/* rwsem.h: R/W semaphores, public interface * * Written by David Howells (dhowells@redhat.com). * Derived from asm-i386/semaphore.h */ #ifndef _LINUX_RWSEM_H #define _LINUX_RWSEM_H #include #ifdef __KERNEL__ #include #include #include #include struct rw_semaphore; #ifdef CONFIG_RWSEM_GENERIC_SPINLOCK #include /* use a generic implementation */ #else #include /* use an arch-specific implementation */ #endif /* * lock for reading */ static inline void down_read(struct rw_semaphore *sem) { might_sleep(); __down_read(sem); } /* * trylock for reading -- returns 1 if successful, 0 if contention */ static inline int down_read_trylock(struct rw_semaphore *sem) { int ret; ret = __down_read_trylock(sem); return ret; } /* * lock for writing */ static inline void down_write(struct rw_semaphore *sem) { might_sleep(); __down_write(sem); } /* * trylock for writing -- returns 1 if successful, 0 if contention */ static inline int down_write_trylock(struct rw_semaphore *sem) { int ret; ret = __down_write_trylock(sem); return ret; } /* * release a read lock */ static inline void up_read(struct rw_semaphore *sem) { __up_read(sem); } /* * release a write lock */ static inline void up_write(struct rw_semaphore *sem) { __up_write(sem); } /* * downgrade write lock to read lock */ static inline void downgrade_write(struct rw_semaphore *sem) { __downgrade_write(sem); } #endif /* __KERNEL__ */ #endif /* _LINUX_RWSEM_H */