2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
29 * @(#)queue.h 8.5 (Berkeley) 8/20/94
30 * $FreeBSD: src/sys/sys/queue.h,v 1.68 2006/10/24 11:20:29 ru Exp $
36 //#include <sys/cdefs.h>
39 * This file defines four types of data structures: singly-linked lists,
40 * singly-linked tail queues, lists and tail queues.
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.
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.
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 only be traversed in the forward direction.
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.
77 * For details on the use of these macros, see the queue(3) manual page.
80 * SLIST LIST STAILQ TAILQ
82 * _HEAD_INITIALIZER + + + +
91 * _FOREACH_SAFE + + + +
92 * _FOREACH_REVERSE - - - +
93 * _FOREACH_REVERSE_SAFE - - - +
94 * _INSERT_HEAD + + + +
95 * _INSERT_BEFORE - + - +
96 * _INSERT_AFTER + + + +
97 * _INSERT_TAIL - - + +
99 * _REMOVE_HEAD + - + -
103 #ifdef QUEUE_MACRO_DEBUG
104 /* Store the last 2 places the queue element or head was altered */
112 #define TRACEBUF struct qm_trace trace;
113 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
115 #define QMD_TRACE_HEAD(head) do { \
116 (head)->trace.prevline = (head)->trace.lastline; \
117 (head)->trace.prevfile = (head)->trace.lastfile; \
118 (head)->trace.lastline = __LINE__; \
119 (head)->trace.lastfile = __FILE__; \
122 #define QMD_TRACE_ELEM(elem) do { \
123 (elem)->trace.prevline = (elem)->trace.lastline; \
124 (elem)->trace.prevfile = (elem)->trace.lastfile; \
125 (elem)->trace.lastline = __LINE__; \
126 (elem)->trace.lastfile = __FILE__; \
130 #define QMD_TRACE_ELEM(elem)
131 #define QMD_TRACE_HEAD(head)
134 #endif /* QUEUE_MACRO_DEBUG */
137 * Singly-linked List declarations.
139 #define SLIST_HEAD(name, type) \
141 struct type *slh_first; /* first element */ \
144 #define SLIST_HEAD_INITIALIZER(head) \
147 #if defined( _WIN32 ) && defined(SLIST_ENTRY)
150 #define SLIST_ENTRY(type) \
152 struct type *sle_next; /* next element */ \
156 * Singly-linked List functions.
158 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
160 #define SLIST_FIRST(head) ((head)->slh_first)
162 #define SLIST_FOREACH(var, head, field) \
163 for ((var) = SLIST_FIRST((head)); \
165 (var) = SLIST_NEXT((var), field))
167 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
168 for ((var) = SLIST_FIRST((head)); \
169 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
172 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
173 for ((varp) = &SLIST_FIRST((head)); \
174 ((var) = *(varp)) != NULL; \
175 (varp) = &SLIST_NEXT((var), field))
177 #define SLIST_INIT(head) do { \
178 SLIST_FIRST((head)) = NULL; \
181 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
182 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
183 SLIST_NEXT((slistelm), field) = (elm); \
186 #define SLIST_INSERT_HEAD(head, elm, field) do { \
187 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
188 SLIST_FIRST((head)) = (elm); \
191 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
193 #define SLIST_REMOVE(head, elm, type, field) do { \
194 if (SLIST_FIRST((head)) == (elm)) { \
195 SLIST_REMOVE_HEAD((head), field); \
198 struct type *curelm = SLIST_FIRST((head)); \
199 while (SLIST_NEXT(curelm, field) != (elm)) \
200 curelm = SLIST_NEXT(curelm, field); \
201 SLIST_NEXT(curelm, field) = \
202 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
204 TRASHIT((elm)->field.sle_next); \
207 #define SLIST_REMOVE_HEAD(head, field) do { \
208 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
212 * Singly-linked Tail queue declarations.
214 #define STAILQ_HEAD(name, type) \
216 struct type *stqh_first;/* first element */ \
217 struct type **stqh_last;/* addr of last next element */ \
220 #define STAILQ_HEAD_INITIALIZER(head) \
221 { NULL, &(head).stqh_first }
223 #define STAILQ_ENTRY(type) \
225 struct type *stqe_next; /* next element */ \
229 * Singly-linked Tail queue functions.
