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

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

#ifndef _ASM_SH_RWSEM_H
#define _ASM_SH_RWSEM_H

#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 LT	1	/*
	2	* include/asm-ppc/rwsem.h: R/W semaphores for SH using the stuff
	3	* in lib/rwsem.c.
	4	*/
	5
	6	#ifndef _ASM_SH_RWSEM_H
	7	#define _ASM_SH_RWSEM_H
	8
	9	#ifdef __KERNEL__
	10	#include <linux/list.h>
	11	#include <linux/spinlock.h>
	12	#include <asm/atomic.h>
	13	#include <asm/system.h>
	14
	15	/*
	16	* the semaphore definition
	17	*/
	18	struct rw_semaphore {
	19	long count;
	20	#define RWSEM_UNLOCKED_VALUE 0x00000000
	21	#define RWSEM_ACTIVE_BIAS 0x00000001
	22	#define RWSEM_ACTIVE_MASK 0x0000ffff
	23	#define RWSEM_WAITING_BIAS (-0x00010000)
	24	#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
	25	#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
	26	spinlock_t wait_lock;
	27	struct list_head wait_list;
afbfb52e PM	28	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	29	struct lockdep_map dep_map;
	30	#endif
1da177e4 LT	31	};
1da177e4 LT	32
afbfb52e PM	33	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	34	# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
	35	#else
	36	# define __RWSEM_DEP_MAP_INIT(lockname)
	37	#endif
	38
1da177e4 LT	39	#define __RWSEM_INITIALIZER(name) \
1da177e4 LT	40	{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \
afbfb52e PM	41	LIST_HEAD_INIT((name).wait_list) \
afbfb52e PM	42	__RWSEM_DEP_MAP_INIT(name) }
1da177e4 LT	43
	44	#define DECLARE_RWSEM(name) \
	45	struct rw_semaphore name = __RWSEM_INITIALIZER(name)
	46
	47	extern struct rw_semaphore rwsem_down_read_failed(struct rw_semaphore sem);
	48	extern struct rw_semaphore rwsem_down_write_failed(struct rw_semaphore sem);
	49	extern struct rw_semaphore rwsem_wake(struct rw_semaphore sem);
	50	extern struct rw_semaphore rwsem_downgrade_wake(struct rw_semaphore sem);
	51
afbfb52e PM	52	extern void __init_rwsem(struct rw_semaphore sem, const char name,
	53	struct lock_class_key *key);
	54
	55	#define init_rwsem(sem) \
	56	do { \
	57	static struct lock_class_key __key; \
	58	\
	59	__init_rwsem((sem), #sem, &__key); \
	60	} while (0)
	61
1da177e4 LT	62	static inline void init_rwsem(struct rw_semaphore *sem)
	63	{
	64	sem->count = RWSEM_UNLOCKED_VALUE;
	65	spin_lock_init(&sem->wait_lock);
	66	INIT_LIST_HEAD(&sem->wait_list);
1da177e4 LT	67	}
	68
	69	/*
	70	* lock for reading
	71	*/
	72	static inline void __down_read(struct rw_semaphore *sem)
	73	{
	74	if (atomic_inc_return((atomic_t *)(&sem->count)) > 0)
	75	smp_wmb();
	76	else
	77	rwsem_down_read_failed(sem);
	78	}
	79
	80	static inline int __down_read_trylock(struct rw_semaphore *sem)
	81	{
	82	int tmp;
	83
	84	while ((tmp = sem->count) >= 0) {
	85	if (tmp == cmpxchg(&sem->count, tmp,
	86	tmp + RWSEM_ACTIVE_READ_BIAS)) {
	87	smp_wmb();
	88	return 1;
	89	}
	90	}
	91	return 0;
	92	}
	93
	94	/*
	95	* lock for writing
	96	*/
	97	static inline void __down_write(struct rw_semaphore *sem)
	98	{
	99	int tmp;
	100
	101	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
	102	(atomic_t *)(&sem->count));
	103	if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
	104	smp_wmb();
	105	else
	106	rwsem_down_write_failed(sem);
	107	}
	108
	109	static inline int __down_write_trylock(struct rw_semaphore *sem)
	110	{
	111	int tmp;
	112
	113	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
	114	RWSEM_ACTIVE_WRITE_BIAS);
	115	smp_wmb();
	116	return tmp == RWSEM_UNLOCKED_VALUE;
	117	}
	118
	119	/*
	120	* unlock after reading
	121	*/
	122	static inline void __up_read(struct rw_semaphore *sem)
	123	{
	124	int tmp;
	125
	126	smp_wmb();
	127	tmp = atomic_dec_return((atomic_t *)(&sem->count));
	128	if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
	129	rwsem_wake(sem);
	130	}
131
132	/*
133	* unlock after writing
134	*/
135	static inline void __up_write(struct rw_semaphore *sem)
136	{
137	smp_wmb();
138	if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
139	(atomic_t *)(&sem->count)) < 0)
140	rwsem_wake(sem);
141	}
142
143	/*
144	* implement atomic add functionality
145	*/
146	static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
147	{
148	atomic_add(delta, (atomic_t *)(&sem->count));
149	}
150
151	/*
152	* downgrade write lock to read lock
153	*/
154	static inline void __downgrade_write(struct rw_semaphore *sem)
155	{
156	int tmp;
157
158	smp_wmb();
159	tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
160	if (tmp < 0)
161	rwsem_downgrade_wake(sem);
162	}
163
afbfb52e PM	164	static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
	165	{
	166	__down_write(sem);
	167	}
	168
1da177e4 LT	169	/*
	170	* implement exchange and add functionality
	171	*/
	172	static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
	173	{
	174	smp_mb();
	175	return atomic_add_return(delta, (atomic_t *)(&sem->count));
	176	}
	177
eb92f4ef RVR	178	static inline int rwsem_is_locked(struct rw_semaphore *sem)
	179	{
	180	return (sem->count != 0);
	181	}
	182
1da177e4 LT	183	#endif /* __KERNEL__ */
1da177e4 LT	184	#endif /* _ASM_SH_RWSEM_H */