#ifndef _LINUX_WAIT_H
  #define _LINUX_WAIT_H
  /*
   * Linux wait queue related types and methods
   */
  #include <linux/list.h>
  #include <linux/stddef.h>
  #include <linux/spinlock.h>
  #include <asm/current.h>
  #include <uapi/linux/wait.h>
  
  typedef struct __wait_queue wait_queue_t;
  typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key);
  int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key);
  
  struct __wait_queue {
  	unsigned int		flags;
  #define WQ_FLAG_EXCLUSIVE	0x01
  	void			*private;
  	wait_queue_func_t	func;
  	struct list_head	task_list;
  };
  
  struct wait_bit_key {
  	void			*flags;
  	int			bit_nr;
  #define WAIT_ATOMIC_T_BIT_NR	-1
  };
  
  struct wait_bit_queue {
  	struct wait_bit_key	key;
  	wait_queue_t		wait;
  };
  
  struct __wait_queue_head {
  	spinlock_t		lock;
  	struct list_head	task_list;
  };
  typedef struct __wait_queue_head wait_queue_head_t;
  
  struct task_struct;
  
  /*
   * Macros for declaration and initialisaton of the datatypes
   */
  
  #define __WAITQUEUE_INITIALIZER(name, tsk) {				\
  	.private	= tsk,						\
  	.func		= default_wake_function,			\
  	.task_list	= { NULL, NULL } }
  
  #define DECLARE_WAITQUEUE(name, tsk)					\
  	wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  
  #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {				\
  	.lock		= __SPIN_LOCK_UNLOCKED(name.lock),		\
  	.task_list	= { &(name).task_list, &(name).task_list } }
  
  #define DECLARE_WAIT_QUEUE_HEAD(name) \
  	wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  
  #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, }
  
  extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
  
  #define init_waitqueue_head(q)				\
  	do {						\
  		static struct lock_class_key __key;	\
  							\
  		__init_waitqueue_head((q), #q, &__key);	\
  	} while (0)
  
  #ifdef CONFIG_LOCKDEP
  # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  	({ init_waitqueue_head(&name); name; })
  # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  	wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  #else
  # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  #endif
  
  static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  {
  	q->flags	= 0;
  	q->private	= p;
  	q->func		= default_wake_function;
  }
  
  static inline void
  init_waitqueue_func_entry(wait_queue_t *q, wait_queue_func_t func)
  {
  	q->flags	= 0;
  	q->private	= NULL;
  	q->func		= func;
  }
  
  static inline int waitqueue_active(wait_queue_head_t *q)
  {
  	return !list_empty(&q->task_list);
  }
  
  extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
  extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
  extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
  
  static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
  {
  	list_add(&new->task_list, &head->task_list);
  }
  
  /*
   * Used for wake-one threads:
   */
  static inline void
  __add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
  {
  	wait->flags |= WQ_FLAG_EXCLUSIVE;
  	__add_wait_queue(q, wait);
  }
  
  static inline void __add_wait_queue_tail(wait_queue_head_t *head,
  					 wait_queue_t *new)
  {
  	list_add_tail(&new->task_list, &head->task_list);
  }
  
  static inline void
  __add_wait_queue_tail_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
  {
  	wait->flags |= WQ_FLAG_EXCLUSIVE;
  	__add_wait_queue_tail(q, wait);
  }
  
  static inline void
  __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
  {
  	list_del(&old->task_list);
  }
  
  void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
  void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
  void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
  void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
  void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
  void __wake_up_bit(wait_queue_head_t *, void *, int);
  int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
  int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
  void wake_up_bit(void *, int);
  void wake_up_atomic_t(atomic_t *);
  int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
  int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
  int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
  wait_queue_head_t *bit_waitqueue(void *, int);
  
