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/*-

 * 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.

 *

 *	@(#)queue.h	8.5 (Berkeley) 8/20/94

 * $FreeBSD$

 */

#ifndef _SYS_QUEUE_H_

#define	_SYS_QUEUE_H_

#include 

/*

 * 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 be traversed in either 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_AFTER		+	-	+	-

 * _REMOVE_HEAD		+	-	+	-

 * _REMOVE		+	+	+	+

 * _SWAP			+	+	+	+

 *

 */

#ifdef QUEUE_MACRO_DEBUG

/* Store the last 2 places the queue element or head was altered */

struct qm_trace {

	unsigned long	 lastline;

	unsigned long	 prevline;

	const char	*lastfile;

	const char	*prevfile;

};

#define	TRACEBUF	struct qm_trace trace;

#define	TRACEBUF_INITIALIZER	{ __FILE__, __LINE__, NULL, 0 } ,

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

#define	QMD_SAVELINK(name, link)	void **name = (void *)&(link)

#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	QMD_SAVELINK(name, link)

#define	TRACEBUF

#define	TRACEBUF_INITIALIZER

#define	TRASHIT(x)

#endif	/* QUEUE_MACRO_DEBUG */

/*

 * Singly-linked List declarations.

 */

#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_EMPTY(head)	((head)->slh_first == NULL)

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

#define	SLIST_FOREACH(var, head, field)					\

	for ((var) = SLIST_FIRST((head));				\

	    (var);							\

	    (var) = SLIST_NEXT((var), field))

#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\

	for ((var) = SLIST_FIRST((head));				\

	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\

	    (var) = (tvar))

#define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\

	for ((varp) = &SLIST_FIRST((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_NEXT((elm), field) = SLIST_NEXT((slistelm), field);	\

	SLIST_NEXT((slistelm), field) = (elm);				\

} while (0)

#define	SLIST_INSERT_HEAD(head, elm, field) do {			\

	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 {			\

	QMD_SAVELINK(oldnext, (elm)->field.sle_next);			\

	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_REMOVE_AFTER(curelm, field);			\

	}								\

	TRASHIT(*oldnext);						\

} while (0)

#define SLIST_REMOVE_AFTER(elm, field) do {				\

	SLIST_NEXT(elm, field) =					\

	    SLIST_NEXT(SLIST_NEXT(elm, field), field);			\

} while (0)

#define	SLIST_REMOVE_HEAD(head, field) do {				\

	SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);	\

} while (0)

#define SLIST_SWAP(head1, head2, type) do {				\

	struct type *swap_first = SLIST_FIRST(head1);			\

	SLIST_FIRST(head1) = SLIST_FIRST(head2);			\

	SLIST_FIRST(head2) = swap_first;				\

} 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 */		\

}

#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_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));				\

	   (var);							\

	   (var) = STAILQ_NEXT((var), field))

#define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\

	for ((var) = STAILQ_FIRST((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));			\

} while (0)

#define	STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {		\

	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 {			\

	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_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 :					\

	    __containerof((head)->stqh_last, struct type, field.stqe_next))

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

#define	STAILQ_REMOVE(head, elm, type, field) do {			\

	QMD_SAVELINK(oldnext, (elm)->field.stqe_next);			\

	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);		\

		STAILQ_REMOVE_AFTER(head, curelm, field);		\

	}								\

	TRASHIT(*oldnext);						\

} while (0)

#define STAILQ_REMOVE_AFTER(head, elm, field) do {			\

	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 {				\

	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 {			\

	if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL)	\

		(head)->stqh_last = &STAILQ_FIRST((head));		\

} while (0)

#define STAILQ_SWAP(head1, head2, type) do {				\

	struct type *swap_first = STAILQ_FIRST(head1);			\

	struct type **swap_last = (head1)->stqh_last;			\

	STAILQ_FIRST(head1) = STAILQ_FIRST(head2);			\

	(head1)->stqh_last = (head2)->stqh_last;			\

	STAILQ_FIRST(head2) = swap_first;				\

	(head2)->stqh_last = swap_last;					\

	if (STAILQ_EMPTY(head1))					\

		(head1)->stqh_last = &STAILQ_FIRST(head1);		\

	if (STAILQ_EMPTY(head2))					\

		(head2)->stqh_last = &STAILQ_FIRST(head2);		\

} while (0)

/*

 * List declarations.

 */

#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(INVARIANTS))

#define	QMD_LIST_CHECK_HEAD(head, field) do {				\

	if (LIST_FIRST((head)) != NULL &&				\

	    LIST_FIRST((head))->field.le_prev !=			\

	     &LIST_FIRST((head)))					\

		panic("Bad list head %p first->prev != head", (head));	\

} while (0)

#define	QMD_LIST_CHECK_NEXT(elm, field) do {				\

	if (LIST_NEXT((elm), field) != NULL &&				\

	    LIST_NEXT((elm), field)->field.le_prev !=			\

	     &((elm)->field.le_next))					\

	     	panic("Bad link elm %p next->prev != elm", (elm));	\

} while (0)

#define	QMD_LIST_CHECK_PREV(elm, field) do {				\

	if (*(elm)->field.le_prev != (elm))				\

		panic("Bad link elm %p prev->next != elm", (elm));	\

} while (0)

#else

#define	QMD_LIST_CHECK_HEAD(head, field)

#define	QMD_LIST_CHECK_NEXT(elm, field)

#define	QMD_LIST_CHECK_PREV(elm, field)

#endif /* (_KERNEL && INVARIANTS) */

#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));				\

	    (var);							\

	    (var) = LIST_NEXT((var), field))

#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\

	for ((var) = LIST_FIRST((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 {			\

