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1da177e4 LT |
1 | /* rwsem-spinlock.h: fallback C implementation |
2 | * | |
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 | |
6 | */ | |
7 | ||
8 | #ifndef _LINUX_RWSEM_SPINLOCK_H | |
9 | #define _LINUX_RWSEM_SPINLOCK_H | |
10 | ||
11 | #ifndef _LINUX_RWSEM_H | |
12 | #error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead" | |
13 | #endif | |
14 | ||
1da177e4 | 15 | #ifdef __KERNEL__ |
1da177e4 LT |
16 | /* |
17 | * the rw-semaphore definition | |
13b9a962 PZ |
18 | * - if count is 0 then there are no active readers or writers |
19 | * - if count is +ve then that is the number of active readers | |
20 | * - if count is -1 then there is one active writer | |
1da177e4 LT |
21 | * - if wait_list is not empty, then there are processes waiting for the semaphore |
22 | */ | |
23 | struct rw_semaphore { | |
13b9a962 | 24 | __s32 count; |
ddb6c9b5 | 25 | raw_spinlock_t wait_lock; |
1da177e4 | 26 | struct list_head wait_list; |
4ea2176d IM |
27 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
28 | struct lockdep_map dep_map; | |
29 | #endif | |
1da177e4 LT |
30 | }; |
31 | ||
12249b34 | 32 | #define RWSEM_UNLOCKED_VALUE 0x00000000 |
4ea2176d | 33 | |
b3c97528 HH |
34 | extern void __down_read(struct rw_semaphore *sem); |
35 | extern int __down_read_trylock(struct rw_semaphore *sem); | |
36 | extern void __down_write(struct rw_semaphore *sem); | |
d4799608 | 37 | extern int __must_check __down_write_killable(struct rw_semaphore *sem); |
b3c97528 HH |
38 | extern int __down_write_trylock(struct rw_semaphore *sem); |
39 | extern void __up_read(struct rw_semaphore *sem); | |
40 | extern void __up_write(struct rw_semaphore *sem); | |
41 | extern void __downgrade_write(struct rw_semaphore *sem); | |
29671f22 | 42 | extern int rwsem_is_locked(struct rw_semaphore *sem); |
eb92f4ef | 43 | |
1da177e4 LT |
44 | #endif /* __KERNEL__ */ |
45 | #endif /* _LINUX_RWSEM_SPINLOCK_H */ |