include/common/queue.h - kernel/skids - Git at Google

 /*
  * 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.
  * 4. 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.
  *
  * $Id: queue.h 1441 2006-02-06 16:03:21Z mrenzmann $
  */

 #ifndef _SYS_QUEUE_H_
 #define	_SYS_QUEUE_H_

 #ifdef MUC_BUILD
 #include <stddef.h>
 #endif

 /*
  * This file defines four types of data structures: singly-linked lists,
  * singly-linked tail queues, lists and tail 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 singly-linked 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
  * 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, at the head of the list, or at the
  * end of the list. Elements being removed from the head of the tail queue
  * should use the explicit macro for this purpose for optimum efficiency.
  * A singly-linked tail queue may only be traversed in the forward direction.
  * Singly-linked tail queues are ideal for applications with large datasets
  * and few or no removals or for implementing a FIFO 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 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.
  *
  * For details on the use of these macros, see the queue(3) manual page.
  *
  *
  *				SLIST	LIST	STAILQ	TAILQ
  * _HEAD			+	+	+	+
  * _HEAD_INITIALIZER		+	+	+	+
  * _ENTRY			+	+	+	+
  * _INIT			+	+	+	+
  * _EMPTY			+	+	+	+
  * _FIRST			+	+	+	+
  * _NEXT			+	+	+	+
  * _PREV			-	-	-	+
  * _LAST			-	-	+	+
  * _FOREACH			+	+	+	+
  * _FOREACH_SAFE		+	+	+	+
  * _FOREACH_REVERSE		-	-	-	+
  * _FOREACH_REVERSE_SAFE	-	-	-	+
  * _INSERT_HEAD			+	+	+	+
  * _INSERT_BEFORE		-	+	-	+
  * _INSERT_AFTER		+	+	+	+
  * _INSERT_TAIL			-	-	+	+
  * _CONCAT			-	-	+	+
  * _REMOVE_HEAD			+	-	+	-
  * _REMOVE			+	+	+	+
  *
  */

 #ifdef MUC_BUILD
 # define QUEUE_MACRO_LOCK_DEBUG	0
 #else
 # define QUEUE_MACRO_LOCK_DEBUG	0
 #endif

 /*
  * Additional fields to try and locate unprotected accesses of fields.
  * These macros provide hooks to a function which is checked when the
  * various queue macros are
  */
 #if QUEUE_MACRO_LOCK_DEBUG
 # define QUEUE_MACRO_LOCK_FIELD(prefix)					\
 		int prefix##lockcontext;

 # define QUEUE_MACRO_LOCK_INIT(prefix, x)	(x)->prefix##lockcontext = 0
 struct os_spinlock;
 int queue_debug_muc_context_check(int* context, const char* file, const int line);
 # define MUC_CONTEXT_CHECK_IN_INTERRUPT		0x00000001
 # define MUC_CONTEXT_CHECK_NOT_IN_INTERRUPT	0x00000002
 # define MUC_CONTEXT_CHECK(context)		queue_debug_muc_context_check(&(context), __FILE__, __LINE__)
 # define QUEUE_MACRO_LOCK_ASSERT(context)	MUC_CONTEXT_CHECK(context)
 #elif defined(SYSTEM_BUILD)
 # define QUEUE_MACRO_LOCK_FIELD(prefix)	int dummy
 # define QUEUE_MACRO_LOCK_INIT(prefix, x)	int dummy
 # define QUEUE_MACRO_LOCK_ASSERT(context)	__queue_macro_lock_assert_noop()
 static __inline int __queue_macro_lock_assert_noop(void) {
 	return 1;
 }
 #else
 # define QUEUE_MACRO_LOCK_FIELD(prefix)
 # define QUEUE_MACRO_LOCK_INIT(prefix, x)
 # define QUEUE_MACRO_LOCK_ASSERT(context)	__queue_macro_lock_assert_noop()
 static __inline__ int __queue_macro_lock_assert_noop(void) {
 	return 1;
 }
 #endif

 #define	QUEUE_MACRO_DEBUG 0
 #if QUEUE_MACRO_DEBUG
 /* Store the last 2 places the queue element or head was altered */
 struct qm_trace {
 	char *lastfile;
 	int lastline;
 	char *prevfile;
 	int prevline;
 };

 #define	TRACEBUF	struct qm_trace trace;
 #define	TRASHIT(x)	do {(x) = (void *)-1;} while (0)

 #define	QMD_TRACE_HEAD(head) do {					\
 	(head)->trace.prevline = (head)->trace.lastline;		\
 	(head)->trace.prevfile = (head)->trace.lastfile;		\
 	(head)->trace.lastline = __LINE__;				\
 	(head)->trace.lastfile = __FILE__;				\
 } while (0)

 #define	QMD_TRACE_ELEM(elem) do {					\
 	(elem)->trace.prevline = (elem)->trace.lastline;		\
 	(elem)->trace.prevfile = (elem)->trace.lastfile;		\
 	(elem)->trace.lastline = __LINE__;				\
 	(elem)->trace.lastfile = __FILE__;				\
 } while (0)

 #else
 #define	QMD_TRACE_ELEM(elem)
 #define	QMD_TRACE_HEAD(head)
 #define	TRACEBUF
 #define	TRASHIT(x)
 #endif	/* QUEUE_MACRO_DEBUG */