  #define wake_up(x)			__wake_up(x, TASK_NORMAL, 1, NULL)
  #define wake_up_nr(x, nr)		__wake_up(x, TASK_NORMAL, nr, NULL)
  #define wake_up_all(x)			__wake_up(x, TASK_NORMAL, 0, NULL)
  #define wake_up_locked(x)		__wake_up_locked((x), TASK_NORMAL, 1)
  #define wake_up_all_locked(x)		__wake_up_locked((x), TASK_NORMAL, 0)
  
  #define wake_up_interruptible(x)	__wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
  #define wake_up_interruptible_nr(x, nr)	__wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
  #define wake_up_interruptible_all(x)	__wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
  #define wake_up_interruptible_sync(x)	__wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
  
  /*
   * Wakeup macros to be used to report events to the targets.
   */
  #define wake_up_poll(x, m)						\
  	__wake_up(x, TASK_NORMAL, 1, (void *) (m))
  #define wake_up_locked_poll(x, m)					\
  	__wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
  #define wake_up_interruptible_poll(x, m)				\
  	__wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
  #define wake_up_interruptible_sync_poll(x, m)				\
  	__wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
  
  #define ___wait_cond_timeout(condition)					\
  ({									\
  	bool __cond = (condition);					\
  	if (__cond && !__ret)						\
  		__ret = 1;						\
  	__cond || !__ret;						\
  })
  
  #define ___wait_is_interruptible(state)					\
  	(!__builtin_constant_p(state) ||				\
  		state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)	\
  
  #define ___wait_event(wq, condition, state, exclusive, ret, cmd)	\
  ({									\
  	__label__ __out;						\
  	wait_queue_t __wait;						\
  	long __ret = ret;						\
  									\
  	INIT_LIST_HEAD(&__wait.task_list);				\
  	if (exclusive)							\
  		__wait.flags = WQ_FLAG_EXCLUSIVE;			\
  	else								\
  		__wait.flags = 0;					\
  									\
  	for (;;) {							\
  		long __int = prepare_to_wait_event(&wq, &__wait, state);\
  									\
  		if (condition)						\
  			break;						\
  									\
  		if (___wait_is_interruptible(state) && __int) {		\
  			__ret = __int;					\
  			if (exclusive) {				\
  				abort_exclusive_wait(&wq, &__wait,	\
  						     state, NULL);	\
  				goto __out;				\
  			}						\
  			break;						\
  		}							\
  									\
  		cmd;							\
  	}								\
  	finish_wait(&wq, &__wait);					\
  __out:	__ret;								\
  })
  
  #define __wait_event(wq, condition)					\
  	(void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,	\
  			    schedule())
  
  /**
   * wait_event - sleep until a condition gets true
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   *
   * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
   * @condition evaluates to true. The @condition is checked each time
   * the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   */
  #define wait_event(wq, condition)					\
  do {									\
  	if (condition)							\
  		break;							\
  	__wait_event(wq, condition);					\
  } while (0)
  
  #define __wait_event_timeout(wq, condition, timeout)			\
  	___wait_event(wq, ___wait_cond_timeout(condition),		\
  		      TASK_UNINTERRUPTIBLE, 0, timeout,			\
  		      __ret = schedule_timeout(__ret))
  
  /**
   * wait_event_timeout - sleep until a condition gets true or a timeout elapses
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @timeout: timeout, in jiffies
   *
   * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
   * @condition evaluates to true. The @condition is checked each time
   * the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function returns 0 if the @timeout elapsed, or the remaining
   * jiffies (at least 1) if the @condition evaluated to %true before
   * the @timeout elapsed.
   */
  #define wait_event_timeout(wq, condition, timeout)			\
  ({									\
  	long __ret = timeout;						\
  	if (!___wait_cond_timeout(condition))				\
  		__ret = __wait_event_timeout(wq, condition, timeout);	\
  	__ret;								\
  })
  
  #define __wait_event_cmd(wq, condition, cmd1, cmd2)			\
  	(void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,	\
  			    cmd1; schedule(); cmd2)
  
