| 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 | |