1/*-
2 * Copyright (c) 1991, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 *	@(#)queue.h	8.5 (Berkeley) 8/20/94
30 * $FreeBSD$
31 */
32
33#ifndef _SYS_QUEUE_H_
34#define	_SYS_QUEUE_H_
35
36#include <sys/cdefs.h>
37
38/*
39 * This file defines four types of data structures: singly-linked lists,
40 * singly-linked tail queues, lists and tail queues.
41 *
42 * A singly-linked list is headed by a single forward pointer. The elements
43 * are singly linked for minimum space and pointer manipulation overhead at
44 * the expense of O(n) removal for arbitrary elements. New elements can be
45 * added to the list after an existing element or at the head of the list.
46 * Elements being removed from the head of the list should use the explicit
47 * macro for this purpose for optimum efficiency. A singly-linked list may
48 * only be traversed in the forward direction.  Singly-linked lists are ideal
49 * for applications with large datasets and few or no removals or for
50 * implementing a LIFO queue.
51 *
52 * A singly-linked tail queue is headed by a pair of pointers, one to the
53 * head of the list and the other to the tail of the list. The elements are
54 * singly linked for minimum space and pointer manipulation overhead at the
55 * expense of O(n) removal for arbitrary elements. New elements can be added
56 * to the list after an existing element, at the head of the list, or at the
57 * end of the list. Elements being removed from the head of the tail queue
58 * should use the explicit macro for this purpose for optimum efficiency.
59 * A singly-linked tail queue may only be traversed in the forward direction.
60 * Singly-linked tail queues are ideal for applications with large datasets
61 * and few or no removals or for implementing a FIFO queue.
62 *
63 * A list is headed by a single forward pointer (or an array of forward
64 * pointers for a hash table header). The elements are doubly linked
65 * so that an arbitrary element can be removed without a need to
66 * traverse the list. New elements can be added to the list before
67 * or after an existing element or at the head of the list. A list
68 * may be traversed in either direction.
69 *
70 * A tail queue is headed by a pair of pointers, one to the head of the
71 * list and the other to the tail of the list. The elements are doubly
72 * linked so that an arbitrary element can be removed without a need to
73 * traverse the list. New elements can be added to the list before or
74 * after an existing element, at the head of the list, or at the end of
75 * the list. A tail queue may be traversed in either direction.
76 *
77 * For details on the use of these macros, see the queue(3) manual page.
78 *
79 *
80 *				SLIST	LIST	STAILQ	TAILQ
81 * _HEAD			+	+	+	+
82 * _CLASS_HEAD			+	+	+	+
83 * _HEAD_INITIALIZER		+	+	+	+
84 * _ENTRY			+	+	+	+
85 * _CLASS_ENTRY			+	+	+	+
86 * _INIT			+	+	+	+
87 * _EMPTY			+	+	+	+
88 * _FIRST			+	+	+	+
89 * _NEXT			+	+	+	+
90 * _PREV			-	+	-	+
91 * _LAST			-	-	+	+
92 * _FOREACH			+	+	+	+
93 * _FOREACH_FROM		+	+	+	+
94 * _FOREACH_SAFE		+	+	+	+
95 * _FOREACH_FROM_SAFE		+	+	+	+
96 * _FOREACH_REVERSE		-	-	-	+
97 * _FOREACH_REVERSE_FROM	-	-	-	+
98 * _FOREACH_REVERSE_SAFE	-	-	-	+
99 * _FOREACH_REVERSE_FROM_SAFE	-	-	-	+
100 * _INSERT_HEAD			+	+	+	+
101 * _INSERT_BEFORE		-	+	-	+
102 * _INSERT_AFTER		+	+	+	+
103 * _INSERT_TAIL			-	-	+	+
104 * _CONCAT			-	-	+	+
105 * _REMOVE_AFTER		+	-	+	-
106 * _REMOVE_HEAD			+	-	+	-
107 * _REMOVE			+	+	+	+
108 * _SWAP			+	+	+	+
109 *
110 */
111#ifdef QUEUE_MACRO_DEBUG
112/* Store the last 2 places the queue element or head was altered */
113struct qm_trace {
114	unsigned long	 lastline;
115	unsigned long	 prevline;
116	const char	*lastfile;
117	const char	*prevfile;
118};
119
120#define	TRACEBUF	struct qm_trace trace;
121#define	TRACEBUF_INITIALIZER	{ __LINE__, 0, __FILE__, NULL } ,
122#define	TRASHIT(x)	do {(x) = (void *)-1;} while (0)
123#define	QMD_SAVELINK(name, link)	void **name = (void *)&(link)
124
125#define	QMD_TRACE_HEAD(head) do {					\
126	(head)->trace.prevline = (head)->trace.lastline;		\
127	(head)->trace.prevfile = (head)->trace.lastfile;		\
