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c4e05116 IM |
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> | |
c7af77b5 | 9 | #include <linux/sched.h> |
b17b0153 | 10 | #include <linux/sched/debug.h> |
9984de1a | 11 | #include <linux/export.h> |
c4e05116 | 12 | #include <linux/rwsem.h> |
60063497 | 13 | #include <linux/atomic.h> |
c4e05116 | 14 | |
7a215f89 | 15 | #include "rwsem.h" |
4fc828e2 | 16 | |
c4e05116 IM |
17 | /* |
18 | * lock for reading | |
19 | */ | |
c7af77b5 | 20 | void __sched down_read(struct rw_semaphore *sem) |
c4e05116 IM |
21 | { |
22 | might_sleep(); | |
23 | rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_); | |
24 | ||
4fe87745 | 25 | LOCK_CONTENDED(sem, __down_read_trylock, __down_read); |
19c5d690 | 26 | rwsem_set_reader_owned(sem); |
c4e05116 IM |
27 | } |
28 | ||
29 | EXPORT_SYMBOL(down_read); | |
30 | ||
31 | /* | |
32 | * trylock for reading -- returns 1 if successful, 0 if contention | |
33 | */ | |
34 | int down_read_trylock(struct rw_semaphore *sem) | |
35 | { | |
36 | int ret = __down_read_trylock(sem); | |
37 | ||
19c5d690 | 38 | if (ret == 1) { |
c4e05116 | 39 | rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_); |
19c5d690 WL |
40 | rwsem_set_reader_owned(sem); |
41 | } | |
c4e05116 IM |
42 | return ret; |
43 | } | |
44 | ||
45 | EXPORT_SYMBOL(down_read_trylock); | |
46 | ||
47 | /* | |
48 | * lock for writing | |
49 | */ | |
c7af77b5 | 50 | void __sched down_write(struct rw_semaphore *sem) |
c4e05116 IM |
51 | { |
52 | might_sleep(); | |
53 | rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); | |
54 | ||
4fe87745 | 55 | LOCK_CONTENDED(sem, __down_write_trylock, __down_write); |
4fc828e2 | 56 | rwsem_set_owner(sem); |
c4e05116 IM |
57 | } |
58 | ||
59 | EXPORT_SYMBOL(down_write); | |
60 | ||
916633a4 MH |
61 | /* |
62 | * lock for writing | |
63 | */ | |
64 | int __sched down_write_killable(struct rw_semaphore *sem) | |
65 | { | |
66 | might_sleep(); | |
67 | rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); | |
68 | ||
69 | if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock, __down_write_killable)) { | |
70 | rwsem_release(&sem->dep_map, 1, _RET_IP_); | |
71 | return -EINTR; | |
72 | } | |
73 | ||
74 | rwsem_set_owner(sem); | |
75 | return 0; | |
76 | } | |
77 | ||
78 | EXPORT_SYMBOL(down_write_killable); | |
79 | ||
c4e05116 IM |
80 | /* |
81 | * trylock for writing -- returns 1 if successful, 0 if contention | |
82 | */ | |
83 | int down_write_trylock(struct rw_semaphore *sem) | |
84 | { | |
85 | int ret = __down_write_trylock(sem); | |
86 | ||
4fc828e2 | 87 | if (ret == 1) { |
428e6ce0 | 88 | rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_); |
4fc828e2 DB |
89 | rwsem_set_owner(sem); |
90 | } | |
91 | ||
c4e05116 IM |
92 | return ret; |
93 | } | |
94 | ||
95 | EXPORT_SYMBOL(down_write_trylock); | |
96 | ||
97 | /* | |
98 | * release a read lock | |
99 | */ | |
100 | void up_read(struct rw_semaphore *sem) | |
101 | { | |
102 | rwsem_release(&sem->dep_map, 1, _RET_IP_); | |
103 | ||
104 | __up_read(sem); | |
105 | } | |
106 | ||
107 | EXPORT_SYMBOL(up_read); | |
108 | ||
109 | /* | |
110 | * release a write lock | |
111 | */ | |
112 | void up_write(struct rw_semaphore *sem) | |
113 | { | |
114 | rwsem_release(&sem->dep_map, 1, _RET_IP_); | |
115 | ||
4fc828e2 | 116 | rwsem_clear_owner(sem); |
c4e05116 IM |
117 | __up_write(sem); |
118 | } | |
119 | ||
120 | EXPORT_SYMBOL(up_write); | |
121 | ||
122 | /* | |
123 | * downgrade write lock to read lock | |
124 | */ | |
125 | void downgrade_write(struct rw_semaphore *sem) | |
126 | { | |
6419c4af O |
127 | lock_downgrade(&sem->dep_map, _RET_IP_); |
128 | ||
19c5d690 | 129 | rwsem_set_reader_owned(sem); |
c4e05116 IM |
130 | __downgrade_write(sem); |
131 | } | |
132 | ||
133 | EXPORT_SYMBOL(downgrade_write); | |
4ea2176d IM |
134 | |
135 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
136 | ||
137 | void down_read_nested(struct rw_semaphore *sem, int subclass) | |
138 | { | |
139 | might_sleep(); | |
140 | rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_); | |
141 | ||
4fe87745 | 142 | LOCK_CONTENDED(sem, __down_read_trylock, __down_read); |
19c5d690 | 143 | rwsem_set_reader_owned(sem); |
4ea2176d IM |
144 | } |
145 | ||
146 | EXPORT_SYMBOL(down_read_nested); | |
147 | ||
1b963c81 JK |
148 | void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest) |
149 | { | |
150 | might_sleep(); | |
151 | rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_); | |
152 | ||
153 | LOCK_CONTENDED(sem, __down_write_trylock, __down_write); | |
4fc828e2 | 154 | rwsem_set_owner(sem); |
1b963c81 JK |
155 | } |
156 | ||
157 | EXPORT_SYMBOL(_down_write_nest_lock); | |
158 | ||
84759c6d KO |
159 | void down_read_non_owner(struct rw_semaphore *sem) |
160 | { | |
161 | might_sleep(); | |
162 | ||
163 | __down_read(sem); | |
164 | } | |
165 | ||
166 | EXPORT_SYMBOL(down_read_non_owner); | |
167 | ||
4ea2176d IM |
168 | void down_write_nested(struct rw_semaphore *sem, int subclass) |
169 | { | |
170 | might_sleep(); | |
171 | rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_); | |
172 | ||
4fe87745 | 173 | LOCK_CONTENDED(sem, __down_write_trylock, __down_write); |
4fc828e2 | 174 | rwsem_set_owner(sem); |
4ea2176d IM |
175 | } |
176 | ||
177 | EXPORT_SYMBOL(down_write_nested); | |
178 | ||
887bddfa AV |
179 | int __sched down_write_killable_nested(struct rw_semaphore *sem, int subclass) |
180 | { | |
181 | might_sleep(); | |
182 | rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_); | |
183 | ||
184 | if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock, __down_write_killable)) { | |
185 | rwsem_release(&sem->dep_map, 1, _RET_IP_); | |
186 | return -EINTR; | |
187 | } | |
188 | ||
189 | rwsem_set_owner(sem); | |
190 | return 0; | |
191 | } | |
192 | ||
193 | EXPORT_SYMBOL(down_write_killable_nested); | |
194 | ||
84759c6d KO |
195 | void up_read_non_owner(struct rw_semaphore *sem) |
196 | { | |
197 | __up_read(sem); | |
198 | } | |
199 | ||
200 | EXPORT_SYMBOL(up_read_non_owner); | |
201 | ||
4ea2176d IM |
202 | #endif |
203 | ||
204 |