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