1154956Sscottl/*- 2154956Sscottl * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 3154956Sscottl * 4154956Sscottl * Redistribution and use in source and binary forms, with or without 5154956Sscottl * modification, are permitted provided that the following conditions 6154956Sscottl * are met: 7154956Sscottl * 1. Redistributions of source code must retain the above copyright 8154956Sscottl * notice, this list of conditions and the following disclaimer. 9154956Sscottl * 2. Redistributions in binary form must reproduce the above copyright 10154956Sscottl * notice, this list of conditions and the following disclaimer in the 11154956Sscottl * documentation and/or other materials provided with the distribution. 12154956Sscottl * 13155121Sjhb * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14154956Sscottl * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15154956Sscottl * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16155121Sjhb * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17154956Sscottl * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18154956Sscottl * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19154956Sscottl * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20154956Sscottl * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21154956Sscottl * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22154956Sscottl * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23154956Sscottl * SUCH DAMAGE. 24154956Sscottl * 25154956Sscottl * $FreeBSD: stable/11/sys/sys/_rwlock.h 367457 2020-11-07 18:10:59Z dim $ 26154956Sscottl */ 27154956Sscottl 28154956Sscottl#ifndef _SYS__RWLOCK_H_ 29154956Sscottl#define _SYS__RWLOCK_H_ 30154956Sscottl 31242515Sattilio#include <machine/param.h> 32242515Sattilio 33154956Sscottl/* 34155121Sjhb * Reader/writer lock. 35242515Sattilio * 36242901Sattilio * All reader/writer lock implementations must always have a member 37242901Sattilio * called rw_lock. Other locking primitive structures are not allowed to 38242901Sattilio * use this name for their members. 39242901Sattilio * If this rule needs to change, the bits in the reader/writer lock 40242901Sattilio * implementation must be modified appropriately. 41154956Sscottl */ 42154956Sscottlstruct rwlock { 43167787Sjhb struct lock_object lock_object; 44154956Sscottl volatile uintptr_t rw_lock; 45154956Sscottl}; 46154956Sscottl 47242515Sattilio/* 48242515Sattilio * Members of struct rwlock_padalign must mirror members of struct rwlock. 49242901Sattilio * rwlock_padalign rwlocks can use the rwlock(9) API transparently without 50242901Sattilio * modification. 51242901Sattilio * Pad-aligned rwlocks used within structures should generally be the 52242901Sattilio * first member of the struct. Otherwise, the compiler can generate 53242901Sattilio * additional padding for the struct to keep a correct alignment for 54242901Sattilio * the rwlock. 55242515Sattilio */ 56242515Sattiliostruct rwlock_padalign { 57242515Sattilio struct lock_object lock_object; 58242515Sattilio volatile uintptr_t rw_lock; 59242515Sattilio} __aligned(CACHE_LINE_SIZE); 60242515Sattilio 61154956Sscottl#endif /* !_SYS__RWLOCK_H_ */ 62