1*22ce4affSfengbojiang /*-
2*22ce4affSfengbojiang * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3*22ce4affSfengbojiang *
4*22ce4affSfengbojiang * Copyright (c) 2020 The FreeBSD Foundation
5*22ce4affSfengbojiang *
6*22ce4affSfengbojiang * This software was developed by Mark Johnston under sponsorship from
7*22ce4affSfengbojiang * the FreeBSD Foundation.
8*22ce4affSfengbojiang *
9*22ce4affSfengbojiang * Redistribution and use in source and binary forms, with or without
10*22ce4affSfengbojiang * modification, are permitted provided that the following conditions are
11*22ce4affSfengbojiang * met:
12*22ce4affSfengbojiang * 1. Redistributions of source code must retain the above copyright
13*22ce4affSfengbojiang * notice, this list of conditions and the following disclaimer.
14*22ce4affSfengbojiang * 2. Redistributions in binary form must reproduce the above copyright
15*22ce4affSfengbojiang * notice, this list of conditions and the following disclaimer in
16*22ce4affSfengbojiang * the documentation and/or other materials provided with the distribution.
17*22ce4affSfengbojiang *
18*22ce4affSfengbojiang * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19*22ce4affSfengbojiang * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20*22ce4affSfengbojiang * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21*22ce4affSfengbojiang * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22*22ce4affSfengbojiang * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23*22ce4affSfengbojiang * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24*22ce4affSfengbojiang * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25*22ce4affSfengbojiang * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26*22ce4affSfengbojiang * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27*22ce4affSfengbojiang * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28*22ce4affSfengbojiang * SUCH DAMAGE.
29*22ce4affSfengbojiang *
30*22ce4affSfengbojiang * $FreeBSD$
31*22ce4affSfengbojiang */
32*22ce4affSfengbojiang
33*22ce4affSfengbojiang #ifndef __SYS__BLOCKCOUNT_H__
34*22ce4affSfengbojiang #define __SYS__BLOCKCOUNT_H__
35*22ce4affSfengbojiang
36*22ce4affSfengbojiang #include <machine/atomic.h>
37*22ce4affSfengbojiang
38*22ce4affSfengbojiang typedef struct _blockcount {
39*22ce4affSfengbojiang unsigned int __count;
40*22ce4affSfengbojiang } blockcount_t;
41*22ce4affSfengbojiang
42*22ce4affSfengbojiang #define _BLOCKCOUNT_WAITERS_FLAG (1U << 31)
43*22ce4affSfengbojiang #define _BLOCKCOUNT_COUNT(c) ((c) & ~_BLOCKCOUNT_WAITERS_FLAG)
44*22ce4affSfengbojiang #define _BLOCKCOUNT_WAITERS(c) (((c) & _BLOCKCOUNT_WAITERS_FLAG) != 0)
45*22ce4affSfengbojiang
46*22ce4affSfengbojiang static inline unsigned int
blockcount_read(blockcount_t * count)47*22ce4affSfengbojiang blockcount_read(blockcount_t *count)
48*22ce4affSfengbojiang {
49*22ce4affSfengbojiang return (_BLOCKCOUNT_COUNT(atomic_load_int(&count->__count)));
50*22ce4affSfengbojiang }
51*22ce4affSfengbojiang
52*22ce4affSfengbojiang #endif /* !__SYS__BLOCKCOUNT_H__ */
53