diff --git a/src/node.cc b/src/node.cc
index a3bc129641..e80fec8f82 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -2650,7 +2650,7 @@ int Start(int argc, char *argv[]) {
   v8::Context::Scope context_scope(context);
 
   // Create the main node::Isolate object
-  Isolate::New(uv_default_loop());
+  Isolate* isolate = Isolate::New(uv_default_loop());
 
   Handle<Object> process_l = SetupProcessObject(argc, argv);
 
@@ -2669,6 +2669,8 @@ int Start(int argc, char *argv[]) {
 
   EmitExit(process_l);
 
+  isolate->Dispose();
+
 #ifndef NDEBUG
   // Clean up.
   context.Dispose();
diff --git a/src/node_isolate.cc b/src/node_isolate.cc
index af2f83fa8e..1255850d6f 100644
--- a/src/node_isolate.cc
+++ b/src/node_isolate.cc
@@ -20,6 +20,9 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 #include "node_isolate.h"
+
+#include <stdlib.h>
+#include <string.h>
 #include <assert.h>
 
 
@@ -34,9 +37,34 @@ Isolate* Isolate::New(uv_loop_t* loop) {
 Isolate::Isolate(uv_loop_t* loop) {
   loop_ = loop;
   isolate_ = v8::Isolate::GetCurrent();
+  SLIST_INIT(&at_exit_callbacks_);
   assert(isolate_->GetData() == NULL);
   isolate_->SetData(this);
 }
 
 
+void Isolate::AtExit(AtExitCallback callback, void* arg) {
+  struct AtExitCallbackInfo* it = new AtExitCallbackInfo;
+
+  NODE_ISOLATE_CHECK(this);
+
+  it->callback_ = callback;
+  it->arg_ = arg;
+
+  SLIST_INSERT_HEAD(&at_exit_callbacks_, it, entries_);
+}
+
+
+void Isolate::Dispose() {
+  struct AtExitCallbackInfo* it;
+
+  NODE_ISOLATE_CHECK(this);
+
+  SLIST_FOREACH(it, &at_exit_callbacks_, entries_) {
+    it->callback_(it->arg_);
+    delete it;
+  }
+}
+
+
 } // namespace node
diff --git a/src/node_isolate.h b/src/node_isolate.h
index df74a5f01d..415f69525f 100644
--- a/src/node_isolate.h
+++ b/src/node_isolate.h
@@ -22,8 +22,9 @@
 #ifndef SRC_NODE_ISOLATE_H_
 #define SRC_NODE_ISOLATE_H_
 
-#include <v8.h>
-#include <uv.h>
+#include "queue.h"
+#include "v8.h"
+#include "uv.h"
 
 #ifdef NDEBUG
 # define NODE_ISOLATE_CHECK(ptr) ((void) (ptr))
@@ -42,6 +43,8 @@ namespace node {
 
 class Isolate {
 public:
+  typedef void (*AtExitCallback)(void* arg);
+
   static Isolate* New(uv_loop_t* loop);
 
   static Isolate* GetCurrent() {
@@ -58,8 +61,24 @@ public:
     return isolate_;
   }
 
+  /* Register a handler that should run when the current isolate exits.
+   * Handlers run in LIFO order.
+   */
+  void AtExit(AtExitCallback callback, void *arg);
+
+  /* Shutdown the isolate. Call this method at thread death. */
+  void Dispose();
+
 private:
   Isolate(uv_loop_t* loop);
+
+  struct AtExitCallbackInfo {
+    SLIST_ENTRY(AtExitCallbackInfo) entries_;
+    AtExitCallback callback_;
+    void* arg_;
+  };
+
+  SLIST_HEAD(AtExitCallbacks, AtExitCallbackInfo) at_exit_callbacks_;
   v8::Isolate* isolate_;
   uv_loop_t* loop_;
 };
diff --git a/src/queue.h b/src/queue.h
new file mode 100644
index 0000000000..ea2b7b4b17
--- /dev/null
+++ b/src/queue.h
@@ -0,0 +1,741 @@
+/*	$NetBSD: queue.h,v 1.53 2011/11/19 22:51:31 tls Exp $	*/
+
+/*
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  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.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ *	@(#)queue.h	8.5 (Berkeley) 8/20/94
+ */
+
+#ifndef	_SYS_QUEUE_H_
+#define	_SYS_QUEUE_H_
+
+/*
+ * This file defines five types of data structures: singly-linked lists,
+ * lists, simple queues, tail queues, and circular queues.
