diff options
Diffstat (limited to 'kernel/wait.c')
| -rw-r--r-- | kernel/wait.c | 377 | 
1 files changed, 0 insertions, 377 deletions
diff --git a/kernel/wait.c b/kernel/wait.c deleted file mode 100644 index d550920e040..00000000000 --- a/kernel/wait.c +++ /dev/null @@ -1,377 +0,0 @@ -/* - * Generic waiting primitives. - * - * (C) 2004 Nadia Yvette Chambers, Oracle - */ -#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); - - -/* - * 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 critical region). - */ -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); - -/** - * finish_wait - clean up after waiting in a queue - * @q: waitqueue waited on - * @wait: wait descriptor - * - * Sets current thread back to running state and removes - * the wait descriptor from the given waitqueue if still - * queued. - */ -void 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); - -/** - * abort_exclusive_wait - abort exclusive waiting in a queue - * @q: waitqueue waited on - * @wait: wait descriptor - * @mode: runstate of the waiter to be woken - * @key: key to identify a wait bit queue or %NULL - * - * Sets current thread back to running state and removes - * the wait descriptor from the given waitqueue if still - * queued. - * - * Wakes up the next waiter if the caller is concurrently - * woken up through the queue. - * - * This prevents waiter starvation where an exclusive waiter - * aborts and is woken up concurrently and no one wakes up - * the next waiter. - */ -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); - -/* - * 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(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); - -/** - * 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 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); - -/* - * Manipulate the atomic_t address to produce a better bit waitqueue table hash - * index (we're keying off bit -1, but that would produce a horrible hash - * value). - */ -static inline wait_queue_head_t *atomic_t_waitqueue(atomic_t *p) -{ -	if (BITS_PER_LONG == 64) { -		unsigned long q = (unsigned long)p; -		return bit_waitqueue((void *)(q & ~1), q & 1); -	} -	return bit_waitqueue(p, 0); -} - -static int wake_atomic_t_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); -	atomic_t *val = key->flags; - -	if (wait_bit->key.flags != key->flags || -	    wait_bit->key.bit_nr != key->bit_nr || -	    atomic_read(val) != 0) -		return 0; -	return autoremove_wake_function(wait, mode, sync, key); -} - -/* - * To allow interruptible waiting and asynchronous (i.e. nonblocking) waiting, - * the actions of __wait_on_atomic_t() are permitted return codes.  Nonzero - * return codes halt waiting and return. - */ -static __sched -int __wait_on_atomic_t(wait_queue_head_t *wq, struct wait_bit_queue *q, -		       int (*action)(atomic_t *), unsigned mode) -{ -	atomic_t *val; -	int ret = 0; - -	do { -		prepare_to_wait(wq, &q->wait, mode); -		val = q->key.flags; -		if (atomic_read(val) == 0) -			break; -		ret = (*action)(val); -	} while (!ret && atomic_read(val) != 0); -	finish_wait(wq, &q->wait); -	return ret; -} - -#define DEFINE_WAIT_ATOMIC_T(name, p)					\ -	struct wait_bit_queue name = {					\ -		.key = __WAIT_ATOMIC_T_KEY_INITIALIZER(p),		\ -		.wait	= {						\ -			.private	= current,			\ -			.func		= wake_atomic_t_function,	\ -			.task_list	=				\ -				LIST_HEAD_INIT((name).wait.task_list),	\ -		},							\ -	} - -__sched int out_of_line_wait_on_atomic_t(atomic_t *p, int (*action)(atomic_t *), -					 unsigned mode) -{ -	wait_queue_head_t *wq = atomic_t_waitqueue(p); -	DEFINE_WAIT_ATOMIC_T(wait, p); - -	return __wait_on_atomic_t(wq, &wait, action, mode); -} -EXPORT_SYMBOL(out_of_line_wait_on_atomic_t); - -/** - * wake_up_atomic_t - Wake up a waiter on a atomic_t - * @p: The atomic_t being waited on, a kernel virtual address - * - * Wake up anyone waiting for the atomic_t to go to zero. - * - * Abuse the bit-waker function and its waitqueue hash table set (the atomic_t - * check is done by the waiter's wake function, not the by the waker itself). - */ -void wake_up_atomic_t(atomic_t *p) -{ -	__wake_up_bit(atomic_t_waitqueue(p), p, WAIT_ATOMIC_T_BIT_NR); -} -EXPORT_SYMBOL(wake_up_atomic_t);  | 
