2 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #ifndef _SYS__RWLOCK_H_
30 #define _SYS__RWLOCK_H_
32 #include <machine/param.h>
37 * All reader/writer lock implementations must always have a member
38 * called rw_lock. Other locking primitive structures are not allowed to
39 * use this name for their members.
40 * If this rule needs to change, the bits in the reader/writer lock
41 * implementation must be modified appropriately.
44 struct lock_object lock_object;
45 volatile uintptr_t rw_lock;
49 * Members of struct rwlock_padalign must mirror members of struct rwlock.
50 * rwlock_padalign rwlocks can use the rwlock(9) API transparently without
52 * Pad-aligned rwlocks used within structures should generally be the
53 * first member of the struct. Otherwise, the compiler can generate
54 * additional padding for the struct to keep a correct alignment for
57 struct rwlock_padalign {
58 struct lock_object lock_object;
59 volatile uintptr_t rw_lock;
60 } __aligned(CACHE_LINE_SIZE);
62 #endif /* !_SYS__RWLOCK_H_ */