xref: /titanic_41/usr/src/uts/common/sys/queue.h (revision 710f7c23e0f1abee9935d4db2d0a90ca0ddee3db)
1 /*	$NetBSD: queue.h,v 1.42 2005/07/13 15:08:24 wiz Exp $	*/
2 
3 /*
4  * Copyright (c) 1991, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  *	@(#)queue.h	8.5 (Berkeley) 8/20/94
32  */
33 /*
34  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
35  * Use is subject to license terms.
36  */
37 
38 #ifndef	_SYS_QUEUE_H
39 #define	_SYS_QUEUE_H
40 
41 #include <sys/note.h>
42 
43 #ifdef	__cplusplus
44 extern "C" {
45 #endif
46 
47 /*
48  * This file defines five types of data structures: singly-linked lists,
49  * lists, simple queues, tail queues, and circular queues.
50  *
51  * A singly-linked list is headed by a single forward pointer. The
52  * elements are singly linked for minimum space and pointer manipulation
53  * overhead at the expense of O(n) removal for arbitrary elements. New
54  * elements can be added to the list after an existing element or at the
55  * head of the list.  Elements being removed from the head of the list
56  * should use the explicit macro for this purpose for optimum
57  * efficiency. A singly-linked list may only be traversed in the forward
58  * direction.  Singly-linked lists are ideal for applications with large
59  * datasets and few or no removals or for implementing a LIFO queue.
60  *
61  * A list is headed by a single forward pointer (or an array of forward
62  * pointers for a hash table header). The elements are doubly linked
63  * so that an arbitrary element can be removed without a need to
64  * traverse the list. New elements can be added to the list before
65  * or after an existing element or at the head of the list. A list
66  * may only be traversed in the forward direction.
67  *
68  * A simple queue is headed by a pair of pointers, one the head of the
69  * list and the other to the tail of the list. The elements are singly
70  * linked to save space, so elements can only be removed from the
71  * head of the list. New elements can be added to the list after
72  * an existing element, at the head of the list, or at the end of the
73  * list. A simple queue may only be traversed in the forward direction.
74  *
75  * A tail queue is headed by a pair of pointers, one to the head of the
76  * list and the other to the tail of the list. The elements are doubly
77  * linked so that an arbitrary element can be removed without a need to
78  * traverse the list. New elements can be added to the list before or
79  * after an existing element, at the head of the list, or at the end of
80  * the list. A tail queue may be traversed in either direction.
81  *
82  * A circle queue is headed by a pair of pointers, one to the head of the
83  * list and the other to the tail of the list. The elements are doubly
84  * linked so that an arbitrary element can be removed without a need to
85  * traverse the list. New elements can be added to the list before or after
86  * an existing element, at the head of the list, or at the end of the list.
87  * A circle queue may be traversed in either direction, but has a more
88  * complex end of list detection.
89  *
90  * For details on the use of these macros, see the queue(3) manual page.
91  */
92 
93 /*
94  * List definitions.
95  */
96 #define	LIST_HEAD(name, type)						\
97 struct name {								\
98 	struct type *lh_first;	/* first element */			\
99 }
100 
101 #define	LIST_HEAD_INITIALIZER(head)					\
102 	{ NULL }
103 
104 #define	LIST_ENTRY(type)						\
105 struct {								\
106 	struct type *le_next;	/* next element */			\
107 	struct type **le_prev;	/* address of previous next element */	\
108 }
109 
110 /*
111  * List functions.
