1*199767f8SToomas Soome /*- 2*199767f8SToomas Soome * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 3*199767f8SToomas Soome * All rights reserved. 4*199767f8SToomas Soome * 5*199767f8SToomas Soome * Redistribution and use in source and binary forms, with or without 6*199767f8SToomas Soome * modification, are permitted provided that the following conditions 7*199767f8SToomas Soome * are met: 8*199767f8SToomas Soome * 1. Redistributions of source code must retain the above copyright 9*199767f8SToomas Soome * notice, this list of conditions and the following disclaimer. 10*199767f8SToomas Soome * 2. Redistributions in binary form must reproduce the above copyright 11*199767f8SToomas Soome * notice, this list of conditions and the following disclaimer in the 12*199767f8SToomas Soome * documentation and/or other materials provided with the distribution. 13*199767f8SToomas Soome * 14*199767f8SToomas Soome * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15*199767f8SToomas Soome * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16*199767f8SToomas Soome * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17*199767f8SToomas Soome * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18*199767f8SToomas Soome * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19*199767f8SToomas Soome * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20*199767f8SToomas Soome * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21*199767f8SToomas Soome * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22*199767f8SToomas Soome * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23*199767f8SToomas Soome * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24*199767f8SToomas Soome * SUCH DAMAGE. 25*199767f8SToomas Soome * 26*199767f8SToomas Soome * $FreeBSD$ 27*199767f8SToomas Soome */ 28*199767f8SToomas Soome 29*199767f8SToomas Soome #ifndef _SYS__RWLOCK_H_ 30*199767f8SToomas Soome #define _SYS__RWLOCK_H_ 31*199767f8SToomas Soome 32*199767f8SToomas Soome #include <machine/param.h> 33*199767f8SToomas Soome 34*199767f8SToomas Soome /* 35*199767f8SToomas Soome * Reader/writer lock. 36*199767f8SToomas Soome * 37*199767f8SToomas Soome * All reader/writer lock implementations must always have a member 38*199767f8SToomas Soome * called rw_lock. Other locking primitive structures are not allowed to 39*199767f8SToomas Soome * use this name for their members. 40*199767f8SToomas Soome * If this rule needs to change, the bits in the reader/writer lock 41*199767f8SToomas Soome * implementation must be modified appropriately. 42*199767f8SToomas Soome */ 43*199767f8SToomas Soome struct rwlock { 44*199767f8SToomas Soome struct lock_object lock_object; 45*199767f8SToomas Soome volatile uintptr_t rw_lock; 46*199767f8SToomas Soome }; 47*199767f8SToomas Soome 48*199767f8SToomas Soome /* 49*199767f8SToomas Soome * Members of struct rwlock_padalign must mirror members of struct rwlock. 50*199767f8SToomas Soome * rwlock_padalign rwlocks can use the rwlock(9) API transparently without 51*199767f8SToomas Soome * modification. 52*199767f8SToomas Soome * Pad-aligned rwlocks used within structures should generally be the 53*199767f8SToomas Soome * first member of the struct. Otherwise, the compiler can generate 54*199767f8SToomas Soome * additional padding for the struct to keep a correct alignment for 55*199767f8SToomas Soome * the rwlock. 56*199767f8SToomas Soome */ 57*199767f8SToomas Soome struct rwlock_padalign { 58*199767f8SToomas Soome struct lock_object lock_object; 59*199767f8SToomas Soome volatile uintptr_t rw_lock; 60*199767f8SToomas Soome } __aligned(CACHE_LINE_SIZE); 61*199767f8SToomas Soome 62*199767f8SToomas Soome #endif /* !_SYS__RWLOCK_H_ */ 63