 /*
  * Singly-linked List declarations.
  */
 #define	SLIST_HEAD(name, type)						\
 struct name {								\
 	struct type *slh_first;	/* first element */			\
 	QUEUE_MACRO_LOCK_FIELD(slh_);					\
 }

 #define	SLIST_HEAD_INITIALIZER(head)					\
 	{ NULL }

 #define	SLIST_ENTRY(type)						\
 struct {								\
 	struct type *sle_next;	/* next element */			\
 }

 #define SLIST_LOCK_ASSERT(head)		\
 	QUEUE_MACRO_LOCK_ASSERT((head)->slh_lockcontext)

 /*
  * Singly-linked List functions.
  */
 #define	SLIST_EMPTY(head)	((head)->slh_first == NULL)

 #define	SLIST_FIRST(head)	((head)->slh_first)

 #define	SLIST_FOREACH(var, head, field)					\
 	for ((var) = SLIST_FIRST((head));				\
 	    SLIST_LOCK_ASSERT((head)) && (var);				\
 	    (var) = SLIST_NEXT((var), field))

 #define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
 	for ((var) = SLIST_FIRST((head));				\
 	    SLIST_LOCK_ASSERT((head)) &&				\
 	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\
 	    (var) = (tvar))

 #define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
 	for ((varp) = &SLIST_FIRST((head));				\
 	    SLIST_LOCK_ASSERT((head)) &&				\
 	    ((var) = *(varp)) != NULL;					\
 	    (varp) = &SLIST_NEXT((var), field))

 #define	SLIST_INIT(head) do {						\
 	SLIST_FIRST((head)) = NULL;					\
 } while (0)

 #define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
 	SLIST_LOCK_ASSERT((head));					\
 	SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);	\
 	SLIST_NEXT((slistelm), field) = (elm);				\
 } while (0)

 #define	SLIST_INSERT_HEAD(head, elm, field) do {			\
 	SLIST_LOCK_ASSERT((head));					\
 	SLIST_NEXT((elm), field) = SLIST_FIRST((head));			\
 	SLIST_FIRST((head)) = (elm);					\
 } while (0)

 #define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)

 #define	SLIST_REMOVE(head, elm, type, field) do {			\
 	SLIST_LOCK_ASSERT((head));					\
 	if (SLIST_FIRST((head)) == (elm)) {				\
 		SLIST_REMOVE_HEAD((head), field);			\
 	}								\
 	else {								\
 		struct type *curelm = SLIST_FIRST((head));		\
 		while (SLIST_NEXT(curelm, field) != (elm))		\
 			curelm = SLIST_NEXT(curelm, field);		\
 		SLIST_NEXT(curelm, field) =				\
 		    SLIST_NEXT(SLIST_NEXT(curelm, field), field);	\
 	}								\
 } while (0)

 #define	SLIST_REMOVE_HEAD(head, field) do {				\
 	SLIST_LOCK_ASSERT((head));					\
 	SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);	\
 } while (0)

 /*
  * 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 */		\
 	QUEUE_MACRO_LOCK_FIELD(stqh_);	/* debug locking primitive */	\
 }

 #define	STAILQ_HEAD_INITIALIZER(head)					\
 	{ NULL, &(head).stqh_first }

 #define	STAILQ_ENTRY(type)						\
 struct {								\
 	struct type *stqe_next;	/* next element */			\
 }

 #define STAILQ_LOCK_ASSERT(head)	\
 	QUEUE_MACRO_LOCK_ASSERT((head)->stqh_lockcontext)
 #if QUEUE_MACRO_LOCK_DEBUG
 # define STAILQ_INIT_LOCK_DEBUG(head, lock)	(head)->stqh_lock = lock;
 #else
 # define STAILQ_INIT_LOCK_DEBUG(head, intref)
 #endif

 /*
  * Singly-linked Tail queue functions.
  */
 #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 (0)

 #define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)

 #define	STAILQ_FIRST(head)	((head)->stqh_first)

 #define	STAILQ_FOREACH(var, head, field)				\
 	for((var) = STAILQ_FIRST((head));				\
 	   STAILQ_LOCK_ASSERT((head)) && (var);				\
 	   (var) = STAILQ_NEXT((var), field))


 #define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\
 	for ((var) = STAILQ_FIRST((head));				\
 	    STAILQ_LOCK_ASSERT((head)) &&				\
 	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
 	    (var) = (tvar))

 #define	STAILQ_INIT(head) do {						\
 	STAILQ_FIRST((head)) = NULL;					\
 	(head)->stqh_last = &STAILQ_FIRST((head));			\
 	QUEUE_MACRO_LOCK_INIT(stqh_, (head));				\
 } while (0)

 #define	STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {		\
 	STAILQ_LOCK_ASSERT(head);					\
 	if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
 	STAILQ_NEXT((tqelm), field) = (elm);				\
 } while (0)

 #define	STAILQ_INSERT_HEAD(head, elm, field) do {			\
 	STAILQ_LOCK_ASSERT(head);					\
 	if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL)	\
 		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
 	STAILQ_FIRST((head)) = (elm);					\
 } while (0)