+ *
+ * A singly-linked list is headed by a single forward pointer. The
+ * elements are singly linked for minimum space and pointer manipulation
+ * overhead at the expense of O(n) removal for arbitrary elements. New
+ * elements can be added to the list after an existing element or at the
+ * head of the list.  Elements being removed from the head of the list
+ * should use the explicit macro for this purpose for optimum
+ * efficiency. A singly-linked list may only be traversed in the forward
+ * direction.  Singly-linked lists are ideal for applications with large
+ * datasets and few or no removals or for implementing a LIFO queue.
+ *
+ * A list is headed by a single forward pointer (or an array of forward
+ * pointers for a hash table header). The elements are doubly linked
+ * so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may only be traversed in the forward direction.
+ *
+ * A simple queue is headed by a pair of pointers, one the head of the
+ * list and the other to the tail of the list. The elements are singly
+ * linked to save space, so elements can only be removed from the
+ * head of the list. New elements can be added to the list after
+ * an existing element, at the head of the list, or at the end of the
+ * list. A simple queue may only be traversed in the forward direction.
+ *
+ * A tail queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
+ *
+ * A circle queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the list.
+ * A circle queue may be traversed in either direction, but has a more
+ * complex end of list detection.
+ *
+ * For details on the use of these macros, see the queue(3) manual page.
+ */
+
+/*
+ * List definitions.
+ */
+#define	LIST_HEAD(name, type)						\
+struct name {								\
+	struct type *lh_first;	/* first element */			\
+}
+
+#define	LIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define	LIST_ENTRY(type)						\
+struct {								\
+	struct type *le_next;	/* next element */			\
+	struct type **le_prev;	/* address of previous next element */	\
+}
+
+/*
+ * List functions.
+ */
+#if defined(_KERNEL) && defined(QUEUEDEBUG)
+#define	QUEUEDEBUG_LIST_INSERT_HEAD(head, elm, field)			\
+	if ((head)->lh_first &&						\
+	    (head)->lh_first->field.le_prev != &(head)->lh_first)	\
+		panic("LIST_INSERT_HEAD %p %s:%d", (head), __FILE__, __LINE__);
+#define	QUEUEDEBUG_LIST_OP(elm, field)					\
+	if ((elm)->field.le_next &&					\
+	    (elm)->field.le_next->field.le_prev !=			\
+	    &(elm)->field.le_next)					\
+		panic("LIST_* forw %p %s:%d", (elm), __FILE__, __LINE__);\
+	if (*(elm)->field.le_prev != (elm))				\
+		panic("LIST_* back %p %s:%d", (elm), __FILE__, __LINE__);
+#define	QUEUEDEBUG_LIST_POSTREMOVE(elm, field)				\
+	(elm)->field.le_next = (void *)1L;				\
+	(elm)->field.le_prev = (void *)1L;
+#else
+#define	QUEUEDEBUG_LIST_INSERT_HEAD(head, elm, field)
+#define	QUEUEDEBUG_LIST_OP(elm, field)
+#define	QUEUEDEBUG_LIST_POSTREMOVE(elm, field)
+#endif
+
+#define	LIST_INIT(head) do {						\
+	(head)->lh_first = NULL;					\
+} while (/*CONSTCOND*/0)
+
+#define	LIST_INSERT_AFTER(listelm, elm, field) do {			\
+	QUEUEDEBUG_LIST_OP((listelm), field)				\
+	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
+		(listelm)->field.le_next->field.le_prev =		\
+		    &(elm)->field.le_next;				\
+	(listelm)->field.le_next = (elm);				\
+	(elm)->field.le_prev = &(listelm)->field.le_next;		\
+} while (/*CONSTCOND*/0)
+
+#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
+	QUEUEDEBUG_LIST_OP((listelm), field)				\
+	(elm)->field.le_prev = (listelm)->field.le_prev;		\
+	(elm)->field.le_next = (listelm);				\
+	*(listelm)->field.le_prev = (elm);				\