128	(head)->trace.lastline = __LINE__;				\
129	(head)->trace.lastfile = __FILE__;				\
130} while (0)
131
132#define	QMD_TRACE_ELEM(elem) do {					\
133	(elem)->trace.prevline = (elem)->trace.lastline;		\
134	(elem)->trace.prevfile = (elem)->trace.lastfile;		\
135	(elem)->trace.lastline = __LINE__;				\
136	(elem)->trace.lastfile = __FILE__;				\
137} while (0)
138
139#else
140#define	QMD_TRACE_ELEM(elem)
141#define	QMD_TRACE_HEAD(head)
142#define	QMD_SAVELINK(name, link)
143#define	TRACEBUF
144#define	TRACEBUF_INITIALIZER
145#define	TRASHIT(x)
146#endif	/* QUEUE_MACRO_DEBUG */
147
148#ifdef __cplusplus
149/*
150 * In C++ there can be structure lists and class lists:
151 */
152#define	QUEUE_TYPEOF(type) type
153#else
154#define	QUEUE_TYPEOF(type) struct type
155#endif
156
157/*
158 * Singly-linked List declarations.
159 */
160#define	SLIST_HEAD(name, type)						\
161struct name {								\
162	struct type *slh_first;	/* first element */			\
163}
164
165#define	SLIST_CLASS_HEAD(name, type)					\
166struct name {								\
167	class type *slh_first;	/* first element */			\
168}
169
170#define	SLIST_HEAD_INITIALIZER(head)					\
171	{ NULL }
172
173#define	SLIST_ENTRY(type)						\
174struct {								\
175	struct type *sle_next;	/* next element */			\
176}
177
178#define	SLIST_CLASS_ENTRY(type)						\
179struct {								\
180	class type *sle_next;		/* next element */		\
181}
182
183/*
184 * Singly-linked List functions.
185 */
186#define	SLIST_EMPTY(head)	((head)->slh_first == NULL)
187
188#define	SLIST_FIRST(head)	((head)->slh_first)
189
190#define	SLIST_FOREACH(var, head, field)					\
191	for ((var) = SLIST_FIRST((head));				\
192	    (var);							\
193	    (var) = SLIST_NEXT((var), field))
194
195#define	SLIST_FOREACH_FROM(var, head, field)				\
196	for ((var) = ((var) ? (var) : SLIST_FIRST((head)));		\
197	    (var);							\
198	    (var) = SLIST_NEXT((var), field))
199
200#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
201	for ((var) = SLIST_FIRST((head));				\
202	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\
203	    (var) = (tvar))
204
205#define	SLIST_FOREACH_FROM_SAFE(var, head, field, tvar)			\
206	for ((var) = ((var) ? (var) : SLIST_FIRST((head)));		\
207	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\
208	    (var) = (tvar))
209
210#define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
211	for ((varp) = &SLIST_FIRST((head));				\
212	    ((var) = *(varp)) != NULL;					\
213	    (varp) = &SLIST_NEXT((var), field))
214
215#define	SLIST_INIT(head) do {						\
216	SLIST_FIRST((head)) = NULL;					\
217} while (0)
218
219#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
220	SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);	\
221	SLIST_NEXT((slistelm), field) = (elm);				\
222} while (0)
223
224#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
225	SLIST_NEXT((elm), field) = SLIST_FIRST((head));			\
226	SLIST_FIRST((head)) = (elm);					\
227} while (0)
228
229#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
230
231#define	SLIST_REMOVE(head, elm, type, field) do {			\
232	QMD_SAVELINK(oldnext, (elm)->field.sle_next);			\
233	if (SLIST_FIRST((head)) == (elm)) {				\
234		SLIST_REMOVE_HEAD((head), field);			\
235	}								\
236	else {								\
237		QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head);		\
238		while (SLIST_NEXT(curelm, field) != (elm))		\
239			curelm = SLIST_NEXT(curelm, field);		\
240		SLIST_REMOVE_AFTER(curelm, field);			\
241	}								\
242	TRASHIT(*oldnext);						\
243} while (0)
244
245#define SLIST_REMOVE_AFTER(elm, field) do {				\
246	SLIST_NEXT(elm, field) =					\
247	    SLIST_NEXT(SLIST_NEXT(elm, field), field);			\
248} while (0)
249
250#define	SLIST_REMOVE_HEAD(head, field) do {				\
251	SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);	\
252} while (0)
253
254#define SLIST_SWAP(head1, head2, type) do {				\
255	QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1);		\
256	SLIST_FIRST(head1) = SLIST_FIRST(head2);			\
257	SLIST_FIRST(head2) = swap_first;				\
258} while (0)
259
260/*
261 * Singly-linked Tail queue declarations.