  /**
   * wait_event_cmd - sleep until a condition gets true
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @cmd1: the command will be executed before sleep
   * @cmd2: the command will be executed after sleep
   *
   * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
   * @condition evaluates to true. The @condition is checked each time
   * the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   */
  #define wait_event_cmd(wq, condition, cmd1, cmd2)			\
  do {									\
  	if (condition)							\
  		break;							\
  	__wait_event_cmd(wq, condition, cmd1, cmd2);			\
  } while (0)
  
  #define __wait_event_interruptible(wq, condition)			\
  	___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,		\
  		      schedule())
  
  /**
   * wait_event_interruptible - sleep until a condition gets true
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function will return -ERESTARTSYS if it was interrupted by a
   * signal and 0 if @condition evaluated to true.
   */
  #define wait_event_interruptible(wq, condition)				\
  ({									\
  	int __ret = 0;							\
  	if (!(condition))						\
  		__ret = __wait_event_interruptible(wq, condition);	\
  	__ret;								\
  })
  
  #define __wait_event_interruptible_timeout(wq, condition, timeout)	\
  	___wait_event(wq, ___wait_cond_timeout(condition),		\
  		      TASK_INTERRUPTIBLE, 0, timeout,			\
  		      __ret = schedule_timeout(__ret))
  
  /**
   * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @timeout: timeout, in jiffies
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * Returns:
   * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
   * a signal, or the remaining jiffies (at least 1) if the @condition
   * evaluated to %true before the @timeout elapsed.
   */
  #define wait_event_interruptible_timeout(wq, condition, timeout)	\
  ({									\
  	long __ret = timeout;						\
  	if (!___wait_cond_timeout(condition))				\
  		__ret = __wait_event_interruptible_timeout(wq,		\
  						condition, timeout);	\
  	__ret;								\
  })
  
  #define __wait_event_hrtimeout(wq, condition, timeout, state)		\
  ({									\
  	int __ret = 0;							\
  	struct hrtimer_sleeper __t;					\
  									\
  	hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,		\
  			      HRTIMER_MODE_REL);			\
  	hrtimer_init_sleeper(&__t, current);				\
  	if ((timeout).tv64 != KTIME_MAX)				\
  		hrtimer_start_range_ns(&__t.timer, timeout,		\
  				       current->timer_slack_ns,		\
  				       HRTIMER_MODE_REL);		\
  									\
  	__ret = ___wait_event(wq, condition, state, 0, 0,		\
  		if (!__t.task) {					\
  			__ret = -ETIME;					\
  			break;						\
  		}							\
  		schedule());						\
  									\
  	hrtimer_cancel(&__t.timer);					\
  	destroy_hrtimer_on_stack(&__t.timer);				\
  	__ret;								\
  })
  
  /**
   * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @timeout: timeout, as a ktime_t
   *
   * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function returns 0 if @condition became true, or -ETIME if the timeout
   * elapsed.
   */
  #define wait_event_hrtimeout(wq, condition, timeout)			\
  ({									\
  	int __ret = 0;							\
  	if (!(condition))						\
  		__ret = __wait_event_hrtimeout(wq, condition, timeout,	\
  					       TASK_UNINTERRUPTIBLE);	\
  	__ret;								\
  })
  
  /**
   * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @timeout: timeout, as a ktime_t
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function returns 0 if @condition became true, -ERESTARTSYS if it was
   * interrupted by a signal, or -ETIME if the timeout elapsed.
   */
  #define wait_event_interruptible_hrtimeout(wq, condition, timeout)	\
  ({									\
  	long __ret = 0;							\
  	if (!(condition))						\
  		__ret = __wait_event_hrtimeout(wq, condition, timeout,	\
  					       TASK_INTERRUPTIBLE);	\
  	__ret;								\
  })
  
  #define __wait_event_interruptible_exclusive(wq, condition)		\
  	___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,		\
  		      schedule())
  
  #define wait_event_interruptible_exclusive(wq, condition)		\
  ({									\
  	int __ret = 0;							\
  	if (!(condition))						\
  		__ret = __wait_event_interruptible_exclusive(wq, condition);\
  	__ret;								\
  })
  
