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716154c5 BB |
1 | /*****************************************************************************\ |
2 | * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC. | |
3 | * Copyright (C) 2007 The Regents of the University of California. | |
4 | * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). | |
5 | * Written by Brian Behlendorf <behlendorf1@llnl.gov>. | |
715f6251 | 6 | * UCRL-CODE-235197 |
7 | * | |
716154c5 | 8 | * This file is part of the SPL, Solaris Porting Layer. |
3d6af2dd | 9 | * For details, see <http://zfsonlinux.org/>. |
716154c5 BB |
10 | * |
11 | * The SPL is free software; you can redistribute it and/or modify it | |
12 | * under the terms of the GNU General Public License as published by the | |
13 | * Free Software Foundation; either version 2 of the License, or (at your | |
14 | * option) any later version. | |
715f6251 | 15 | * |
716154c5 | 16 | * The SPL is distributed in the hope that it will be useful, but WITHOUT |
715f6251 | 17 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
18 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
19 | * for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU General Public License along | |
716154c5 BB |
22 | * with the SPL. If not, see <http://www.gnu.org/licenses/>. |
23 | \*****************************************************************************/ | |
715f6251 | 24 | |
09b414e8 | 25 | #ifndef _SPL_RWLOCK_H |
e8b31e84 | 26 | #define _SPL_RWLOCK_H |
f1ca4da6 | 27 | |
f4b37741 | 28 | #include <sys/types.h> |
d28db80f | 29 | #include <linux/rwsem.h> |
46aa7b39 | 30 | #include <linux/rwsem_compat.h> |
f1ca4da6 | 31 | |
32 | typedef enum { | |
374303a3 | 33 | RW_DRIVER = 2, |
692ae8d3 OF |
34 | RW_DEFAULT = 4, |
35 | RW_NOLOCKDEP = 5 | |
f1ca4da6 | 36 | } krw_type_t; |
37 | ||
38 | typedef enum { | |
374303a3 CC |
39 | RW_NONE = 0, |
40 | RW_WRITER = 1, | |
41 | RW_READER = 2 | |
f1ca4da6 | 42 | } krw_t; |
43 | ||
a00b3eb5 CC |
44 | /* |
45 | * If CONFIG_RWSEM_SPIN_ON_OWNER is defined, rw_semaphore will have an owner | |
46 | * field, so we don't need our own. | |
47 | */ | |
d28db80f | 48 | typedef struct { |
374303a3 | 49 | struct rw_semaphore rw_rwlock; |
a00b3eb5 | 50 | #ifndef CONFIG_RWSEM_SPIN_ON_OWNER |
374303a3 | 51 | kthread_t *rw_owner; |
a00b3eb5 | 52 | #endif |
692ae8d3 OF |
53 | #ifdef CONFIG_LOCKDEP |
54 | krw_type_t rw_type; | |
55 | #endif /* CONFIG_LOCKDEP */ | |
d28db80f | 56 | } krwlock_t; |
f1ca4da6 | 57 | |
a00b3eb5 | 58 | #define SEM(rwp) (&(rwp)->rw_rwlock) |
d28db80f | 59 | |
d28db80f BB |
60 | static inline void |
61 | spl_rw_set_owner(krwlock_t *rwp) | |
62 | { | |
a00b3eb5 CC |
63 | /* |
64 | * If CONFIG_RWSEM_SPIN_ON_OWNER is defined, down_write, up_write, | |
65 | * downgrade_write and __init_rwsem will set/clear owner for us. | |
66 | */ | |
