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 * $FreeBSD$ 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_tryrlock(struct rangelock *lock, off_t start, off_t end, 79 struct mtx *ilk); 80 void *rangelock_wlock(struct rangelock *lock, off_t start, off_t end, 81 struct mtx *ilk); 82 void *rangelock_trywlock(struct rangelock *lock, off_t start, off_t end, 83 struct mtx *ilk); 84 void rlqentry_free(struct rl_q_entry *rlqe); 85 86 #endif /* _KERNEL */ 87 88 #endif /* _SYS_RANGELOCK_H */ 89