FreeBSD/Linux Kernel Cross Reference
sys/sys/once.h
1 /* $NetBSD: once.h,v 1.3 2006/01/16 21:45:38 yamt Exp $ */
2
3 /*-
4 * Copyright (c)2005 YAMAMOTO Takashi,
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, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #ifndef _SYS_ONCE_H_
30 #define _SYS_ONCE_H_
31
32 #include <sys/lock.h>
33
34 typedef struct {
35 struct simplelock o_lock;
36 int o_flags;
37 #define ONCE_RUNNING 1
38 #define ONCE_DONE 2
39 } once_t;
40
41 int _run_once(once_t *, int (*)(void));
42
43 #define ONCE_DECL(o) \
44 once_t (o) = { \
45 .o_lock = SIMPLELOCK_INITIALIZER, \
46 .o_flags = 0, \
47 };
48
49 #define RUN_ONCE(o, fn) \
50 (__predict_true(((o)->o_flags & ONCE_DONE) != 0) ? 0 : _run_once((o), (fn)))
51
52 #endif /* _SYS_ONCE_H_ */
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