wait_bit_action_f *action, unsigned mode)
	42	{
	43	int ret = 0;
	44
	45	do {
	46	prepare_to_wait(wq_head, &wbq_entry->wq_entry, mode);
	47	if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags))
	48	ret = (*action)(&wbq_entry->key, mode);
	49	} while (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags) && !ret);
97fb7a0a	50
5dd43ce2	51	finish_wait(wq_head, &wbq_entry->wq_entry);
97fb7a0a	52
5dd43ce2 IM	53	return ret;
	54	}
	55	EXPORT_SYMBOL(__wait_on_bit);
	56
	57	int __sched out_of_line_wait_on_bit(void *word, int bit,
	58	wait_bit_action_f *action, unsigned mode)
	59	{
	60	struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
	61	DEFINE_WAIT_BIT(wq_entry, word, bit);
	62
	63	return __wait_on_bit(wq_head, &wq_entry, action, mode);
	64	}
	65	EXPORT_SYMBOL(out_of_line_wait_on_bit);
	66
	67	int __sched out_of_line_wait_on_bit_timeout(
	68	void word, int bit, wait_bit_action_f action,
	69	unsigned mode, unsigned long timeout)
	70	{
	71	struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
	72	DEFINE_WAIT_BIT(wq_entry, word, bit);
	73
	74	wq_entry.key.timeout = jiffies + timeout;
97fb7a0a	75
5dd43ce2 IM	76	return __wait_on_bit(wq_head, &wq_entry, action, mode);
	77	}
	78	EXPORT_SYMBOL_GPL(out_of_line_wait_on_bit_timeout);
	79
	80	int __sched
	81	__wait_on_bit_lock(struct wait_queue_head wq_head, struct wait_bit_queue_entry wbq_entry,
	82	wait_bit_action_f *action, unsigned mode)
	83	{
	84	int ret = 0;
	85
	86	for (;;) {
	87	prepare_to_wait_exclusive(wq_head, &wbq_entry->wq_entry, mode);
	88	if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) {
	89	ret = action(&wbq_entry->key, mode);
	90	/*
	91	* See the comment in prepare_to_wait_event().
	92	* finish_wait() does not necessarily takes wwq_head->lock,
	93	* but test_and_set_bit() implies mb() which pairs with
	94	* smp_mb__after_atomic() before wake_up_page().
	95	*/
	96	if (ret)
	97	finish_wait(wq_head, &wbq_entry->wq_entry);
	98	}
	99	if (!test_and_set_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) {
	100	if (!ret)
	101	finish_wait(wq_head, &wbq_entry->wq_entry);
	102	return 0;
	103	} else if (ret) {
	104	return ret;
	105	}
	106	}
	107	}
	108	EXPORT_SYMBOL(__wait_on_bit_lock);
	109
	110	int __sched out_of_line_wait_on_bit_lock(void *word, int bit,
	111	wait_bit_action_f *action, unsigned mode)
	112	{
	113	struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
	114	DEFINE_WAIT_BIT(wq_entry, word, bit);
	115
	116	return __wait_on_bit_lock(wq_head, &wq_entry, action, mode);
	117	}
	118	EXPORT_SYMBOL(out_of_line_wait_on_bit_lock);
	119
	120	void __wake_up_bit(struct wait_queue_head wq_head, void word, int bit)
	121	{
	122	struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit);
97fb7a0a	123
5dd43ce2 IM	124	if (waitqueue_active(wq_head))
	125	__wake_up(wq_head, TASK_NORMAL, 1, &key);
	126	}
	127	EXPORT_SYMBOL(__wake_up_bit);
	128
	129	/**
	130	* wake_up_bit - wake up a waiter on a bit
	131	* @word: the word being waited on, a kernel virtual address
	132	* @bit: the bit of the word being waited on
	133	*
	134	* There is a standard hashed waitqueue table for generic use. This
	135	* is the part of the hashtable's accessor API that wakes up waiters
	136	* on a bit. For instance, if one were to have waiters on a bitflag,
	137	* one would call wake_up_bit() after clearing the bit.
	138	*
	139	* In order for this to function properly, as it uses waitqueue_active()
	140	* internally, some kind of memory barrier must be done prior to calling
	141	* this. Typically, this will be smp_mb__after_atomic(), but in some
	142	* cases where bitflags are manipulated non-atomically under a lock, one
	143	* may need to use a less regular barrier, such fs/inode.c's smp_mb(),
	144	* because spin_unlock() does not guarantee a memory barrier.
