[net-next-2.6.git] / arch / powerpc / include / asm / rwsem.h

#ifndef _ASM_POWERPC_RWSEM_H
#define _ASM_POWERPC_RWSEM_H

#ifndef _LINUX_RWSEM_H
#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
#endif

#ifdef __KERNEL__

/*
 * R/W semaphores for PPC using the stuff in lib/rwsem.c.
 * Adapted largely from include/asm-i386/rwsem.h
 * by Paul Mackerras <paulus@samba.org>.
 */

#include <linux/list.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>
#include <asm/system.h>

/*
 * the semaphore definition
 */
#ifdef CONFIG_PPC64
# define RWSEM_ACTIVE_MASK		0xffffffffL
#else
# define RWSEM_ACTIVE_MASK		0x0000ffffL
#endif

#define RWSEM_UNLOCKED_VALUE		0x00000000L
#define RWSEM_ACTIVE_BIAS		0x00000001L
#define RWSEM_WAITING_BIAS		(-RWSEM_ACTIVE_MASK-1)
#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)

struct rw_semaphore {
	long			count;
	spinlock_t		wait_lock;
	struct list_head	wait_list;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
	struct lockdep_map	dep_map;
#endif
};

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
#else
# define __RWSEM_DEP_MAP_INIT(lockname)
#endif

#define __RWSEM_INITIALIZER(name)				\
{								\
	RWSEM_UNLOCKED_VALUE,					\
	__SPIN_LOCK_UNLOCKED((name).wait_lock),			\
	LIST_HEAD_INIT((name).wait_list)			\
	__RWSEM_DEP_MAP_INIT(name)				\
}

#define DECLARE_RWSEM(name)		\
	struct rw_semaphore name = __RWSEM_INITIALIZER(name)

extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);

extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
			 struct lock_class_key *key);

#define init_rwsem(sem)					\
	do {						\
		static struct lock_class_key __key;	\
							\
		__init_rwsem((sem), #sem, &__key);	\
	} while (0)

/*
 * lock for reading
 */
static inline void __down_read(struct rw_semaphore *sem)
{
	if (unlikely(atomic_long_inc_return((atomic_long_t *)&sem->count) <= 0))
		rwsem_down_read_failed(sem);
}

static inline int __down_read_trylock(struct rw_semaphore *sem)
{
	long tmp;

	while ((tmp = sem->count) >= 0) {
		if (tmp == cmpxchg(&sem->count, tmp,
				   tmp + RWSEM_ACTIVE_READ_BIAS)) {
			return 1;
		}
	}
	return 0;
}

/*
 * lock for writing
 */
static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
{
	long tmp;

	tmp = atomic_long_add_return(RWSEM_ACTIVE_WRITE_BIAS,
				     (atomic_long_t *)&sem->count);
	if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
		rwsem_down_write_failed(sem);
}

static inline void __down_write(struct rw_semaphore *sem)
{
	__down_write_nested(sem, 0);
}

static inline int __down_write_trylock(struct rw_semaphore *sem)
{
	long tmp;

	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
		      RWSEM_ACTIVE_WRITE_BIAS);
	return tmp == RWSEM_UNLOCKED_VALUE;
}

/*
 * unlock after reading
 */
static inline void __up_read(struct rw_semaphore *sem)
{
	long tmp;

	tmp = atomic_long_dec_return((atomic_long_t *)&sem->count);
	if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
		rwsem_wake(sem);
}

/*
 * unlock after writing
 */
static inline void __up_write(struct rw_semaphore *sem)
{
	if (unlikely(atomic_long_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
				 (atomic_long_t *)&sem->count) < 0))
		rwsem_wake(sem);
}

/*
 * implement atomic add functionality
 */
static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
{
	atomic_long_add(delta, (atomic_long_t *)&sem->count);
}