  
  #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
  ({									\
  	int __ret = 0;							\
  	DEFINE_WAIT(__wait);						\
  	if (exclusive)							\
  		__wait.flags |= WQ_FLAG_EXCLUSIVE;			\
  	do {								\
  		if (likely(list_empty(&__wait.task_list)))		\
  			__add_wait_queue_tail(&(wq), &__wait);		\
  		set_current_state(TASK_INTERRUPTIBLE);			\
  		if (signal_pending(current)) {				\
  			__ret = -ERESTARTSYS;				\
  			break;						\
  		}							\
  		if (irq)						\
  			spin_unlock_irq(&(wq).lock);			\
  		else							\
  			spin_unlock(&(wq).lock);			\
  		schedule();						\
  		if (irq)						\
  			spin_lock_irq(&(wq).lock);			\
  		else							\
  			spin_lock(&(wq).lock);				\
  	} while (!(condition));						\
  	__remove_wait_queue(&(wq), &__wait);				\
  	__set_current_state(TASK_RUNNING);				\
  	__ret;								\
  })
  
  
  /**
   * wait_event_interruptible_locked - sleep until a condition gets true
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * It must be called with wq.lock being held.  This spinlock is
   * unlocked while sleeping but @condition testing is done while lock
   * is held and when this macro exits the lock is held.
   *
   * The lock is locked/unlocked using spin_lock()/spin_unlock()
   * functions which must match the way they are locked/unlocked outside
   * of this macro.
   *
   * wake_up_locked() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function will return -ERESTARTSYS if it was interrupted by a
   * signal and 0 if @condition evaluated to true.
   */
  #define wait_event_interruptible_locked(wq, condition)			\
  	((condition)							\
  	 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
  
  /**
   * wait_event_interruptible_locked_irq - sleep until a condition gets true
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * It must be called with wq.lock being held.  This spinlock is
   * unlocked while sleeping but @condition testing is done while lock
   * is held and when this macro exits the lock is held.
   *
   * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
   * functions which must match the way they are locked/unlocked outside
   * of this macro.
   *
   * wake_up_locked() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function will return -ERESTARTSYS if it was interrupted by a
   * signal and 0 if @condition evaluated to true.
   */
  #define wait_event_interruptible_locked_irq(wq, condition)		\
  	((condition)							\
  	 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
  
  /**
   * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * It must be called with wq.lock being held.  This spinlock is
   * unlocked while sleeping but @condition testing is done while lock
   * is held and when this macro exits the lock is held.
   *
   * The lock is locked/unlocked using spin_lock()/spin_unlock()
   * functions which must match the way they are locked/unlocked outside
   * of this macro.
   *
   * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
   * set thus when other process waits process on the list if this
   * process is awaken further processes are not considered.
   *
   * wake_up_locked() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function will return -ERESTARTSYS if it was interrupted by a
   * signal and 0 if @condition evaluated to true.
   */
  #define wait_event_interruptible_exclusive_locked(wq, condition)	\
  	((condition)							\
  	 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
  
  /**
   * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * It must be called with wq.lock being held.  This spinlock is
   * unlocked while sleeping but @condition testing is done while lock
   * is held and when this macro exits the lock is held.
   *
   * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
   * functions which must match the way they are locked/unlocked outside
   * of this macro.
   *
   * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
   * set thus when other process waits process on the list if this
   * process is awaken further processes are not considered.
   *
   * wake_up_locked() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function will return -ERESTARTSYS if it was interrupted by a
   * signal and 0 if @condition evaluated to true.
   */
  #define wait_event_interruptible_exclusive_locked_irq(wq, condition)	\
  	((condition)							\
  	 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
  
  
  #define __wait_event_killable(wq, condition)				\
  	___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
  
