sys/arch/x86/include/rwlock.h

   1 /*      $NetBSD: rwlock.h,v 1.5 2008/04/28 20:23:40 martin Exp $        */
   2
   3 /*-
   4  * Copyright (c) 2002, 2006 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Jason R. Thorpe and Andrew Doran.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #ifndef _X86_RWLOCK_H_
  33 #define _X86_RWLOCK_H_
  34
  35 struct krwlock {
  36         volatile uintptr_t      rw_owner;
  37 };
  38
  39 #ifdef __RWLOCK_PRIVATE
  40
  41 #define __HAVE_SIMPLE_RW_LOCKS          1
  42 #define __HAVE_RW_STUBS                 1
  43
  44 /*
  45  * RW_RECEIVE: no memory barrier required, as 'ret' implies a load fence.
  46  */
  47 #define RW_RECEIVE(rw)                  /* nothing */
  48
  49 /*
  50  * RW_GIVE: no memory barrier required, as _lock_cas() will take care of it.
  51  */
  52 #define RW_GIVE(rw)                     /* nothing */
  53
  54 #define RW_CAS(p, o, n)                 \
  55     (_atomic_cas_ulong((volatile unsigned long *)(p), (o), (n)) == (o))
  56
  57 unsigned long   _atomic_cas_ulong(volatile unsigned long *,
  58     unsigned long, unsigned long);
  59
  60 #endif  /* __RWLOCK_PRIVATE */
  61
  62 #endif /* _X86_RWLOCK_H_ */