1 /* $NetBSD: subr_once.c,v 1.2 2005/12/11 12:24:30 christos 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 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: subr_once.c,v 1.2 2005/12/11 12:24:30 christos Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/proc.h> 35 #include <sys/once.h> 36 37 void 38 _run_once(once_t *o, void (*fn)(void)) 39 { 40 41 simple_lock(&o->o_lock); 42 while ((o->o_flags & ONCE_RUNNING) != 0) { 43 ltsleep(o, PUSER, "runonce", 0, &o->o_lock); 44 } 45 if (o->o_flags & ONCE_DONE) { 46 goto done; 47 } 48 o->o_flags |= ONCE_RUNNING; 49 simple_unlock(&o->o_lock); 50 51 (*fn)(); 52 53 simple_lock(&o->o_lock); 54 o->o_flags = ONCE_DONE; 55 wakeup(o); 56 done: 57 simple_unlock(&o->o_lock); 58 } 59