include/linux/wait.h

#ifndef _LINUX_WAIT_H
#define _LINUX_WAIT_H

#define WNOHANG		0x00000001
#define WUNTRACED	0x00000002

#define __WNOTHREAD	0x20000000	/* Don't wait on children of other threads in this group */
#define __WALL		0x40000000	/* Wait on all children, regardless of type */
#define __WCLONE	0x80000000	/* Wait only on non-SIGCHLD children */

#ifdef __KERNEL__

#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/stddef.h>
#include <linux/spinlock.h>
#include <linux/config.h>

#include <asm/page.h>
#include <asm/processor.h>

/*
 * Debug control.  Slow but useful.
 */
#if defined(CONFIG_DEBUG_WAITQ)
#define WAITQUEUE_DEBUG 1
#else
#define WAITQUEUE_DEBUG 0
#endif

struct __wait_queue {
	unsigned int flags;
#define WQ_FLAG_EXCLUSIVE	0x01
	struct task_struct * task;
	struct list_head task_list;
#if WAITQUEUE_DEBUG
	long __magic;
	long __waker;
#endif
};
typedef struct __wait_queue wait_queue_t;

/*
 * 'dual' spinlock architecture. Can be switched between spinlock_t and
 * rwlock_t locks via changing this define. Since waitqueues are quite
 * decoupled in the new architecture, lightweight 'simple' spinlocks give
 * us slightly better latencies and smaller waitqueue structure size.
 */
#define USE_RW_WAIT_QUEUE_SPINLOCK 0

#if USE_RW_WAIT_QUEUE_SPINLOCK
# define wq_lock_t rwlock_t
# define WAITQUEUE_RW_LOCK_UNLOCKED RW_LOCK_UNLOCKED

# define wq_read_lock read_lock
# define wq_read_lock_irqsave read_lock_irqsave
# define wq_read_unlock_irqrestore read_unlock_irqrestore
# define wq_read_unlock read_unlock
# define wq_write_lock_irq write_lock_irq
# define wq_write_lock_irqsave write_lock_irqsave
# define wq_write_unlock_irqrestore write_unlock_irqrestore
# define wq_write_unlock write_unlock
#else
# define wq_lock_t spinlock_t
# define WAITQUEUE_RW_LOCK_UNLOCKED SPIN_LOCK_UNLOCKED

# define wq_read_lock spin_lock
# define wq_read_lock_irqsave spin_lock_irqsave
# define wq_read_unlock spin_unlock
# define wq_read_unlock_irqrestore spin_unlock_irqrestore
# define wq_write_lock_irq spin_lock_irq
# define wq_write_lock_irqsave spin_lock_irqsave
# define wq_write_unlock_irqrestore spin_unlock_irqrestore
# define wq_write_unlock spin_unlock
#endif

struct __wait_queue_head {
	wq_lock_t lock;
	struct list_head task_list;
#if WAITQUEUE_DEBUG
	long __magic;
	long __creator;
#endif
};
typedef struct __wait_queue_head wait_queue_head_t;


/*
 * Debugging macros.  We eschew `do { } while (0)' because gcc can generate
 * spurious .aligns.
 */
#if WAITQUEUE_DEBUG
#define WQ_BUG()	BUG()
#define CHECK_MAGIC(x)							\
	do {									\
		if ((x) != (long)&(x)) {					\
			printk("bad magic %lx (should be %lx), ",		\
				(long)x, (long)&(x));				\
			WQ_BUG();						\
		}								\
	} while (0)
#define CHECK_MAGIC_WQHEAD(x)							\
	do {									\
		if ((x)->__magic != (long)&((x)->__magic)) {			\
			printk("bad magic %lx (should be %lx, creator %lx), ",	\
			(x)->__magic, (long)&((x)->__magic), (x)->__creator);	\
			WQ_BUG();						\
		}								\
	} while (0)
#define WQ_CHECK_LIST_HEAD(list) 						\
	do {									\
		if (!(list)->next || !(list)->prev)				\
			WQ_BUG();						\
	} while(0)
#define WQ_NOTE_WAKER(tsk)							\
	do {									\
		(tsk)->__waker = (long)__builtin_return_address(0);		\
	} while (0)
#else
#define WQ_BUG()
#define CHECK_MAGIC(x)
#define CHECK_MAGIC_WQHEAD(x)
#define WQ_CHECK_LIST_HEAD(list)
#define WQ_NOTE_WAKER(tsk)
#endif

