[linux.git] / include / asm-sh / rwsem.h

/*
 * include/asm-sh/rwsem.h: R/W semaphores for SH using the stuff
 * in lib/rwsem.c.
 */

#ifndef _ASM_SH_RWSEM_H
#define _ASM_SH_RWSEM_H

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

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

/*
 * the semaphore definition
 */
struct rw_semaphore {
	long		count;
#define RWSEM_UNLOCKED_VALUE		0x00000000
#define RWSEM_ACTIVE_BIAS		0x00000001
#define RWSEM_ACTIVE_MASK		0x0000ffff
#define RWSEM_WAITING_BIAS		(-0x00010000)
#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
	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, \
	  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)

static inline void init_rwsem(struct rw_semaphore *sem)
{
	sem->count = RWSEM_UNLOCKED_VALUE;
	spin_lock_init(&sem->wait_lock);
	INIT_LIST_HEAD(&sem->wait_list);
}

/*
 * lock for reading
 */
static inline void __down_read(struct rw_semaphore *sem)
{
	if (atomic_inc_return((atomic_t *)(&sem->count)) > 0)
		smp_wmb();
	else
		rwsem_down_read_failed(sem);
}

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

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

/*
 * lock for writing
 */
static inline void __down_write(struct rw_semaphore *sem)
{
	int tmp;

	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
				(atomic_t *)(&sem->count));
	if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
		smp_wmb();
	else
		rwsem_down_write_failed(sem);
}

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

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

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

	smp_wmb();
	tmp = atomic_dec_return((atomic_t *)(&sem->count));
	if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
		rwsem_wake(sem);
}

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

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

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

	smp_wmb();
	tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
	if (tmp < 0)
		rwsem_downgrade_wake(sem);
}

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

/*
 * implement exchange and add functionality
 */
static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
{
	smp_mb();
	return atomic_add_return(delta, (atomic_t *)(&sem->count));
}

