1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2005 John Baldwin <jhb@FreeBSD.org>
5 * Copyright (c) 2020 The FreeBSD Foundation
6 *
7 * Portions of this software were developed by Mark Johnston under
8 * sponsorship from the FreeBSD Foundation.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#ifndef __SYS_BLOCKCOUNT_H__
33#define __SYS_BLOCKCOUNT_H__
34
35#ifdef _KERNEL
36
37#include <sys/systm.h>
38#include <sys/_blockcount.h>
39
40struct lock_object;
41
42int _blockcount_sleep(blockcount_t *bc, struct lock_object *, const char *wmesg,
43 int prio);
44void _blockcount_wakeup(blockcount_t *bc, u_int old);
45
46static __inline void
47blockcount_init(blockcount_t *bc)
48{
49 atomic_store_int(&bc->__count, 0);
50}
51
52static __inline void
53blockcount_acquire(blockcount_t *bc, u_int n)
54{
55#ifdef INVARIANTS
56 u_int old;
57
58 old = atomic_fetchadd_int(&bc->__count, n);
59 KASSERT(old + n > old, ("%s: counter overflow %p", __func__, bc));
60#else
61 atomic_add_int(&bc->__count, n);
62#endif
63}
64
65static __inline void
66blockcount_release(blockcount_t *bc, u_int n)
67{
68 u_int old;
69
70 atomic_thread_fence_rel();
71 old = atomic_fetchadd_int(&bc->__count, -n);
72 KASSERT(old >= n, ("%s: counter underflow %p", __func__, bc));
73 if (_BLOCKCOUNT_COUNT(old) == n && _BLOCKCOUNT_WAITERS(old))
74 _blockcount_wakeup(bc, old);
75}
76
77static __inline void
78_blockcount_wait(blockcount_t *bc, struct lock_object *lo, const char *wmesg,
79 int prio)
80{
81 KASSERT((prio & ~PRIMASK) == 0, ("%s: invalid prio %x", __func__, prio));
82
83 while (_blockcount_sleep(bc, lo, wmesg, prio) == EAGAIN)
84 ;
85}
86
87#define blockcount_sleep(bc, lo, wmesg, prio) \
88 _blockcount_sleep((bc), (struct lock_object *)(lo), (wmesg), (prio))
89#define blockcount_wait(bc, lo, wmesg, prio) \
90 _blockcount_wait((bc), (struct lock_object *)(lo), (wmesg), (prio))
91
92#endif /* _KERNEL */
93#endif /* !__SYS_BLOCKCOUNT_H__ */