231 #define STAILQ_CONCAT(head1, head2) do { \
232 if (!STAILQ_EMPTY((head2))) { \
233 *(head1)->stqh_last = (head2)->stqh_first; \
234 (head1)->stqh_last = (head2)->stqh_last; \
235 STAILQ_INIT((head2)); \
239 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
241 #define STAILQ_FIRST(head) ((head)->stqh_first)
243 #define STAILQ_FOREACH(var, head, field) \
244 for((var) = STAILQ_FIRST((head)); \
246 (var) = STAILQ_NEXT((var), field))
249 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
250 for ((var) = STAILQ_FIRST((head)); \
251 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
254 #define STAILQ_INIT(head) do { \
255 STAILQ_FIRST((head)) = NULL; \
256 (head)->stqh_last = &STAILQ_FIRST((head)); \
259 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
260 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
261 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
262 STAILQ_NEXT((tqelm), field) = (elm); \
265 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
266 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
267 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
268 STAILQ_FIRST((head)) = (elm); \
271 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
272 STAILQ_NEXT((elm), field) = NULL; \
273 *(head)->stqh_last = (elm); \
274 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
277 #define STAILQ_LAST(head, type, field) \
278 (STAILQ_EMPTY((head)) ? \
280 ((struct type *)(void *) \
281 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
283 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
285 #define STAILQ_REMOVE(head, elm, type, field) do { \
286 if (STAILQ_FIRST((head)) == (elm)) { \
287 STAILQ_REMOVE_HEAD((head), field); \
290 struct type *curelm = STAILQ_FIRST((head)); \
291 while (STAILQ_NEXT(curelm, field) != (elm)) \
292 curelm = STAILQ_NEXT(curelm, field); \
293 if ((STAILQ_NEXT(curelm, field) = \
294 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
295 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
297 TRASHIT((elm)->field.stqe_next); \
300 #define STAILQ_REMOVE_HEAD(head, field) do { \
301 if ((STAILQ_FIRST((head)) = \
302 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
303 (head)->stqh_last = &STAILQ_FIRST((head)); \
310 #define LIST_HEAD(name, type) \
312 struct type *lh_first; /* first element */ \
315 #define LIST_HEAD_INITIALIZER(head) \
318 #define LIST_ENTRY(type) \
320 struct type *le_next; /* next element */ \
321 struct type **le_prev; /* address of previous next element */ \
328 #if (defined(_KERNEL) && defined(INVARIANTS))
329 #define QMD_LIST_CHECK_HEAD(head, field) do { \
330 if (LIST_FIRST((head)) != NULL && \
331 LIST_FIRST((head))->field.le_prev != \
332 &LIST_FIRST((head))) \
333 panic("Bad list head %p first->prev != head", (head)); \
336 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
337 if (LIST_NEXT((elm), field) != NULL && \
338 LIST_NEXT((elm), field)->field.le_prev != \
339 &((elm)->field.le_next)) \
340 panic("Bad link elm %p next->prev != elm", (elm)); \
343 #define QMD_LIST_CHECK_PREV(elm, field) do { \
344 if (*(elm)->field.le_prev != (elm)) \
345 panic("Bad link elm %p prev->next != elm", (elm)); \
348 #define QMD_LIST_CHECK_HEAD(head, field)
349 #define QMD_LIST_CHECK_NEXT(elm, field)
350 #define QMD_LIST_CHECK_PREV(elm, field)
351 #endif /* (_KERNEL && INVARIANTS) */
353 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
355 #define LIST_FIRST(head) ((head)->lh_first)
357 #define LIST_FOREACH(var, head, field) \
358 for ((var) = LIST_FIRST((head)); \
360 (var) = LIST_NEXT((var), field))
362 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
363 for ((var) = LIST_FIRST((head)); \
364 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
367 #define LIST_INIT(head) do { \
368 LIST_FIRST((head)) = NULL; \
371 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
372 QMD_LIST_CHECK_NEXT(listelm, field); \
373 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
374 LIST_NEXT((listelm), field)->field.le_prev = \
375 &LIST_NEXT((elm), field); \
376 LIST_NEXT((listelm), field) = (elm); \
377 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
380 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
381 QMD_LIST_CHECK_PREV(listelm, field); \
382 (elm)->field.le_prev = (listelm)->field.le_prev; \
383 LIST_NEXT((elm), field) = (listelm); \
384 *(listelm)->field.le_prev = (elm); \
385 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
388 #define LIST_INSERT_HEAD(head, elm, field) do { \
389 QMD_LIST_CHECK_HEAD((head), field); \
390 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
391 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
392 LIST_FIRST((head)) = (elm); \
393 (elm)->field.le_prev = &LIST_FIRST((head)); \
396 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
398 #define LIST_REMOVE(elm, field) do { \
399 QMD_LIST_CHECK_NEXT(elm, field); \
400 QMD_LIST_CHECK_PREV(elm, field); \
401 if (LIST_NEXT((elm), field) != NULL) \
402 LIST_NEXT((elm), field)->field.le_prev = \
403 (elm)->field.le_prev; \
404 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
405 TRASHIT((elm)->field.le_next); \
406 TRASHIT((elm)->field.le_prev); \
408 #endif /* LIST_HEAD */
411 * Tail queue declarations.
413 #define TAILQ_HEAD(name, type) \
415 struct type *tqh_first; /* first element */ \
416 struct type **tqh_last; /* addr of last next element */ \
420 #define TAILQ_HEAD_INITIALIZER(head) \
421 { NULL, &(head).tqh_first }
423 #define TAILQ_ENTRY(type) \
425 struct type *tqe_next; /* next element */ \
426 struct type **tqe_prev; /* address of previous next element */ \
431 * Tail queue functions.
