#ifndef _ALPHA_RWSEM_H#define _ALPHA_RWSEM_H /* * Written by Ivan Kokshaysky <ink@jurassic.park.msu.ru>, 2001. * Based on asm-alpha/semaphore.h and asm-i386/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/compiler.h>#include <linux/list.h>#include <linux/spinlock.h> struct rwsem_waiter; 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 *);extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem); /* * the semaphore definition */struct rw_semaphore {	long			count;#define RWSEM_UNLOCKED_VALUE		0x0000000000000000L#define RWSEM_ACTIVE_BIAS		0x0000000000000001L#define RWSEM_ACTIVE_MASK		0x00000000ffffffffL#define RWSEM_WAITING_BIAS		(-0x0000000100000000L)#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;}; #define __RWSEM_INITIALIZER(name) \	{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \	LIST_HEAD_INIT((name).wait_list) } #define DECLARE_RWSEM(name) \	struct rw_semaphore name = __RWSEM_INITIALIZER(name) 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);} static inline void __down_read(struct rw_semaphore *sem){	long oldcount;#ifndef	CONFIG_SMP	oldcount = sem->count;	sem->count += RWSEM_ACTIVE_READ_BIAS;#else	long temp;	__asm__ __volatile__(	"1:	ldq_l	%0,%1\n"	"	addq	%0,%3,%2\n"	"	stq_c	%2,%1\n"	"	beq	%2,2f\n"	"	mb\n"	".subsection 2\n"	"2:	br	1b\n"	".previous"	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)	:"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");#endif	if (unlikely(oldcount < 0))		rwsem_down_read_failed(sem);} /* * trylock for reading -- returns 1 if successful, 0 if contention */static inline int __down_read_trylock(struct rw_semaphore *sem){	long old, new, res; 	res = sem->count;	do {		new = res + RWSEM_ACTIVE_READ_BIAS;		if (new <= 0)			break;		old = res;		res = cmpxchg(&sem->count, old, new);	} while (res != old);	return res >= 0 ? 1 : 0;} static inline void __down_write(struct rw_semaphore *sem){	long oldcount;#ifndef	CONFIG_SMP	oldcount = sem->count;	sem->count += RWSEM_ACTIVE_WRITE_BIAS;#else	long temp;	__asm__ __volatile__(	"1:	ldq_l	%0,%1\n"	"	addq	%0,%3,%2\n"	"	stq_c	%2,%1\n"	"	beq	%2,2f\n"	"	mb\n"	".subsection 2\n"	"2:	br	1b\n"	".previous"	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)	:"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");#endif	if (unlikely(oldcount))		rwsem_down_write_failed(sem);} /* * trylock for writing -- returns 1 if successful, 0 if contention */static inline int __down_write_trylock(struct rw_semaphore *sem){	long ret = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,			   RWSEM_ACTIVE_WRITE_BIAS);	if (ret == RWSEM_UNLOCKED_VALUE)		return 1;	return 0;} static inline void __up_read(struct rw_semaphore *sem){	long oldcount;#ifndef	CONFIG_SMP	oldcount = sem->count;	sem->count -= RWSEM_ACTIVE_READ_BIAS;#else	long temp;	__asm__ __volatile__(	"	mb\n"	"1:	ldq_l	%0,%1\n"	"	subq	%0,%3,%2\n"	"	stq_c	%2,%1\n"	"	beq	%2,2f\n"	".subsection 2\n"	"2:	br	1b\n"	".previous"	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)	:"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");#endif	if (unlikely(oldcount < 0))		if ((int)oldcount - RWSEM_ACTIVE_READ_BIAS == 0)			rwsem_wake(sem);} static inline void __up_write(struct rw_semaphore *sem){	long count;#ifndef	CONFIG_SMP	sem->count -= RWSEM_ACTIVE_WRITE_BIAS;	count = sem->count;#else	long temp;	__asm__ __volatile__(	"	mb\n"	"1:	ldq_l	%0,%1\n"	"	subq	%0,%3,%2\n"	"	stq_c	%2,%1\n"	"	beq	%2,2f\n"	"	subq	%0,%3,%0\n"	".subsection 2\n"	"2:	br	1b\n"	".previous"	:"=&r" (count), "=m" (sem->count), "=&r" (temp)	:"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");#endif	if (unlikely(count))		if ((int)count == 0)			rwsem_wake(sem);} /* * downgrade write lock to read lock */static inline void __downgrade_write(struct rw_semaphore *sem){	long oldcount;#ifndef	CONFIG_SMP	oldcount = sem->count;	sem->count -= RWSEM_WAITING_BIAS;#else	long temp;	__asm__ __volatile__(	"1:	ldq_l	%0,%1\n"	"	addq	%0,%3,%2\n"	"	stq_c	%2,%1\n"	"	beq	%2,2f\n"	"	mb\n"	".subsection 2\n"	"2:	br	1b\n"	".previous"	:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)	:"Ir" (-RWSEM_WAITING_BIAS), "m" (sem->count) : "memory");#endif	if (unlikely(oldcount < 0))		rwsem_downgrade_wake(sem);} static inline void rwsem_atomic_add(long val, struct rw_semaphore *sem){#ifndef	CONFIG_SMP	sem->count += val;#else	long temp;	__asm__ __volatile__(	"1:	ldq_l	%0,%1\n"	"	addq	%0,%2,%0\n"	"	stq_c	%0,%1\n"	"	beq	%0,2f\n"	".subsection 2\n"	"2:	br	1b\n"	".previous"	:"=&r" (temp), "=m" (sem->count)	:"Ir" (val), "m" (sem->count));#endif} static inline long rwsem_atomic_update(long val, struct rw_semaphore *sem){#ifndef	CONFIG_SMP	sem->count += val;	return sem->count;#else	long ret, temp;	__asm__ __volatile__(	"1:	ldq_l	%0,%1\n"	"	addq 	%0,%3,%2\n"	"	addq	%0,%3,%0\n"	"	stq_c	%2,%1\n"	"	beq	%2,2f\n"	".subsection 2\n"	"2:	br	1b\n"	".previous"	:"=&r" (ret), "=m" (sem->count), "=&r" (temp)	:"Ir" (val), "m" (sem->count)); 	return ret;#endif} static inline int rwsem_is_locked(struct rw_semaphore *sem){	return (sem->count != 0);} #endif /* __KERNEL__ */#endif /* _ALPHA_RWSEM_H */