include/linux/wait_bit.h - linux - Git at Google

 #ifndef _LINUX_WAIT_BIT_H
 #define _LINUX_WAIT_BIT_H

 /*
  * Linux wait-bit related types and methods:
  */
 #include <linux/wait.h>

 struct wait_bit_key {
 	void			*flags;
 	int			bit_nr;
 #define WAIT_ATOMIC_T_BIT_NR	-1
 	unsigned long		timeout;
 };

 struct wait_bit_queue_entry {
 	struct wait_bit_key	key;
 	struct wait_queue_entry	wq_entry;
 };

 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)					\
 	{ .flags = word, .bit_nr = bit, }

 #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p)					\
 	{ .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }

 typedef int wait_bit_action_f(struct wait_bit_key *key, int mode);
 void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit);
 int __wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry, wait_bit_action_f *action, unsigned int mode);
 int __wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry, wait_bit_action_f *action, unsigned int mode);
 void wake_up_bit(void *word, int bit);
 void wake_up_atomic_t(atomic_t *p);
 int out_of_line_wait_on_bit(void *word, int, wait_bit_action_f *action, unsigned int mode);
 int out_of_line_wait_on_bit_timeout(void *word, int, wait_bit_action_f *action, unsigned int mode, unsigned long timeout);
 int out_of_line_wait_on_bit_lock(void *word, int, wait_bit_action_f *action, unsigned int mode);
 int out_of_line_wait_on_atomic_t(atomic_t *p, int (*)(atomic_t *), unsigned int mode);
 struct wait_queue_head *bit_waitqueue(void *word, int bit);
 extern void __init wait_bit_init(void);

 int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);

 #define DEFINE_WAIT_BIT(name, word, bit)					\
 	struct wait_bit_queue_entry name = {					\
 		.key = __WAIT_BIT_KEY_INITIALIZER(word, bit),			\
 		.wq_entry = {							\
 			.private	= current,				\
 			.func		= wake_bit_function,			\
 			.task_list	=					\
 				LIST_HEAD_INIT((name).wq_entry.task_list),	\
 		},								\
 	}

 extern int bit_wait(struct wait_bit_key *key, int bit);
 extern int bit_wait_io(struct wait_bit_key *key, int bit);
 extern int bit_wait_timeout(struct wait_bit_key *key, int bit);
 extern int bit_wait_io_timeout(struct wait_bit_key *key, int bit);

 /**
  * wait_on_bit - wait for a bit to be cleared
  * @word: the word being waited on, a kernel virtual address
  * @bit: the bit of the word being waited on
  * @mode: the task state to sleep in
  *
  * There is a standard hashed waitqueue table for generic use. This
  * is the part of the hashtable's accessor API that waits on a bit.
  * For instance, if one were to have waiters on a bitflag, one would
  * call wait_on_bit() in threads waiting for the bit to clear.
  * One uses wait_on_bit() where one is waiting for the bit to clear,
  * but has no intention of setting it.
  * Returned value will be zero if the bit was cleared, or non-zero
  * if the process received a signal and the mode permitted wakeup
  * on that signal.
  */
 static inline int
 wait_on_bit(unsigned long *word, int bit, unsigned mode)
 {
 	might_sleep();
 	if (!test_bit(bit, word))
 		return 0;
 	return out_of_line_wait_on_bit(word, bit,
 				       bit_wait,
 				       mode);
 }

 /**
  * wait_on_bit_io - wait for a bit to be cleared
  * @word: the word being waited on, a kernel virtual address
  * @bit: the bit of the word being waited on
  * @mode: the task state to sleep in
  *
  * Use the standard hashed waitqueue table to wait for a bit
  * to be cleared.  This is similar to wait_on_bit(), but calls
  * io_schedule() instead of schedule() for the actual waiting.
  *
  * Returned value will be zero if the bit was cleared, or non-zero
  * if the process received a signal and the mode permitted wakeup
  * on that signal.
  */
 static inline int
 wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
 {
 	might_sleep();
 	if (!test_bit(bit, word))
 		return 0;
 	return out_of_line_wait_on_bit(word, bit,
 				       bit_wait_io,
 				       mode);
 }

 /**
  * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
  * @word: the word being waited on, a kernel virtual address
  * @bit: the bit of the word being waited on
  * @mode: the task state to sleep in
  * @timeout: timeout, in jiffies
  *
  * Use the standard hashed waitqueue table to wait for a bit
  * to be cleared. This is similar to wait_on_bit(), except also takes a
  * timeout parameter.
  *
  * Returned value will be zero if the bit was cleared before the
  * @timeout elapsed, or non-zero if the @timeout elapsed or process
  * received a signal and the mode permitted wakeup on that signal.
  */
 static inline int
 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
 		    unsigned long timeout)
 {
 	might_sleep();
 	if (!test_bit(bit, word))
 		return 0;
 	return out_of_line_wait_on_bit_timeout(word, bit,
 					       bit_wait_timeout,
 					       mode, timeout);
 }

