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 typedef enum {
38 	RW_DEFAULT = 4		/* kernel default rwlock */
39 } krw_type_t;
40 
41 
42 typedef enum {
43 	RW_NONE		= 0,
44 	RW_WRITER	= 1,
45 	RW_READER	= 2
46 } krw_t;
47 
48 typedef	struct sx	krwlock_t;
49 
50 #ifndef OPENSOLARIS_WITNESS
51 #define	RW_FLAGS	(SX_DUPOK | SX_NEW | SX_NOWITNESS)
52 #else
53 #define	RW_FLAGS	(SX_DUPOK | SX_NEW)
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 #define	rw_init(lock, desc, type, arg)	do {				\
61 	const char *_name;						\
62 	ASSERT((type) == 0 || (type) == RW_DEFAULT);			\
63 	for (_name = #lock; *_name != '\0'; _name++) {			\
64 		if (*_name >= 'a' && *_name <= 'z')			\
65 			break;						\
66 	}								\
67 	if (*_name == '\0')						\
68 		_name = #lock;						\
69 	sx_init_flags((lock), _name, RW_FLAGS);				\
70 } while (0)
71 #define	rw_destroy(lock)	sx_destroy(lock)
72 #define	rw_enter(lock, how)	do {					\
73 	if ((how) == RW_READER)						\
74 		sx_slock(lock);						\
75 	else /* if ((how) == RW_WRITER) */				\
76 		sx_xlock(lock);						\
77 	} while (0)
78 
79 #define	rw_tryenter(lock, how)			   \
80 	((how) == RW_READER ? sx_try_slock(lock) : sx_try_xlock(lock))
81 #define	rw_exit(lock)		sx_unlock(lock)
82 #define	rw_downgrade(lock)	sx_downgrade(lock)
83 #define	rw_tryupgrade(lock)	sx_try_upgrade(lock)
84 #define	rw_read_held(lock)					  \
85 	((lock)->sx_lock != SX_LOCK_UNLOCKED &&	  \
86 	    ((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 #define	rw_owner(lock)		sx_xholder(lock)
91 
92 #endif	/* _OPENSOLARIS_SYS_RWLOCK_H_ */
93