[PATCH] lockdep: prove rwsem locking correctness
[linux-2.6.git] / kernel / rwsem.c
1 /* kernel/rwsem.c: R/W semaphores, public implementation
2  *
3  * Written by David Howells (dhowells@redhat.com).
4  * Derived from asm-i386/semaphore.h
5  */
6
7 #include <linux/types.h>
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/rwsem.h>
11
12 #include <asm/system.h>
13 #include <asm/atomic.h>
14
15 /*
16  * lock for reading
17  */
18 void down_read(struct rw_semaphore *sem)
19 {
20         might_sleep();
21         rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
22
23         __down_read(sem);
24 }
25
26 EXPORT_SYMBOL(down_read);
27
28 /*
29  * trylock for reading -- returns 1 if successful, 0 if contention
30  */
31 int down_read_trylock(struct rw_semaphore *sem)
32 {
33         int ret = __down_read_trylock(sem);
34
35         if (ret == 1)
36                 rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);
37         return ret;
38 }
39
40 EXPORT_SYMBOL(down_read_trylock);
41
42 /*
43  * lock for writing
44  */
45 void down_write(struct rw_semaphore *sem)
46 {
47         might_sleep();
48         rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
49
50         __down_write(sem);
51 }
52
53 EXPORT_SYMBOL(down_write);
54
55 /*
56  * trylock for writing -- returns 1 if successful, 0 if contention
57  */
58 int down_write_trylock(struct rw_semaphore *sem)
59 {
60         int ret = __down_write_trylock(sem);
61
62         if (ret == 1)
63                 rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
64         return ret;
65 }
66
67 EXPORT_SYMBOL(down_write_trylock);
68
69 /*
70  * release a read lock
71  */
72 void up_read(struct rw_semaphore *sem)
73 {
74         rwsem_release(&sem->dep_map, 1, _RET_IP_);
75
76         __up_read(sem);
77 }
78
79 EXPORT_SYMBOL(up_read);
80
81 /*
82  * release a write lock
83  */
84 void up_write(struct rw_semaphore *sem)
85 {
86         rwsem_release(&sem->dep_map, 1, _RET_IP_);
87
88         __up_write(sem);
89 }
90
91 EXPORT_SYMBOL(up_write);
92
93 /*
94  * downgrade write lock to read lock
95  */
96 void downgrade_write(struct rw_semaphore *sem)
97 {
98         /*
99          * lockdep: a downgraded write will live on as a write
100          * dependency.
101          */
102         __downgrade_write(sem);
103 }
104
105 EXPORT_SYMBOL(downgrade_write);
106
107 #ifdef CONFIG_DEBUG_LOCK_ALLOC
108
109 void down_read_nested(struct rw_semaphore *sem, int subclass)
110 {
111         might_sleep();
112         rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_);
113
114         __down_read(sem);
115 }
116
117 EXPORT_SYMBOL(down_read_nested);
118
119 void down_read_non_owner(struct rw_semaphore *sem)
120 {
121         might_sleep();
122
123         __down_read(sem);
124 }
125
126 EXPORT_SYMBOL(down_read_non_owner);
127
128 void down_write_nested(struct rw_semaphore *sem, int subclass)
129 {
130         might_sleep();
131         rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_);
132
133         __down_write_nested(sem, subclass);
134 }
135
136 EXPORT_SYMBOL(down_write_nested);
137
138 void up_read_non_owner(struct rw_semaphore *sem)
139 {
140         __up_read(sem);
141 }
142
143 EXPORT_SYMBOL(up_read_non_owner);
144
145 #endif
146
147