/* 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 <linux/linkage.h> #define RWSEM_DEBUG 0 #ifdef __KERNEL__ #include <linux/config.h> #include <linux/types.h> #include <linux/kernel.h> #include <asm/system.h> #include <asm/atomic.h> struct rw_semaphore; #ifdef CONFIG_RWSEM_GENERIC_SPINLOCK #include <linux/rwsem-spinlock.h> /* use a generic implementation */ #else #include <asm/rwsem.h> /* use an arch-specific implementation */ #endif #ifndef rwsemtrace #if RWSEM_DEBUG extern void FASTCALL(rwsemtrace(struct rw_semaphore *sem, const char *str)); #else #define rwsemtrace(SEM,FMT) #endif #endif /* * lock for reading */ static inline void down_read(struct rw_semaphore *sem) { might_sleep(); rwsemtrace(sem,"Entering down_read"); __down_read(sem); rwsemtrace(sem,"Leaving down_read"); } /* * trylock for reading -- returns 1 if successful, 0 if contention */ static inline int down_read_trylock(struct rw_semaphore *sem) { int ret; rwsemtrace(sem,"Entering down_read_trylock"); ret = __down_read_trylock(sem); rwsemtrace(sem,"Leaving down_read_trylock"); return ret; } /* * lock for writing */ static inline void down_write(struct rw_semaphore *sem) { might_sleep(); rwsemtrace(sem,"Entering down_write"); __down_write(sem); rwsemtrace(sem,"Leaving down_write"); } /* * trylock for writing -- returns 1 if successful, 0 if contention */ static inline int down_write_trylock(struct rw_semaphore *sem) { int ret; rwsemtrace(sem,"Entering down_write_trylock"); ret = __down_write_trylock(sem); rwsemtrace(sem,"Leaving down_write_trylock"); return ret; } /* * release a read lock */ static inline void up_read(struct rw_semaphore *sem) { rwsemtrace(sem,"Entering up_read"); __up_read(sem); rwsemtrace(sem,"Leaving up_read"); } /* * release a write lock */ static inline void up_write(struct rw_semaphore *sem) { rwsemtrace(sem,"Entering up_write"); __up_write(sem); rwsemtrace(sem,"Leaving up_write"); } /* * downgrade write lock to read lock */ static inline void downgrade_write(struct rw_semaphore *sem) { rwsemtrace(sem,"Entering downgrade_write"); __downgrade_write(sem); rwsemtrace(sem,"Leaving downgrade_write"); } #endif /* __KERNEL__ */ #endif /* _LINUX_RWSEM_H */