+	(listelm)->field.le_prev = &(elm)->field.le_next;		\
+} while (/*CONSTCOND*/0)
+
+#define	LIST_INSERT_HEAD(head, elm, field) do {				\
+	QUEUEDEBUG_LIST_INSERT_HEAD((head), (elm), field)		\
+	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
+		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
+	(head)->lh_first = (elm);					\
+	(elm)->field.le_prev = &(head)->lh_first;			\
+} while (/*CONSTCOND*/0)
+
+#define	LIST_REMOVE(elm, field) do {					\
+	QUEUEDEBUG_LIST_OP((elm), field)				\
+	if ((elm)->field.le_next != NULL)				\
+		(elm)->field.le_next->field.le_prev = 			\
+		    (elm)->field.le_prev;				\
+	*(elm)->field.le_prev = (elm)->field.le_next;			\
+	QUEUEDEBUG_LIST_POSTREMOVE((elm), field)			\
+} while (/*CONSTCOND*/0)
+
+#define	LIST_FOREACH(var, head, field)					\
+	for ((var) = ((head)->lh_first);				\
+		(var);							\
+		(var) = ((var)->field.le_next))
+
+#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = LIST_FIRST((head));				\
+		(var) && ((tvar) = LIST_NEXT((var), field), 1);		\
+		(var) = (tvar))
+/*
+ * List access methods.
+ */
+#define	LIST_EMPTY(head)		((head)->lh_first == NULL)
+#define	LIST_FIRST(head)		((head)->lh_first)
+#define	LIST_NEXT(elm, field)		((elm)->field.le_next)
+
+
+/*
+ * Singly-linked List definitions.
+ */
+#define	SLIST_HEAD(name, type)						\
+struct name {								\
+	struct type *slh_first;	/* first element */			\
+}
+
+#define	SLIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define	SLIST_ENTRY(type)						\
+struct {								\
+	struct type *sle_next;	/* next element */			\
+}
+
+/*
+ * Singly-linked List functions.
+ */
+#define	SLIST_INIT(head) do {						\
+	(head)->slh_first = NULL;					\
+} while (/*CONSTCOND*/0)
+
+#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
+	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
+	(slistelm)->field.sle_next = (elm);				\
+} while (/*CONSTCOND*/0)
+
+#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
+	(elm)->field.sle_next = (head)->slh_first;			\
+	(head)->slh_first = (elm);					\
+} while (/*CONSTCOND*/0)
+
+#define	SLIST_REMOVE_HEAD(head, field) do {				\
+	(head)->slh_first = (head)->slh_first->field.sle_next;		\
+} while (/*CONSTCOND*/0)
+
+#define	SLIST_REMOVE(head, elm, type, field) do {			\
+	if ((head)->slh_first == (elm)) {				\
+		SLIST_REMOVE_HEAD((head), field);			\
+	}								\
+	else {								\
+		struct type *curelm = (head)->slh_first;		\
+		while(curelm->field.sle_next != (elm))			\
+			curelm = curelm->field.sle_next;		\
+		curelm->field.sle_next =				\
+		    curelm->field.sle_next->field.sle_next;		\
+	}								\
+} while (/*CONSTCOND*/0)
+
+#define	SLIST_REMOVE_AFTER(slistelm, field) do {			\
+	(slistelm)->field.sle_next =					\
+	    SLIST_NEXT(SLIST_NEXT((slistelm), field), field);		\
+} while (/*CONSTCOND*/0)
+
+#define	SLIST_FOREACH(var, head, field)					\
+	for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
+
+#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = SLIST_FIRST((head));				\
+	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Singly-linked List access methods.
+ */
+#define	SLIST_EMPTY(head)	((head)->slh_first == NULL)
+#define	SLIST_FIRST(head)	((head)->slh_first)
+#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
+
+
+/*
+ * Singly-linked Tail queue declarations.
+ */
+#define	STAILQ_HEAD(name, type)					\
+struct name {								\
+	struct type *stqh_first;	/* first element */			\
+	struct type **stqh_last;	/* addr of last next element */		\
+}
+
+#define	STAILQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).stqh_first }
+
+#define	STAILQ_ENTRY(type)						\
+struct {								\
+	struct type *stqe_next;	/* next element */			\
+}
+
+/*
+ * Singly-linked Tail queue functions.
