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
 39struct 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 */
 59struct rangelock {
 60	TAILQ_HEAD(, rl_q_entry) rl_waiters;
 61	struct rl_q_entry	*rl_currdep;
 62};
 63
 64#ifdef _KERNEL
 65
 66struct mtx;
 67
 68void	 rangelock_init(struct rangelock *lock);
 69void	 rangelock_destroy(struct rangelock *lock);
 70void	 rangelock_unlock(struct rangelock *lock, void *cookie,
 71	    struct mtx *ilk);
 72void	*rangelock_unlock_range(struct rangelock *lock, void *cookie,
 73	    off_t start, off_t end, struct mtx *ilk);
 74void	*rangelock_rlock(struct rangelock *lock, off_t start, off_t end,
 75	    struct mtx *ilk);
 76void	*rangelock_tryrlock(struct rangelock *lock, off_t start, off_t end,
 77	    struct mtx *ilk);
 78void	*rangelock_wlock(struct rangelock *lock, off_t start, off_t end,
 79	    struct mtx *ilk);
 80void	*rangelock_trywlock(struct rangelock *lock, off_t start, off_t end,
 81	    struct mtx *ilk);
 82void	 rlqentry_free(struct rl_q_entry *rlqe);
 83#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
 84void	_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 */