	145	*/
	146	void wake_up_bit(void *word, int bit)
	147	{
	148	__wake_up_bit(bit_waitqueue(word, bit), word, bit);
	149	}
	150	EXPORT_SYMBOL(wake_up_bit);
	151
6b2bb726 PZ	152	wait_queue_head_t __var_waitqueue(void p)
6b2bb726 PZ	153	{
b3fc5c9b	154	return bit_wait_table + hash_ptr(p, WAIT_TABLE_BITS);
6b2bb726 PZ	155	}
	156	EXPORT_SYMBOL(__var_waitqueue);
	157
	158	static int
	159	var_wake_function(struct wait_queue_entry *wq_entry, unsigned int mode,
	160	int sync, void *arg)
	161	{
	162	struct wait_bit_key *key = arg;
	163	struct wait_bit_queue_entry *wbq_entry =
	164	container_of(wq_entry, struct wait_bit_queue_entry, wq_entry);
	165
	166	if (wbq_entry->key.flags != key->flags \|\|
	167	wbq_entry->key.bit_nr != key->bit_nr)
	168	return 0;
	169
	170	return autoremove_wake_function(wq_entry, mode, sync, key);
	171	}
	172
	173	void init_wait_var_entry(struct wait_bit_queue_entry wbq_entry, void var, int flags)
	174	{
	175	*wbq_entry = (struct wait_bit_queue_entry){
	176	.key = {
	177	.flags = (var),
	178	.bit_nr = -1,
	179	},
	180	.wq_entry = {
	181	.private = current,
	182	.func = var_wake_function,
	183	.entry = LIST_HEAD_INIT(wbq_entry->wq_entry.entry),
	184	},
	185	};
	186	}
	187	EXPORT_SYMBOL(init_wait_var_entry);
	188
	189	void wake_up_var(void *var)
	190	{
	191	__wake_up_bit(__var_waitqueue(var), var, -1);
	192	}
	193	EXPORT_SYMBOL(wake_up_var);
	194
5dd43ce2 IM	195	__sched int bit_wait(struct wait_bit_key *word, int mode)
	196	{
	197	schedule();
	198	if (signal_pending_state(mode, current))
	199	return -EINTR;
97fb7a0a	200
5dd43ce2 IM	201	return 0;
	202	}
	203	EXPORT_SYMBOL(bit_wait);
	204
	205	__sched int bit_wait_io(struct wait_bit_key *word, int mode)
	206	{
	207	io_schedule();
	208	if (signal_pending_state(mode, current))
	209	return -EINTR;
97fb7a0a	210
5dd43ce2 IM	211	return 0;
	212	}
	213	EXPORT_SYMBOL(bit_wait_io);
	214
	215	__sched int bit_wait_timeout(struct wait_bit_key *word, int mode)
	216	{
	217	unsigned long now = READ_ONCE(jiffies);
97fb7a0a	218
5dd43ce2 IM	219	if (time_after_eq(now, word->timeout))
	220	return -EAGAIN;
	221	schedule_timeout(word->timeout - now);
	222	if (signal_pending_state(mode, current))
	223	return -EINTR;
97fb7a0a	224
5dd43ce2 IM	225	return 0;
	226	}
	227	EXPORT_SYMBOL_GPL(bit_wait_timeout);
	228
	229	__sched int bit_wait_io_timeout(struct wait_bit_key *word, int mode)
	230	{
	231	unsigned long now = READ_ONCE(jiffies);
97fb7a0a	232
5dd43ce2 IM	233	if (time_after_eq(now, word->timeout))
	234	return -EAGAIN;
	235	io_schedule_timeout(word->timeout - now);
	236	if (signal_pending_state(mode, current))
	237	return -EINTR;
97fb7a0a	238
5dd43ce2 IM	239	return 0;
	240	}
	241	EXPORT_SYMBOL_GPL(bit_wait_io_timeout);
5822a454 IM	242
	243	void __init wait_bit_init(void)
	244	{
	245	int i;
	246
	247	for (i = 0; i < WAIT_TABLE_SIZE; i++)
	248	init_waitqueue_head(bit_wait_table + i);
	249	}