+ */
+#define	STAILQ_INIT(head) do {						\
+	(head)->stqh_first = NULL;					\
+	(head)->stqh_last = &(head)->stqh_first;				\
+} while (/*CONSTCOND*/0)
+
+#define	STAILQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)	\
+		(head)->stqh_last = &(elm)->field.stqe_next;		\
+	(head)->stqh_first = (elm);					\
+} while (/*CONSTCOND*/0)
+
+#define	STAILQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.stqe_next = NULL;					\
+	*(head)->stqh_last = (elm);					\
+	(head)->stqh_last = &(elm)->field.stqe_next;			\
+} while (/*CONSTCOND*/0)
+
+#define	STAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.stqe_next = (listelm)->field.stqe_next) == NULL)\
+		(head)->stqh_last = &(elm)->field.stqe_next;		\
+	(listelm)->field.stqe_next = (elm);				\
+} while (/*CONSTCOND*/0)
+
+#define	STAILQ_REMOVE_HEAD(head, field) do {				\
+	if (((head)->stqh_first = (head)->stqh_first->field.stqe_next) == NULL) \
+		(head)->stqh_last = &(head)->stqh_first;			\
+} while (/*CONSTCOND*/0)
+
+#define	STAILQ_REMOVE(head, elm, type, field) do {			\
+	if ((head)->stqh_first == (elm)) {				\
+		STAILQ_REMOVE_HEAD((head), field);			\
+	} else {							\
+		struct type *curelm = (head)->stqh_first;		\
+		while (curelm->field.stqe_next != (elm))			\
+			curelm = curelm->field.stqe_next;		\
+		if ((curelm->field.stqe_next =				\
+			curelm->field.stqe_next->field.stqe_next) == NULL) \
+			    (head)->stqh_last = &(curelm)->field.stqe_next; \
+	}								\
+} while (/*CONSTCOND*/0)
+
+#define	STAILQ_FOREACH(var, head, field)				\
+	for ((var) = ((head)->stqh_first);				\
+		(var);							\
+		(var) = ((var)->field.stqe_next))
+
+#define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = STAILQ_FIRST((head));				\
+	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
+#define	STAILQ_CONCAT(head1, head2) do {				\
+	if (!STAILQ_EMPTY((head2))) {					\
+		*(head1)->stqh_last = (head2)->stqh_first;		\
+		(head1)->stqh_last = (head2)->stqh_last;		\
+		STAILQ_INIT((head2));					\
+	}								\
+} while (/*CONSTCOND*/0)
+
+#define	STAILQ_LAST(head, type, field)					\
+	(STAILQ_EMPTY((head)) ?						\
+		NULL :							\
+	        ((struct type *)(void *)				\
+		((char *)((head)->stqh_last) - offsetof(struct type, field))))
+
+/*
+ * Singly-linked Tail queue access methods.
+ */
+#define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)
+#define	STAILQ_FIRST(head)	((head)->stqh_first)
+#define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)
+
+
+/*
+ * Simple queue definitions.
+ */
+#define	SIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqh_first;	/* first element */			\
+	struct type **sqh_last;	/* addr of last next element */		\
+}
+
+#define	SIMPLEQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).sqh_first }
+
+#define	SIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqe_next;	/* next element */			\
+}
+
+/*
+ * Simple queue functions.