112  */
113 #if defined(_KERNEL) && defined(QUEUEDEBUG)
114 #define	QUEUEDEBUG_LIST_INSERT_HEAD(head, elm, field)			\
115 	if ((head)->lh_first &&						\
116 	    (head)->lh_first->field.le_prev != &(head)->lh_first)	\
117 		panic("LIST_INSERT_HEAD %p %s:%d", (head), __FILE__, __LINE__);
118 #define	QUEUEDEBUG_LIST_OP(elm, field)					\
119 	if ((elm)->field.le_next &&					\
120 	    (elm)->field.le_next->field.le_prev !=			\
121 	    &(elm)->field.le_next)					\
122 		panic("LIST_* forw %p %s:%d", (elm), __FILE__, __LINE__);\
123 	if (*(elm)->field.le_prev != (elm))				\
124 		panic("LIST_* back %p %s:%d", (elm), __FILE__, __LINE__);
125 #define	QUEUEDEBUG_LIST_POSTREMOVE(elm, field)				\
126 	(elm)->field.le_next = (void *)1L;				\
127 	(elm)->field.le_prev = (void *)1L;
128 #else
129 #define	QUEUEDEBUG_LIST_INSERT_HEAD(head, elm, field)
130 #define	QUEUEDEBUG_LIST_OP(elm, field)
131 #define	QUEUEDEBUG_LIST_POSTREMOVE(elm, field)
132 #endif
133 
134 #define	LIST_INIT(head) do {						\
135 	(head)->lh_first = NULL;					\
136 	_NOTE(CONSTCOND)						\
137 } while (0)
138 
139 #define	LIST_INSERT_AFTER(listelm, elm, field) do {			\
140 	QUEUEDEBUG_LIST_OP((listelm), field)				\
141 	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
142 		(listelm)->field.le_next->field.le_prev =		\
143 		    &(elm)->field.le_next;				\
144 	(listelm)->field.le_next = (elm);				\
145 	(elm)->field.le_prev = &(listelm)->field.le_next;		\
146 	_NOTE(CONSTCOND)						\
147 } while (0)
148 
149 #define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
150 	QUEUEDEBUG_LIST_OP((listelm), field)				\
151 	(elm)->field.le_prev = (listelm)->field.le_prev;		\
152 	(elm)->field.le_next = (listelm);				\
153 	*(listelm)->field.le_prev = (elm);				\
154 	(listelm)->field.le_prev = &(elm)->field.le_next;		\
155 	_NOTE(CONSTCOND)						\
156 } while (0)
157 
158 #define	LIST_INSERT_HEAD(head, elm, field) do {				\
159 	QUEUEDEBUG_LIST_INSERT_HEAD((head), (elm), field)		\
160 	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
161 		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
162 	(head)->lh_first = (elm);					\
163 	(elm)->field.le_prev = &(head)->lh_first;			\
164 	_NOTE(CONSTCOND)						\
165 } while (0)
166 
167 #define	LIST_REMOVE(elm, field) do {					\
168 	QUEUEDEBUG_LIST_OP((elm), field)				\
169 	if ((elm)->field.le_next != NULL)				\
170 		(elm)->field.le_next->field.le_prev = 			\
171 		    (elm)->field.le_prev;				\
172 	*(elm)->field.le_prev = (elm)->field.le_next;			\
173 	QUEUEDEBUG_LIST_POSTREMOVE((elm), field)			\
174 	_NOTE(CONSTCOND)						\
175 } while (0)
176 
177 #define	LIST_FOREACH(var, head, field)					\
178 	for ((var) = ((head)->lh_first);				\
179 		(var);							\
180 		(var) = ((var)->field.le_next))
181 
182 /*
183  * List access methods.
184  */
185 #define	LIST_EMPTY(head)		((head)->lh_first == NULL)
186 #define	LIST_FIRST(head)		((head)->lh_first)
187 #define	LIST_NEXT(elm, field)		((elm)->field.le_next)
188 
189 
190 /*
191  * Singly-linked List definitions.
192  */
193 #define	SLIST_HEAD(name, type)						\
194 struct name {								\
195 	struct type *slh_first;	/* first element */			\
196 }
197 
198 #define	SLIST_HEAD_INITIALIZER(head)					\
199 	{ NULL }
200 
201 #define	SLIST_ENTRY(type)						\
202 struct {								\
203 	struct type *sle_next;	/* next element */			\
204 }
205 
206 /*
207  * Singly-linked List functions.
