/* rwsem-spinlock.h: fallback C implementation * * Copyright (c) 2001 David Howells (dhowells@redhat.com). * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de> * - Derived also from comments by Linus */ #ifndef _LINUX_RWSEM_SPINLOCK_H #define _LINUX_RWSEM_SPINLOCK_H #ifndef _LINUX_RWSEM_H #error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead" #endif #include <linux/spinlock.h> #include <linux/list.h> #ifdef __KERNEL__ #include <linux/types.h> struct rwsem_waiter; /* * the rw-semaphore definition * - if activity is 0 then there are no active readers or writers * - if activity is +ve then that is the number of active readers * - if activity is -1 then there is one active writer * - if wait_list is not empty, then there are processes waiting for the semaphore */ struct rw_semaphore { __s32 activity; 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) \ { 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT } #define DECLARE_RWSEM(name) \ struct rw_semaphore name = __RWSEM_INITIALIZER(name) extern void FASTCALL(init_rwsem(struct rw_semaphore *sem)); extern void FASTCALL(__down_read(struct rw_semaphore *sem)); extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem)); extern void FASTCALL(__down_write(struct rw_semaphore *sem)); extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem)); extern void FASTCALL(__up_read(struct rw_semaphore *sem)); extern void FASTCALL(__up_write(struct rw_semaphore *sem)); extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem)); #endif /* __KERNEL__ */ #endif /* _LINUX_RWSEM_SPINLOCK_H */