rwsem.h revision 219820 
1/*-
2 * Copyright (c) 2010 Isilon Systems, Inc.
3 * Copyright (c) 2010 iX Systems, Inc.
4 * Copyright (c) 2010 Panasas, Inc.
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#ifndef	_LINUX_RWSEM_H_
29#define	_LINUX_RWSEM_H_
30
31#include <sys/param.h>
32#include <sys/lock.h>
33#include <sys/sx.h>
34
35struct rw_semaphore {
36	struct sx sx;
37};
38
39#define	down_write(_rw)			sx_xlock(&(_rw)->sx)
40#define	up_write(_rw)			sx_xunlock(&(_rw)->sx)
41#define	down_read(_rw)			sx_slock(&(_rw)->sx)
42#define	up_read(_rw)			sx_sunlock(&(_rw)->sx)
43#define	down_read_trylock(_rw)		!!sx_try_slock(&(_rw)->sx)
44#define	down_write_trylock(_rw)		!!sx_try_xlock(&(_rw)->sx)
45#define	downgrade_write(_rw)		sx_downgrade(&(_rw)->sx)
46#define	down_read_nested(_rw, _sc)	down_read(_rw)
47
48static inline void
49init_rwsem(struct rw_semaphore *rw)
50{
51
52	memset(&rw->sx, 0, sizeof(rw->sx));
53	sx_init_flags(&rw->sx, "lnxrwsem", SX_NOWITNESS);
54}
55
56#endif	/* _LINUX_RWSEM_H_ */
57