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

#endif /* __KERNEL__ */
#endif /* _ASM_SH_RWSEM_H */
Commit	Line	Data
1da177e4	1	/*
711be605	2	* include/asm-sh/rwsem.h: R/W semaphores for SH using the stuff
1da177e4 LT	3	* in lib/rwsem.c.
	4	*/
	5
	6	#ifndef _ASM_SH_RWSEM_H
	7	#define _ASM_SH_RWSEM_H
	8
711be605 RD	9	#ifndef _LINUX_RWSEM_H
	10	#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
	11	#endif
	12
1da177e4 LT	13	#ifdef __KERNEL__
	14	#include <linux/list.h>
	15	#include <linux/spinlock.h>
	16	#include <asm/atomic.h>
	17	#include <asm/system.h>
	18
	19	/*
	20	* the semaphore definition
	21	*/
	22	struct rw_semaphore {
	23	long count;
	24	#define RWSEM_UNLOCKED_VALUE 0x00000000
	25	#define RWSEM_ACTIVE_BIAS 0x00000001
	26	#define RWSEM_ACTIVE_MASK 0x0000ffff
	27	#define RWSEM_WAITING_BIAS (-0x00010000)
	28	#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
	29	#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
	30	spinlock_t wait_lock;
	31	struct list_head wait_list;
afbfb52e PM	32	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	33	struct lockdep_map dep_map;
	34	#endif
1da177e4 LT	35	};
1da177e4 LT	36
afbfb52e PM	37	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	38	# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
	39	#else
	40	# define __RWSEM_DEP_MAP_INIT(lockname)
	41	#endif
	42
1da177e4 LT	43	#define __RWSEM_INITIALIZER(name) \
1da177e4 LT	44	{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \
afbfb52e PM	45	LIST_HEAD_INIT((name).wait_list) \
afbfb52e PM	46	__RWSEM_DEP_MAP_INIT(name) }
1da177e4 LT	47
	48	#define DECLARE_RWSEM(name) \
	49	struct rw_semaphore name = __RWSEM_INITIALIZER(name)
	50
	51	extern struct rw_semaphore rwsem_down_read_failed(struct rw_semaphore sem);
	52	extern struct rw_semaphore rwsem_down_write_failed(struct rw_semaphore sem);
	53	extern struct rw_semaphore rwsem_wake(struct rw_semaphore sem);
	54	extern struct rw_semaphore rwsem_downgrade_wake(struct rw_semaphore sem);
	55
afbfb52e PM	56	extern void __init_rwsem(struct rw_semaphore sem, const char name,
	57	struct lock_class_key *key);
	58
	59	#define init_rwsem(sem) \
	60	do { \
	61	static struct lock_class_key __key; \
	62	\
	63	__init_rwsem((sem), #sem, &__key); \
	64	} while (0)
	65
1da177e4 LT	66	static inline void init_rwsem(struct rw_semaphore *sem)
	67	{
	68	sem->count = RWSEM_UNLOCKED_VALUE;
	69	spin_lock_init(&sem->wait_lock);
	70	INIT_LIST_HEAD(&sem->wait_list);
1da177e4 LT	71	}
	72
	73	/*
	74	* lock for reading
	75	*/
	76	static inline void __down_read(struct rw_semaphore *sem)
	77	{
	78	if (atomic_inc_return((atomic_t *)(&sem->count)) > 0)
	79	smp_wmb();
	80	else
	81	rwsem_down_read_failed(sem);
	82	}
	83
	84	static inline int __down_read_trylock(struct rw_semaphore *sem)
	85	{
	86	int tmp;
	87
	88	while ((tmp = sem->count) >= 0) {
	89	if (tmp == cmpxchg(&sem->count, tmp,
	90	tmp + RWSEM_ACTIVE_READ_BIAS)) {
	91	smp_wmb();
	92	return 1;
	93	}
	94	}
	95	return 0;
	96	}
	97
	98	/*
	99	* lock for writing
	100	*/
	101	static inline void __down_write(struct rw_semaphore *sem)
	102	{
	103	int tmp;
	104
	105	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
	106	(atomic_t *)(&sem->count));
	107	if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
	108	smp_wmb();
	109	else
	110	rwsem_down_write_failed(sem);
	111	}
	112
	113	static inline int __down_write_trylock(struct rw_semaphore *sem)
	114	{
	115	int tmp;
	116
	117	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
	118	RWSEM_ACTIVE_WRITE_BIAS);
	119	smp_wmb();
	120	return tmp == RWSEM_UNLOCKED_VALUE;
	121	}
	122
	123	/*
	124	* unlock after reading
	125	*/
	126	static inline void __up_read(struct rw_semaphore *sem)
	127	{
	128	int tmp;
	129
	130	smp_wmb();
	131	tmp = atomic_dec_return((atomic_t *)(&sem->count));
	132	if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
	133	rwsem_wake(sem);
	134	}
135
136	/*
137	* unlock after writing
138	*/
139	static inline void __up_write(struct rw_semaphore *sem)
140	{
141	smp_wmb();
142	if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
143	(atomic_t *)(&sem->count)) < 0)
144	rwsem_wake(sem);
145	}
146
147	/*
148	* implement atomic add functionality
149	*/
150	static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
151	{
152	atomic_add(delta, (atomic_t *)(&sem->count));
153	}
154
155	/*
156	* downgrade write lock to read lock
157	*/
158	static inline void __downgrade_write(struct rw_semaphore *sem)
159	{
160	int tmp;
161
162	smp_wmb();
163	tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
164	if (tmp < 0)
165	rwsem_downgrade_wake(sem);
166	}
167
afbfb52e PM	168	static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
	169	{
	170	__down_write(sem);
	171	}
	172
1da177e4 LT	173	/*
	174	* implement exchange and add functionality
	175	*/
	176	static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
	177	{
	178	smp_mb();
	179	return atomic_add_return(delta, (atomic_t *)(&sem->count));
	180	}
	181
eb92f4ef RVR	182	static inline int rwsem_is_locked(struct rw_semaphore *sem)
	183	{
	184	return (sem->count != 0);
	185	}
	186
1da177e4 LT	187	#endif /* __KERNEL__ */
1da177e4 LT	188	#endif /* _ASM_SH_RWSEM_H */