208  */
209 #define	SLIST_INIT(head) do {						\
210 	(head)->slh_first = NULL;					\
211 	_NOTE(CONSTCOND)						\
212 } while (0)
213 
214 #define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
215 	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
216 	(slistelm)->field.sle_next = (elm);				\
217 	_NOTE(CONSTCOND)						\
218 } while (0)
219 
220 #define	SLIST_INSERT_HEAD(head, elm, field) do {			\
221 	(elm)->field.sle_next = (head)->slh_first;			\
222 	(head)->slh_first = (elm);					\
223 	_NOTE(CONSTCOND)						\
224 } while (0)
225 
226 #define	SLIST_REMOVE_HEAD(head, field) do {				\
227 	(head)->slh_first = (head)->slh_first->field.sle_next;		\
228 	_NOTE(CONSTCOND)						\
229 } while (0)
230 
231 #define	SLIST_REMOVE(head, elm, type, field) do {			\
232 	if ((head)->slh_first == (elm)) {				\
233 		SLIST_REMOVE_HEAD((head), field);			\
234 	}								\
235 	else {								\
236 		struct type *curelm = (head)->slh_first;		\
237 		while (curelm->field.sle_next != (elm))			\
238 			curelm = curelm->field.sle_next;		\
239 		curelm->field.sle_next =				\
240 		    curelm->field.sle_next->field.sle_next;		\
241 	}								\
242 	_NOTE(CONSTCOND)						\
243 } while (0)
244 
245 #define	SLIST_FOREACH(var, head, field)					\
246 	for ((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
247 
248 /*
249  * Singly-linked List access methods.
250  */
251 #define	SLIST_EMPTY(head)	((head)->slh_first == NULL)
252 #define	SLIST_FIRST(head)	((head)->slh_first)
253 #define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
254 
255 
256 /*
257  * Singly-linked Tail queue declarations.
258  */
259 #define	STAILQ_HEAD(name, type)						\
260 struct name {								\
261 	struct type *stqh_first;	/* first element */		\
262 	struct type **stqh_last;	/* addr of last next element */	\
263 }
264 
265 #define	STAILQ_HEAD_INITIALIZER(head)					\
266 	{ NULL, &(head).stqh_first }
267 
268 #define	STAILQ_ENTRY(type)						\
269 struct {								\
270 	struct type *stqe_next;	/* next element */		\
271 }
272 
273 /*
274  * Singly-linked Tail queue functions.
275  */
276 #define	STAILQ_INIT(head) do {						\
277 	(head)->stqh_first = NULL;					\
278 	(head)->stqh_last = &(head)->stqh_first;			\
279 	_NOTE(CONSTCOND)						\
280 } while (0)
281 
282 #define	STAILQ_INSERT_HEAD(head, elm, field) do {			\
283 	if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)	\
284 		(head)->stqh_last = &(elm)->field.stqe_next;		\
285 	(head)->stqh_first = (elm);					\
286 	_NOTE(CONSTCOND)						\
287 } while (0)
288 
289 #define	STAILQ_INSERT_TAIL(head, elm, field) do {			\
290 	(elm)->field.stqe_next = NULL;					\
291 	*(head)->stqh_last = (elm);					\
292 	(head)->stqh_last = &(elm)->field.stqe_next;			\
293 	_NOTE(CONSTCOND)						\
294 } while (0)
295 
296 #define	STAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
297 	if (((elm)->field.stqe_next = (listelm)->field.stqe_next)	\
298 	    == NULL)							\
299 		(head)->stqh_last = &(elm)->field.stqe_next;		\
300 	(listelm)->field.stqe_next = (elm);				\
301 	_NOTE(CONSTCOND)						\
302 } while (0)
303 
304 #define	STAILQ_REMOVE_HEAD(head, field) do {				\
305 	if (((head)->stqh_first = (head)->stqh_first->field.stqe_next)	\
306 	    == NULL) 							\
307 		(head)->stqh_last = &(head)->stqh_first;		\
308 	_NOTE(CONSTCOND)						\
309 } while (0)
310 
311 #define	STAILQ_REMOVE(head, elm, type, field) do {			\
312 	if ((head)->stqh_first == (elm)) {				\
313 		STAILQ_REMOVE_HEAD((head), field);			\
314 	} else {							\
315 		struct type *curelm = (head)->stqh_first;		\
316 		while (curelm->field.stqe_next != (elm))		\
317 			curelm = curelm->field.stqe_next;		\
318 		if ((curelm->field.stqe_next =				\
319 			curelm->field.stqe_next->field.stqe_next) == NULL) \
320 			    (head)->stqh_last = &(curelm)->field.stqe_next; \
321 	}								\
322 	_NOTE(CONSTCOND)						\
323 } while (0)
324 
325 #define	STAILQ_FOREACH(var, head, field)				\
326 	for ((var) = ((head)->stqh_first);				\
327 		(var);							\
328 		(var) = ((var)->field.stqe_next))
329 
330 /*
331  * Singly-linked Tail queue access methods.