 /**
  * wait_on_bit_action - wait for a bit to be cleared
  * @word: the word being waited on, a kernel virtual address
  * @bit: the bit of the word being waited on
  * @action: the function used to sleep, which may take special actions
  * @mode: the task state to sleep in
  *
  * Use the standard hashed waitqueue table to wait for a bit
  * to be cleared, and allow the waiting action to be specified.
  * This is like wait_on_bit() but allows fine control of how the waiting
  * is done.
  *
  * Returned value will be zero if the bit was cleared, or non-zero
  * if the process received a signal and the mode permitted wakeup
  * on that signal.
  */
 static inline int
 wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
 		   unsigned mode)
 {
 	might_sleep();
 	if (!test_bit(bit, word))
 		return 0;
 	return out_of_line_wait_on_bit(word, bit, action, mode);
 }

 /**
  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
  * @word: the word being waited on, a kernel virtual address
  * @bit: the bit of the word being waited on
  * @mode: the task state to sleep in
  *
  * There is a standard hashed waitqueue table for generic use. This
  * is the part of the hashtable's accessor API that waits on a bit
  * when one intends to set it, for instance, trying to lock bitflags.
  * For instance, if one were to have waiters trying to set bitflag
  * and waiting for it to clear before setting it, one would call
  * wait_on_bit() in threads waiting to be able to set the bit.
  * One uses wait_on_bit_lock() where one is waiting for the bit to
  * clear with the intention of setting it, and when done, clearing it.
  *
  * Returns zero if the bit was (eventually) found to be clear and was
  * set.  Returns non-zero if a signal was delivered to the process and
  * the @mode allows that signal to wake the process.
  */
 static inline int
 wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
 {
 	might_sleep();
 	if (!test_and_set_bit(bit, word))
 		return 0;
 	return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
 }

 /**
  * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
  * @word: the word being waited on, a kernel virtual address
  * @bit: the bit of the word being waited on
  * @mode: the task state to sleep in
  *
  * Use the standard hashed waitqueue table to wait for a bit
  * to be cleared and then to atomically set it.  This is similar
  * to wait_on_bit(), but calls io_schedule() instead of schedule()
  * for the actual waiting.
  *
  * Returns zero if the bit was (eventually) found to be clear and was
  * set.  Returns non-zero if a signal was delivered to the process and
  * the @mode allows that signal to wake the process.
  */
 static inline int
 wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
 {
 	might_sleep();
 	if (!test_and_set_bit(bit, word))
 		return 0;
 	return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
 }

 /**
  * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
  * @word: the word being waited on, a kernel virtual address
  * @bit: the bit of the word being waited on
  * @action: the function used to sleep, which may take special actions
  * @mode: the task state to sleep in
  *
  * Use the standard hashed waitqueue table to wait for a bit
  * to be cleared and then to set it, and allow the waiting action
  * to be specified.
  * This is like wait_on_bit() but allows fine control of how the waiting
  * is done.
  *
  * Returns zero if the bit was (eventually) found to be clear and was
  * set.  Returns non-zero if a signal was delivered to the process and
  * the @mode allows that signal to wake the process.
  */
 static inline int
 wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
 			unsigned mode)
 {
 	might_sleep();
 	if (!test_and_set_bit(bit, word))
 		return 0;
 	return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 }

 /**
  * wait_on_atomic_t - Wait for an atomic_t to become 0
  * @val: The atomic value being waited on, a kernel virtual address
  * @action: the function used to sleep, which may take special actions
  * @mode: the task state to sleep in
  *
  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
  * the purpose of getting a waitqueue, but we set the key to a bit number
  * outside of the target 'word'.
  */
 static inline
 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
 {
 	might_sleep();
 	if (atomic_read(val) == 0)
 		return 0;
 	return out_of_line_wait_on_atomic_t(val, action, mode);
 }

 #endif /* _LINUX_WAIT_BIT_H */
	#ifndef _LINUX_WAIT_BIT_H
	#define _LINUX_WAIT_BIT_H

	/*
	* Linux wait-bit related types and methods:
	*/
	#include <linux/wait.h>

	struct wait_bit_key {
	void *flags;
	int bit_nr;
	#define WAIT_ATOMIC_T_BIT_NR -1
	unsigned long timeout;
	};

	struct wait_bit_queue_entry {
	struct wait_bit_key key;
	struct wait_queue_entry wq_entry;
	};

