[deliverable/linux.git] / include / asm-ppc64 / semaphore.h

#ifndef _PPC64_SEMAPHORE_H
#define _PPC64_SEMAPHORE_H

/*
 * Remove spinlock-based RW semaphores; RW semaphore definitions are
 * now in rwsem.h and we use the generic lib/rwsem.c implementation.
 * Rework semaphores to use atomic_dec_if_positive.
 * -- Paul Mackerras (paulus@samba.org)
 */

#ifdef __KERNEL__

#include <asm/atomic.h>
#include <asm/system.h>
#include <linux/wait.h>
#include <linux/rwsem.h>

struct semaphore {
	/*
	 * Note that any negative value of count is equivalent to 0,
	 * but additionally indicates that some process(es) might be
	 * sleeping on `wait'.
	 */
	atomic_t count;
	wait_queue_head_t wait;
};

#define __SEMAPHORE_INITIALIZER(name, n)				\
{									\
	.count		= ATOMIC_INIT(n),				\
	.wait		= __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)	\
}

#define __MUTEX_INITIALIZER(name) \
	__SEMAPHORE_INITIALIZER(name, 1)

#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
	struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)

#define DECLARE_MUTEX(name)		__DECLARE_SEMAPHORE_GENERIC(name, 1)
#define DECLARE_MUTEX_LOCKED(name)	__DECLARE_SEMAPHORE_GENERIC(name, 0)

static inline void sema_init (struct semaphore *sem, int val)
{
	atomic_set(&sem->count, val);
	init_waitqueue_head(&sem->wait);
}

static inline void init_MUTEX (struct semaphore *sem)
{
	sema_init(sem, 1);
}

static inline void init_MUTEX_LOCKED (struct semaphore *sem)
{
	sema_init(sem, 0);
}

extern void __down(struct semaphore * sem);
extern int  __down_interruptible(struct semaphore * sem);
extern void __up(struct semaphore * sem);

static inline void down(struct semaphore * sem)
{
	might_sleep();

	/*
	 * Try to get the semaphore, take the slow path if we fail.
	 */
	if (unlikely(atomic_dec_return(&sem->count) < 0))
		__down(sem);
}

static inline int down_interruptible(struct semaphore * sem)
{
	int ret = 0;

	might_sleep();

	if (unlikely(atomic_dec_return(&sem->count) < 0))
		ret = __down_interruptible(sem);
	return ret;
}

static inline int down_trylock(struct semaphore * sem)
{
	return atomic_dec_if_positive(&sem->count) < 0;
}

static inline void up(struct semaphore * sem)
{
	if (unlikely(atomic_inc_return(&sem->count) <= 0))
		__up(sem);
}

#endif /* __KERNEL__ */

#endif /* !(_PPC64_SEMAPHORE_H) */
Commit	Line	Data
1da177e4 LT	1	#ifndef _PPC64_SEMAPHORE_H
	2	#define _PPC64_SEMAPHORE_H
	3
	4	/*
	5	* Remove spinlock-based RW semaphores; RW semaphore definitions are
	6	* now in rwsem.h and we use the generic lib/rwsem.c implementation.
	7	* Rework semaphores to use atomic_dec_if_positive.
	8	* -- Paul Mackerras (paulus@samba.org)
	9	*/
	10
	11	#ifdef __KERNEL__
	12
	13	#include <asm/atomic.h>
	14	#include <asm/system.h>
	15	#include <linux/wait.h>
	16	#include <linux/rwsem.h>
	17
	18	struct semaphore {
	19	/*
	20	* Note that any negative value of count is equivalent to 0,
	21	* but additionally indicates that some process(es) might be
	22	* sleeping on `wait'.
	23	*/
	24	atomic_t count;
	25	wait_queue_head_t wait;
	26	};
	27
	28	#define __SEMAPHORE_INITIALIZER(name, n) \
	29	{ \
	30	.count = ATOMIC_INIT(n), \
	31	.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
	32	}
	33
	34	#define __MUTEX_INITIALIZER(name) \
	35	__SEMAPHORE_INITIALIZER(name, 1)
	36
	37	#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
	38	struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
	39
	40	#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
	41	#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0)
	42
	43	static inline void sema_init (struct semaphore *sem, int val)
	44	{
	45	atomic_set(&sem->count, val);
	46	init_waitqueue_head(&sem->wait);
	47	}
	48
	49	static inline void init_MUTEX (struct semaphore *sem)
	50	{
	51	sema_init(sem, 1);
	52	}
	53
	54	static inline void init_MUTEX_LOCKED (struct semaphore *sem)
	55	{
	56	sema_init(sem, 0);
	57	}
	58
	59	extern void __down(struct semaphore * sem);
	60	extern int __down_interruptible(struct semaphore * sem);
	61	extern void __up(struct semaphore * sem);
	62
	63	static inline void down(struct semaphore * sem)
	64	{
65	might_sleep();
66
67	/*
68	* Try to get the semaphore, take the slow path if we fail.
69	*/
70	if (unlikely(atomic_dec_return(&sem->count) < 0))
71	__down(sem);
72	}
73
74	static inline int down_interruptible(struct semaphore * sem)
75	{
76	int ret = 0;
77
78	might_sleep();
79
80	if (unlikely(atomic_dec_return(&sem->count) < 0))
81	ret = __down_interruptible(sem);
82	return ret;
83	}
84
85	static inline int down_trylock(struct semaphore * sem)
86	{
87	return atomic_dec_if_positive(&sem->count) < 0;
88	}
89
90	static inline void up(struct semaphore * sem)
91	{
92	if (unlikely(atomic_inc_return(&sem->count) <= 0))
93	__up(sem);
94	}
95
96	#endif /* __KERNEL__ */
97
98	#endif /* !(_PPC64_SEMAPHORE_H) */