332  */
333 #define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)
334 #define	STAILQ_FIRST(head)	((head)->stqh_first)
335 #define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)
336 
337 
338 /*
339  * Simple queue definitions.
340  */
341 #define	SIMPLEQ_HEAD(name, type)					\
342 struct name {								\
343 	struct type *sqh_first;	/* first element */		\
344 	struct type **sqh_last;	/* addr of last next element */	\
345 }
346 
347 #define	SIMPLEQ_HEAD_INITIALIZER(head)					\
348 	{ NULL, &(head).sqh_first }
349 
350 #define	SIMPLEQ_ENTRY(type)						\
351 struct {								\
352 	struct type *sqe_next;	/* next element */			\
353 }
354 
355 /*
356  * Simple queue functions.
357  */
358 #define	SIMPLEQ_INIT(head) do {						\
359 	(head)->sqh_first = NULL;					\
360 	(head)->sqh_last = &(head)->sqh_first;				\
361 	_NOTE(CONSTCOND)						\
362 } while (0)
363 
364 #define	SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
365 	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
366 		(head)->sqh_last = &(elm)->field.sqe_next;		\
367 	(head)->sqh_first = (elm);					\
368 	_NOTE(CONSTCOND)						\
369 } while (0)
370 
371 #define	SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
372 	(elm)->field.sqe_next = NULL;					\
373 	*(head)->sqh_last = (elm);					\
374 	(head)->sqh_last = &(elm)->field.sqe_next;			\
375 	_NOTE(CONSTCOND)						\
376 } while (0)
377 
378 #define	SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
379 	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
380 		(head)->sqh_last = &(elm)->field.sqe_next;		\
381 	(listelm)->field.sqe_next = (elm);				\
382 	_NOTE(CONSTCOND)						\
383 } while (0)
384 
385 #define	SIMPLEQ_REMOVE_HEAD(head, field) do {				\
386 	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
387 		(head)->sqh_last = &(head)->sqh_first;			\
388 	_NOTE(CONSTCOND)						\
389 } while (0)
390 
391 #define	SIMPLEQ_REMOVE(head, elm, type, field) do {			\
392 	if ((head)->sqh_first == (elm)) {				\
393 		SIMPLEQ_REMOVE_HEAD((head), field);			\
394 	} else {							\
395 		struct type *curelm = (head)->sqh_first;		\
396 		while (curelm->field.sqe_next != (elm))			\
397 			curelm = curelm->field.sqe_next;		\
398 		if ((curelm->field.sqe_next =				\
399 			curelm->field.sqe_next->field.sqe_next) == NULL) \
400 			    (head)->sqh_last = &(curelm)->field.sqe_next; \
401 	}								\
402 	_NOTE(CONSTCOND)						\
403 } while (0)
404 
405 #define	SIMPLEQ_FOREACH(var, head, field)				\
406 	for ((var) = ((head)->sqh_first);				\
407 		(var);							\
408 		(var) = ((var)->field.sqe_next))
409 
410 /*
411  * Simple queue access methods.
412  */
413 #define	SIMPLEQ_EMPTY(head)		((head)->sqh_first == NULL)
414 #define	SIMPLEQ_FIRST(head)		((head)->sqh_first)
415 #define	SIMPLEQ_NEXT(elm, field)	((elm)->field.sqe_next)
416 
417 
418 /*
419  * Tail queue definitions.