	#define __WAIT_BIT_KEY_INITIALIZER(word, bit) \
	{ .flags = word, .bit_nr = bit, }

	#define __WAIT_ATOMIC_T_KEY_INITIALIZER(p) \
	{ .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }

	typedef int wait_bit_action_f(struct wait_bit_key *key, int mode);
	void __wake_up_bit(struct wait_queue_head wq_head, void word, int bit);
	int __wait_on_bit(struct wait_queue_head wq_head, struct wait_bit_queue_entry wbq_entry, wait_bit_action_f *action, unsigned int mode);
	int __wait_on_bit_lock(struct wait_queue_head wq_head, struct wait_bit_queue_entry wbq_entry, wait_bit_action_f *action, unsigned int mode);
	void wake_up_bit(void *word, int bit);
	void wake_up_atomic_t(atomic_t *p);
	int out_of_line_wait_on_bit(void word, int, wait_bit_action_f action, unsigned int mode);
	int out_of_line_wait_on_bit_timeout(void word, int, wait_bit_action_f action, unsigned int mode, unsigned long timeout);
	int out_of_line_wait_on_bit_lock(void word, int, wait_bit_action_f action, unsigned int mode);
	int out_of_line_wait_on_atomic_t(atomic_t p, int ()(atomic_t *), unsigned int mode);
	struct wait_queue_head bit_waitqueue(void word, int bit);
	extern void __init wait_bit_init(void);

	int wake_bit_function(struct wait_queue_entry wq_entry, unsigned mode, int sync, void key);

	#define DEFINE_WAIT_BIT(name, word, bit) \
	struct wait_bit_queue_entry name = { \
	.key = __WAIT_BIT_KEY_INITIALIZER(word, bit), \
	.wq_entry = { \
	.private = current, \
	.func = wake_bit_function, \
	.task_list = \
	LIST_HEAD_INIT((name).wq_entry.task_list), \
	}, \
	}

	extern int bit_wait(struct wait_bit_key *key, int bit);
	extern int bit_wait_io(struct wait_bit_key *key, int bit);
	extern int bit_wait_timeout(struct wait_bit_key *key, int bit);
	extern int bit_wait_io_timeout(struct wait_bit_key *key, int bit);

	/**
	* wait_on_bit - wait for a bit to be cleared
	* @word: the word being waited on, a kernel virtual address
	* @bit: the bit of the word being waited on
	* @mode: the task state to sleep in
	*
	* There is a standard hashed waitqueue table for generic use. This
	* is the part of the hashtable's accessor API that waits on a bit.
	* For instance, if one were to have waiters on a bitflag, one would
	* call wait_on_bit() in threads waiting for the bit to clear.
	* One uses wait_on_bit() where one is waiting for the bit to clear,
	* but has no intention of setting it.
	* Returned value will be zero if the bit was cleared, or non-zero
	* if the process received a signal and the mode permitted wakeup
	* on that signal.
	*/
	static inline int
	wait_on_bit(unsigned long *word, int bit, unsigned mode)
	{
	might_sleep();
	if (!test_bit(bit, word))
	return 0;
	return out_of_line_wait_on_bit(word, bit,
	bit_wait,
	mode);
	}

	/**
	* wait_on_bit_io - wait for a bit to be cleared
	* @word: the word being waited on, a kernel virtual address
	* @bit: the bit of the word being waited on
	* @mode: the task state to sleep in
	*
	* Use the standard hashed waitqueue table to wait for a bit
	* to be cleared. This is similar to wait_on_bit(), but calls
	* io_schedule() instead of schedule() for the actual waiting.
	*
	* Returned value will be zero if the bit was cleared, or non-zero
	* if the process received a signal and the mode permitted wakeup
	* on that signal.
	*/
	static inline int
	wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
	{
	might_sleep();
	if (!test_bit(bit, word))
	return 0;
	return out_of_line_wait_on_bit(word, bit,
	bit_wait_io,
	mode);
	}

	/**
	* wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
	* @word: the word being waited on, a kernel virtual address
	* @bit: the bit of the word being waited on
	* @mode: the task state to sleep in
	* @timeout: timeout, in jiffies
	*
	* Use the standard hashed waitqueue table to wait for a bit
	* to be cleared. This is similar to wait_on_bit(), except also takes a
	* timeout parameter.
	*
	* Returned value will be zero if the bit was cleared before the
	* @timeout elapsed, or non-zero if the @timeout elapsed or process
	* received a signal and the mode permitted wakeup on that signal.
	*/
	static inline int
	wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
	unsigned long timeout)
	{
	might_sleep();
	if (!test_bit(bit, word))
	return 0;
	return out_of_line_wait_on_bit_timeout(word, bit,
	bit_wait_timeout,
	mode, timeout);
	}