67 | #ifndef CONFIG_RWSEM_SPIN_ON_OWNER | |
4f8e643a | 68 | rwp->rw_owner = current; |
a00b3eb5 | 69 | #endif |
d28db80f BB |
70 | } |
71 | ||
72 | static inline void | |
73 | spl_rw_clear_owner(krwlock_t *rwp) | |
74 | { | |
a00b3eb5 | 75 | #ifndef CONFIG_RWSEM_SPIN_ON_OWNER |
4f8e643a | 76 | rwp->rw_owner = NULL; |
a00b3eb5 | 77 | #endif |
d28db80f BB |
78 | } |
79 | ||
80 | static inline kthread_t * | |
81 | rw_owner(krwlock_t *rwp) | |
82 | { | |
a00b3eb5 CC |
83 | #ifdef CONFIG_RWSEM_SPIN_ON_OWNER |
84 | return SEM(rwp)->owner; | |
85 | #else | |
4f8e643a | 86 | return rwp->rw_owner; |
a00b3eb5 | 87 | #endif |
d28db80f BB |
88 | } |
89 | ||
692ae8d3 OF |
90 | #ifdef CONFIG_LOCKDEP |
91 | static inline void | |
92 | spl_rw_set_type(krwlock_t *rwp, krw_type_t type) | |
93 | { | |
94 | rwp->rw_type = type; | |
95 | } | |
96 | static inline void | |
97 | spl_rw_lockdep_off_maybe(krwlock_t *rwp) \ | |
98 | { \ | |
99 | if (rwp && rwp->rw_type == RW_NOLOCKDEP) \ | |
100 | lockdep_off(); \ | |
101 | } | |
102 | static inline void | |
103 | spl_rw_lockdep_on_maybe(krwlock_t *rwp) \ | |
104 | { \ | |
105 | if (rwp && rwp->rw_type == RW_NOLOCKDEP) \ | |
106 | lockdep_on(); \ | |
107 | } | |
108 | #else /* CONFIG_LOCKDEP */ | |
109 | #define spl_rw_set_type(rwp, type) | |
110 | #define spl_rw_lockdep_off_maybe(rwp) | |
111 | #define spl_rw_lockdep_on_maybe(rwp) | |
112 | #endif /* CONFIG_LOCKDEP */ | |
113 | ||
d28db80f BB |
114 | static inline int |
115 | RW_READ_HELD(krwlock_t *rwp) | |
116 | { | |
86c16c59 | 117 | return (spl_rwsem_is_locked(SEM(rwp)) && rw_owner(rwp) == NULL); |
d28db80f BB |
118 | } |
119 | ||
120 | static inline int | |
121 | RW_WRITE_HELD(krwlock_t *rwp) | |
122 | { | |
4f8e643a | 123 | return (rw_owner(rwp) == current); |
d28db80f BB |
124 | } |
125 | ||
126 | static inline int | |
127 | RW_LOCK_HELD(krwlock_t *rwp) | |
128 | { | |
46aa7b39 | 129 | return spl_rwsem_is_locked(SEM(rwp)); |
d28db80f BB |
130 | } |
131 | ||
132 | /* | |
133 | * The following functions must be a #define and not static inline. | |
134 | * This ensures that the native linux semaphore functions (down/up) | |
135 | * will be correctly located in the users code which is important | |
136 | * for the built in kernel lock analysis tools | |
137 | */ | |
374303a3 CC |
138 | #define rw_init(rwp, name, type, arg) \ |
139 | ({ \ | |
140 | static struct lock_class_key __key; \ | |
692ae8d3 | 141 | ASSERT(type == RW_DEFAULT || type == RW_NOLOCKDEP); \ |
374303a3 CC |
142 | \ |
143 | __init_rwsem(SEM(rwp), #rwp, &__key); \ | |
144 | spl_rw_clear_owner(rwp); \ | |
692ae8d3 | 145 | spl_rw_set_type(rwp, type); \ |
e811949a | 146 | }) |
f1ca4da6 | 147 | |
374303a3 CC |
148 | #define rw_destroy(rwp) \ |
149 | ({ \ | |
150 | VERIFY(!RW_LOCK_HELD(rwp)); \ | |
e811949a | 151 | }) |
ed61a7d0 | 152 | |
374303a3 CC |
153 | #define rw_tryenter(rwp, rw) \ |
