/* $Id: rwsem.h,v 1.5 2001/11/18 00:12:56 davem Exp $ * rwsem.h: R/W semaphores implemented using CAS * * Written by David S. Miller (davem@redhat.com), 2001. * Derived from asm-i386/rwsem.h */ #ifndef _SPARC64_RWSEM_H #define _SPARC64_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/rwsem-const.h> struct rwsem_waiter; struct rw_semaphore { signed int count; 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); } extern void __down_read(struct rw_semaphore *sem); extern int __down_read_trylock(struct rw_semaphore *sem); extern void __down_write(struct rw_semaphore *sem); extern int __down_write_trylock(struct rw_semaphore *sem); extern void __up_read(struct rw_semaphore *sem); extern void __up_write(struct rw_semaphore *sem); extern void __downgrade_write(struct rw_semaphore *sem); static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem) { return atomic_add_return(delta, (atomic_t *)(&sem->count)); } static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem) { atomic_add(delta, (atomic_t *)(&sem->count)); } static inline int rwsem_is_locked(struct rw_semaphore *sem) { return (sem->count != 0); } #endif /* __KERNEL__ */ #endif /* _SPARC64_RWSEM_H */