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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) \ |
4ea2176d | 47 | { 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEP_MAP_INIT(name) } |
1da177e4 LT |
48 | |
49 | #define DECLARE_RWSEM(name) \ | |
50 | struct rw_semaphore name = __RWSEM_INITIALIZER(name) | |
51 | ||
4ea2176d IM |
52 | extern void __init_rwsem(struct rw_semaphore *sem, const char *name, |
53 | struct lock_class_key *key); | |
54 | ||
55 | #define init_rwsem(sem) \ | |
56 | do { \ | |
57 | static struct lock_class_key __key; \ | |
58 | \ | |
59 | __init_rwsem((sem), #sem, &__key); \ | |
60 | } while (0) | |
61 | ||
1da177e4 LT |
62 | extern void FASTCALL(__down_read(struct rw_semaphore *sem)); |
63 | extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem)); | |
64 | extern void FASTCALL(__down_write(struct rw_semaphore *sem)); | |
4ea2176d | 65 | extern void FASTCALL(__down_write_nested(struct rw_semaphore *sem, int subclass)); |
1da177e4 LT |
66 | extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem)); |
67 | extern void FASTCALL(__up_read(struct rw_semaphore *sem)); | |
68 | extern void FASTCALL(__up_write(struct rw_semaphore *sem)); | |
69 | extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem)); | |
70 | ||
eb92f4ef RVR |
71 | static inline int rwsem_is_locked(struct rw_semaphore *sem) |
72 | { | |
73 | return (sem->activity != 0); | |
74 | } | |
75 | ||
1da177e4 LT |
76 | #endif /* __KERNEL__ */ |
77 | #endif /* _LINUX_RWSEM_SPINLOCK_H */ |