FreeBSD/Linux Kernel Cross Reference
sys/sys/rangelock.h
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2009 Konstantin Belousov <kib@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice unmodified, this list of conditions, and the following
12 * disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * $FreeBSD: releng/12.0/sys/sys/rangelock.h 326256 2017-11-27 15:01:59Z pfg $
29 */
30
31 #ifndef _SYS_RANGELOCK_H
32 #define _SYS_RANGELOCK_H
33
34 #include <sys/queue.h>
35
36 #define RL_LOCK_READ 0x0001
37 #define RL_LOCK_WRITE 0x0002
38 #define RL_LOCK_TYPE_MASK 0x0003
39 #define RL_LOCK_GRANTED 0x0004
40
41 struct rl_q_entry;
42
43 /*
44 * The structure representing the range lock. Caller may request
45 * read or write access to the range of bytes. Access is granted if
46 * all existing lock owners are compatible with the request. Two lock
47 * owners are compatible if their ranges do not overlap, or both
48 * owners are for read.
49 *
50 * Access to the structure itself is synchronized with the externally
51 * supplied mutex.
52 *
53 * rl_waiters is the queue containing in order (a) granted write lock
54 * requests, (b) granted read lock requests, and (c) in order of arrival,
55 * lock requests which cannot be granted yet.
56 *
57 * rl_currdep is the first lock request that cannot be granted now due
58 * to the preceding requests conflicting with it (i.e., it points to
59 * position (c) in the list above).
60 */
61 struct rangelock {
62 TAILQ_HEAD(, rl_q_entry) rl_waiters;
63 struct rl_q_entry *rl_currdep;
64 };
65
66 #ifdef _KERNEL
67
68 struct mtx;
69
70 void rangelock_init(struct rangelock *lock);
71 void rangelock_destroy(struct rangelock *lock);
72 void rangelock_unlock(struct rangelock *lock, void *cookie,
73 struct mtx *ilk);
74 void *rangelock_unlock_range(struct rangelock *lock, void *cookie,
75 off_t start, off_t end, struct mtx *ilk);
76 void *rangelock_rlock(struct rangelock *lock, off_t start, off_t end,
77 struct mtx *ilk);
78 void *rangelock_wlock(struct rangelock *lock, off_t start, off_t end,
79 struct mtx *ilk);
80 void rlqentry_free(struct rl_q_entry *rlqe);
81
82 #endif /* _KERNEL */
83
84 #endif /* _SYS_RANGELOCK_H */
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