1/*-
2 * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD$
27 */
28
29#ifndef _OPENSOLARIS_SYS_RWLOCK_H_
30#define	_OPENSOLARIS_SYS_RWLOCK_H_
31
32#include <sys/param.h>
33#include <sys/proc.h>
34#include <sys/lock.h>
35#include <sys/sx.h>
36
37#ifdef _KERNEL
38
39typedef enum {
40	RW_DEFAULT = 4		/* kernel default rwlock */
41} krw_type_t;
42
43typedef enum {
44	RW_WRITER,
45	RW_READER
46} krw_t;
47
48typedef	struct sx	krwlock_t;
49
50#ifndef OPENSOLARIS_WITNESS
51#define	RW_FLAGS	(SX_DUPOK | SX_NOWITNESS)
52#else
53#define	RW_FLAGS	(SX_DUPOK)
54#endif
55
56#define	RW_READ_HELD(x)		(rw_read_held((x)))
57#define	RW_WRITE_HELD(x)	(rw_write_held((x)))
58#define	RW_LOCK_HELD(x)		(rw_lock_held((x)))
59#define	RW_ISWRITER(x)		(rw_iswriter(x))
60
61#define	rw_init(lock, desc, type, arg)	do {				\
62	const char *_name;						\
63	ASSERT((type) == 0 || (type) == RW_DEFAULT);			\
64	KASSERT(((lock)->lock_object.lo_flags & LO_ALLMASK) !=		\
65	    LO_EXPECTED, ("lock %s already initialized", #lock));	\
66	bzero((lock), sizeof(struct sx));				\
67	for (_name = #lock; *_name != '\0'; _name++) {			\
68		if (*_name >= 'a' && *_name <= 'z')			\
69			break;						\
70	}								\
71	if (*_name == '\0')						\
72		_name = #lock;						\
73	sx_init_flags((lock), _name, RW_FLAGS);				\
74} while (0)
75#define	rw_destroy(lock)	sx_destroy(lock)
76#define	rw_enter(lock, how)	do {					\
77	if ((how) == RW_READER)						\
78		sx_slock(lock);						\
79	else /* if ((how) == RW_WRITER) */				\
80		sx_xlock(lock);						\
81} while (0)
82#define	rw_tryenter(lock, how)	((how) == RW_READER ? sx_try_slock(lock) : sx_try_xlock(lock))
83#define	rw_exit(lock)		sx_unlock(lock)
84#define	rw_downgrade(lock)	sx_downgrade(lock)
85#define	rw_tryupgrade(lock)	sx_try_upgrade(lock)
86#define	rw_read_held(lock)	((lock)->sx_lock != SX_LOCK_UNLOCKED && ((lock)->sx_lock & SX_LOCK_SHARED))
87#define	rw_write_held(lock)	sx_xlocked(lock)
88#define	rw_lock_held(lock)	(rw_read_held(lock) || rw_write_held(lock))
89#define	rw_iswriter(lock)	sx_xlocked(lock)
90/* TODO: Change to sx_xholder() once it is moved from kern_sx.c to sx.h. */
91#define	rw_owner(lock)		((lock)->sx_lock & SX_LOCK_SHARED ? NULL : (struct thread *)SX_OWNER((lock)->sx_lock))
92
93#endif	/* defined(_KERNEL) */
94
95#endif	/* _OPENSOLARIS_SYS_RWLOCK_H_ */
96