262 */
263#define	STAILQ_HEAD(name, type)						\
264struct name {								\
265	struct type *stqh_first;/* first element */			\
266	struct type **stqh_last;/* addr of last next element */		\
267}
268
269#define	STAILQ_CLASS_HEAD(name, type)					\
270struct name {								\
271	class type *stqh_first;	/* first element */			\
272	class type **stqh_last;	/* addr of last next element */		\
273}
274
275#define	STAILQ_HEAD_INITIALIZER(head)					\
276	{ NULL, &(head).stqh_first }
277
278#define	STAILQ_ENTRY(type)						\
279struct {								\
280	struct type *stqe_next;	/* next element */			\
281}
282
283#define	STAILQ_CLASS_ENTRY(type)					\
284struct {								\
285	class type *stqe_next;	/* next element */			\
286}
287
288/*
289 * Singly-linked Tail queue functions.
290 */
291#define	STAILQ_CONCAT(head1, head2) do {				\
292	if (!STAILQ_EMPTY((head2))) {					\
293		*(head1)->stqh_last = (head2)->stqh_first;		\
294		(head1)->stqh_last = (head2)->stqh_last;		\
295		STAILQ_INIT((head2));					\
296	}								\
297} while (0)
298
299#define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)
300
301#define	STAILQ_FIRST(head)	((head)->stqh_first)
302
303#define	STAILQ_FOREACH(var, head, field)				\
304	for((var) = STAILQ_FIRST((head));				\
305	   (var);							\
306	   (var) = STAILQ_NEXT((var), field))
307
308#define	STAILQ_FOREACH_FROM(var, head, field)				\
309	for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));		\
310	   (var);							\
311	   (var) = STAILQ_NEXT((var), field))
312
313#define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\
314	for ((var) = STAILQ_FIRST((head));				\
315	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
316	    (var) = (tvar))
317
318#define	STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)		\
319	for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));		\
320	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
321	    (var) = (tvar))
322
323#define	STAILQ_INIT(head) do {						\
324	STAILQ_FIRST((head)) = NULL;					\
325	(head)->stqh_last = &STAILQ_FIRST((head));			\
326} while (0)
327
328#define	STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {		\
329	if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
330		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
331	STAILQ_NEXT((tqelm), field) = (elm);				\
332} while (0)
333
334#define	STAILQ_INSERT_HEAD(head, elm, field) do {			\
335	if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL)	\
336		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
337	STAILQ_FIRST((head)) = (elm);					\
338} while (0)
339
340#define	STAILQ_INSERT_TAIL(head, elm, field) do {			\
341	STAILQ_NEXT((elm), field) = NULL;				\
342	*(head)->stqh_last = (elm);					\
343	(head)->stqh_last = &STAILQ_NEXT((elm), field);			\
344} while (0)
345
346#define	STAILQ_LAST(head, type, field)				\
347	(STAILQ_EMPTY((head)) ? NULL :				\
348	    __containerof((head)->stqh_last,			\
349	    QUEUE_TYPEOF(type), field.stqe_next))
350
351#define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)
352
353#define	STAILQ_REMOVE(head, elm, type, field) do {			\
354	QMD_SAVELINK(oldnext, (elm)->field.stqe_next);			\
355	if (STAILQ_FIRST((head)) == (elm)) {				\
356		STAILQ_REMOVE_HEAD((head), field);			\
357	}								\
358	else {								\
359		QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head);	\
360		while (STAILQ_NEXT(curelm, field) != (elm))		\
361			curelm = STAILQ_NEXT(curelm, field);		\
362		STAILQ_REMOVE_AFTER(head, curelm, field);		\
363	}								\
