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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 | ||
15 | #include <linux/spinlock.h> | |
16 | #include <linux/list.h> | |
17 | ||
18 | #ifdef __KERNEL__ | |
19 | ||
20 | #include <linux/types.h> | |
21 | ||
22 | struct rwsem_waiter; | |
23 | ||
24 | /* | |
25 | * the rw-semaphore definition | |
26 | * - if activity is 0 then there are no active readers or writers | |
27 | * - if activity is +ve then that is the number of active readers | |
28 | * - if activity is -1 then there is one active writer | |
29 | * - if wait_list is not empty, then there are processes waiting for the semaphore | |
30 | */ | |
31 | struct rw_semaphore { | |
32 | __s32 activity; | |
33 | spinlock_t wait_lock; | |
34 | struct list_head wait_list; | |
4ea2176d IM |
35 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
36 | struct lockdep_map dep_map; | |
37 | #endif | |
1da177e4 LT |
38 | }; |
39 | ||
4ea2176d IM |
40 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
41 | # define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname } | |
42 | #else | |
43 | # define __RWSEM_DEP_MAP_INIT(lockname) | |
44 | #endif | |
45 | ||
1da177e4 | 46 | #define __RWSEM_INITIALIZER(name) \ |
6cfd76a2 PZ |
47 | { 0, __SPIN_LOCK_UNLOCKED(name.wait_lock), LIST_HEAD_INIT((name).wait_list) \ |
48 | __RWSEM_DEP_MAP_INIT(name) } | |
1da177e4 LT |
49 | |
50 | #define DECLARE_RWSEM(name) \ | |
51 | struct rw_semaphore name = __RWSEM_INITIALIZER(name) | |
52 | ||
4ea2176d IM |
53 | extern void __init_rwsem(struct rw_semaphore *sem, const char *name, |
54 | struct lock_class_key *key); | |
55 | ||
56 | #define init_rwsem(sem) \ | |
57 | do { \ | |
58 | static struct lock_class_key __key; \ | |
59 | \ | |
60 | __init_rwsem((sem), #sem, &__key); \ | |
61 | } while (0) | |
62 | ||
b3c97528 HH |
63 | extern void __down_read(struct rw_semaphore *sem); |
64 | extern int __down_read_trylock(struct rw_semaphore *sem); | |
65 | extern void __down_write(struct rw_semaphore *sem); | |
66 | extern void __down_write_nested(struct rw_semaphore *sem, int subclass); | |
67 | extern int __down_write_trylock(struct rw_semaphore *sem); | |
68 | extern void __up_read(struct rw_semaphore *sem); | |
69 | extern void __up_write(struct rw_semaphore *sem); | |
70 | extern void __downgrade_write(struct rw_semaphore *sem); | |
29671f22 | 71 | extern int rwsem_is_locked(struct rw_semaphore *sem); |
eb92f4ef | 72 | |
1da177e4 LT |
73 | #endif /* __KERNEL__ */ |
74 | #endif /* _LINUX_RWSEM_SPINLOCK_H */ |