1 /* rwsem-spinlock.h: fallback C implementation
3 * Copyright (c) 2001 David Howells (dhowells@redhat.com).
4 * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de>
5 * - Derived also from comments by Linus
7 * Trylock by Brian Watson (Brian.J.Watson@compaq.com).
10 #ifndef _LINUX_RWSEM_SPINLOCK_H
11 #define _LINUX_RWSEM_SPINLOCK_H
13 #ifndef _LINUX_RWSEM_H
14 #error please dont include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead
17 #include <linux/spinlock.h>
18 #include <linux/list.h>
22 #include <linux/types.h>
27 * the rw-semaphore definition
28 * - if activity is 0 then there are no active readers or writers
29 * - if activity is +ve then that is the number of active readers
30 * - if activity is -1 then there is one active writer
31 * - if wait_list is not empty, then there are processes waiting for the semaphore
36 struct list_head wait_list;
46 #define __RWSEM_DEBUG_INIT , 0
48 #define __RWSEM_DEBUG_INIT /* */
51 #define __RWSEM_INITIALIZER(name) \
52 { 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT }
54 #define DECLARE_RWSEM(name) \
55 struct rw_semaphore name = __RWSEM_INITIALIZER(name)
57 extern void FASTCALL(init_rwsem(struct rw_semaphore *sem));
58 extern void FASTCALL(__down_read(struct rw_semaphore *sem));
59 extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem));
60 extern void FASTCALL(__down_write(struct rw_semaphore *sem));
61 extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem));
62 extern void FASTCALL(__up_read(struct rw_semaphore *sem));
63 extern void FASTCALL(__up_write(struct rw_semaphore *sem));
65 #endif /* __KERNEL__ */
66 #endif /* _LINUX_RWSEM_SPINLOCK_H */