+ */
+#define	SIMPLEQ_INIT(head) do {						\
+	(head)->sqh_first = NULL;					\
+	(head)->sqh_last = &(head)->sqh_first;				\
+} while (/*CONSTCOND*/0)
+
+#define	SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(head)->sqh_first = (elm);					\
+} while (/*CONSTCOND*/0)
+
+#define	SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqe_next = NULL;					\
+	*(head)->sqh_last = (elm);					\
+	(head)->sqh_last = &(elm)->field.sqe_next;			\
+} while (/*CONSTCOND*/0)
+
+#define	SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(listelm)->field.sqe_next = (elm);				\
+} while (/*CONSTCOND*/0)
+
+#define	SIMPLEQ_REMOVE_HEAD(head, field) do {				\
+	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
+		(head)->sqh_last = &(head)->sqh_first;			\
+} while (/*CONSTCOND*/0)
+
+#define	SIMPLEQ_REMOVE(head, elm, type, field) do {			\
+	if ((head)->sqh_first == (elm)) {				\
+		SIMPLEQ_REMOVE_HEAD((head), field);			\
+	} else {							\
+		struct type *curelm = (head)->sqh_first;		\
+		while (curelm->field.sqe_next != (elm))			\
+			curelm = curelm->field.sqe_next;		\
+		if ((curelm->field.sqe_next =				\
+			curelm->field.sqe_next->field.sqe_next) == NULL) \
+			    (head)->sqh_last = &(curelm)->field.sqe_next; \
+	}								\
+} while (/*CONSTCOND*/0)
+
+#define	SIMPLEQ_FOREACH(var, head, field)				\
+	for ((var) = ((head)->sqh_first);				\
+		(var);							\
+		(var) = ((var)->field.sqe_next))
+
+#define	SIMPLEQ_FOREACH_SAFE(var, head, field, next)			\
+	for ((var) = ((head)->sqh_first);				\
+		(var) && ((next = ((var)->field.sqe_next)), 1);		\
+		(var) = (next))
+
+#define	SIMPLEQ_CONCAT(head1, head2) do {				\
+	if (!SIMPLEQ_EMPTY((head2))) {					\
+		*(head1)->sqh_last = (head2)->sqh_first;		\
+		(head1)->sqh_last = (head2)->sqh_last;		\
+		SIMPLEQ_INIT((head2));					\
+	}								\
+} while (/*CONSTCOND*/0)
+
+#define	SIMPLEQ_LAST(head, type, field)					\
+	(SIMPLEQ_EMPTY((head)) ?						\
+		NULL :							\
+	        ((struct type *)(void *)				\
+		((char *)((head)->sqh_last) - offsetof(struct type, field))))
+
+/*
+ * Simple queue access methods.
+ */
+#define	SIMPLEQ_EMPTY(head)		((head)->sqh_first == NULL)
+#define	SIMPLEQ_FIRST(head)		((head)->sqh_first)
+#define	SIMPLEQ_NEXT(elm, field)	((elm)->field.sqe_next)
+
+
+/*
+ * Tail queue definitions.
+ */
+#define	_TAILQ_HEAD(name, type, qual)					\
+struct name {								\
+	qual type *tqh_first;		/* first element */		\
+	qual type *qual *tqh_last;	/* addr of last next element */	\
+}
+#define TAILQ_HEAD(name, type)	_TAILQ_HEAD(name, struct type,)
+
+#define	TAILQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).tqh_first }
+
+#define	_TAILQ_ENTRY(type, qual)					\
+struct {								\
+	qual type *tqe_next;		/* next element */		\
+	qual type *qual *tqe_prev;	/* address of previous next element */\
+}
+#define TAILQ_ENTRY(type)	_TAILQ_ENTRY(struct type,)
+
+/*
+ * Tail queue functions.