/*
 * downgrade write lock to read lock
 */
static inline void __downgrade_write(struct rw_semaphore *sem)
{
	long tmp;

	tmp = atomic_long_add_return(-RWSEM_WAITING_BIAS,
				     (atomic_long_t *)&sem->count);
	if (tmp < 0)
		rwsem_downgrade_wake(sem);
}

/*
 * implement exchange and add functionality
 */
static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
{
	return atomic_long_add_return(delta, (atomic_long_t *)&sem->count);
}

static inline int rwsem_is_locked(struct rw_semaphore *sem)
{
	return sem->count != 0;
}

#endif	/* __KERNEL__ */
#endif	/* _ASM_POWERPC_RWSEM_H */
Commit	Line	Data
342e73b3 JL	1	#ifndef _ASM_POWERPC_RWSEM_H
	2	#define _ASM_POWERPC_RWSEM_H
	3
20b31b53 RD	4	#ifndef _LINUX_RWSEM_H
	5	#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
	6	#endif
	7
342e73b3 JL	8	#ifdef __KERNEL__
342e73b3 JL	9
1da177e4	10	/*
b8b572e1 SR	11	* R/W semaphores for PPC using the stuff in lib/rwsem.c.
b8b572e1 SR	12	* Adapted largely from include/asm-i386/rwsem.h
1da177e4	13	* by Paul Mackerras <paulus@samba.org>.
1da177e4 LT	14	*/
1da177e4 LT	15
1da177e4 LT	16	#include <linux/list.h>
	17	#include <linux/spinlock.h>
	18	#include <asm/atomic.h>
	19	#include <asm/system.h>
	20
	21	/*
	22	* the semaphore definition
	23	*/
529b7307 BH	24	#ifdef CONFIG_PPC64
	25	# define RWSEM_ACTIVE_MASK 0xffffffffL
	26	#else
	27	# define RWSEM_ACTIVE_MASK 0x0000ffffL
	28	#endif
	29
	30	#define RWSEM_UNLOCKED_VALUE 0x00000000L
	31	#define RWSEM_ACTIVE_BIAS 0x00000001L
	32	#define RWSEM_WAITING_BIAS (-RWSEM_ACTIVE_MASK-1)
1da177e4 LT	33	#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
1da177e4 LT	34	#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
529b7307 BH	35
	36	struct rw_semaphore {
	37	long count;
1da177e4 LT	38	spinlock_t wait_lock;
1da177e4 LT	39	struct list_head wait_list;
945feb17 BH	40	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	41	struct lockdep_map dep_map;
	42	#endif
1da177e4 LT	43	};
1da177e4 LT	44
945feb17 BH	45	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	46	# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
	47	#else
	48	# define __RWSEM_DEP_MAP_INIT(lockname)
	49	#endif
	50
529b7307 BH	51	#define __RWSEM_INITIALIZER(name) \
	52	{ \
	53	RWSEM_UNLOCKED_VALUE, \
	54	__SPIN_LOCK_UNLOCKED((name).wait_lock), \
	55	LIST_HEAD_INIT((name).wait_list) \
	56	__RWSEM_DEP_MAP_INIT(name) \
	57	}
1da177e4 LT	58
	59	#define DECLARE_RWSEM(name) \
	60	struct rw_semaphore name = __RWSEM_INITIALIZER(name)
	61
	62	extern struct rw_semaphore rwsem_down_read_failed(struct rw_semaphore sem);
	63	extern struct rw_semaphore rwsem_down_write_failed(struct rw_semaphore sem);
	64	extern struct rw_semaphore rwsem_wake(struct rw_semaphore sem);
	65	extern struct rw_semaphore rwsem_downgrade_wake(struct rw_semaphore sem);
	66
945feb17 BH	67	extern void __init_rwsem(struct rw_semaphore sem, const char name,
	68	struct lock_class_key *key);
	69
	70	#define init_rwsem(sem) \
	71	do { \
	72	static struct lock_class_key __key; \
	73	\
	74	__init_rwsem((sem), #sem, &__key); \
	75	} while (0)
1da177e4 LT	76
