Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * include/asm-ppc/rwsem.h: R/W semaphores for SH using the stuff | |
3 | * in lib/rwsem.c. | |
4 | */ | |
5 | ||
6 | #ifndef _ASM_SH_RWSEM_H | |
7 | #define _ASM_SH_RWSEM_H | |
8 | ||
9 | #ifdef __KERNEL__ | |
10 | #include <linux/list.h> | |
11 | #include <linux/spinlock.h> | |
12 | #include <asm/atomic.h> | |
13 | #include <asm/system.h> | |
14 | ||
15 | /* | |
16 | * the semaphore definition | |
17 | */ | |
18 | struct rw_semaphore { | |
19 | long count; | |
20 | #define RWSEM_UNLOCKED_VALUE 0x00000000 | |
21 | #define RWSEM_ACTIVE_BIAS 0x00000001 | |
22 | #define RWSEM_ACTIVE_MASK 0x0000ffff | |
23 | #define RWSEM_WAITING_BIAS (-0x00010000) | |
24 | #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS | |
25 | #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) | |
26 | spinlock_t wait_lock; | |
27 | struct list_head wait_list; | |
afbfb52e PM |
28 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
29 | struct lockdep_map dep_map; | |
30 | #endif | |
1da177e4 LT |
31 | }; |
32 | ||
afbfb52e PM |
33 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
34 | # define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname } | |
35 | #else | |
36 | # define __RWSEM_DEP_MAP_INIT(lockname) | |
37 | #endif | |
38 | ||
1da177e4 LT |
39 | #define __RWSEM_INITIALIZER(name) \ |
40 | { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \ | |
afbfb52e PM |
41 | LIST_HEAD_INIT((name).wait_list) \ |
42 | __RWSEM_DEP_MAP_INIT(name) } | |
1da177e4 LT |
43 | |
44 | #define DECLARE_RWSEM(name) \ | |
45 | struct rw_semaphore name = __RWSEM_INITIALIZER(name) | |
46 | ||
47 | extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem); | |
48 | extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem); | |
49 | extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem); | |
50 | extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem); | |
51 | ||
afbfb52e PM |
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 | static inline void init_rwsem(struct rw_semaphore *sem) |
63 | { | |
64 | sem->count = RWSEM_UNLOCKED_VALUE; | |
65 | spin_lock_init(&sem->wait_lock); | |
66 | INIT_LIST_HEAD(&sem->wait_list); | |
1da177e4 LT |
67 | } |
68 | ||
69 | /* | |
70 | * lock for reading | |
71 | */ | |
72 | static inline void __down_read(struct rw_semaphore *sem) | |
73 | { | |
74 | if (atomic_inc_return((atomic_t *)(&sem->count)) > 0) | |
75 | smp_wmb(); | |
76 | else | |
77 | rwsem_down_read_failed(sem); | |
78 | } | |
79 | ||
80 | static inline int __down_read_trylock(struct rw_semaphore *sem) | |
81 | { | |
82 | int tmp; | |
83 | ||
84 | while ((tmp = sem->count) >= 0) { | |
85 | if (tmp == cmpxchg(&sem->count, tmp, | |
86 | tmp + RWSEM_ACTIVE_READ_BIAS)) { | |
87 | smp_wmb(); | |
88 | return 1; | |
89 | } | |
90 | } | |
91 | return 0; | |
92 | } | |
93 | ||
94 | /* | |
95 | * lock for writing | |
96 | */ | |
97 | static inline void __down_write(struct rw_semaphore *sem) | |
98 | { | |
99 | int tmp; | |
100 | ||
101 | tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS, | |
102 | (atomic_t *)(&sem->count)); | |
103 | if (tmp == RWSEM_ACTIVE_WRITE_BIAS) | |
104 | smp_wmb(); | |
105 | else | |
106 | rwsem_down_write_failed(sem); | |
107 | } | |
108 | ||
109 | static inline int __down_write_trylock(struct rw_semaphore *sem) | |
110 | { | |
111 | int tmp; | |
112 | ||
113 | tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE, | |
114 | RWSEM_ACTIVE_WRITE_BIAS); | |
115 | smp_wmb(); | |
116 | return tmp == RWSEM_UNLOCKED_VALUE; | |
117 | } | |
118 | ||
119 | /* | |
120 | * unlock after reading | |
121 | */ | |
122 | static inline void __up_read(struct rw_semaphore *sem) | |
123 | { | |
124 | int tmp; | |
125 | ||
126 | smp_wmb(); | |
127 | tmp = atomic_dec_return((atomic_t *)(&sem->count)); | |
128 | if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0) | |
129 | rwsem_wake(sem); | |
130 | } | |
131 | ||
132 | /* | |
133 | * unlock after writing | |
134 | */ | |
135 | static inline void __up_write(struct rw_semaphore *sem) | |
136 | { | |
137 | smp_wmb(); | |
138 | if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS, | |
139 | (atomic_t *)(&sem->count)) < 0) | |
140 | rwsem_wake(sem); | |
141 | } | |
142 | ||
143 | /* | |
144 | * implement atomic add functionality | |
145 | */ | |
146 | static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem) | |
147 | { | |
148 | atomic_add(delta, (atomic_t *)(&sem->count)); | |
149 | } | |
150 | ||
151 | /* | |
152 | * downgrade write lock to read lock | |
153 | */ | |
154 | static inline void __downgrade_write(struct rw_semaphore *sem) | |
155 | { | |
156 | int tmp; | |
157 | ||
158 | smp_wmb(); | |
159 | tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count)); | |
160 | if (tmp < 0) | |
161 | rwsem_downgrade_wake(sem); | |
162 | } | |
163 | ||
afbfb52e PM |
164 | static inline void __down_write_nested(struct rw_semaphore *sem, int subclass) |
165 | { | |
166 | __down_write(sem); | |
167 | } | |
168 | ||
1da177e4 LT |
169 | /* |
170 | * implement exchange and add functionality | |
171 | */ | |
172 | static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem) | |
173 | { | |
174 | smp_mb(); | |
175 | return atomic_add_return(delta, (atomic_t *)(&sem->count)); | |
176 | } | |
177 | ||
eb92f4ef RVR |
178 | static inline int rwsem_is_locked(struct rw_semaphore *sem) |
179 | { | |
180 | return (sem->count != 0); | |
181 | } | |
182 | ||
1da177e4 LT |
183 | #endif /* __KERNEL__ */ |
184 | #endif /* _ASM_SH_RWSEM_H */ |