_mutex.h revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
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 * 3. Berkeley Software Design Inc's name may not be used to endorse or
15 *    promote products derived from this software without specific prior
16 *    written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * $FreeBSD: stable/11/sys/sys/_mutex.h 330897 2018-03-14 03:19:51Z eadler $
31 */
32
33#ifndef _SYS__MUTEX_H_
34#define	_SYS__MUTEX_H_
35
36#include <machine/param.h>
37
38/*
39 * Sleep/spin mutex.
40 *
41 * All mutex implementations must always have a member called mtx_lock.
42 * Other locking primitive structures are not allowed to use this name
43 * for their members.
44 * If this rule needs to change, the bits in the mutex implementation must
45 * be modified appropriately.
46 */
47struct mtx {
48	struct lock_object	lock_object;	/* Common lock properties. */
49	volatile uintptr_t	mtx_lock;	/* Owner and flags. */
50};
51
52/*
53 * Members of struct mtx_padalign must mirror members of struct mtx.
54 * mtx_padalign mutexes can use the mtx(9) API transparently without
55 * modification.
56 * Pad-aligned mutexes used within structures should generally be the
57 * first member of the struct.  Otherwise, the compiler can generate
58 * additional padding for the struct to keep a correct alignment for
59 * the mutex.
60 */
61struct mtx_padalign {
62	struct lock_object	lock_object;	/* Common lock properties. */
63	volatile uintptr_t	mtx_lock;	/* Owner and flags. */
64} __aligned(CACHE_LINE_SIZE);
65
66#endif /* !_SYS__MUTEX_H_ */
67