 #define	STAILQ_INSERT_TAIL(head, elm, field) do {			\
 	STAILQ_LOCK_ASSERT(head);					\
 	STAILQ_NEXT((elm), field) = NULL;				\
 	*(head)->stqh_last = (elm);					\
 	(head)->stqh_last = &STAILQ_NEXT((elm), field);			\
 } while (0)

 #define	STAILQ_LAST(head, type, field)					\
 	(STAILQ_EMPTY((head)) ?						\
 		NULL :							\
 	        ((struct type *)					\
 		((char *)((head)->stqh_last) - __offsetof(struct type, field))))

 #define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)

 #define	STAILQ_REMOVE(head, elm, type, field) do {			\
 	STAILQ_LOCK_ASSERT(head);					\
 	if (STAILQ_FIRST((head)) == (elm)) {				\
 		STAILQ_REMOVE_HEAD((head), field);			\
 	}								\
 	else {								\
 		struct type *curelm = STAILQ_FIRST((head));		\
 		while (STAILQ_NEXT(curelm, field) != (elm))		\
 			curelm = STAILQ_NEXT(curelm, field);		\
 		if ((STAILQ_NEXT(curelm, field) =			\
 		     STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
 			(head)->stqh_last = &STAILQ_NEXT((curelm), field);\
 	}								\
 } while (0)


 #define	STAILQ_REMOVE_AFTER(head, elm, field) do {			\
 	STAILQ_LOCK_ASSERT(head);					\
 	if (STAILQ_NEXT(elm, field)) {		\
 		if ((STAILQ_NEXT(elm, field) =			\
 		    STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)\
 			(head)->stqh_last = &STAILQ_NEXT((elm), field); \
 	}								\
 } while (0)


 #define	STAILQ_REMOVE_HEAD(head, field) do {				\
 	STAILQ_LOCK_ASSERT(head);					\
 	if ((STAILQ_FIRST((head)) =					\
 	     STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)		\
 		(head)->stqh_last = &STAILQ_FIRST((head));		\
 } while (0)

 #define	STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {			\
 	STAILQ_LOCK_ASSERT(head);					\
 	if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL)	\
 		(head)->stqh_last = &STAILQ_FIRST((head));		\
 } while (0)

 /*
  * List declarations.
  */
 #define	ATH_LIST_HEAD(name, type)					\
 struct name {								\
 	struct type *lh_first;	/* first element */			\
 	QUEUE_MACRO_LOCK_FIELD(lh_);					\
 }

 #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 */	\
 }

 #define LIST_LOCK_ASSERT(head)	\
 	QUEUE_MACRO_LOCK_ASSERT((head)->lh_lockcontext)

 /*
  * List functions.
  */

 #define	LIST_EMPTY(head)	((head)->lh_first == NULL)

 #define	LIST_FIRST(head)	((head)->lh_first)

 #define	LIST_FOREACH(var, head, field)					\
 	for ((var) = LIST_FIRST((head));				\
 	    LIST_LOCK_ASSERT((head)) && (var);				\
 	    (var) = LIST_NEXT((var), field))

 #define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
 	for ((var) = LIST_FIRST((head));				\
 	    LIST_LOCK_ASSERT((head)) &&					\
 	    (var) && ((tvar) = LIST_NEXT((var), field), 1);		\
 	    (var) = (tvar))

 #define	LIST_INIT(head) do {						\
 	LIST_FIRST((head)) = NULL;					\
 } while (0)

 #define	LIST_INSERT_AFTER(listelm, elm, field) do {			\
 	if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 		LIST_NEXT((listelm), field)->field.le_prev =		\
 		    &LIST_NEXT((elm), field);				\
 	LIST_NEXT((listelm), field) = (elm);				\
 	(elm)->field.le_prev = &LIST_NEXT((listelm), field);		\
 } while (0)

 #define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
 	(elm)->field.le_prev = (listelm)->field.le_prev;		\
 	LIST_NEXT((elm), field) = (listelm);				\
 	*(listelm)->field.le_prev = (elm);				\
 	(listelm)->field.le_prev = &LIST_NEXT((elm), field);		\
 } while (0)

 #define	LIST_INSERT_HEAD(head, elm, field) do {				\
 	LIST_LOCK_ASSERT((head));					\
 	if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)	\
 		LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 	LIST_FIRST((head)) = (elm);					\
 	(elm)->field.le_prev = &LIST_FIRST((head));			\
 } while (0)

 #define	LIST_NEXT(elm, field)	((elm)->field.le_next)

 #define	LIST_REMOVE(elm, field) do {					\
 	if (LIST_NEXT((elm), field) != NULL)				\
 		LIST_NEXT((elm), field)->field.le_prev = 		\
 		    (elm)->field.le_prev;				\
 	*(elm)->field.le_prev = LIST_NEXT((elm), field);		\
 } while (0)

 /*
  * Tail queue declarations.
  */
 #define	TAILQ_HEAD(name, type)						\
 struct name {								\
 	struct type *tqh_first;	/* first element */			\
 	struct type **tqh_last;	/* addr of last next element */		\
 	TRACEBUF							\
 	QUEUE_MACRO_LOCK_FIELD(tqh_);					\
 }

 #define	TAILQ_HEAD_INITIALIZER(head)					\
 	{ NULL, &(head).tqh_first }
 #if (!defined(TAILQ_ENTRY))
 #define	TAILQ_ENTRY(type)						\
 struct {								\
 	struct type *tqe_next;	/* next element */			\
 	struct type **tqe_prev;	/* address of previous next element */	\
 	TRACEBUF							\
 }
 #endif

