1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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
28 #ifndef __REFCNT_H__
29 #define __REFCNT_H__
30
31 #include <machine/atomic.h>
32
33 #include "pjdlog.h"
34
35 typedef unsigned int refcnt_t;
36
37 static __inline void
refcnt_init(refcnt_t * count,unsigned int v)38 refcnt_init(refcnt_t *count, unsigned int v)
39 {
40
41 *count = v;
42 }
43
44 static __inline void
refcnt_acquire(refcnt_t * count)45 refcnt_acquire(refcnt_t *count)
46 {
47
48 atomic_add_acq_int(count, 1);
49 }
50
51 static __inline unsigned int
refcnt_release(refcnt_t * count)52 refcnt_release(refcnt_t *count)
53 {
54 unsigned int old;
55
56 /* XXX: Should this have a rel membar? */
57 old = atomic_fetchadd_int(count, -1);
58 PJDLOG_ASSERT(old > 0);
59 return (old - 1);
60 }
61
62 #endif /* ! __REFCNT_H__ */
63