+ */
+#if defined(_KERNEL) && defined(QUEUEDEBUG)
+#define	QUEUEDEBUG_TAILQ_INSERT_HEAD(head, elm, field)			\
+	if ((head)->tqh_first &&					\
+	    (head)->tqh_first->field.tqe_prev != &(head)->tqh_first)	\
+		panic("TAILQ_INSERT_HEAD %p %s:%d", (head), __FILE__, __LINE__);
+#define	QUEUEDEBUG_TAILQ_INSERT_TAIL(head, elm, field)			\
+	if (*(head)->tqh_last != NULL)					\
+		panic("TAILQ_INSERT_TAIL %p %s:%d", (head), __FILE__, __LINE__);
+#define	QUEUEDEBUG_TAILQ_OP(elm, field)					\
+	if ((elm)->field.tqe_next &&					\
+	    (elm)->field.tqe_next->field.tqe_prev !=			\
+	    &(elm)->field.tqe_next)					\
+		panic("TAILQ_* forw %p %s:%d", (elm), __FILE__, __LINE__);\
+	if (*(elm)->field.tqe_prev != (elm))				\
+		panic("TAILQ_* back %p %s:%d", (elm), __FILE__, __LINE__);
+#define	QUEUEDEBUG_TAILQ_PREREMOVE(head, elm, field)			\
+	if ((elm)->field.tqe_next == NULL &&				\
+	    (head)->tqh_last != &(elm)->field.tqe_next)			\
+		panic("TAILQ_PREREMOVE head %p elm %p %s:%d",		\
+		      (head), (elm), __FILE__, __LINE__);
+#define	QUEUEDEBUG_TAILQ_POSTREMOVE(elm, field)				\
+	(elm)->field.tqe_next = (void *)1L;				\
+	(elm)->field.tqe_prev = (void *)1L;
+#else
+#define	QUEUEDEBUG_TAILQ_INSERT_HEAD(head, elm, field)
+#define	QUEUEDEBUG_TAILQ_INSERT_TAIL(head, elm, field)
+#define	QUEUEDEBUG_TAILQ_OP(elm, field)
+#define	QUEUEDEBUG_TAILQ_PREREMOVE(head, elm, field)
+#define	QUEUEDEBUG_TAILQ_POSTREMOVE(elm, field)
+#endif
+
+#define	TAILQ_INIT(head) do {						\
+	(head)->tqh_first = NULL;					\
+	(head)->tqh_last = &(head)->tqh_first;				\
+} while (/*CONSTCOND*/0)
+
+#define	TAILQ_INSERT_HEAD(head, elm, field) do {			\
+	QUEUEDEBUG_TAILQ_INSERT_HEAD((head), (elm), field)		\
+	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
+		(head)->tqh_first->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(head)->tqh_first = (elm);					\
+	(elm)->field.tqe_prev = &(head)->tqh_first;			\
+} while (/*CONSTCOND*/0)
+
+#define	TAILQ_INSERT_TAIL(head, elm, field) do {			\
+	QUEUEDEBUG_TAILQ_INSERT_TAIL((head), (elm), field)		\
+	(elm)->field.tqe_next = NULL;					\
+	(elm)->field.tqe_prev = (head)->tqh_last;			\
+	*(head)->tqh_last = (elm);					\
+	(head)->tqh_last = &(elm)->field.tqe_next;			\
+} while (/*CONSTCOND*/0)
+
+#define	TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	QUEUEDEBUG_TAILQ_OP((listelm), field)				\
+	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
+		(elm)->field.tqe_next->field.tqe_prev = 		\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(listelm)->field.tqe_next = (elm);				\
+	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
+} while (/*CONSTCOND*/0)
+
+#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
+	QUEUEDEBUG_TAILQ_OP((listelm), field)				\
+	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
+	(elm)->field.tqe_next = (listelm);				\
+	*(listelm)->field.tqe_prev = (elm);				\
+	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
+} while (/*CONSTCOND*/0)
+
+#define	TAILQ_REMOVE(head, elm, field) do {				\
+	QUEUEDEBUG_TAILQ_PREREMOVE((head), (elm), field)		\
+	QUEUEDEBUG_TAILQ_OP((elm), field)				\
+	if (((elm)->field.tqe_next) != NULL)				\
+		(elm)->field.tqe_next->field.tqe_prev = 		\
+		    (elm)->field.tqe_prev;				\
+	else								\
+		(head)->tqh_last = (elm)->field.tqe_prev;		\
+	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
+	QUEUEDEBUG_TAILQ_POSTREMOVE((elm), field);			\
+} while (/*CONSTCOND*/0)
+
+#define	TAILQ_FOREACH(var, head, field)					\
+	for ((var) = ((head)->tqh_first);				\
+		(var);							\
+		(var) = ((var)->field.tqe_next))
+
+#define	TAILQ_FOREACH_SAFE(var, head, field, next)			\
+	for ((var) = ((head)->tqh_first);				\
+	        (var) != NULL && ((next) = TAILQ_NEXT(var, field), 1);	\
+		(var) = (next))
+
+#define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
+	for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last));	\
+		(var);							\
+		(var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last)))
+
+#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, prev)	\
+	for ((var) = TAILQ_LAST((head), headname);			\
+		(var) && ((prev) = TAILQ_PREV((var), headname, field), 1);\
+		(var) = (prev))
+
+#define	TAILQ_CONCAT(head1, head2, field) do {				\
+	if (!TAILQ_EMPTY(head2)) {					\
+		*(head1)->tqh_last = (head2)->tqh_first;		\
+		(head2)->tqh_first->field.tqe_prev = (head1)->tqh_last;	\
+		(head1)->tqh_last = (head2)->tqh_last;			\
+		TAILQ_INIT((head2));					\
+	}								\
+} while (/*CONSTCOND*/0)
+
+/*
+ * Tail queue access methods.