 #define TAILQ_LOCK_ASSERT(head)	\
 	QUEUE_MACRO_LOCK_ASSERT((head)->tqh_lockcontext)

 /*
  * Tail queue functions.
  */
 #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));					\
 		QMD_TRACE_HEAD(head);					\
 		QMD_TRACE_HEAD(head2);					\
 	}								\
 } while (0)

 #define	TAILQ_EMPTY(head)	((head)->tqh_first == NULL)

 #define	TAILQ_FIRST(head)	((head)->tqh_first)

 #define	TAILQ_FOREACH(var, head, field)					\
 	for ((var) = TAILQ_FIRST((head));				\
 	    TAILQ_LOCK_ASSERT((head)) && (var);				\
 	    (var) = TAILQ_NEXT((var), field))

 #define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
 	for ((var) = TAILQ_FIRST((head));				\
 	    TAILQ_LOCK_ASSERT((head)) &&				\
 	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
 	    (var) = (tvar))

 #define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
 	for ((var) = TAILQ_LAST((head), headname);			\
 	    TAILQ_LOCK_ASSERT((head)) && (var);				\
 	    (var) = TAILQ_PREV((var), headname, field))

 #define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
 	for ((var) = TAILQ_LAST((head), headname);			\
 	    TAILQ_LOCK_ASSERT((head)) &&				\
 	    (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
 	    (var) = (tvar))

 #define	TAILQ_INIT(head) do {						\
 	TAILQ_FIRST((head)) = NULL;					\
 	(head)->tqh_last = &TAILQ_FIRST((head));			\
 	QMD_TRACE_HEAD(head);						\
 } while (0)

 #define	TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
 	TAILQ_LOCK_ASSERT((head));					\
 	if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 		TAILQ_NEXT((elm), field)->field.tqe_prev =		\
 		    &TAILQ_NEXT((elm), field);				\
 	else {								\
 		(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
 		QMD_TRACE_HEAD(head);					\
 	}								\
 	TAILQ_NEXT((listelm), field) = (elm);				\
 	(elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);		\
 	QMD_TRACE_ELEM(&(elm)->field);					\
 	QMD_TRACE_ELEM(&listelm->field);				\
 } while (0)

 #define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
 	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
 	TAILQ_NEXT((elm), field) = (listelm);				\
 	*(listelm)->field.tqe_prev = (elm);				\
 	(listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);		\
 	QMD_TRACE_ELEM(&(elm)->field);					\
 	QMD_TRACE_ELEM(&listelm->field);				\
 } while (0)

 #define	TAILQ_INSERT_HEAD(head, elm, field) do {			\
 	TAILQ_LOCK_ASSERT((head));					\
 	if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)	\
 		TAILQ_FIRST((head))->field.tqe_prev =			\
 		    &TAILQ_NEXT((elm), field);				\
 	else								\
 		(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
 	TAILQ_FIRST((head)) = (elm);					\
 	(elm)->field.tqe_prev = &TAILQ_FIRST((head));			\
 	QMD_TRACE_HEAD(head);						\
 	QMD_TRACE_ELEM(&(elm)->field);					\
 } while (0)

 #define	TAILQ_INSERT_TAIL(head, elm, field) do {			\
 	TAILQ_LOCK_ASSERT((head));					\
 	TAILQ_NEXT((elm), field) = NULL;				\
 	(elm)->field.tqe_prev = (head)->tqh_last;			\
 	*(head)->tqh_last = (elm);					\
 	(head)->tqh_last = &TAILQ_NEXT((elm), field);			\
 	QMD_TRACE_HEAD(head);						\
 	QMD_TRACE_ELEM(&(elm)->field);					\
 } while (0)

 #define	TAILQ_LAST(head, headname)					\
 	(*(((struct headname *)((head)->tqh_last))->tqh_last))

 #define	TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)

 #define	TAILQ_PREV(elm, headname, field)				\
 	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))

 #define	TAILQ_REMOVE(head, elm, field) do {				\
 	TAILQ_LOCK_ASSERT((head));					\
 	if ((TAILQ_NEXT((elm), field)) != NULL)				\
 		TAILQ_NEXT((elm), field)->field.tqe_prev =		\
 		    (elm)->field.tqe_prev;				\
 	else {								\
 		(head)->tqh_last = (elm)->field.tqe_prev;		\
 		QMD_TRACE_HEAD(head);					\
 	}								\
 	*(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);		\
 	TRASHIT((elm)->field.tqe_next);					\
 	TRASHIT((elm)->field.tqe_prev);					\
 	QMD_TRACE_ELEM(&(elm)->field);					\
 } while (0)


 #ifdef _KERNEL

 /*
  * XXX insque() and remque() are an old way of handling certain queues.
  * They bogusly assumes that all queue heads look alike.
  */

 struct quehead {
 	struct quehead *qh_link;
 	struct quehead *qh_rlink;
 };