/*
 * Macros for declaration and initialization of the datatypes
 */

#if WAITQUEUE_DEBUG
# define __WAITQUEUE_DEBUG_INIT(name) (long)&(name).__magic, 0
# define __WAITQUEUE_HEAD_DEBUG_INIT(name) (long)&(name).__magic, (long)&(name).__magic
#else
# define __WAITQUEUE_DEBUG_INIT(name)
# define __WAITQUEUE_HEAD_DEBUG_INIT(name)
#endif

#define __WAITQUEUE_INITIALIZER(name, tsk) {				\
	task:		tsk,						\
	task_list:	{ NULL, NULL },					\
			 __WAITQUEUE_DEBUG_INIT(name)}

#define DECLARE_WAITQUEUE(name, tsk)					\
	wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)

#define __WAIT_QUEUE_HEAD_INITIALIZER(name) {				\
	lock:		WAITQUEUE_RW_LOCK_UNLOCKED,			\
	task_list:	{ &(name).task_list, &(name).task_list },	\
			__WAITQUEUE_HEAD_DEBUG_INIT(name)}

#define DECLARE_WAIT_QUEUE_HEAD(name) \
	wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)

static inline void init_waitqueue_head(wait_queue_head_t *q)
{
#if WAITQUEUE_DEBUG
	if (!q)
		WQ_BUG();
#endif
	q->lock = WAITQUEUE_RW_LOCK_UNLOCKED;
	INIT_LIST_HEAD(&q->task_list);
#if WAITQUEUE_DEBUG
	q->__magic = (long)&q->__magic;
	q->__creator = (long)current_text_addr();
#endif
}

static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
{
#if WAITQUEUE_DEBUG
	if (!q || !p)
		WQ_BUG();
#endif
	q->flags = 0;
	q->task = p;
#if WAITQUEUE_DEBUG
	q->__magic = (long)&q->__magic;
#endif
}

static inline int waitqueue_active(wait_queue_head_t *q)
{
#if WAITQUEUE_DEBUG
	if (!q)
		WQ_BUG();
	CHECK_MAGIC_WQHEAD(q);
#endif

	return !list_empty(&q->task_list);
}

static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
{
#if WAITQUEUE_DEBUG
	if (!head || !new)
		WQ_BUG();
	CHECK_MAGIC_WQHEAD(head);
	CHECK_MAGIC(new->__magic);
	if (!head->task_list.next || !head->task_list.prev)
		WQ_BUG();
#endif
	list_add(&new->task_list, &head->task_list);
}

/*
 * Used for wake-one threads:
 */
static inline void __add_wait_queue_tail(wait_queue_head_t *head,
						wait_queue_t *new)
{
#if WAITQUEUE_DEBUG
	if (!head || !new)
		WQ_BUG();
	CHECK_MAGIC_WQHEAD(head);
	CHECK_MAGIC(new->__magic);
	if (!head->task_list.next || !head->task_list.prev)
		WQ_BUG();
#endif
	list_add_tail(&new->task_list, &head->task_list);
}

static inline void __remove_wait_queue(wait_queue_head_t *head,
							wait_queue_t *old)
{
#if WAITQUEUE_DEBUG
	if (!old)
		WQ_BUG();
	CHECK_MAGIC(old->__magic);
#endif
	list_del(&old->task_list);
}

#endif /* __KERNEL__ */

#endif