1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS 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__RWLOCK_H_ 32 #define _SYS__RWLOCK_H_ 33 34 #include <machine/param.h> 35 36 /* 37 * Reader/writer lock. 38 * 39 * All reader/writer lock implementations must always have a member 40 * called rw_lock. Other locking primitive structures are not allowed to 41 * use this name for their members. 42 * If this rule needs to change, the bits in the reader/writer lock 43 * implementation must be modified appropriately. 44 */ 45 struct rwlock { 46 struct lock_object lock_object; 47 volatile uintptr_t rw_lock; 48 }; 49 50 /* 51 * Members of struct rwlock_padalign must mirror members of struct rwlock. 52 * rwlock_padalign rwlocks can use the rwlock(9) API transparently without 53 * modification. 54 * Pad-aligned rwlocks 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 rwlock. 58 */ 59 struct rwlock_padalign { 60 struct lock_object lock_object; 61 volatile uintptr_t rw_lock; 62 } __aligned(CACHE_LINE_SIZE); 63 64 #endif /* !_SYS__RWLOCK_H_ */ 65