+ */
+#define	TAILQ_EMPTY(head)		((head)->tqh_first == NULL)
+#define	TAILQ_FIRST(head)		((head)->tqh_first)
+#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
+
+#define	TAILQ_LAST(head, headname) \
+	(*(((struct headname *)((head)->tqh_last))->tqh_last))
+#define	TAILQ_PREV(elm, headname, field) \
+	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+
+
+/*
+ * Circular queue definitions.
+ */
+#if defined(_KERNEL) && defined(QUEUEDEBUG)
+#define QUEUEDEBUG_CIRCLEQ_HEAD(head, field)				\
+	if ((head)->cqh_first != (void *)(head) &&			\
+	    (head)->cqh_first->field.cqe_prev != (void *)(head))	\
+		panic("CIRCLEQ head forw %p %s:%d", (head),		\
+		      __FILE__, __LINE__);				\
+	if ((head)->cqh_last != (void *)(head) &&			\
+	    (head)->cqh_last->field.cqe_next != (void *)(head))		\
+		panic("CIRCLEQ head back %p %s:%d", (head),		\
+		      __FILE__, __LINE__);
+#define QUEUEDEBUG_CIRCLEQ_ELM(head, elm, field)			\
+	if ((elm)->field.cqe_next == (void *)(head)) {			\
+		if ((head)->cqh_last != (elm))				\
+			panic("CIRCLEQ elm last %p %s:%d", (elm),	\
+			      __FILE__, __LINE__);			\
+	} else {							\
+		if ((elm)->field.cqe_next->field.cqe_prev != (elm))	\
+			panic("CIRCLEQ elm forw %p %s:%d", (elm),	\
+			      __FILE__, __LINE__);			\
+	}								\
+	if ((elm)->field.cqe_prev == (void *)(head)) {			\
+		if ((head)->cqh_first != (elm))				\
+			panic("CIRCLEQ elm first %p %s:%d", (elm),	\
+			      __FILE__, __LINE__);			\
+	} else {							\
+		if ((elm)->field.cqe_prev->field.cqe_next != (elm))	\
+			panic("CIRCLEQ elm prev %p %s:%d", (elm),	\
+			      __FILE__, __LINE__);			\
+	}
+#define QUEUEDEBUG_CIRCLEQ_POSTREMOVE(elm, field)			\
+	(elm)->field.cqe_next = (void *)1L;				\
+	(elm)->field.cqe_prev = (void *)1L;
+#else
+#define QUEUEDEBUG_CIRCLEQ_HEAD(head, field)
+#define QUEUEDEBUG_CIRCLEQ_ELM(head, elm, field)
+#define QUEUEDEBUG_CIRCLEQ_POSTREMOVE(elm, field)
+#endif
+
+#define	CIRCLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *cqh_first;		/* first element */		\
+	struct type *cqh_last;		/* last element */		\
+}
+
+#define	CIRCLEQ_HEAD_INITIALIZER(head)					\
+	{ (void *)&head, (void *)&head }
+
+#define	CIRCLEQ_ENTRY(type)						\
+struct {								\
+	struct type *cqe_next;		/* next element */		\
+	struct type *cqe_prev;		/* previous element */		\
+}
+
+/*
+ * Circular queue functions.
