xref: /illumos-gate/usr/src/boot/sys/sys/_mutex.h (revision 199767f8)
1 /*-
2  * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  * 3. Berkeley Software Design Inc's name may not be used to endorse or
13  *    promote products derived from this software without specific prior
14  *    written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  *
28  * $FreeBSD$
29  */
30 
31 #ifndef _SYS__MUTEX_H_
32 #define	_SYS__MUTEX_H_
33 
34 #include <machine/param.h>
35 
36 /*
37  * Sleep/spin mutex.
38  *
39  * All mutex implementations must always have a member called mtx_lock.
40  * Other locking primitive structures are not allowed to use this name
41  * for their members.
42  * If this rule needs to change, the bits in the mutex implementation must
43  * be modified appropriately.
44  */
45 struct mtx {
46 	struct lock_object	lock_object;	/* Common lock properties. */
47 	volatile uintptr_t	mtx_lock;	/* Owner and flags. */
48 };
49 
50 /*
51  * Members of struct mtx_padalign must mirror members of struct mtx.
52  * mtx_padalign mutexes can use the mtx(9) API transparently without
53  * modification.
54  * Pad-aligned mutexes used within structures should generally be the
55  * first member of the struct.  Otherwise, the compiler can generate
56  * additional padding for the struct to keep a correct alignment for
57  * the mutex.
58  */
59 struct mtx_padalign {
60 	struct lock_object	lock_object;	/* Common lock properties. */
61 	volatile uintptr_t	mtx_lock;	/* Owner and flags. */
62 } __aligned(CACHE_LINE_SIZE);
63 
64 #endif /* !_SYS__MUTEX_H_ */
65