420  */
421 #define	_TAILQ_HEAD(name, type)						\
422 struct name {								\
423 	type *tqh_first;		/* first element */		\
424 	type **tqh_last;	/* addr of last next element */		\
425 }
426 #define	TAILQ_HEAD(name, type)	_TAILQ_HEAD(name, struct type)
427 
428 #define	TAILQ_HEAD_INITIALIZER(head)					\
429 	{ NULL, &(head).tqh_first }
430 
431 #define	_TAILQ_ENTRY(type)						\
432 struct {								\
433 	type *tqe_next;		/* next element */			\
434 	type **tqe_prev;	/* address of previous next element */\
435 }
436 #define	TAILQ_ENTRY(type)	_TAILQ_ENTRY(struct type)
437 
438 /*
439  * Tail queue functions.
440  */
441 #if defined(_KERNEL) && defined(QUEUEDEBUG)
442 #define	QUEUEDEBUG_TAILQ_INSERT_HEAD(head, elm, field)			\
443 	if ((head)->tqh_first &&					\
444 	    (head)->tqh_first->field.tqe_prev != &(head)->tqh_first)	\
445 		panic("TAILQ_INSERT_HEAD %p %s:%d", (void *)(head),	\
446 		    __FILE__, __LINE__);
447 #define	QUEUEDEBUG_TAILQ_INSERT_TAIL(head, elm, field)			\
448 	if (*(head)->tqh_last != NULL)					\
449 		panic("TAILQ_INSERT_TAIL %p %s:%d", (void *)(head),	\
450 		    __FILE__, __LINE__);
451 #define	QUEUEDEBUG_TAILQ_OP(elm, field)					\
452 	if ((elm)->field.tqe_next &&					\
453 	    (elm)->field.tqe_next->field.tqe_prev !=			\
454 	    &(elm)->field.tqe_next)					\
455 		panic("TAILQ_* forw %p %s:%d", (void *)(elm),		\
456 		    __FILE__, __LINE__);\
457 	if (*(elm)->field.tqe_prev != (elm))				\
458 		panic("TAILQ_* back %p %s:%d", (void *)(elm),		\
459 		    __FILE__, __LINE__);
460 #define	QUEUEDEBUG_TAILQ_PREREMOVE(head, elm, field)			\
461 	if ((elm)->field.tqe_next == NULL &&				\
462 	    (head)->tqh_last != &(elm)->field.tqe_next)			\
463 		panic("TAILQ_PREREMOVE head %p elm %p %s:%d",		\
464 		    (void *)(head), (void *)(elm), __FILE__, __LINE__);
465 #define	QUEUEDEBUG_TAILQ_POSTREMOVE(elm, field)				\
466 	(elm)->field.tqe_next = (void *)1L;				\
467 	(elm)->field.tqe_prev = (void *)1L;
468 #else
469 #define	QUEUEDEBUG_TAILQ_INSERT_HEAD(head, elm, field)
470 #define	QUEUEDEBUG_TAILQ_INSERT_TAIL(head, elm, field)
471 #define	QUEUEDEBUG_TAILQ_OP(elm, field)
472 #define	QUEUEDEBUG_TAILQ_PREREMOVE(head, elm, field)
473 #define	QUEUEDEBUG_TAILQ_POSTREMOVE(elm, field)
474 #endif
475 
476 #define	TAILQ_INIT(head) do {						\
477 	(head)->tqh_first = NULL;					\
478 	(head)->tqh_last = &(head)->tqh_first;				\
479 	_NOTE(CONSTCOND)						\
480 } while (0)
481 
482 #define	TAILQ_INSERT_HEAD(head, elm, field) do {			\
483 	QUEUEDEBUG_TAILQ_INSERT_HEAD((head), (elm), field)		\
484 	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
485 		(head)->tqh_first->field.tqe_prev =			\
486 		    &(elm)->field.tqe_next;				\
487 	else								\
488 		(head)->tqh_last = &(elm)->field.tqe_next;		\
489 	(head)->tqh_first = (elm);					\
490 	(elm)->field.tqe_prev = &(head)->tqh_first;			\
491 	_NOTE(CONSTCOND)						\
492 } while (0)
493 
494 #define	TAILQ_INSERT_TAIL(head, elm, field) do {			\
495 	QUEUEDEBUG_TAILQ_INSERT_TAIL((head), (elm), field)		\
