#ifndef _ASM_POWERPC_RWSEM_H#define _ASM_POWERPC_RWSEM_H #ifdef __KERNEL__ /* * include/asm-powerpc/rwsem.h: 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 */struct rw_semaphore {	/* XXX this should be able to be an atomic_t  -- paulus */	signed int		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;#if RWSEM_DEBUG	int			debug;#endif}; /* * initialisation */#if RWSEM_DEBUG#define __RWSEM_DEBUG_INIT      , 0#else#define __RWSEM_DEBUG_INIT	/* */#endif #define __RWSEM_INITIALIZER(name) \	{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \	  LIST_HEAD_INIT((name).wait_list) \	  __RWSEM_DEBUG_INIT } #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); 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);#if RWSEM_DEBUG	sem->debug = 0;#endif} /* * lock for reading */static inline void __down_read(struct rw_semaphore *sem){	if (unlikely(atomic_inc_return((atomic_t *)(&sem->count)) <= 0))		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)) {			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 (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))		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);	return tmp == RWSEM_UNLOCKED_VALUE;} /* * unlock after reading */static inline void __up_read(struct rw_semaphore *sem){	int tmp; 	tmp = atomic_dec_return((atomic_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_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; 	tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));	if (tmp < 0)		rwsem_downgrade_wake(sem);} /* * implement exchange and add functionality */static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem){	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_POWERPC_RWSEM_H */