  /**
   * wait_event_killable - sleep until a condition gets true
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   *
   * The process is put to sleep (TASK_KILLABLE) until the
   * @condition evaluates to true or a signal is received.
   * The @condition is checked each time the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * The function will return -ERESTARTSYS if it was interrupted by a
   * signal and 0 if @condition evaluated to true.
   */
  #define wait_event_killable(wq, condition)				\
  ({									\
  	int __ret = 0;							\
  	if (!(condition))						\
  		__ret = __wait_event_killable(wq, condition);		\
  	__ret;								\
  })
  
  
  #define __wait_event_lock_irq(wq, condition, lock, cmd)			\
  	(void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,	\
  			    spin_unlock_irq(&lock);			\
  			    cmd;					\
  			    schedule();					\
  			    spin_lock_irq(&lock))
  
  /**
   * wait_event_lock_irq_cmd - sleep until a condition gets true. The
   *			     condition is checked under the lock. This
   *			     is expected to be called with the lock
   *			     taken.
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @lock: a locked spinlock_t, which will be released before cmd
   *	  and schedule() and reacquired afterwards.
   * @cmd: a command which is invoked outside the critical section before
   *	 sleep
   *
   * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
   * @condition evaluates to true. The @condition is checked each time
   * the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * This is supposed to be called while holding the lock. The lock is
   * dropped before invoking the cmd and going to sleep and is reacquired
   * afterwards.
   */
  #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)		\
  do {									\
  	if (condition)							\
  		break;							\
  	__wait_event_lock_irq(wq, condition, lock, cmd);		\
  } while (0)
  
  /**
   * wait_event_lock_irq - sleep until a condition gets true. The
   *			 condition is checked under the lock. This
   *			 is expected to be called with the lock
   *			 taken.
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @lock: a locked spinlock_t, which will be released before schedule()
   *	  and reacquired afterwards.
   *
   * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
   * @condition evaluates to true. The @condition is checked each time
   * the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * This is supposed to be called while holding the lock. The lock is
   * dropped before going to sleep and is reacquired afterwards.
   */
  #define wait_event_lock_irq(wq, condition, lock)			\
  do {									\
  	if (condition)							\
  		break;							\
  	__wait_event_lock_irq(wq, condition, lock, );			\
  } while (0)
  
  
  #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)	\
  	___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,		\
  		      spin_unlock_irq(&lock);				\
  		      cmd;						\
  		      schedule();					\
  		      spin_lock_irq(&lock))
  
  /**
   * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
   *		The condition is checked under the lock. This is expected to
   *		be called with the lock taken.
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @lock: a locked spinlock_t, which will be released before cmd and
   *	  schedule() and reacquired afterwards.
   * @cmd: a command which is invoked outside the critical section before
   *	 sleep
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or a signal is received. The @condition is
   * checked each time the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * This is supposed to be called while holding the lock. The lock is
   * dropped before invoking the cmd and going to sleep and is reacquired
   * afterwards.
   *
   * The macro will return -ERESTARTSYS if it was interrupted by a signal
   * and 0 if @condition evaluated to true.
   */
  #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd)	\
  ({									\
  	int __ret = 0;							\
  	if (!(condition))						\
  		__ret = __wait_event_interruptible_lock_irq(wq,		\
  						condition, lock, cmd);	\
  	__ret;								\
  })
  
  /**
   * wait_event_interruptible_lock_irq - sleep until a condition gets true.
   *		The condition is checked under the lock. This is expected
   *		to be called with the lock taken.
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @lock: a locked spinlock_t, which will be released before schedule()
   *	  and reacquired afterwards.
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or signal is received. The @condition is
   * checked each time the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * This is supposed to be called while holding the lock. The lock is
   * dropped before going to sleep and is reacquired afterwards.
   *
   * The macro will return -ERESTARTSYS if it was interrupted by a signal
   * and 0 if @condition evaluated to true.
   */
  #define wait_event_interruptible_lock_irq(wq, condition, lock)		\
  ({									\
  	int __ret = 0;							\
  	if (!(condition))						\
  		__ret = __wait_event_interruptible_lock_irq(wq,		\
  						condition, lock,);	\
  	__ret;								\
  })
  
