1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 29 #ifndef _SYS_RANGELOCK_H 30 #define _SYS_RANGELOCK_H 31 32 #include <sys/queue.h> 33 34 #define RL_LOCK_READ 0x0001 35 #define RL_LOCK_WRITE 0x0002 36 #define RL_LOCK_TYPE_MASK 0x0003 37 #define RL_LOCK_GRANTED 0x0004 38 39 struct rl_q_entry; 40 41 /* 42 * The structure representing the range lock. Caller may request 43 * read or write access to the range of bytes. Access is granted if 44 * all existing lock owners are compatible with the request. Two lock 45 * owners are compatible if their ranges do not overlap, or both 46 * owners are for read. 47 * 48 * Access to the structure itself is synchronized with the externally 49 * supplied mutex. 50 * 51 * rl_waiters is the queue containing in order (a) granted write lock 52 * requests, (b) granted read lock requests, and (c) in order of arrival, 53 * lock requests which cannot be granted yet. 54 * 55 * rl_currdep is the first lock request that cannot be granted now due 56 * to the preceding requests conflicting with it (i.e., it points to 57 * position (c) in the list above). 58 */ 59 struct rangelock { 60 TAILQ_HEAD(, rl_q_entry) rl_waiters; 61 struct rl_q_entry *rl_currdep; 62 }; 63 64 #ifdef _KERNEL 65 66 struct mtx; 67 68 void rangelock_init(struct rangelock *lock); 69 void rangelock_destroy(struct rangelock *lock); 70 void rangelock_unlock(struct rangelock *lock, void *cookie, 71 struct mtx *ilk); 72 void *rangelock_unlock_range(struct rangelock *lock, void *cookie, 73 off_t start, off_t end, struct mtx *ilk); 74 void *rangelock_rlock(struct rangelock *lock, off_t start, off_t end, 75 struct mtx *ilk); 76 void *rangelock_tryrlock(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 *rangelock_trywlock(struct rangelock *lock, off_t start, off_t end, 81 struct mtx *ilk); 82 void rlqentry_free(struct rl_q_entry *rlqe); 83 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 84 void _rangelock_cookie_assert(void *cookie, int what, const char *file, 85 int line); 86 #endif 87 88 #ifdef INVARIANTS 89 #define rangelock_cookie_assert_(cookie, what, file, line) \ 90 _rangelock_cookie_assert((cookie), (what), (file), (line)) 91 #else 92 #define rangelock_cookie_assert_(cookie, what, file, line) (void)0 93 #endif 94 95 #define rangelock_cookie_assert(cookie, what) \ 96 rangelock_cookie_assert_((cookie), (what), __FILE__, __LINE__) 97 98 /* 99 * Assertion flags. 100 */ 101 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 102 #define RCA_LOCKED 0x0001 103 #define RCA_RLOCKED 0x0002 104 #define RCA_WLOCKED 0x0004 105 #endif 106 107 #endif /* _KERNEL */ 108 109 #endif /* _SYS_RANGELOCK_H */ 110