1 /* $NetBSD: rwsem.h,v 1.1 2014/07/16 20:59:58 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2014 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 /*
33 * These are not really semaphores; they are just reader/writer sleep
34 * locks, whereas what Linux calls an rwlock is a reader/writer spin
35 * lock.
36 *
37 * Notes on porting:
38 *
39 * - Linux does not have destroy_rwsem. You must add it yourself in
40 * the appropriate place.
41 */
42
43 #ifndef _LINUX_RWSEM_H_
44 #define _LINUX_RWSEM_H_
45
46 #include <sys/mutex.h>
47
48 struct rw_semaphore {
49 krwlock_t rws_lock;
50 };
51
52 static inline void
init_rwsem(struct rw_semaphore * rwsem)53 init_rwsem(struct rw_semaphore *rwsem)
54 {
55
56 rw_init(&rwsem->rws_lock);
57 }
58
59 static inline void
destroy_rwsem(struct rw_semaphore * rwsem)60 destroy_rwsem(struct rw_semaphore *rwsem)
61 {
62
63 rw_destroy(&rwsem->rws_lock);
64 }
65
66 static inline void
down_read(struct rw_semaphore * rwsem)67 down_read(struct rw_semaphore *rwsem)
68 {
69
70 rw_enter(&rwsem->rws_lock, RW_READER);
71 }
72
73 static inline void
down_write(struct rw_semaphore * rwsem)74 down_write(struct rw_semaphore *rwsem)
75 {
76
77 rw_enter(&rwsem->rws_lock, RW_WRITER);
78 }
79
80 static inline void
up_read(struct rw_semaphore * rwsem)81 up_read(struct rw_semaphore *rwsem)
82 {
83
84 rw_exit(&rwsem->rws_lock);
85 }
86
87 static inline void
up_write(struct rw_semaphore * rwsem)88 up_write(struct rw_semaphore *rwsem)
89 {
90
91 rw_exit(&rwsem->rws_lock);
92 }
93
94 #endif /* _LINUX_RWSEM_H_ */
95