  #define __wait_event_interruptible_lock_irq_timeout(wq, condition,	\
  						    lock, timeout)	\
  	___wait_event(wq, ___wait_cond_timeout(condition),		\
  		      TASK_INTERRUPTIBLE, 0, timeout,			\
  		      spin_unlock_irq(&lock);				\
  		      __ret = schedule_timeout(__ret);			\
  		      spin_lock_irq(&lock));
  
  /**
   * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
   *		true or a timeout elapses. The condition is checked under
   *		the lock. This is expected to be called with the lock taken.
   * @wq: the waitqueue to wait on
   * @condition: a C expression for the event to wait for
   * @lock: a locked spinlock_t, which will be released before schedule()
   *	  and reacquired afterwards.
   * @timeout: timeout, in jiffies
   *
   * The process is put to sleep (TASK_INTERRUPTIBLE) until the
   * @condition evaluates to true or signal is received. The @condition is
   * checked each time the waitqueue @wq is woken up.
   *
   * wake_up() has to be called after changing any variable that could
   * change the result of the wait condition.
   *
   * This is supposed to be called while holding the lock. The lock is
   * dropped before going to sleep and is reacquired afterwards.
   *
   * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
   * was interrupted by a signal, and the remaining jiffies otherwise
   * if the condition evaluated to true before the timeout elapsed.
   */
  #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,	\
  						  timeout)		\
  ({									\
  	long __ret = timeout;						\
  	if (!___wait_cond_timeout(condition))				\
  		__ret = __wait_event_interruptible_lock_irq_timeout(	\
  					wq, condition, lock, timeout);	\
  	__ret;								\
  })
  
  
  /*
   * These are the old interfaces to sleep waiting for an event.
   * They are racy.  DO NOT use them, use the wait_event* interfaces above.
   * We plan to remove these interfaces.
   */
  extern void sleep_on(wait_queue_head_t *q);
  extern long sleep_on_timeout(wait_queue_head_t *q, signed long timeout);
  extern void interruptible_sleep_on(wait_queue_head_t *q);
  extern long interruptible_sleep_on_timeout(wait_queue_head_t *q, signed long timeout);
  
  /*
   * Waitqueues which are removed from the waitqueue_head at wakeup time
   */
  void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
  void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
  long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
  void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
  void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
  int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
  int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
  
  #define DEFINE_WAIT_FUNC(name, function)				\
  	wait_queue_t name = {						\
  		.private	= current,				\
  		.func		= function,				\
  		.task_list	= LIST_HEAD_INIT((name).task_list),	\
  	}
  
  #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
  
  #define DEFINE_WAIT_BIT(name, word, bit)				\
  	struct wait_bit_queue name = {					\
  		.key = __WAIT_BIT_KEY_INITIALIZER(word, bit),		\
  		.wait	= {						\
  			.private	= current,			\
  			.func		= wake_bit_function,		\
  			.task_list	=				\
  				LIST_HEAD_INIT((name).wait.task_list),	\
  		},							\
  	}
  
  #define init_wait(wait)							\
  	do {								\
  		(wait)->private = current;				\
  		(wait)->func = autoremove_wake_function;		\
  		INIT_LIST_HEAD(&(wait)->task_list);			\
  		(wait)->flags = 0;					\
  	} while (0)
  
  /**
   * 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
   * @action: the function used to sleep, which may take special actions
   * @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.
   */
  static inline int
  wait_on_bit(void *word, int bit, int (*action)(void *), unsigned mode)
  {
  	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
   * @action: the function used to sleep, which may take special actions
   * @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.
   */
  static inline int
  wait_on_bit_lock(void *word, int bit, int (*action)(void *), unsigned mode)
  {
  	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)
  {
  	if (atomic_read(val) == 0)
  		return 0;
  	return out_of_line_wait_on_atomic_t(val, action, mode);
  }
  
  #endif /* _LINUX_WAIT_H */