+ */
+#define	CIRCLEQ_INIT(head) do {						\
+	(head)->cqh_first = (void *)(head);				\
+	(head)->cqh_last = (void *)(head);				\
+} while (/*CONSTCOND*/0)
+
+#define	CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	QUEUEDEBUG_CIRCLEQ_HEAD((head), field)				\
+	QUEUEDEBUG_CIRCLEQ_ELM((head), (listelm), field)		\
+	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
+	(elm)->field.cqe_prev = (listelm);				\
+	if ((listelm)->field.cqe_next == (void *)(head))		\
+		(head)->cqh_last = (elm);				\
+	else								\
+		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
+	(listelm)->field.cqe_next = (elm);				\
+} while (/*CONSTCOND*/0)
+
+#define	CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {		\
+	QUEUEDEBUG_CIRCLEQ_HEAD((head), field)				\
+	QUEUEDEBUG_CIRCLEQ_ELM((head), (listelm), field)		\
+	(elm)->field.cqe_next = (listelm);				\
+	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
+	if ((listelm)->field.cqe_prev == (void *)(head))		\
+		(head)->cqh_first = (elm);				\
+	else								\
+		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
+	(listelm)->field.cqe_prev = (elm);				\
+} while (/*CONSTCOND*/0)
+
+#define	CIRCLEQ_INSERT_HEAD(head, elm, field) do {			\
+	QUEUEDEBUG_CIRCLEQ_HEAD((head), field)				\
+	(elm)->field.cqe_next = (head)->cqh_first;			\
+	(elm)->field.cqe_prev = (void *)(head);				\
+	if ((head)->cqh_last == (void *)(head))				\
+		(head)->cqh_last = (elm);				\
+	else								\
+		(head)->cqh_first->field.cqe_prev = (elm);		\
+	(head)->cqh_first = (elm);					\
+} while (/*CONSTCOND*/0)
+
+#define	CIRCLEQ_INSERT_TAIL(head, elm, field) do {			\
+	QUEUEDEBUG_CIRCLEQ_HEAD((head), field)				\
+	(elm)->field.cqe_next = (void *)(head);				\
+	(elm)->field.cqe_prev = (head)->cqh_last;			\
+	if ((head)->cqh_first == (void *)(head))			\
+		(head)->cqh_first = (elm);				\
+	else								\
+		(head)->cqh_last->field.cqe_next = (elm);		\
+	(head)->cqh_last = (elm);					\
+} while (/*CONSTCOND*/0)
+
+#define	CIRCLEQ_REMOVE(head, elm, field) do {				\
+	QUEUEDEBUG_CIRCLEQ_HEAD((head), field)				\
+	QUEUEDEBUG_CIRCLEQ_ELM((head), (elm), field)			\
+	if ((elm)->field.cqe_next == (void *)(head))			\
+		(head)->cqh_last = (elm)->field.cqe_prev;		\
+	else								\
+		(elm)->field.cqe_next->field.cqe_prev =			\
+		    (elm)->field.cqe_prev;				\
+	if ((elm)->field.cqe_prev == (void *)(head))			\
+		(head)->cqh_first = (elm)->field.cqe_next;		\
+	else								\
+		(elm)->field.cqe_prev->field.cqe_next =			\
+		    (elm)->field.cqe_next;				\
+	QUEUEDEBUG_CIRCLEQ_POSTREMOVE((elm), field)			\
+} while (/*CONSTCOND*/0)
+
+#define	CIRCLEQ_FOREACH(var, head, field)				\
+	for ((var) = ((head)->cqh_first);				\
+		(var) != (const void *)(head);				\
+		(var) = ((var)->field.cqe_next))
+
+#define	CIRCLEQ_FOREACH_REVERSE(var, head, field)			\
+	for ((var) = ((head)->cqh_last);				\
+		(var) != (const void *)(head);				\
+		(var) = ((var)->field.cqe_prev))
+
+/*
+ * Circular queue access methods.
+ */
+#define	CIRCLEQ_EMPTY(head)		((head)->cqh_first == (void *)(head))
+#define	CIRCLEQ_FIRST(head)		((head)->cqh_first)
+#define	CIRCLEQ_LAST(head)		((head)->cqh_last)
+#define	CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
+#define	CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
+
+#define CIRCLEQ_LOOP_NEXT(head, elm, field)				\
+	(((elm)->field.cqe_next == (void *)(head))			\
+	    ? ((head)->cqh_first)					\
+	    : (elm->field.cqe_next))
+#define CIRCLEQ_LOOP_PREV(head, elm, field)				\
+	(((elm)->field.cqe_prev == (void *)(head))			\
+	    ? ((head)->cqh_last)					\
+	    : (elm->field.cqe_prev))
+
+#endif	/* !_SYS_QUEUE_H_ */