FreeBSD/Linux Kernel Cross Reference
sys/sys/once.h
1 /* $NetBSD: once.h,v 1.7 2019/03/19 08:16:51 ryo Exp $ */
2
3 /*-
4 * Copyright (c)2005 YAMAMOTO Takashi,
5 * Copyright (c)2008 Antti Kantee,
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following 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 AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #ifndef _SYS_ONCE_H_
31 #define _SYS_ONCE_H_
32
33 typedef struct {
34 int o_error;
35 uint16_t o_refcnt;
36 uint16_t o_status;
37 #define ONCE_VIRGIN 0
38 #define ONCE_RUNNING 1
39 #define ONCE_DONE 2
40 } once_t;
41
42 void once_init(void);
43 int _init_once(once_t *, int (*)(void));
44 void _fini_once(once_t *, void (*)(void));
45
46 #define ONCE_DECL(o) \
47 once_t (o) = { \
48 .o_status = 0, \
49 .o_refcnt = 0, \
50 };
51
52 #define RUN_ONCE(o, fn) \
53 (__predict_true((o)->o_status == ONCE_DONE) ? \
54 ((o)->o_error) : _init_once((o), (fn)))
55
56 #define INIT_ONCE(o, fn) _init_once((o), (fn))
57 #define FINI_ONCE(o, fn) _fini_once((o), (fn))
58
59 #endif /* _SYS_ONCE_H_ */
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