 #if defined(__GNUC__) || defined(__INTEL_COMPILER)

 static __inline void
 insque(void *a, void *b)
 {
 	struct quehead *element = (struct quehead *)a,
 		 *head = (struct quehead *)b;

 	element->qh_link = head->qh_link;
 	element->qh_rlink = head;
 	head->qh_link = element;
 	element->qh_link->qh_rlink = element;
 }

 static __inline void
 remque(void *a)
 {
 	struct quehead *element = (struct quehead *)a;

 	element->qh_link->qh_rlink = element->qh_rlink;
 	element->qh_rlink->qh_link = element->qh_link;
 	element->qh_rlink = 0;
 }

 #else /* !(__GNUC__ || __INTEL_COMPILER) */

 void	insque(void *a, void *b);
 void	remque(void *a);

 #endif /* __GNUC__ || __INTEL_COMPILER */

 #endif /* _KERNEL */

 #endif /* !_SYS_QUEUE_H_ */
	/*
	* 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.
	* 4. 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.
	*
	* $Id: queue.h 1441 2006-02-06 16:03:21Z mrenzmann $
	*/

	#ifndef _SYS_QUEUE_H_
	#define _SYS_QUEUE_H_

	#ifdef MUC_BUILD
	#include <stddef.h>
	#endif

	/*
	* This file defines four types of data structures: singly-linked lists,
	* singly-linked tail queues, lists and tail 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 singly-linked 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
	* 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, at the head of the list, or at the
	* end of the list. Elements being removed from the head of the tail queue
	* should use the explicit macro for this purpose for optimum efficiency.
	* A singly-linked tail queue may only be traversed in the forward direction.
	* Singly-linked tail queues are ideal for applications with large datasets
	* and few or no removals or for implementing a FIFO 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 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.
	*
	* For details on the use of these macros, see the queue(3) manual page.
	*
	*
	* SLIST LIST STAILQ TAILQ
	* _HEAD + + + +
	* _HEAD_INITIALIZER + + + +
	* _ENTRY + + + +
	* _INIT + + + +
	* _EMPTY + + + +
	* _FIRST + + + +
	* _NEXT + + + +
	* _PREV - - - +
	* _LAST - - + +
	* _FOREACH + + + +
	* _FOREACH_SAFE + + + +
	* _FOREACH_REVERSE - - - +
	* _FOREACH_REVERSE_SAFE - - - +
	* _INSERT_HEAD + + + +
	* _INSERT_BEFORE - + - +
	* _INSERT_AFTER + + + +
	* _INSERT_TAIL - - + +
	* _CONCAT - - + +
	* _REMOVE_HEAD + - + -
	* _REMOVE + + + +
	*
	*/

	#ifdef MUC_BUILD
	# define QUEUE_MACRO_LOCK_DEBUG 0
	#else
	# define QUEUE_MACRO_LOCK_DEBUG 0
	#endif

	/*
	* Additional fields to try and locate unprotected accesses of fields.
	* These macros provide hooks to a function which is checked when the
	* various queue macros are
	*/
	#if QUEUE_MACRO_LOCK_DEBUG
	# define QUEUE_MACRO_LOCK_FIELD(prefix) \
	int prefix##lockcontext;

	# define QUEUE_MACRO_LOCK_INIT(prefix, x) (x)->prefix##lockcontext = 0
	struct os_spinlock;
	int queue_debug_muc_context_check(int* context, const char* file, const int line);
	# define MUC_CONTEXT_CHECK_IN_INTERRUPT 0x00000001
	# define MUC_CONTEXT_CHECK_NOT_IN_INTERRUPT 0x00000002
	# define MUC_CONTEXT_CHECK(context) queue_debug_muc_context_check(&(context), __FILE__, __LINE__)
	# define QUEUE_MACRO_LOCK_ASSERT(context) MUC_CONTEXT_CHECK(context)
	#elif defined(SYSTEM_BUILD)
	# define QUEUE_MACRO_LOCK_FIELD(prefix) int dummy
	# define QUEUE_MACRO_LOCK_INIT(prefix, x) int dummy
	# define QUEUE_MACRO_LOCK_ASSERT(context) __queue_macro_lock_assert_noop()
	static __inline int __queue_macro_lock_assert_noop(void) {
	return 1;
	}
	#else
	# define QUEUE_MACRO_LOCK_FIELD(prefix)
	# define QUEUE_MACRO_LOCK_INIT(prefix, x)
	# define QUEUE_MACRO_LOCK_ASSERT(context) __queue_macro_lock_assert_noop()
	static __inline__ int __queue_macro_lock_assert_noop(void) {
	return 1;
	}
	#endif

	#define QUEUE_MACRO_DEBUG 0
	#if QUEUE_MACRO_DEBUG
	/* Store the last 2 places the queue element or head was altered */
	struct qm_trace {
	char *lastfile;
	int lastline;
	char *prevfile;
	int prevline;
	};

	#define TRACEBUF struct qm_trace trace;
	#define TRASHIT(x) do {(x) = (void *)-1;} while (0)

	#define QMD_TRACE_HEAD(head) do { \
	(head)->trace.prevline = (head)->trace.lastline; \
	(head)->trace.prevfile = (head)->trace.lastfile; \
	(head)->trace.lastline = __LINE__; \
	(head)->trace.lastfile = __FILE__; \
	} while (0)

	#define QMD_TRACE_ELEM(elem) do { \
	(elem)->trace.prevline = (elem)->trace.lastline; \
	(elem)->trace.prevfile = (elem)->trace.lastfile; \
	(elem)->trace.lastline = __LINE__; \
	(elem)->trace.lastfile = __FILE__; \
	} while (0)

