umtx.h revision 139825 
1/*-
2 * Copyright (c) 2002, Jeffrey Roberson <jeff@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 unmodified, this list of conditions, and the following
10 *    disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/sys/umtx.h 139825 2005-01-07 02:29:27Z imp $
27 *
28 */
29
30#ifndef _SYS_UMTX_H_
31#define	_SYS_UMTX_H_
32
33#include <sys/limits.h>
34
35/*
36 * See pthread_*
37 */
38
39#define	UMTX_UNOWNED	0x0
40#define	UMTX_CONTESTED	LONG_MIN
41
42struct umtx {
43	void	*u_owner;	/* Owner of the mutex. */
44};
45
46/* op code for _umtx_op */
47#define UMTX_OP_LOCK		0
48#define UMTX_OP_UNLOCK		1
49#define UMTX_OP_WAIT		2
50#define UMTX_OP_WAKE		3
51
52#ifndef _KERNEL
53
54/*
55 * System calls for acquiring and releasing contested mutexes.
56 */
57/* deprecated becaues it can only use thread id */
58int _umtx_lock(struct umtx *mtx);
59/* deprecated becaues it can only use thread id */
60int _umtx_unlock(struct umtx *mtx);
61int _umtx_op(struct umtx *umtx, int op, long id, void *uaddr, void *uaddr2);
62
63/*
64 * Standard api.  Try uncontested acquire/release and asks the
65 * kernel to resolve failures.
66 */
67static __inline void
68umtx_init(struct umtx *umtx)
69{
70	umtx->u_owner = UMTX_UNOWNED;
71}
72
73static __inline long
74umtx_owner(struct umtx *umtx)
75{
76	return ((long)umtx->u_owner & ~LONG_MIN);
77}
78
79static __inline int
80umtx_lock(struct umtx *umtx, long id)
81{
82	if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
83	    (void *)id) == 0)
84		if (_umtx_op(umtx, UMTX_OP_LOCK, id, 0, 0) == -1)
85			return (errno);
86	return (0);
87}
88
89static __inline int
90umtx_trylock(struct umtx *umtx, long id)
91{
92	if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
93	    (void *)id) == 0)
94		return (EBUSY);
95	return (0);
96}
97
98static __inline int
99umtx_timedlock(struct umtx *umtx, long id, const struct timespec *abstime)
100{
101	if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
102	    (void *)id) == 0)
103		if (_umtx_op(umtx, UMTX_OP_LOCK, id, 0, (void *)abstime) == -1)
104			return (errno);
105	return (0);
106}
107
108static __inline int
109umtx_unlock(struct umtx *umtx, long id)
110{
111	if (atomic_cmpset_rel_ptr(&umtx->u_owner, (void *)id,
112	    (void *)UMTX_UNOWNED) == 0)
113		if (_umtx_op(umtx, UMTX_OP_UNLOCK, id, 0, 0) == -1)
114			return (errno);
115	return (0);
116}
117
118/* Unlock umtx and wait on a user address. */
119
120static __inline int
121umtx_wait(struct umtx *umtx, long id)
122{
123	if (_umtx_op(umtx, UMTX_OP_WAIT, id, 0, 0) == -1)
124		return (errno);
125	return (0);
126}
127
128static __inline int
129umtx_timedwait(struct umtx *umtx, long id, const struct timespec *abstime)
130{
131	if (_umtx_op(umtx, UMTX_OP_WAIT, id, 0, (void *)abstime) == -1)
132		return (errno);
133	return (0);
134}
135
136/* Wake threads waiting on a user address. */
137static __inline int
138umtx_wake(struct umtx *umtx, int nr_wakeup)
139{
140	/* return how many threads were woke up, -1 if error */
141	return _umtx_op(umtx, UMTX_OP_WAKE, nr_wakeup, 0, 0);
142}
143
144#endif /* !_KERNEL */
145#endif /* !_SYS_UMTX_H_ */
146