refcnt.h revision 367457 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2005 John Baldwin <jhb@FreeBSD.org>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD: stable/11/sbin/hastd/refcnt.h 367457 2020-11-07 18:10:59Z dim $
28 */
29
30#ifndef __REFCNT_H__
31#define __REFCNT_H__
32
33#include <machine/atomic.h>
34
35#include "pjdlog.h"
36
37typedef unsigned int refcnt_t;
38
39static __inline void
40refcnt_init(refcnt_t *count, unsigned int v)
41{
42
43	*count = v;
44}
45
46static __inline void
47refcnt_acquire(refcnt_t *count)
48{
49
50	atomic_add_acq_int(count, 1);
51}
52
53static __inline unsigned int
54refcnt_release(refcnt_t *count)
55{
56	unsigned int old;
57
58	/* XXX: Should this have a rel membar? */
59	old = atomic_fetchadd_int(count, -1);
60	PJDLOG_ASSERT(old > 0);
61	return (old - 1);
62}
63
64#endif	/* ! __REFCNT_H__ */
65