496 	(elm)->field.tqe_next = NULL;					\
497 	(elm)->field.tqe_prev = (head)->tqh_last;			\
498 	*(head)->tqh_last = (elm);					\
499 	(head)->tqh_last = &(elm)->field.tqe_next;			\
500 	_NOTE(CONSTCOND)						\
501 } while (0)
502 
503 #define	TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
504 	QUEUEDEBUG_TAILQ_OP((listelm), field)				\
505 	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
506 		(elm)->field.tqe_next->field.tqe_prev = 		\
507 		    &(elm)->field.tqe_next;				\
508 	else								\
509 		(head)->tqh_last = &(elm)->field.tqe_next;		\
510 	(listelm)->field.tqe_next = (elm);				\
511 	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
512 	_NOTE(CONSTCOND)						\
513 } while (0)
514 
515 #define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
516 	QUEUEDEBUG_TAILQ_OP((listelm), field)				\
517 	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
518 	(elm)->field.tqe_next = (listelm);				\
519 	*(listelm)->field.tqe_prev = (elm);				\
520 	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
521 	_NOTE(CONSTCOND)						\
522 } while (0)
523 
524 #define	TAILQ_REMOVE(head, elm, field) do {				\
525 	QUEUEDEBUG_TAILQ_PREREMOVE((head), (elm), field)		\
526 	QUEUEDEBUG_TAILQ_OP((elm), field)				\
527 	if (((elm)->field.tqe_next) != NULL)				\
528 		(elm)->field.tqe_next->field.tqe_prev = 		\
529 		    (elm)->field.tqe_prev;				\
530 	else								\
531 		(head)->tqh_last = (elm)->field.tqe_prev;		\
532 	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
533 	QUEUEDEBUG_TAILQ_POSTREMOVE((elm), field);			\
534 	_NOTE(CONSTCOND)						\
535 } while (0)
536 
537 #define	TAILQ_FOREACH(var, head, field)					\
538 	for ((var) = ((head)->tqh_first);				\
539 		(var);							\
540 		(var) = ((var)->field.tqe_next))
541 
542 #define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
543 	for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last));\
544 		(var);							\
545 		(var) = 						\
546 		    (*(((struct headname *)((var)->field.tqe_prev))->tqh_last)))
547 
548 /*
549  * Tail queue access methods.
550  */
551 #define	TAILQ_EMPTY(head)		((head)->tqh_first == NULL)
552 #define	TAILQ_FIRST(head)		((head)->tqh_first)
553 #define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
554 
555 #define	TAILQ_LAST(head, headname) \
556 	(*(((struct headname *)((head)->tqh_last))->tqh_last))
557 #define	TAILQ_PREV(elm, headname, field) \
558 	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
559 
560 
561 /*
562  * Circular queue definitions.
563  */
564 #define	CIRCLEQ_HEAD(name, type)					\
565 struct name {								\
566 	struct type *cqh_first;		/* first element */	\
567 	struct type *cqh_last;		/* last element */		\
568 }
569 
570 #define	CIRCLEQ_HEAD_INITIALIZER(head)					\
571 	{ (void *)&head, (void *)&head }
572 
573 #define	CIRCLEQ_ENTRY(type)						\
574 struct {								\
575 	struct type *cqe_next;		/* next element */		\
576 	struct type *cqe_prev;		/* previous element */		\
577 }
578 
579 /*
580  * Circular queue functions.