364	TRASHIT(*oldnext);						\
365} while (0)
366
367#define STAILQ_REMOVE_AFTER(head, elm, field) do {			\
368	if ((STAILQ_NEXT(elm, field) =					\
369	     STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)	\
370		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
371} while (0)
372
373#define	STAILQ_REMOVE_HEAD(head, field) do {				\
374	if ((STAILQ_FIRST((head)) =					\
375	     STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)		\
376		(head)->stqh_last = &STAILQ_FIRST((head));		\
377} while (0)
378
379#define STAILQ_SWAP(head1, head2, type) do {				\
380	QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1);		\
381	QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last;		\
382	STAILQ_FIRST(head1) = STAILQ_FIRST(head2);			\
383	(head1)->stqh_last = (head2)->stqh_last;			\
384	STAILQ_FIRST(head2) = swap_first;				\
385	(head2)->stqh_last = swap_last;					\
386	if (STAILQ_EMPTY(head1))					\
387		(head1)->stqh_last = &STAILQ_FIRST(head1);		\
388	if (STAILQ_EMPTY(head2))					\
389		(head2)->stqh_last = &STAILQ_FIRST(head2);		\
390} while (0)
391
392
393/*
394 * List declarations.
395 */
396#define	LIST_HEAD(name, type)						\
397struct name {								\
398	struct type *lh_first;	/* first element */			\
399}
400
401#define	LIST_CLASS_HEAD(name, type)					\
402struct name {								\
403	class type *lh_first;	/* first element */			\
404}
405
406#define	LIST_HEAD_INITIALIZER(head)					\
407	{ NULL }
408
409#define	LIST_ENTRY(type)						\
410struct {								\
411	struct type *le_next;	/* next element */			\
412	struct type **le_prev;	/* address of previous next element */	\
413}
414
415#define	LIST_CLASS_ENTRY(type)						\
416struct {								\
417	class type *le_next;	/* next element */			\
418	class type **le_prev;	/* address of previous next element */	\
419}
420
421/*
422 * List functions.
423 */
424
425#if (defined(_KERNEL) && defined(INVARIANTS))
426#define	QMD_LIST_CHECK_HEAD(head, field) do {				\
427	if (LIST_FIRST((head)) != NULL &&				\
428	    LIST_FIRST((head))->field.le_prev !=			\
429	     &LIST_FIRST((head)))					\
430		panic("Bad list head %p first->prev != head", (head));	\
431} while (0)
432
433#define	QMD_LIST_CHECK_NEXT(elm, field) do {				\
434	if (LIST_NEXT((elm), field) != NULL &&				\
435	    LIST_NEXT((elm), field)->field.le_prev !=			\
436	     &((elm)->field.le_next))					\
437	     	panic("Bad link elm %p next->prev != elm", (elm));	\
438} while (0)
439
440#define	QMD_LIST_CHECK_PREV(elm, field) do {				\
441	if (*(elm)->field.le_prev != (elm))				\
442		panic("Bad link elm %p prev->next != elm", (elm));	\
443} while (0)
444#else
445#define	QMD_LIST_CHECK_HEAD(head, field)
446#define	QMD_LIST_CHECK_NEXT(elm, field)
447#define	QMD_LIST_CHECK_PREV(elm, field)
448#endif /* (_KERNEL && INVARIANTS) */
449
450#define	LIST_EMPTY(head)	((head)->lh_first == NULL)
451
452#define	LIST_FIRST(head)	((head)->lh_first)
453
454#define	LIST_FOREACH(var, head, field)					\
455	for ((var) = LIST_FIRST((head));				\
456	    (var);							\
457	    (var) = LIST_NEXT((var), field))
458
459#define	LIST_FOREACH_FROM(var, head, field)				\
460	for ((var) = ((var) ? (var) : LIST_FIRST((head)));		\
461	    (var);							\
462	    (var) = LIST_NEXT((var), field))
463
464#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
465	for ((var) = LIST_FIRST((head));				\
466	    (var) && ((tvar) = LIST_NEXT((var), field), 1);		\
467	    (var) = (tvar))
468
469#define	LIST_FOREACH_FROM_SAFE(var, head, field, tvar)			\
470	for ((var) = ((var) ? (var) : LIST_FIRST((head)));		\