	#else
	#define QMD_TRACE_ELEM(elem)
	#define QMD_TRACE_HEAD(head)
	#define TRACEBUF
	#define TRASHIT(x)
	#endif /* QUEUE_MACRO_DEBUG */

	/*
	* Singly-linked List declarations.
	*/
	#define SLIST_HEAD(name, type) \
	struct name { \
	struct type slh_first; / first element */ \
	QUEUE_MACRO_LOCK_FIELD(slh_); \
	}

	#define SLIST_HEAD_INITIALIZER(head) \
	{ NULL }

	#define SLIST_ENTRY(type) \
	struct { \
	struct type sle_next; / next element */ \
	}

	#define SLIST_LOCK_ASSERT(head) \
	QUEUE_MACRO_LOCK_ASSERT((head)->slh_lockcontext)

	/*
	* Singly-linked List functions.
	*/
	#define SLIST_EMPTY(head) ((head)->slh_first == NULL)

	#define SLIST_FIRST(head) ((head)->slh_first)

	#define SLIST_FOREACH(var, head, field) \
	for ((var) = SLIST_FIRST((head)); \
	SLIST_LOCK_ASSERT((head)) && (var); \
	(var) = SLIST_NEXT((var), field))

	#define SLIST_FOREACH_SAFE(var, head, field, tvar) \
	for ((var) = SLIST_FIRST((head)); \
	SLIST_LOCK_ASSERT((head)) && \
	(var) && ((tvar) = SLIST_NEXT((var), field), 1); \
	(var) = (tvar))

	#define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
	for ((varp) = &SLIST_FIRST((head)); \
	SLIST_LOCK_ASSERT((head)) && \
	((var) = *(varp)) != NULL; \
	(varp) = &SLIST_NEXT((var), field))

	#define SLIST_INIT(head) do { \
	SLIST_FIRST((head)) = NULL; \
	} while (0)

	#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
	SLIST_LOCK_ASSERT((head)); \
	SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
	SLIST_NEXT((slistelm), field) = (elm); \
	} while (0)

	#define SLIST_INSERT_HEAD(head, elm, field) do { \
	SLIST_LOCK_ASSERT((head)); \
	SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
	SLIST_FIRST((head)) = (elm); \
	} while (0)

	#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)

	#define SLIST_REMOVE(head, elm, type, field) do { \
	SLIST_LOCK_ASSERT((head)); \
	if (SLIST_FIRST((head)) == (elm)) { \
	SLIST_REMOVE_HEAD((head), field); \
	} \
	else { \
	struct type *curelm = SLIST_FIRST((head)); \
	while (SLIST_NEXT(curelm, field) != (elm)) \
	curelm = SLIST_NEXT(curelm, field); \
	SLIST_NEXT(curelm, field) = \
	SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
	} \
	} while (0)

	#define SLIST_REMOVE_HEAD(head, field) do { \
	SLIST_LOCK_ASSERT((head)); \
	SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
	} while (0)

	/*
	* 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 */ \
	QUEUE_MACRO_LOCK_FIELD(stqh_); /* debug locking primitive */ \
	}

	#define STAILQ_HEAD_INITIALIZER(head) \
	{ NULL, &(head).stqh_first }

	#define STAILQ_ENTRY(type) \
	struct { \
	struct type stqe_next; / next element */ \
	}

	#define STAILQ_LOCK_ASSERT(head) \
	QUEUE_MACRO_LOCK_ASSERT((head)->stqh_lockcontext)
	#if QUEUE_MACRO_LOCK_DEBUG
	# define STAILQ_INIT_LOCK_DEBUG(head, lock) (head)->stqh_lock = lock;
	#else
	# define STAILQ_INIT_LOCK_DEBUG(head, intref)
	#endif

	/*
	* Singly-linked Tail queue functions.
	*/
	#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 (0)

	#define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)

	#define STAILQ_FIRST(head) ((head)->stqh_first)

	#define STAILQ_FOREACH(var, head, field) \
	for((var) = STAILQ_FIRST((head)); \
	STAILQ_LOCK_ASSERT((head)) && (var); \
	(var) = STAILQ_NEXT((var), field))


	#define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
	for ((var) = STAILQ_FIRST((head)); \
	STAILQ_LOCK_ASSERT((head)) && \
	(var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
	(var) = (tvar))

	#define STAILQ_INIT(head) do { \
	STAILQ_FIRST((head)) = NULL; \
	(head)->stqh_last = &STAILQ_FIRST((head)); \
	QUEUE_MACRO_LOCK_INIT(stqh_, (head)); \
	} while (0)

	#define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
	STAILQ_LOCK_ASSERT(head); \
	if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
	(head)->stqh_last = &STAILQ_NEXT((elm), field); \
	STAILQ_NEXT((tqelm), field) = (elm); \
	} while (0)

	#define STAILQ_INSERT_HEAD(head, elm, field) do { \
	STAILQ_LOCK_ASSERT(head); \
	if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
	(head)->stqh_last = &STAILQ_NEXT((elm), field); \
	STAILQ_FIRST((head)) = (elm); \
	} while (0)