581  */
582 #define	CIRCLEQ_INIT(head) do {						\
583 	(head)->cqh_first = (void *)(head);				\
584 	(head)->cqh_last = (void *)(head);				\
585 	_NOTE(CONSTCOND)						\
586 } while (0)
587 
588 #define	CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
589 	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
590 	(elm)->field.cqe_prev = (listelm);				\
591 	if ((listelm)->field.cqe_next == (void *)(head))		\
592 		(head)->cqh_last = (elm);				\
593 	else								\
594 		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
595 	(listelm)->field.cqe_next = (elm);				\
596 	_NOTE(CONSTCOND)						\
597 } while (0)
598 
599 #define	CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {		\
600 	(elm)->field.cqe_next = (listelm);				\
601 	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
602 	if ((listelm)->field.cqe_prev == (void *)(head))		\
603 		(head)->cqh_first = (elm);				\
604 	else								\
605 		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
606 	(listelm)->field.cqe_prev = (elm);				\
607 	_NOTE(CONSTCOND)						\
608 } while (0)
609 
610 #define	CIRCLEQ_INSERT_HEAD(head, elm, field) do {			\
611 	(elm)->field.cqe_next = (head)->cqh_first;			\
612 	(elm)->field.cqe_prev = (void *)(head);				\
613 	if ((head)->cqh_last == (void *)(head))			\
614 		(head)->cqh_last = (elm);				\
615 	else								\
616 		(head)->cqh_first->field.cqe_prev = (elm);		\
617 	(head)->cqh_first = (elm);					\
618 	_NOTE(CONSTCOND)						\
619 } while (0)
620 
621 #define	CIRCLEQ_INSERT_TAIL(head, elm, field) do {			\
622 	(elm)->field.cqe_next = (void *)(head);				\
623 	(elm)->field.cqe_prev = (head)->cqh_last;			\
624 	if ((head)->cqh_first == (void *)(head))			\
625 		(head)->cqh_first = (elm);				\
626 	else								\
627 		(head)->cqh_last->field.cqe_next = (elm);		\
628 	(head)->cqh_last = (elm);					\
629 	_NOTE(CONSTCOND)						\
630 } while (0)
631 
632 #define	CIRCLEQ_REMOVE(head, elm, field) do {				\
633 	if ((elm)->field.cqe_next == (void *)(head))			\
634 		(head)->cqh_last = (elm)->field.cqe_prev;		\
635 	else								\
636 		(elm)->field.cqe_next->field.cqe_prev =			\
637 		    (elm)->field.cqe_prev;				\
638 	if ((elm)->field.cqe_prev == (void *)(head))			\
639 		(head)->cqh_first = (elm)->field.cqe_next;		\
640 	else								\
641 		(elm)->field.cqe_prev->field.cqe_next =			\
642 		    (elm)->field.cqe_next;				\
643 	_NOTE(CONSTCOND)						\
644 } while (0)
645 
646 #define	CIRCLEQ_FOREACH(var, head, field)				\
647 	for ((var) = ((head)->cqh_first);				\
648 		(var) != (void *)(head);				\
649 		(var) = ((var)->field.cqe_next))
650 
651 #define	CIRCLEQ_FOREACH_REVERSE(var, head, field)			\
652 	for ((var) = ((head)->cqh_last);				\
653 		(var) != (void *)(head);				\
654 		(var) = ((var)->field.cqe_prev))
655 
656 /*
657  * Circular queue access methods.
658  */
659 #define	CIRCLEQ_EMPTY(head)		((head)->cqh_first == (void *)(head))
660 #define	CIRCLEQ_FIRST(head)		((head)->cqh_first)
661 #define	CIRCLEQ_LAST(head)		((head)->cqh_last)
662 #define	CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
663 #define	CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
664 
665 #define	CIRCLEQ_LOOP_NEXT(head, elm, field)				\
666 	(((elm)->field.cqe_next == (void *)(head))			\
667 	    ? ((head)->cqh_first)					\
668 	    : (elm->field.cqe_next))
669 #define	CIRCLEQ_LOOP_PREV(head, elm, field)				\
670 	(((elm)->field.cqe_prev == (void *)(head))			\
671 	    ? ((head)->cqh_last)					\
672 	    : (elm->field.cqe_prev))
673 
674 #ifdef	__cplusplus
675 }
676 #endif
677 
678 #endif	/* !_SYS_QUEUE_H */
679