471	    (var) && ((tvar) = LIST_NEXT((var), field), 1);		\
472	    (var) = (tvar))
473
474#define	LIST_INIT(head) do {						\
475	LIST_FIRST((head)) = NULL;					\
476} while (0)
477
478#define	LIST_INSERT_AFTER(listelm, elm, field) do {			\
479	QMD_LIST_CHECK_NEXT(listelm, field);				\
480	if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
481		LIST_NEXT((listelm), field)->field.le_prev =		\
482		    &LIST_NEXT((elm), field);				\
483	LIST_NEXT((listelm), field) = (elm);				\
484	(elm)->field.le_prev = &LIST_NEXT((listelm), field);		\
485} while (0)
486
487#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
488	QMD_LIST_CHECK_PREV(listelm, field);				\
489	(elm)->field.le_prev = (listelm)->field.le_prev;		\
490	LIST_NEXT((elm), field) = (listelm);				\
491	*(listelm)->field.le_prev = (elm);				\
492	(listelm)->field.le_prev = &LIST_NEXT((elm), field);		\
493} while (0)
494
495#define	LIST_INSERT_HEAD(head, elm, field) do {				\
496	QMD_LIST_CHECK_HEAD((head), field);				\
497	if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)	\
498		LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
499	LIST_FIRST((head)) = (elm);					\
500	(elm)->field.le_prev = &LIST_FIRST((head));			\
501} while (0)
502
503#define	LIST_NEXT(elm, field)	((elm)->field.le_next)
504
505#define	LIST_PREV(elm, head, type, field)			\
506	((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :	\
507	    __containerof((elm)->field.le_prev,			\
508	    QUEUE_TYPEOF(type), field.le_next))
509
510#define	LIST_REMOVE(elm, field) do {					\
511	QMD_SAVELINK(oldnext, (elm)->field.le_next);			\
512	QMD_SAVELINK(oldprev, (elm)->field.le_prev);			\
513	QMD_LIST_CHECK_NEXT(elm, field);				\
514	QMD_LIST_CHECK_PREV(elm, field);				\
515	if (LIST_NEXT((elm), field) != NULL)				\
516		LIST_NEXT((elm), field)->field.le_prev = 		\
517		    (elm)->field.le_prev;				\
518	*(elm)->field.le_prev = LIST_NEXT((elm), field);		\
519	TRASHIT(*oldnext);						\
520	TRASHIT(*oldprev);						\
521} while (0)
522
523#define LIST_SWAP(head1, head2, type, field) do {			\
524	QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1);		\
525	LIST_FIRST((head1)) = LIST_FIRST((head2));			\
526	LIST_FIRST((head2)) = swap_tmp;					\
527	if ((swap_tmp = LIST_FIRST((head1))) != NULL)			\
528		swap_tmp->field.le_prev = &LIST_FIRST((head1));		\
529	if ((swap_tmp = LIST_FIRST((head2))) != NULL)			\
530		swap_tmp->field.le_prev = &LIST_FIRST((head2));		\
531} while (0)
532
533/*
534 * Tail queue declarations.
535 */
536#define	TAILQ_HEAD(name, type)						\
537struct name {								\
538	struct type *tqh_first;	/* first element */			\
539	struct type **tqh_last;	/* addr of last next element */		\
540	TRACEBUF							\
541}
542
543#define	TAILQ_CLASS_HEAD(name, type)					\
544struct name {								\
545	class type *tqh_first;	/* first element */			\
546	class type **tqh_last;	/* addr of last next element */		\
547	TRACEBUF							\
548}
549
550#define	TAILQ_HEAD_INITIALIZER(head)					\
551	{ NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
552
553#define	TAILQ_ENTRY(type)						\
554struct {								\
555	struct type *tqe_next;	/* next element */			\
556	struct type **tqe_prev;	/* address of previous next element */	\
557	TRACEBUF							\
558}
559
560#define	TAILQ_CLASS_ENTRY(type)						\
561struct {								\
562	class type *tqe_next;	/* next element */			\
563	class type **tqe_prev;	/* address of previous next element */	\
564	TRACEBUF							\
565}
566
567/*
568 * Tail queue functions.