	#define STAILQ_INSERT_TAIL(head, elm, field) do { \
	STAILQ_LOCK_ASSERT(head); \
	STAILQ_NEXT((elm), field) = NULL; \
	*(head)->stqh_last = (elm); \
	(head)->stqh_last = &STAILQ_NEXT((elm), field); \
	} while (0)

	#define STAILQ_LAST(head, type, field) \
	(STAILQ_EMPTY((head)) ? \
	NULL : \
	((struct type *) \
	((char *)((head)->stqh_last) - __offsetof(struct type, field))))

	#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)

	#define STAILQ_REMOVE(head, elm, type, field) do { \
	STAILQ_LOCK_ASSERT(head); \
	if (STAILQ_FIRST((head)) == (elm)) { \
	STAILQ_REMOVE_HEAD((head), field); \
	} \
	else { \
	struct type *curelm = STAILQ_FIRST((head)); \
	while (STAILQ_NEXT(curelm, field) != (elm)) \
	curelm = STAILQ_NEXT(curelm, field); \
	if ((STAILQ_NEXT(curelm, field) = \
	STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
	(head)->stqh_last = &STAILQ_NEXT((curelm), field);\
	} \
	} while (0)


	#define STAILQ_REMOVE_AFTER(head, elm, field) do { \
	STAILQ_LOCK_ASSERT(head); \
	if (STAILQ_NEXT(elm, field)) { \
	if ((STAILQ_NEXT(elm, field) = \
	STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)\
	(head)->stqh_last = &STAILQ_NEXT((elm), field); \
	} \
	} while (0)


	#define STAILQ_REMOVE_HEAD(head, field) do { \
	STAILQ_LOCK_ASSERT(head); \
	if ((STAILQ_FIRST((head)) = \
	STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
	(head)->stqh_last = &STAILQ_FIRST((head)); \
	} while (0)

	#define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
	STAILQ_LOCK_ASSERT(head); \
	if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
	(head)->stqh_last = &STAILQ_FIRST((head)); \
	} while (0)

	/*
	* List declarations.
	*/
	#define ATH_LIST_HEAD(name, type) \
	struct name { \
	struct type lh_first; / first element */ \
	QUEUE_MACRO_LOCK_FIELD(lh_); \
	}

	#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 */ \
	}

	#define LIST_LOCK_ASSERT(head) \
	QUEUE_MACRO_LOCK_ASSERT((head)->lh_lockcontext)

	/*
	* List functions.
	*/

	#define LIST_EMPTY(head) ((head)->lh_first == NULL)

	#define LIST_FIRST(head) ((head)->lh_first)

	#define LIST_FOREACH(var, head, field) \
	for ((var) = LIST_FIRST((head)); \
	LIST_LOCK_ASSERT((head)) && (var); \
	(var) = LIST_NEXT((var), field))

	#define LIST_FOREACH_SAFE(var, head, field, tvar) \
	for ((var) = LIST_FIRST((head)); \
	LIST_LOCK_ASSERT((head)) && \
	(var) && ((tvar) = LIST_NEXT((var), field), 1); \
	(var) = (tvar))

	#define LIST_INIT(head) do { \
	LIST_FIRST((head)) = NULL; \
	} while (0)

	#define LIST_INSERT_AFTER(listelm, elm, field) do { \
	if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
	LIST_NEXT((listelm), field)->field.le_prev = \
	&LIST_NEXT((elm), field); \
	LIST_NEXT((listelm), field) = (elm); \
	(elm)->field.le_prev = &LIST_NEXT((listelm), field); \
	} while (0)

	#define LIST_INSERT_BEFORE(listelm, elm, field) do { \
	(elm)->field.le_prev = (listelm)->field.le_prev; \
	LIST_NEXT((elm), field) = (listelm); \
	*(listelm)->field.le_prev = (elm); \
	(listelm)->field.le_prev = &LIST_NEXT((elm), field); \
	} while (0)

	#define LIST_INSERT_HEAD(head, elm, field) do { \
	LIST_LOCK_ASSERT((head)); \
	if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
	LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
	LIST_FIRST((head)) = (elm); \
	(elm)->field.le_prev = &LIST_FIRST((head)); \
	} while (0)

	#define LIST_NEXT(elm, field) ((elm)->field.le_next)

	#define LIST_REMOVE(elm, field) do { \
	if (LIST_NEXT((elm), field) != NULL) \
	LIST_NEXT((elm), field)->field.le_prev = \
	(elm)->field.le_prev; \
	*(elm)->field.le_prev = LIST_NEXT((elm), field); \
	} while (0)

	/*
	* Tail queue declarations.
	*/
	#define TAILQ_HEAD(name, type) \
	struct name { \
	struct type tqh_first; / first element */ \
	struct type *tqh_last; / addr of last next element */ \
	TRACEBUF \
	QUEUE_MACRO_LOCK_FIELD(tqh_); \
	}

	#define TAILQ_HEAD_INITIALIZER(head) \
	{ NULL, &(head).tqh_first }
	#if (!defined(TAILQ_ENTRY))
	#define TAILQ_ENTRY(type) \
	struct { \
	struct type tqe_next; / next element */ \
	struct type *tqe_prev; / address of previous next element */ \
	TRACEBUF \
	}
	#endif

	#define TAILQ_LOCK_ASSERT(head) \
	QUEUE_MACRO_LOCK_ASSERT((head)->tqh_lockcontext)

