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5b88fdd9 SF |
1 | /* |
2 | * Copyright (C) 2005-2016 Junjiro R. Okajima | |
3 | * | |
4 | * This program, aufs is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
16 | */ | |
17 | ||
18 | /* | |
19 | * simple read-write semaphore wrappers | |
20 | */ | |
21 | ||
22 | #ifndef __AUFS_RWSEM_H__ | |
23 | #define __AUFS_RWSEM_H__ | |
24 | ||
25 | #ifdef __KERNEL__ | |
26 | ||
27 | #include "debug.h" | |
28 | ||
29 | struct au_rwsem { | |
30 | struct rw_semaphore rwsem; | |
31 | #ifdef CONFIG_AUFS_DEBUG | |
32 | /* just for debugging, not almighty counter */ | |
33 | atomic_t rcnt, wcnt; | |
34 | #endif | |
35 | }; | |
36 | ||
37 | #ifdef CONFIG_LOCKDEP | |
38 | #define au_lockdep_set_name(rw) \ | |
39 | lockdep_set_class_and_name(&(rw)->rwsem, \ | |
40 | /*original key*/(rw)->rwsem.dep_map.key, \ | |
41 | /*name*/#rw) | |
42 | #else | |
43 | #define au_lockdep_set_name(rw) do {} while (0) | |
44 | #endif | |
45 | ||
46 | #ifdef CONFIG_AUFS_DEBUG | |
47 | #define AuDbgCntInit(rw) do { \ | |
48 | atomic_set(&(rw)->rcnt, 0); \ | |
49 | atomic_set(&(rw)->wcnt, 0); \ | |
50 | smp_mb(); /* atomic set */ \ | |
51 | } while (0) | |
52 | ||
53 | #define AuDbgCnt(rw, cnt) atomic_read(&(rw)->cnt) | |
54 | #define AuDbgCntInc(rw, cnt) atomic_inc(&(rw)->cnt) | |
55 | #define AuDbgCntDec(rw, cnt) WARN_ON(atomic_dec_return(&(rw)->cnt) < 0) | |
56 | #define AuDbgRcntInc(rw) AuDbgCntInc(rw, rcnt) | |
57 | #define AuDbgRcntDec(rw) AuDbgCntDec(rw, rcnt) | |
58 | #define AuDbgWcntInc(rw) AuDbgCntInc(rw, wcnt) | |
59 | #define AuDbgWcntDec(rw) AuDbgCntDec(rw, wcnt) | |
60 | #else | |
61 | #define AuDbgCnt(rw, cnt) 0 | |
62 | #define AuDbgCntInit(rw) do {} while (0) | |
63 | #define AuDbgRcntInc(rw) do {} while (0) | |
64 | #define AuDbgRcntDec(rw) do {} while (0) | |
65 | #define AuDbgWcntInc(rw) do {} while (0) | |
66 | #define AuDbgWcntDec(rw) do {} while (0) | |
67 | #endif /* CONFIG_AUFS_DEBUG */ | |
68 | ||
69 | /* to debug easier, do not make them inlined functions */ | |
70 | #define AuRwMustNoWaiters(rw) AuDebugOn(rwsem_is_contended(&(rw)->rwsem)) | |
71 | /* rwsem_is_locked() is unusable */ | |
72 | #define AuRwMustReadLock(rw) AuDebugOn(AuDbgCnt(rw, rcnt) <= 0) | |
73 | #define AuRwMustWriteLock(rw) AuDebugOn(AuDbgCnt(rw, wcnt) <= 0) | |
74 | #define AuRwMustAnyLock(rw) AuDebugOn(AuDbgCnt(rw, rcnt) <= 0 \ | |
75 | && AuDbgCnt(rw, wcnt) <= 0) | |
76 | #define AuRwDestroy(rw) AuDebugOn(AuDbgCnt(rw, rcnt) \ | |
77 | || AuDbgCnt(rw, wcnt)) | |
78 | ||
79 | #define au_rw_init(rw) do { \ | |
80 | AuDbgCntInit(rw); \ | |
81 | init_rwsem(&(rw)->rwsem); \ | |
82 | au_lockdep_set_name(rw); \ | |
83 | } while (0) | |
84 | ||
85 | #define au_rw_init_wlock(rw) do { \ | |
86 | au_rw_init(rw); \ | |
87 | down_write(&(rw)->rwsem); \ | |
88 | AuDbgWcntInc(rw); \ | |
89 | } while (0) | |
90 | ||
91 | #define au_rw_init_wlock_nested(rw, lsc) do { \ | |
92 | au_rw_init(rw); \ | |
93 | down_write_nested(&(rw)->rwsem, lsc); \ | |
94 | AuDbgWcntInc(rw); \ | |
95 | } while (0) | |
96 | ||
97 | static inline void au_rw_read_lock(struct au_rwsem *rw) | |
98 | { | |
99 | down_read(&rw->rwsem); | |
100 | AuDbgRcntInc(rw); | |
101 | } | |
102 | ||