569 */
570#if (defined(_KERNEL) && defined(INVARIANTS))
571#define	QMD_TAILQ_CHECK_HEAD(head, field) do {				\
572	if (!TAILQ_EMPTY(head) &&					\
573	    TAILQ_FIRST((head))->field.tqe_prev !=			\
574	     &TAILQ_FIRST((head)))					\
575		panic("Bad tailq head %p first->prev != head", (head));	\
576} while (0)
577
578#define	QMD_TAILQ_CHECK_TAIL(head, field) do {				\
579	if (*(head)->tqh_last != NULL)					\
580	    	panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); 	\
581} while (0)
582
583#define	QMD_TAILQ_CHECK_NEXT(elm, field) do {				\
584	if (TAILQ_NEXT((elm), field) != NULL &&				\
585	    TAILQ_NEXT((elm), field)->field.tqe_prev !=			\
586	     &((elm)->field.tqe_next))					\
587		panic("Bad link elm %p next->prev != elm", (elm));	\
588} while (0)
589
590#define	QMD_TAILQ_CHECK_PREV(elm, field) do {				\
591	if (*(elm)->field.tqe_prev != (elm))				\
592		panic("Bad link elm %p prev->next != elm", (elm));	\
593} while (0)
594#else
595#define	QMD_TAILQ_CHECK_HEAD(head, field)
596#define	QMD_TAILQ_CHECK_TAIL(head, headname)
597#define	QMD_TAILQ_CHECK_NEXT(elm, field)
598#define	QMD_TAILQ_CHECK_PREV(elm, field)
599#endif /* (_KERNEL && INVARIANTS) */
600
601#define	TAILQ_CONCAT(head1, head2, field) do {				\
602	if (!TAILQ_EMPTY(head2)) {					\
603		*(head1)->tqh_last = (head2)->tqh_first;		\
604		(head2)->tqh_first->field.tqe_prev = (head1)->tqh_last;	\
605		(head1)->tqh_last = (head2)->tqh_last;			\
606		TAILQ_INIT((head2));					\
607		QMD_TRACE_HEAD(head1);					\
608		QMD_TRACE_HEAD(head2);					\
609	}								\
610} while (0)
611
612#define	TAILQ_EMPTY(head)	((head)->tqh_first == NULL)
613
614#define	TAILQ_FIRST(head)	((head)->tqh_first)
615
616#define	TAILQ_FOREACH(var, head, field)					\
617	for ((var) = TAILQ_FIRST((head));				\
618	    (var);							\
619	    (var) = TAILQ_NEXT((var), field))
620
621#define	TAILQ_FOREACH_FROM(var, head, field)				\
622	for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));		\
623	    (var);							\
624	    (var) = TAILQ_NEXT((var), field))
625
626#define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
627	for ((var) = TAILQ_FIRST((head));				\
628	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
629	    (var) = (tvar))
630
631#define	TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)			\
632	for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));		\
633	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
634	    (var) = (tvar))
635
636#define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
637	for ((var) = TAILQ_LAST((head), headname);			\
638	    (var);							\
639	    (var) = TAILQ_PREV((var), headname, field))
640
641#define	TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field)		\
642	for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));	\
643	    (var);							\
644	    (var) = TAILQ_PREV((var), headname, field))
645
646#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
647	for ((var) = TAILQ_LAST((head), headname);			\
648	    (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
649	    (var) = (tvar))
650
651#define	TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
652	for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));	\
653	    (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
654	    (var) = (tvar))
655
656#define	TAILQ_INIT(head) do {						\
657	TAILQ_FIRST((head)) = NULL;					\
658	(head)->tqh_last = &TAILQ_FIRST((head));			\
659	QMD_TRACE_HEAD(head);						\
660} while (0)
661
662#define	TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
663	QMD_TAILQ_CHECK_NEXT(listelm, field);				\