	/*
	* Tail queue functions.
	*/
	#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)); \
	QMD_TRACE_HEAD(head); \
	QMD_TRACE_HEAD(head2); \
	} \
	} while (0)

	#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)

	#define TAILQ_FIRST(head) ((head)->tqh_first)

	#define TAILQ_FOREACH(var, head, field) \
	for ((var) = TAILQ_FIRST((head)); \
	TAILQ_LOCK_ASSERT((head)) && (var); \
	(var) = TAILQ_NEXT((var), field))

	#define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
	for ((var) = TAILQ_FIRST((head)); \
	TAILQ_LOCK_ASSERT((head)) && \
	(var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
	(var) = (tvar))

	#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
	for ((var) = TAILQ_LAST((head), headname); \
	TAILQ_LOCK_ASSERT((head)) && (var); \
	(var) = TAILQ_PREV((var), headname, field))

	#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
	for ((var) = TAILQ_LAST((head), headname); \
	TAILQ_LOCK_ASSERT((head)) && \
	(var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
	(var) = (tvar))

	#define TAILQ_INIT(head) do { \
	TAILQ_FIRST((head)) = NULL; \
	(head)->tqh_last = &TAILQ_FIRST((head)); \
	QMD_TRACE_HEAD(head); \
	} while (0)

	#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
	TAILQ_LOCK_ASSERT((head)); \
	if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
	TAILQ_NEXT((elm), field)->field.tqe_prev = \
	&TAILQ_NEXT((elm), field); \
	else { \
	(head)->tqh_last = &TAILQ_NEXT((elm), field); \
	QMD_TRACE_HEAD(head); \
	} \
	TAILQ_NEXT((listelm), field) = (elm); \
	(elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
	QMD_TRACE_ELEM(&(elm)->field); \
	QMD_TRACE_ELEM(&listelm->field); \
	} while (0)

	#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
	(elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
	TAILQ_NEXT((elm), field) = (listelm); \
	*(listelm)->field.tqe_prev = (elm); \
	(listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
	QMD_TRACE_ELEM(&(elm)->field); \
	QMD_TRACE_ELEM(&listelm->field); \
	} while (0)

	#define TAILQ_INSERT_HEAD(head, elm, field) do { \
	TAILQ_LOCK_ASSERT((head)); \
	if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
	TAILQ_FIRST((head))->field.tqe_prev = \
	&TAILQ_NEXT((elm), field); \
	else \
	(head)->tqh_last = &TAILQ_NEXT((elm), field); \
	TAILQ_FIRST((head)) = (elm); \
	(elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
	QMD_TRACE_HEAD(head); \
	QMD_TRACE_ELEM(&(elm)->field); \
	} while (0)

	#define TAILQ_INSERT_TAIL(head, elm, field) do { \
	TAILQ_LOCK_ASSERT((head)); \
	TAILQ_NEXT((elm), field) = NULL; \
	(elm)->field.tqe_prev = (head)->tqh_last; \
	*(head)->tqh_last = (elm); \
	(head)->tqh_last = &TAILQ_NEXT((elm), field); \
	QMD_TRACE_HEAD(head); \
	QMD_TRACE_ELEM(&(elm)->field); \
	} while (0)

	#define TAILQ_LAST(head, headname) \
	((((struct headname )((head)->tqh_last))->tqh_last))

	#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)

	#define TAILQ_PREV(elm, headname, field) \
	((((struct headname )((elm)->field.tqe_prev))->tqh_last))

	#define TAILQ_REMOVE(head, elm, field) do { \
	TAILQ_LOCK_ASSERT((head)); \
	if ((TAILQ_NEXT((elm), field)) != NULL) \
	TAILQ_NEXT((elm), field)->field.tqe_prev = \
	(elm)->field.tqe_prev; \
	else { \
	(head)->tqh_last = (elm)->field.tqe_prev; \
	QMD_TRACE_HEAD(head); \
	} \
	*(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
	TRASHIT((elm)->field.tqe_next); \
	TRASHIT((elm)->field.tqe_prev); \
	QMD_TRACE_ELEM(&(elm)->field); \
	} while (0)


	#ifdef _KERNEL

	/*
	* XXX insque() and remque() are an old way of handling certain queues.
	* They bogusly assumes that all queue heads look alike.
	*/

	struct quehead {
	struct quehead *qh_link;
	struct quehead *qh_rlink;
	};

	#if defined(__GNUC__) \|\| defined(__INTEL_COMPILER)

	static __inline void
	insque(void a, void b)
	{
	struct quehead element = (struct quehead )a,
	head = (struct quehead )b;

	element->qh_link = head->qh_link;
	element->qh_rlink = head;
	head->qh_link = element;
	element->qh_link->qh_rlink = element;
	}

	static __inline void
	remque(void *a)
	{
	struct quehead element = (struct quehead )a;

	element->qh_link->qh_rlink = element->qh_rlink;
	element->qh_rlink->qh_link = element->qh_link;
	element->qh_rlink = 0;
	}

	#else /* !(__GNUC__ \|\| __INTEL_COMPILER) */

	void insque(void a, void b);
	void remque(void *a);

	#endif /* __GNUC__ \|\| __INTEL_COMPILER */

	#endif /* _KERNEL */

	#endif /* !_SYS_QUEUE_H_ */