	/**
	* wait_on_bit_action - wait for a bit to be cleared
	* @word: the word being waited on, a kernel virtual address
	* @bit: the bit of the word being waited on
	* @action: the function used to sleep, which may take special actions
	* @mode: the task state to sleep in
	*
	* Use the standard hashed waitqueue table to wait for a bit
	* to be cleared, and allow the waiting action to be specified.
	* This is like wait_on_bit() but allows fine control of how the waiting
	* is done.
	*
	* Returned value will be zero if the bit was cleared, or non-zero
	* if the process received a signal and the mode permitted wakeup
	* on that signal.
	*/
	static inline int
	wait_on_bit_action(unsigned long word, int bit, wait_bit_action_f action,
	unsigned mode)
	{
	might_sleep();
	if (!test_bit(bit, word))
	return 0;
	return out_of_line_wait_on_bit(word, bit, action, mode);
	}

	/**
	* wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
	* @word: the word being waited on, a kernel virtual address
	* @bit: the bit of the word being waited on
	* @mode: the task state to sleep in
	*
	* There is a standard hashed waitqueue table for generic use. This
	* is the part of the hashtable's accessor API that waits on a bit
	* when one intends to set it, for instance, trying to lock bitflags.
	* For instance, if one were to have waiters trying to set bitflag
	* and waiting for it to clear before setting it, one would call
	* wait_on_bit() in threads waiting to be able to set the bit.
	* One uses wait_on_bit_lock() where one is waiting for the bit to
	* clear with the intention of setting it, and when done, clearing it.
	*
	* Returns zero if the bit was (eventually) found to be clear and was
	* set. Returns non-zero if a signal was delivered to the process and
	* the @mode allows that signal to wake the process.
	*/
	static inline int
	wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
	{
	might_sleep();
	if (!test_and_set_bit(bit, word))
	return 0;
	return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
	}

	/**
	* wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
	* @word: the word being waited on, a kernel virtual address
	* @bit: the bit of the word being waited on
	* @mode: the task state to sleep in
	*
	* Use the standard hashed waitqueue table to wait for a bit
	* to be cleared and then to atomically set it. This is similar
	* to wait_on_bit(), but calls io_schedule() instead of schedule()
	* for the actual waiting.
	*
	* Returns zero if the bit was (eventually) found to be clear and was
	* set. Returns non-zero if a signal was delivered to the process and
	* the @mode allows that signal to wake the process.
	*/
	static inline int
	wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
	{
	might_sleep();
	if (!test_and_set_bit(bit, word))
	return 0;
	return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
	}

	/**
	* wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
	* @word: the word being waited on, a kernel virtual address
	* @bit: the bit of the word being waited on
	* @action: the function used to sleep, which may take special actions
	* @mode: the task state to sleep in
	*
	* Use the standard hashed waitqueue table to wait for a bit
	* to be cleared and then to set it, and allow the waiting action
	* to be specified.
	* This is like wait_on_bit() but allows fine control of how the waiting
	* is done.
	*
	* Returns zero if the bit was (eventually) found to be clear and was
	* set. Returns non-zero if a signal was delivered to the process and
	* the @mode allows that signal to wake the process.
	*/
	static inline int
	wait_on_bit_lock_action(unsigned long word, int bit, wait_bit_action_f action,
	unsigned mode)
	{
	might_sleep();
	if (!test_and_set_bit(bit, word))
	return 0;
	return out_of_line_wait_on_bit_lock(word, bit, action, mode);
	}

	/**
	* wait_on_atomic_t - Wait for an atomic_t to become 0
	* @val: The atomic value being waited on, a kernel virtual address
	* @action: the function used to sleep, which may take special actions
	* @mode: the task state to sleep in
	*
	* Wait for an atomic_t to become 0. We abuse the bit-wait waitqueue table for
	* the purpose of getting a waitqueue, but we set the key to a bit number
	* outside of the target 'word'.
	*/
	static inline
	int wait_on_atomic_t(atomic_t val, int (action)(atomic_t *), unsigned mode)
	{
	might_sleep();
	if (atomic_read(val) == 0)
	return 0;
	return out_of_line_wait_on_atomic_t(val, action, mode);
	}

	#endif /* _LINUX_WAIT_BIT_H */