664	if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
665		TAILQ_NEXT((elm), field)->field.tqe_prev = 		\
666		    &TAILQ_NEXT((elm), field);				\
667	else {								\
668		(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
669		QMD_TRACE_HEAD(head);					\
670	}								\
671	TAILQ_NEXT((listelm), field) = (elm);				\
672	(elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);		\
673	QMD_TRACE_ELEM(&(elm)->field);					\
674	QMD_TRACE_ELEM(&(listelm)->field);				\
675} while (0)
676
677#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
678	QMD_TAILQ_CHECK_PREV(listelm, field);				\
679	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
680	TAILQ_NEXT((elm), field) = (listelm);				\
681	*(listelm)->field.tqe_prev = (elm);				\
682	(listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);		\
683	QMD_TRACE_ELEM(&(elm)->field);					\
684	QMD_TRACE_ELEM(&(listelm)->field);				\
685} while (0)
686
687#define	TAILQ_INSERT_HEAD(head, elm, field) do {			\
688	QMD_TAILQ_CHECK_HEAD(head, field);				\
689	if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)	\
690		TAILQ_FIRST((head))->field.tqe_prev =			\
691		    &TAILQ_NEXT((elm), field);				\
692	else								\
693		(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
694	TAILQ_FIRST((head)) = (elm);					\
695	(elm)->field.tqe_prev = &TAILQ_FIRST((head));			\
696	QMD_TRACE_HEAD(head);						\
697	QMD_TRACE_ELEM(&(elm)->field);					\
698} while (0)
699
700#define	TAILQ_INSERT_TAIL(head, elm, field) do {			\
701	QMD_TAILQ_CHECK_TAIL(head, field);				\
702	TAILQ_NEXT((elm), field) = NULL;				\
703	(elm)->field.tqe_prev = (head)->tqh_last;			\
704	*(head)->tqh_last = (elm);					\
705	(head)->tqh_last = &TAILQ_NEXT((elm), field);			\
706	QMD_TRACE_HEAD(head);						\
707	QMD_TRACE_ELEM(&(elm)->field);					\
708} while (0)
709
710#define	TAILQ_LAST(head, headname)					\
711	(*(((struct headname *)((head)->tqh_last))->tqh_last))
712
713#define	TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
714
715#define	TAILQ_PREV(elm, headname, field)				\
716	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
717
718#define	TAILQ_REMOVE(head, elm, field) do {				\
719	QMD_SAVELINK(oldnext, (elm)->field.tqe_next);			\
720	QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);			\
721	QMD_TAILQ_CHECK_NEXT(elm, field);				\
722	QMD_TAILQ_CHECK_PREV(elm, field);				\
723	if ((TAILQ_NEXT((elm), field)) != NULL)				\
724		TAILQ_NEXT((elm), field)->field.tqe_prev = 		\
725		    (elm)->field.tqe_prev;				\
726	else {								\
727		(head)->tqh_last = (elm)->field.tqe_prev;		\
728		QMD_TRACE_HEAD(head);					\
729	}								\
730	*(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);		\
731	TRASHIT(*oldnext);						\
732	TRASHIT(*oldprev);						\
733	QMD_TRACE_ELEM(&(elm)->field);					\
734} while (0)
735
736#define TAILQ_SWAP(head1, head2, type, field) do {			\
737	QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first;		\
738	QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last;		\
739	(head1)->tqh_first = (head2)->tqh_first;			\
740	(head1)->tqh_last = (head2)->tqh_last;				\
741	(head2)->tqh_first = swap_first;				\
742	(head2)->tqh_last = swap_last;					\
743	if ((swap_first = (head1)->tqh_first) != NULL)			\
744		swap_first->field.tqe_prev = &(head1)->tqh_first;	\
745	else								\
746		(head1)->tqh_last = &(head1)->tqh_first;		\
747	if ((swap_first = (head2)->tqh_first) != NULL)			\
748		swap_first->field.tqe_prev = &(head2)->tqh_first;	\
749	else								\
750		(head2)->tqh_last = &(head2)->tqh_first;		\
751} while (0)
752
753#endif /* !_SYS_QUEUE_H_ */
754