103 | static inline void au_rw_read_lock_nested(struct au_rwsem *rw, unsigned int lsc) | |
104 | { | |
105 | down_read_nested(&rw->rwsem, lsc); | |
106 | AuDbgRcntInc(rw); | |
107 | } | |
108 | ||
109 | static inline void au_rw_read_unlock(struct au_rwsem *rw) | |
110 | { | |
111 | AuRwMustReadLock(rw); | |
112 | AuDbgRcntDec(rw); | |
113 | up_read(&rw->rwsem); | |
114 | } | |
115 | ||
116 | static inline void au_rw_dgrade_lock(struct au_rwsem *rw) | |
117 | { | |
118 | AuRwMustWriteLock(rw); | |
119 | AuDbgRcntInc(rw); | |
120 | AuDbgWcntDec(rw); | |
121 | downgrade_write(&rw->rwsem); | |
122 | } | |
123 | ||
124 | static inline void au_rw_write_lock(struct au_rwsem *rw) | |
125 | { | |
126 | down_write(&rw->rwsem); | |
127 | AuDbgWcntInc(rw); | |
128 | } | |
129 | ||
130 | static inline void au_rw_write_lock_nested(struct au_rwsem *rw, | |
131 | unsigned int lsc) | |
132 | { | |
133 | down_write_nested(&rw->rwsem, lsc); | |
134 | AuDbgWcntInc(rw); | |
135 | } | |
136 | ||
137 | static inline void au_rw_write_unlock(struct au_rwsem *rw) | |
138 | { | |
139 | AuRwMustWriteLock(rw); | |
140 | AuDbgWcntDec(rw); | |
141 | up_write(&rw->rwsem); | |
142 | } | |
143 | ||
144 | /* why is not _nested version defined */ | |
145 | static inline int au_rw_read_trylock(struct au_rwsem *rw) | |
146 | { | |
147 | int ret; | |
148 | ||
149 | ret = down_read_trylock(&rw->rwsem); | |
150 | if (ret) | |
151 | AuDbgRcntInc(rw); | |
152 | return ret; | |
153 | } | |
154 | ||
155 | static inline int au_rw_write_trylock(struct au_rwsem *rw) | |
156 | { | |
157 | int ret; | |
158 | ||
159 | ret = down_write_trylock(&rw->rwsem); | |
160 | if (ret) | |
161 | AuDbgWcntInc(rw); | |
162 | return ret; | |
163 | } | |
164 | ||
165 | #undef AuDbgCntDec | |
166 | #undef AuDbgRcntInc | |
167 | #undef AuDbgRcntDec | |
168 | #undef AuDbgWcntDec | |
169 | ||
170 | #define AuSimpleLockRwsemFuncs(prefix, param, rwsem) \ | |
171 | static inline void prefix##_read_lock(param) \ | |
172 | { au_rw_read_lock(rwsem); } \ | |
173 | static inline void prefix##_write_lock(param) \ | |
174 | { au_rw_write_lock(rwsem); } \ | |
175 | static inline int prefix##_read_trylock(param) \ | |
176 | { return au_rw_read_trylock(rwsem); } \ | |
177 | static inline int prefix##_write_trylock(param) \ | |
178 | { return au_rw_write_trylock(rwsem); } | |
179 | /* why is not _nested version defined */ | |
180 | /* static inline void prefix##_read_trylock_nested(param, lsc) | |
181 | { au_rw_read_trylock_nested(rwsem, lsc)); } | |
182 | static inline void prefix##_write_trylock_nestd(param, lsc) | |
183 | { au_rw_write_trylock_nested(rwsem, lsc); } */ | |
184 | ||
185 | #define AuSimpleUnlockRwsemFuncs(prefix, param, rwsem) \ | |
186 | static inline void prefix##_read_unlock(param) \ | |
187 | { au_rw_read_unlock(rwsem); } \ | |
188 | static inline void prefix##_write_unlock(param) \ | |
189 | { au_rw_write_unlock(rwsem); } \ | |
190 | static inline void prefix##_downgrade_lock(param) \ | |
191 | { au_rw_dgrade_lock(rwsem); } | |
192 | ||
193 | #define AuSimpleRwsemFuncs(prefix, param, rwsem) \ | |
194 | AuSimpleLockRwsemFuncs(prefix, param, rwsem) \ | |
195 | AuSimpleUnlockRwsemFuncs(prefix, param, rwsem) | |
196 | ||
197 | #endif /* __KERNEL__ */ | |
198 | #endif /* __AUFS_RWSEM_H__ */ |