154 | ({ \ | |
155 | int _rc_ = 0; \ | |
156 | \ | |
692ae8d3 | 157 | spl_rw_lockdep_off_maybe(rwp); \ |
374303a3 CC |
158 | switch (rw) { \ |
159 | case RW_READER: \ | |
160 | _rc_ = down_read_trylock(SEM(rwp)); \ | |
161 | break; \ | |
162 | case RW_WRITER: \ | |
163 | if ((_rc_ = down_write_trylock(SEM(rwp)))) \ | |
164 | spl_rw_set_owner(rwp); \ | |
165 | break; \ | |
166 | default: \ | |
167 | VERIFY(0); \ | |
168 | } \ | |
692ae8d3 | 169 | spl_rw_lockdep_on_maybe(rwp); \ |
374303a3 | 170 | _rc_; \ |
e8b31e84 | 171 | }) |
e8b31e84 | 172 | |
374303a3 CC |
173 | #define rw_enter(rwp, rw) \ |
174 | ({ \ | |
692ae8d3 | 175 | spl_rw_lockdep_off_maybe(rwp); \ |
374303a3 CC |
176 | switch (rw) { \ |
177 | case RW_READER: \ | |
178 | down_read(SEM(rwp)); \ | |
179 | break; \ | |
180 | case RW_WRITER: \ | |
181 | down_write(SEM(rwp)); \ | |
182 | spl_rw_set_owner(rwp); \ | |
183 | break; \ | |
184 | default: \ | |
185 | VERIFY(0); \ | |
186 | } \ | |
692ae8d3 | 187 | spl_rw_lockdep_on_maybe(rwp); \ |
e811949a | 188 | }) |
f1ca4da6 | 189 | |
374303a3 CC |
190 | #define rw_exit(rwp) \ |
191 | ({ \ | |
692ae8d3 | 192 | spl_rw_lockdep_off_maybe(rwp); \ |
374303a3 CC |
193 | if (RW_WRITE_HELD(rwp)) { \ |
194 | spl_rw_clear_owner(rwp); \ | |
195 | up_write(SEM(rwp)); \ | |
196 | } else { \ | |
197 | ASSERT(RW_READ_HELD(rwp)); \ | |
198 | up_read(SEM(rwp)); \ | |
199 | } \ | |
692ae8d3 | 200 | spl_rw_lockdep_on_maybe(rwp); \ |
d28db80f BB |
201 | }) |
202 | ||
374303a3 CC |
203 | #define rw_downgrade(rwp) \ |
204 | ({ \ | |
692ae8d3 | 205 | spl_rw_lockdep_off_maybe(rwp); \ |
374303a3 CC |
206 | spl_rw_clear_owner(rwp); \ |
207 | downgrade_write(SEM(rwp)); \ | |
692ae8d3 | 208 | spl_rw_lockdep_on_maybe(rwp); \ |
d28db80f BB |
209 | }) |
210 | ||
32f5faff | 211 | /* |
a6ae97ca BB |
212 | * This implementation of rw_tryupgrade() behaves slightly differently |
213 | * from its counterparts on other platforms. It drops the RW_READER lock | |
214 | * and then acquires the RW_WRITER lock leaving a small window where no | |
215 | * lock is held. On other platforms the lock is never released during | |
216 | * the upgrade process. This is necessary under Linux because the kernel | |
217 | * does not provide an upgrade function. | |
32f5faff | 218 | */ |
374303a3 CC |
219 | #define rw_tryupgrade(rwp) \ |
220 | ({ \ | |
374303a3 CC |
221 | int _rc_ = 0; \ |
222 | \ | |
a6ae97ca BB |
223 | if (RW_WRITE_HELD(rwp)) { \ |
224 | _rc_ = 1; \ | |
225 | } else { \ | |
f58040c0 CC |
226 | spl_rw_lockdep_off_maybe(rwp); \ |
227 | if ((_rc_ = rwsem_tryupgrade(SEM(rwp)))) \ | |
228 | spl_rw_set_owner(rwp); \ | |
229 | spl_rw_lockdep_on_maybe(rwp); \ | |
374303a3 | 230 | } \ |
374303a3 | 231 | _rc_; \ |
d28db80f BB |
232 | }) |
233 | ||
234 | int spl_rw_init(void); | |
235 | void spl_rw_fini(void); | |
236 | ||
e8b31e84 | 237 | #endif /* _SPL_RWLOCK_H */ |