1 /* $NetBSD: spinlock.h,v 1.7 2016/04/13 08:43:56 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2013 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Taylor R. Campbell.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #ifndef _LINUX_SPINLOCK_H_
33 #define _LINUX_SPINLOCK_H_
34
35 #include <sys/cdefs.h>
36 #include <sys/mutex.h>
37
38 #include <machine/limits.h>
39
40 #define __acquires(lock) /* XXX lockdep stuff */
41 #define __releases(lock) /* XXX lockdep stuff */
42
43 typedef struct spinlock {
44 kmutex_t sl_lock;
45 } spinlock_t;
46
47 static inline int
spin_is_locked(spinlock_t * spinlock)48 spin_is_locked(spinlock_t *spinlock)
49 {
50 return mutex_owned(&spinlock->sl_lock);
51 }
52
53 static inline void
spin_lock(spinlock_t * spinlock)54 spin_lock(spinlock_t *spinlock)
55 {
56 mutex_enter(&spinlock->sl_lock);
57 }
58
59 static inline void
spin_unlock(spinlock_t * spinlock)60 spin_unlock(spinlock_t *spinlock)
61 {
62 mutex_exit(&spinlock->sl_lock);
63 }
64
65 static inline void
spin_lock_irq(spinlock_t * spinlock)66 spin_lock_irq(spinlock_t *spinlock)
67 {
68 spin_lock(spinlock);
69 }
70
71 static inline void
spin_unlock_irq(spinlock_t * spinlock)72 spin_unlock_irq(spinlock_t *spinlock)
73 {
74 spin_unlock(spinlock);
75 }
76
77 /* Must be a macro because the second argument is to be assigned. */
78 #define spin_lock_irqsave(SPINLOCK, FLAGS) \
79 do { \
80 (FLAGS) = 0; \
81 mutex_enter(&((spinlock_t *)(SPINLOCK))->sl_lock); \
82 } while (0)
83
84 static inline void
spin_unlock_irqrestore(spinlock_t * spinlock,unsigned long __unused flags)85 spin_unlock_irqrestore(spinlock_t *spinlock, unsigned long __unused flags)
86 {
87 mutex_exit(&spinlock->sl_lock);
88 }
89
90 static inline void
spin_lock_init(spinlock_t * spinlock)91 spin_lock_init(spinlock_t *spinlock)
92 {
93 /* XXX What's the right IPL? IPL_DRM...? */
94 mutex_init(&spinlock->sl_lock, MUTEX_DEFAULT, IPL_VM);
95 }
96
97 /*
98 * XXX Linux doesn't ever destroy spin locks, it seems. We'll have to
99 * kludge it up.
100 */
101
102 static inline void
spin_lock_destroy(spinlock_t * spinlock)103 spin_lock_destroy(spinlock_t *spinlock)
104 {
105 mutex_destroy(&spinlock->sl_lock);
106 }
107
108 /* This is a macro to make the panic message clearer. */
109 #define assert_spin_locked(spinlock) \
110 KASSERT(mutex_owned(&(spinlock)->sl_lock))
111
112 /*
113 * Stupid reader/writer spin locks. No attempt to avoid writer
114 * starvation. Must allow recursive readers. We use mutex and state
115 * instead of compare-and-swap for expedience and LOCKDEBUG support.
116 */
117
118 typedef struct linux_rwlock {
119 kmutex_t rw_lock;
120 unsigned rw_nreaders;
121 } rwlock_t;
122
123 static inline void
rwlock_init(rwlock_t * rw)124 rwlock_init(rwlock_t *rw)
125 {
126
127 mutex_init(&rw->rw_lock, MUTEX_DEFAULT, IPL_VM);
128 rw->rw_nreaders = 0;
129 }
130
131 static inline void
rwlock_destroy(rwlock_t * rw)132 rwlock_destroy(rwlock_t *rw)
133 {
134
135 KASSERTMSG(rw->rw_nreaders == 0,
136 "rwlock still held by %u readers", rw->rw_nreaders);
137 mutex_destroy(&rw->rw_lock);
138 }
139
140 static inline void
write_lock_irq(rwlock_t * rw)141 write_lock_irq(rwlock_t *rw)
142 {
143
144 for (;;) {
145 mutex_spin_enter(&rw->rw_lock);
146 if (rw->rw_nreaders == 0)
147 break;
148 mutex_spin_exit(&rw->rw_lock);
149 }
150 }
151
152 static inline void
write_unlock_irq(rwlock_t * rw)153 write_unlock_irq(rwlock_t *rw)
154 {
155
156 KASSERT(rw->rw_nreaders == 0);
157 mutex_spin_exit(&rw->rw_lock);
158 }
159
160 static inline void
read_lock(rwlock_t * rw)161 read_lock(rwlock_t *rw)
162 {
163
164 mutex_spin_enter(&rw->rw_lock);
165 KASSERT(rw->rw_nreaders < UINT_MAX);
166 rw->rw_nreaders++;
167 mutex_spin_exit(&rw->rw_lock);
168 }
169
170 static inline void
read_unlock(rwlock_t * rw)171 read_unlock(rwlock_t *rw)
172 {
173
174 mutex_spin_enter(&rw->rw_lock);
175 KASSERT(0 < rw->rw_nreaders);
176 rw->rw_nreaders--;
177 mutex_spin_exit(&rw->rw_lock);
178 }
179
180 #endif /* _LINUX_SPINLOCK_H_ */
181