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 | |
39 | static kmutex_t oncemtx; |
40 | static kcondvar_t oncecv; |
41 | |
42 | void |
43 | once_init(void) |
44 | { |
45 | |
46 | mutex_init(&oncemtx, MUTEX_DEFAULT, IPL_NONE); |
47 | cv_init(&oncecv, "runonce" ); |
48 | } |
49 | |
50 | int |
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 | |