	QMD_LIST_CHECK_NEXT(listelm, field);				\

	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 {			\

	QMD_LIST_CHECK_PREV(listelm, field);				\

	(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 {				\

	QMD_LIST_CHECK_HEAD((head), field);				\

	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_PREV(elm, head, type, field)				\

	((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :		\

	    __containerof((elm)->field.le_prev, struct type, field.le_next))

#define	LIST_REMOVE(elm, field) do {					\

	QMD_SAVELINK(oldnext, (elm)->field.le_next);			\

	QMD_SAVELINK(oldprev, (elm)->field.le_prev);			\

	QMD_LIST_CHECK_NEXT(elm, field);				\

	QMD_LIST_CHECK_PREV(elm, field);				\

	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);		\

	TRASHIT(*oldnext);						\

	TRASHIT(*oldprev);						\

} while (0)

#define LIST_SWAP(head1, head2, type, field) do {			\

	struct type *swap_tmp = LIST_FIRST((head1));			\

	LIST_FIRST((head1)) = LIST_FIRST((head2));			\

	LIST_FIRST((head2)) = swap_tmp;					\

	if ((swap_tmp = LIST_FIRST((head1))) != NULL)			\

		swap_tmp->field.le_prev = &LIST_FIRST((head1));		\

	if ((swap_tmp = LIST_FIRST((head2))) != NULL)			\

		swap_tmp->field.le_prev = &LIST_FIRST((head2));		\

} 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							\

}

#define	TAILQ_HEAD_INITIALIZER(head)					\

	{ NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }

#define	TAILQ_ENTRY(type)						\

struct {								\

	struct type *tqe_next;	/* next element */			\

	struct type **tqe_prev;	/* address of previous next element */	\

	TRACEBUF							\

}

/*

 * Tail queue functions.

 */

#if (defined(_KERNEL) && defined(INVARIANTS))

#define	QMD_TAILQ_CHECK_HEAD(head, field) do {				\

	if (!TAILQ_EMPTY(head) &&					\

	    TAILQ_FIRST((head))->field.tqe_prev !=			\

	     &TAILQ_FIRST((head)))					\

		panic("Bad tailq head %p first->prev != head", (head));	\

} while (0)

#define	QMD_TAILQ_CHECK_TAIL(head, field) do {				\

	if (*(head)->tqh_last != NULL)					\

	    	panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); 	\

} while (0)

#define	QMD_TAILQ_CHECK_NEXT(elm, field) do {				\

	if (TAILQ_NEXT((elm), field) != NULL &&				\

	    TAILQ_NEXT((elm), field)->field.tqe_prev !=			\

	     &((elm)->field.tqe_next))					\

		panic("Bad link elm %p next->prev != elm", (elm));	\

} while (0)

#define	QMD_TAILQ_CHECK_PREV(elm, field) do {				\

	if (*(elm)->field.tqe_prev != (elm))				\

		panic("Bad link elm %p prev->next != elm", (elm));	\

} while (0)

#else

#define	QMD_TAILQ_CHECK_HEAD(head, field)

#define	QMD_TAILQ_CHECK_TAIL(head, headname)

#define	QMD_TAILQ_CHECK_NEXT(elm, field)

#define	QMD_TAILQ_CHECK_PREV(elm, field)

#endif /* (_KERNEL && INVARIANTS) */

#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(head1);					\

		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));				\

	    (var);							\

	    (var) = TAILQ_NEXT((var), field))

#define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\

	for ((var) = TAILQ_FIRST((head));				\

	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\

	    (var) = (tvar))

#define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\

	for ((var) = TAILQ_LAST((head), headname);			\

	    (var);							\

	    (var) = TAILQ_PREV((var), headname, field))

#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\

	for ((var) = TAILQ_LAST((head), headname);			\

	    (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 {		\

	QMD_TAILQ_CHECK_NEXT(listelm, field);				\

	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 {			\

	QMD_TAILQ_CHECK_PREV(listelm, field);				\

	(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 {			\

	QMD_TAILQ_CHECK_HEAD(head, field);				\

	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 {			\

	QMD_TAILQ_CHECK_TAIL(head, field);				\

	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 {				\

	QMD_SAVELINK(oldnext, (elm)->field.tqe_next);			\

	QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);			\

	QMD_TAILQ_CHECK_NEXT(elm, field);				\

	QMD_TAILQ_CHECK_PREV(elm, field);				\

	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(*oldnext);						\

	TRASHIT(*oldprev);						\

	QMD_TRACE_ELEM(&(elm)->field);					\

} while (0)

#define TAILQ_SWAP(head1, head2, type, field) do {			\

	struct type *swap_first = (head1)->tqh_first;			\

	struct type **swap_last = (head1)->tqh_last;			\

	(head1)->tqh_first = (head2)->tqh_first;			\

	(head1)->tqh_last = (head2)->tqh_last;				\

	(head2)->tqh_first = swap_first;				\

	(head2)->tqh_last = swap_last;					\

	if ((swap_first = (head1)->tqh_first) != NULL)			\

		swap_first->field.tqe_prev = &(head1)->tqh_first;	\

	else								\

		(head1)->tqh_last = &(head1)->tqh_first;		\

	if ((swap_first = (head2)->tqh_first) != NULL)			\

		swap_first->field.tqe_prev = &(head2)->tqh_first;	\

	else								\

		(head2)->tqh_last = &(head2)->tqh_first;		\

} 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;

};

#ifdef	__GNUC__

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__ */

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

void	remque(void *a);

#endif /* __GNUC__ */

#endif /* _KERNEL */

#endif /* !_SYS_QUEUE_H_ */