Index: stable/11/sys/sys/refcount.h
===================================================================
--- stable/11/sys/sys/refcount.h	(revision 320980)
+++ stable/11/sys/sys/refcount.h	(revision 320981)
@@ -1,67 +1,77 @@
 /*-
  * Copyright (c) 2005 John Baldwin <jhb@FreeBSD.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
  * $FreeBSD$
  */
 
 #ifndef __SYS_REFCOUNT_H__
 #define __SYS_REFCOUNT_H__
 
 #include <sys/limits.h>
 #include <machine/atomic.h>
 
 #ifdef _KERNEL
 #include <sys/systm.h>
 #else
 #define	KASSERT(exp, msg)	/* */
 #endif
 
 static __inline void
 refcount_init(volatile u_int *count, u_int value)
 {
 
 	*count = value;
 }
 
 static __inline void
 refcount_acquire(volatile u_int *count)
 {
 
 	KASSERT(*count < UINT_MAX, ("refcount %p overflowed", count));
-	atomic_add_acq_int(count, 1);	
+	atomic_add_int(count, 1);
 }
 
 static __inline int
 refcount_release(volatile u_int *count)
 {
 	u_int old;
 
-	/* XXX: Should this have a rel membar? */
+	atomic_thread_fence_rel();
 	old = atomic_fetchadd_int(count, -1);
 	KASSERT(old > 0, ("negative refcount %p", count));
-	return (old == 1);
+	if (old > 1)
+		return (0);
+
+	/*
+	 * Last reference.  Signal the user to call the destructor.
+	 *
+	 * Ensure that the destructor sees all updates.  The fence_rel
+	 * at the start of the function synchronized with this fence.
+	 */
+	atomic_thread_fence_acq();
+	return (1);
 }
 
 #endif	/* ! __SYS_REFCOUNT_H__ */
Index: stable/11
===================================================================
--- stable/11	(revision 320980)
+++ stable/11	(revision 320981)

Property changes on: stable/11
___________________________________________________________________
Modified: svn:mergeinfo
## -0,0 +0,1 ##
   Merged /head:r320501