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/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2005, David Xu <davidxu@freebsd.org>
* All rights reserved.
*
* 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 unmodified, 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <pthread.h>
#include "un-namespace.h"
#include "thr_private.h"
__weak_reference(_thr_once, pthread_once);
__weak_reference(_thr_once, _pthread_once);
#define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT
#define ONCE_DONE PTHREAD_DONE_INIT
#define ONCE_IN_PROGRESS 0x02
#define ONCE_WAIT 0x03
/*
* POSIX:
* The pthread_once() function is not a cancellation point. However,
* if init_routine is a cancellation point and is canceled, the effect
* on once_control shall be as if pthread_once() was never called.
*/
static void
once_cancel_handler(void *arg)
{
pthread_once_t *once_control;
once_control = arg;
if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS,
ONCE_NEVER_DONE))
return;
atomic_store_rel_int(&once_control->state, ONCE_NEVER_DONE);
_thr_umtx_wake(&once_control->state, INT_MAX, 0);
}
int
_thr_once(pthread_once_t *once_control, void (*init_routine)(void))
{
struct pthread *curthread;
int state;
_thr_check_init();
for (;;) {
state = once_control->state;
if (state == ONCE_DONE) {
atomic_thread_fence_acq();
return (0);
}
if (state == ONCE_NEVER_DONE) {
if (atomic_cmpset_int(&once_control->state, state,
ONCE_IN_PROGRESS))
break;
} else if (state == ONCE_IN_PROGRESS) {
if (atomic_cmpset_int(&once_control->state, state,
ONCE_WAIT))
_thr_umtx_wait_uint(&once_control->state,
ONCE_WAIT, NULL, 0);
} else if (state == ONCE_WAIT) {
_thr_umtx_wait_uint(&once_control->state, state,
NULL, 0);
} else
return (EINVAL);
}
curthread = _get_curthread();
THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control);
init_routine();
THR_CLEANUP_POP(curthread, 0);
if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS,
ONCE_DONE))
return (0);
atomic_store_rel_int(&once_control->state, ONCE_DONE);
_thr_umtx_wake(&once_control->state, INT_MAX, 0);
return (0);
}
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