FreeBSD/Linux Kernel Cross Reference
sys/sys/umtx.h
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: releng/5.3/sys/sys/umtx.h 136588 2004-10-16 08:43:07Z cvs2svn $
27 *
28 */
29
30 #ifndef _SYS_UMTX_H_
31 #define _SYS_UMTX_H_
32
33 /*
34 * See pthread_*
35 */
36
37 #define UMTX_UNOWNED 0x0
38
39 struct umtx {
40 void *u_owner; /* Owner of the mutex. */
41 };
42
43 #ifndef _KERNEL
44
45 /*
46 * System calls for acquiring and releasing contested mutexes.
47 */
48 int _umtx_lock(struct umtx *mtx);
49 int _umtx_unlock(struct umtx *mtx);
50
51 /*
52 * Standard api. Try uncontested acquire/release and asks the
53 * kernel to resolve failures.
54 */
55 static __inline int
56 umtx_lock(struct umtx *umtx, long id)
57 {
58 if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
59 (void *)id) == 0)
60 if (_umtx_lock(umtx) == -1)
61 return (errno);
62 return (0);
63 }
64
65 static __inline int
66 umtx_trylock(struct umtx *umtx, long id)
67 {
68 if (atomic_cmpset_acq_ptr(&umtx->u_owner, (void *)UMTX_UNOWNED,
69 (void *)id) == 0)
70 return (EBUSY);
71 return (0);
72 }
73
74 static __inline int
75 umtx_unlock(struct umtx *umtx, long id)
76 {
77 if (atomic_cmpset_rel_ptr(&umtx->u_owner, (void *)id,
78 (void *)UMTX_UNOWNED) == 0)
79 if (_umtx_unlock(umtx) == -1)
80 return (errno);
81 return (0);
82 }
83 #endif /* !_KERNEL */
84
85 #endif /* !_SYS_UMTX_H_ */
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