1/* $NetBSD: subr_once.c,v 1.6 2009/03/15 17:14:40 cegger 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#include <sys/cdefs.h>
31__KERNEL_RCSID(0, "$NetBSD: subr_once.c,v 1.6 2009/03/15 17:14:40 cegger Exp $");
32
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/condvar.h>
36#include <sys/mutex.h>
37#include <sys/once.h>
38
39static kmutex_t oncemtx;
40static kcondvar_t oncecv;
41
42void
43once_init(void)
44{
45
46 mutex_init(&oncemtx, MUTEX_DEFAULT, IPL_NONE);
47 cv_init(&oncecv, "runonce");
48}
49
50int
51_run_once(once_t *o, int (*fn)(void))
52{
53
54 /* Fastpath handled by RUN_ONCE() */
55
56 mutex_enter(&oncemtx);
57 if (o->o_status == ONCE_VIRGIN) {
58 o->o_status = ONCE_RUNNING;
59 mutex_exit(&oncemtx);
60 o->o_error = fn();
61 mutex_enter(&oncemtx);
62 o->o_status = ONCE_DONE;
63 cv_broadcast(&oncecv);
64 }
65 while (o->o_status != ONCE_DONE)
66 cv_wait(&oncecv, &oncemtx);
67 mutex_exit(&oncemtx);
68
69 KASSERT(o->o_status == ONCE_DONE);
70 return o->o_error;
71}
72