	77	/*
	78	* lock for reading
	79	*/
	80	static inline void __down_read(struct rw_semaphore *sem)
	81	{
529b7307	82	if (unlikely(atomic_long_inc_return((atomic_long_t *)&sem->count) <= 0))
1da177e4 LT	83	rwsem_down_read_failed(sem);
	84	}
	85
	86	static inline int __down_read_trylock(struct rw_semaphore *sem)
	87	{
529b7307	88	long tmp;
1da177e4 LT	89
	90	while ((tmp = sem->count) >= 0) {
	91	if (tmp == cmpxchg(&sem->count, tmp,
	92	tmp + RWSEM_ACTIVE_READ_BIAS)) {
	93	return 1;
	94	}
	95	}
	96	return 0;
	97	}
	98
	99	/*
	100	* lock for writing
	101	*/
945feb17	102	static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
1da177e4	103	{
529b7307	104	long tmp;
1da177e4	105
529b7307 BH	106	tmp = atomic_long_add_return(RWSEM_ACTIVE_WRITE_BIAS,
529b7307 BH	107	(atomic_long_t *)&sem->count);
1da177e4 LT	108	if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
	109	rwsem_down_write_failed(sem);
	110	}
	111
945feb17 BH	112	static inline void __down_write(struct rw_semaphore *sem)
	113	{
	114	__down_write_nested(sem, 0);
	115	}
	116
1da177e4 LT	117	static inline int __down_write_trylock(struct rw_semaphore *sem)
1da177e4 LT	118	{
529b7307	119	long tmp;
1da177e4 LT	120
	121	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
	122	RWSEM_ACTIVE_WRITE_BIAS);
	123	return tmp == RWSEM_UNLOCKED_VALUE;
	124	}
	125
	126	/*
	127	* unlock after reading
	128	*/
	129	static inline void __up_read(struct rw_semaphore *sem)
	130	{
529b7307	131	long tmp;
1da177e4	132
529b7307	133	tmp = atomic_long_dec_return((atomic_long_t *)&sem->count);
1da177e4 LT	134	if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
	135	rwsem_wake(sem);
	136	}
	137
	138	/*
	139	* unlock after writing
	140	*/
	141	static inline void __up_write(struct rw_semaphore *sem)
	142	{
529b7307 BH	143	if (unlikely(atomic_long_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
529b7307 BH	144	(atomic_long_t *)&sem->count) < 0))
1da177e4 LT	145	rwsem_wake(sem);
	146	}
	147
	148	/*
	149	* implement atomic add functionality
	150	*/
529b7307	151	static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
1da177e4	152	{
529b7307	153	atomic_long_add(delta, (atomic_long_t *)&sem->count);
1da177e4 LT	154	}
	155
	156	/*
	157	* downgrade write lock to read lock
	158	*/
	159	static inline void __downgrade_write(struct rw_semaphore *sem)
	160	{
529b7307	161	long tmp;
1da177e4	162
529b7307 BH	163	tmp = atomic_long_add_return(-RWSEM_WAITING_BIAS,
529b7307 BH	164	(atomic_long_t *)&sem->count);
1da177e4 LT	165	if (tmp < 0)
	166	rwsem_downgrade_wake(sem);
	167	}
	168
	169	/*
	170	* implement exchange and add functionality
	171	*/
529b7307	172	static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
1da177e4	173	{
529b7307	174	return atomic_long_add_return(delta, (atomic_long_t *)&sem->count);
1da177e4 LT	175	}
1da177e4 LT	176
eb92f4ef RVR	177	static inline int rwsem_is_locked(struct rw_semaphore *sem)
eb92f4ef RVR	178	{
529b7307	179	return sem->count != 0;
eb92f4ef RVR	180	}
eb92f4ef RVR	181
342e73b3 JL	182	#endif /* __KERNEL__ */
342e73b3 JL	183	#endif /* _ASM_POWERPC_RWSEM_H */