72 lines
2.2 KiB
C
72 lines
2.2 KiB
C
/* $NetBSD: subr_once.c,v 1.6 2009/03/15 17:14:40 cegger Exp $ */
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/*-
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* Copyright (c)2005 YAMAMOTO Takashi,
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* Copyright (c)2008 Antti Kantee,
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: subr_once.c,v 1.6 2009/03/15 17:14:40 cegger Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/condvar.h>
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#include <sys/mutex.h>
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#include <sys/once.h>
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static kmutex_t oncemtx;
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static kcondvar_t oncecv;
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void
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once_init(void)
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{
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mutex_init(&oncemtx, MUTEX_DEFAULT, IPL_NONE);
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cv_init(&oncecv, "runonce");
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}
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int
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_run_once(once_t *o, int (*fn)(void))
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{
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/* Fastpath handled by RUN_ONCE() */
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mutex_enter(&oncemtx);
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if (o->o_status == ONCE_VIRGIN) {
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o->o_status = ONCE_RUNNING;
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mutex_exit(&oncemtx);
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o->o_error = fn();
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mutex_enter(&oncemtx);
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o->o_status = ONCE_DONE;
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cv_broadcast(&oncecv);
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}
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while (o->o_status != ONCE_DONE)
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cv_wait(&oncecv, &oncemtx);
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mutex_exit(&oncemtx);
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KASSERT(o->o_status == ONCE_DONE);
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return o->o_error;
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}
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