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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 { | |
e811949a BB |
33 | RW_DRIVER = 2, |
34 | RW_DEFAULT = 4 | |
f1ca4da6 | 35 | } krw_type_t; |
36 | ||
37 | typedef enum { | |
d28db80f | 38 | RW_NONE = 0, |
e811949a BB |
39 | RW_WRITER = 1, |
40 | RW_READER = 2 | |
f1ca4da6 | 41 | } krw_t; |
42 | ||
d28db80f BB |
43 | typedef struct { |
44 | struct rw_semaphore rw_rwlock; | |
45 | kthread_t *rw_owner; | |
46 | } krwlock_t; | |
f1ca4da6 | 47 | |
d28db80f BB |
48 | #define SEM(rwp) ((struct rw_semaphore *)(rwp)) |
49 | ||
d28db80f BB |
50 | static inline void |
51 | spl_rw_set_owner(krwlock_t *rwp) | |
52 | { | |
53 | unsigned long flags; | |
54 | ||
588d9004 | 55 | spl_rwsem_lock_irqsave(&SEM(rwp)->wait_lock, flags); |
d28db80f | 56 | rwp->rw_owner = current; |
588d9004 | 57 | spl_rwsem_unlock_irqrestore(&SEM(rwp)->wait_lock, flags); |
d28db80f BB |
58 | } |
59 | ||
60 | static inline void | |
61 | spl_rw_clear_owner(krwlock_t *rwp) | |
62 | { | |
63 | unsigned long flags; | |
64 | ||
588d9004 | 65 | spl_rwsem_lock_irqsave(&SEM(rwp)->wait_lock, flags); |
d28db80f | 66 | rwp->rw_owner = NULL; |
588d9004 | 67 | spl_rwsem_unlock_irqrestore(&SEM(rwp)->wait_lock, flags); |
d28db80f BB |
68 | } |
69 | ||
70 | static inline kthread_t * | |
71 | rw_owner(krwlock_t *rwp) | |
72 | { | |
73 | unsigned long flags; | |
74 | kthread_t *owner; | |
75 | ||
588d9004 | 76 | spl_rwsem_lock_irqsave(&SEM(rwp)->wait_lock, flags); |
46aa7b39 | 77 | owner = rwp->rw_owner; |
588d9004 | 78 | spl_rwsem_unlock_irqrestore(&SEM(rwp)->wait_lock, flags); |
d28db80f BB |
79 | |
80 | return owner; | |
81 | } | |
82 | ||
83 | static inline int | |
84 | RW_READ_HELD(krwlock_t *rwp) | |
85 | { | |
ac9cc135 AX |
86 | /* |
87 | * Linux 4.8 will set owner to 1 when read held instead of leave it | |
88 | * NULL. So we check whether owner <= 1. | |
89 | */ | |
90 | return (spl_rwsem_is_locked(SEM(rwp)) && | |
91 | (unsigned long)rw_owner(rwp) <= 1); | |
d28db80f BB |
92 | } |
93 | ||
94 | static inline int | |
95 | RW_WRITE_HELD(krwlock_t *rwp) | |
96 | { | |
f6188ddd | 97 | return (spl_rwsem_is_locked(SEM(rwp)) && rw_owner(rwp) == current); |
d28db80f BB |
98 | } |
99 | ||
100 | static inline int | |
101 | RW_LOCK_HELD(krwlock_t *rwp) | |
102 | { | |
46aa7b39 | 103 | return spl_rwsem_is_locked(SEM(rwp)); |
d28db80f BB |
104 | } |
105 | ||
106 | /* | |
107 | * The following functions must be a #define and not static inline. | |
108 | * This ensures that the native linux semaphore functions (down/up) | |
109 | * will be correctly located in the users code which is important | |
110 | * for the built in kernel lock analysis tools | |
111 | */ | |
