/* $NetBSD: pthread_once.c,v 1.5 2025/03/04 00:41:00 riastradh Exp $ */

/* $NetBSD: pthread_once.c,v 1.5 2025/03/04 00:41:00 riastradh Exp $ */

/*-
* Copyright (c) 2001, 2003 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Nathan J. Williams, and by Jason R. Thorpe.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__RCSID("$NetBSD: pthread_once.c,v 1.5 2025/03/04 00:41:00 riastradh Exp $");

/* Need to use libc-private names for atomic operations. */
#include "../../common/lib/libc/atomic/atomic_op_namespace.h"

#include "pthread.h"
#include "pthread_int.h"
#include "reentrant.h"

static void
once_cleanup(void *closure)
{

pthread_mutex_unlock((pthread_mutex_t *)closure);
}

int
pthread_once(pthread_once_t *once_control, void (*routine)(void))
{
if (__predict_false(__uselibcstub))
return __libc_thr_once_stub(once_control, routine);

if (once_control->pto_done == 0) {
pthread_mutex_lock(&once_control->pto_mutex);
pthread_cleanup_push(&once_cleanup, &once_control->pto_mutex);
if (once_control->pto_done == 0) {
routine();
membar_release();
once_control->pto_done = 1;
}
pthread_cleanup_pop(1);
} else {
membar_acquire();
}

return 0;
}

__strong_alias(__libc_thr_once,pthread_once)