112 | #define rw_init(rwp, name, type, arg) \ | |
113 | ({ \ | |
0e77fc11 BB |
114 | static struct lock_class_key __key; \ |
115 | \ | |
116 | __init_rwsem(SEM(rwp), #rwp, &__key); \ | |
d28db80f | 117 | spl_rw_clear_owner(rwp); \ |
e811949a | 118 | }) |
f1ca4da6 | 119 | |
d28db80f BB |
120 | #define rw_destroy(rwp) \ |
121 | ({ \ | |
122 | VERIFY(!RW_LOCK_HELD(rwp)); \ | |
e811949a | 123 | }) |
ed61a7d0 | 124 | |
d28db80f BB |
125 | #define rw_tryenter(rwp, rw) \ |
126 | ({ \ | |
127 | int _rc_ = 0; \ | |
128 | \ | |
129 | switch (rw) { \ | |
130 | case RW_READER: \ | |
131 | _rc_ = down_read_trylock(SEM(rwp)); \ | |
132 | break; \ | |
133 | case RW_WRITER: \ | |
134 | if ((_rc_ = down_write_trylock(SEM(rwp)))) \ | |
135 | spl_rw_set_owner(rwp); \ | |
136 | break; \ | |
137 | default: \ | |
55abb092 | 138 | VERIFY(0); \ |
d28db80f BB |
139 | } \ |
140 | _rc_; \ | |
e8b31e84 | 141 | }) |
e8b31e84 | 142 | |
d28db80f BB |
143 | #define rw_enter(rwp, rw) \ |
144 | ({ \ | |
145 | switch (rw) { \ | |
146 | case RW_READER: \ | |
147 | down_read(SEM(rwp)); \ | |
148 | break; \ | |
149 | case RW_WRITER: \ | |
150 | down_write(SEM(rwp)); \ | |
151 | spl_rw_set_owner(rwp); \ | |
152 | break; \ | |
153 | default: \ | |
55abb092 | 154 | VERIFY(0); \ |
d28db80f | 155 | } \ |
e811949a | 156 | }) |
f1ca4da6 | 157 | |
d28db80f BB |
158 | #define rw_exit(rwp) \ |
159 | ({ \ | |
160 | if (RW_WRITE_HELD(rwp)) { \ | |
161 | spl_rw_clear_owner(rwp); \ | |
162 | up_write(SEM(rwp)); \ | |
163 | } else { \ | |
164 | ASSERT(RW_READ_HELD(rwp)); \ | |
165 | up_read(SEM(rwp)); \ | |
166 | } \ | |
167 | }) | |
168 | ||
169 | #define rw_downgrade(rwp) \ | |
170 | ({ \ | |
171 | spl_rw_clear_owner(rwp); \ | |
172 | downgrade_write(SEM(rwp)); \ | |
173 | }) | |
174 | ||
32f5faff | 175 | /* |
0f836a62 AX |
176 | * This implementation of rw_tryupgrade() behaves slightly differently |
177 | * from its counterparts on other platforms. It drops the RW_READER lock | |
178 | * and then acquires the RW_WRITER lock leaving a small window where no | |
179 | * lock is held. On other platforms the lock is never released during | |
180 | * the upgrade process. This is necessary under Linux because the kernel | |
181 | * does not provide an upgrade function. | |
32f5faff | 182 | */ |
0f836a62 AX |
183 | #define rw_tryupgrade(rwp) \ |
184 | ({ \ | |
185 | int _rc_ = 0; \ | |
186 | \ | |
187 | if (RW_WRITE_HELD(rwp)) { \ | |
188 | _rc_ = 1; \ | |
189 | } else { \ | |
190 | if ((_rc_ = rwsem_tryupgrade(SEM(rwp)))) \ | |
191 | spl_rw_set_owner(rwp); \ | |
192 | } \ | |
193 | _rc_; \ | |
d28db80f BB |
194 | }) |
195 | ||
196 | int spl_rw_init(void); | |
197 | void spl_rw_fini(void); | |
198 | ||
e8b31e84 | 199 | #endif /* _SPL_RWLOCK_H */ |