433 #if (defined(_KERNEL) && defined(INVARIANTS))
434 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
435 if (!TAILQ_EMPTY(head) && \
436 TAILQ_FIRST((head))->field.tqe_prev != \
437 &TAILQ_FIRST((head))) \
438 panic("Bad tailq head %p first->prev != head", (head)); \
441 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
442 if (*(head)->tqh_last != NULL) \
443 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
446 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
447 if (TAILQ_NEXT((elm), field) != NULL && \
448 TAILQ_NEXT((elm), field)->field.tqe_prev != \
449 &((elm)->field.tqe_next)) \
450 panic("Bad link elm %p next->prev != elm", (elm)); \
453 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
454 if (*(elm)->field.tqe_prev != (elm)) \
455 panic("Bad link elm %p prev->next != elm", (elm)); \
458 #define QMD_TAILQ_CHECK_HEAD(head, field)
459 #define QMD_TAILQ_CHECK_TAIL(head, headname)
460 #define QMD_TAILQ_CHECK_NEXT(elm, field)
461 #define QMD_TAILQ_CHECK_PREV(elm, field)
462 #endif /* (_KERNEL && INVARIANTS) */
464 #define TAILQ_CONCAT(head1, head2, field) do { \
465 if (!TAILQ_EMPTY(head2)) { \
466 *(head1)->tqh_last = (head2)->tqh_first; \
467 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
468 (head1)->tqh_last = (head2)->tqh_last; \
469 TAILQ_INIT((head2)); \
470 QMD_TRACE_HEAD(head1); \
471 QMD_TRACE_HEAD(head2); \
475 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
477 #define TAILQ_FIRST(head) ((head)->tqh_first)
479 #define TAILQ_FOREACH(var, head, field) \
480 for ((var) = TAILQ_FIRST((head)); \
482 (var) = TAILQ_NEXT((var), field))
484 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
485 for ((var) = TAILQ_FIRST((head)); \
486 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
489 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
490 for ((var) = TAILQ_LAST((head), headname); \
492 (var) = TAILQ_PREV((var), headname, field))
494 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
495 for ((var) = TAILQ_LAST((head), headname); \
496 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
499 #define TAILQ_INIT(head) do { \
500 TAILQ_FIRST((head)) = NULL; \
501 (head)->tqh_last = &TAILQ_FIRST((head)); \
502 QMD_TRACE_HEAD(head); \
505 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
506 QMD_TAILQ_CHECK_NEXT(listelm, field); \
507 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
508 TAILQ_NEXT((elm), field)->field.tqe_prev = \
509 &TAILQ_NEXT((elm), field); \
511 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
512 QMD_TRACE_HEAD(head); \
514 TAILQ_NEXT((listelm), field) = (elm); \
515 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
516 QMD_TRACE_ELEM(&(elm)->field); \
517 QMD_TRACE_ELEM(&listelm->field); \
520 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
521 QMD_TAILQ_CHECK_PREV(listelm, field); \
522 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
523 TAILQ_NEXT((elm), field) = (listelm); \
524 *(listelm)->field.tqe_prev = (elm); \
525 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
526 QMD_TRACE_ELEM(&(elm)->field); \
527 QMD_TRACE_ELEM(&listelm->field); \
530 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
531 QMD_TAILQ_CHECK_HEAD(head, field); \
532 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
533 TAILQ_FIRST((head))->field.tqe_prev = \
534 &TAILQ_NEXT((elm), field); \
536 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
537 TAILQ_FIRST((head)) = (elm); \
538 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
539 QMD_TRACE_HEAD(head); \
540 QMD_TRACE_ELEM(&(elm)->field); \
543 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
544 QMD_TAILQ_CHECK_TAIL(head, field); \
545 TAILQ_NEXT((elm), field) = NULL; \
546 (elm)->field.tqe_prev = (head)->tqh_last; \
547 *(head)->tqh_last = (elm); \
548 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
549 QMD_TRACE_HEAD(head); \
550 QMD_TRACE_ELEM(&(elm)->field); \
553 #define TAILQ_LAST(head, headname) \
554 (*(((struct headname *)((head)->tqh_last))->tqh_last))
556 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
558 #define TAILQ_PREV(elm, headname, field) \
559 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
561 #define TAILQ_REMOVE(head, elm, field) do { \
562 QMD_TAILQ_CHECK_NEXT(elm, field); \
563 QMD_TAILQ_CHECK_PREV(elm, field); \
564 if ((TAILQ_NEXT((elm), field)) != NULL) \
565 TAILQ_NEXT((elm), field)->field.tqe_prev = \
566 (elm)->field.tqe_prev; \
568 (head)->tqh_last = (elm)->field.tqe_prev; \
569 QMD_TRACE_HEAD(head); \
571 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
572 TRASHIT((elm)->field.tqe_next); \
573 TRASHIT((elm)->field.tqe_prev); \
574 QMD_TRACE_ELEM(&(elm)->field); \
581 * XXX insque() and remque() are an old way of handling certain queues.
582 * They bogusly assumes that all queue heads look alike.
586 struct quehead *qh_link;
587 struct quehead *qh_rlink;
590 #ifdef __CC_SUPPORTS___INLINE
593 insque(void *a, void *b)
595 struct quehead *element = (struct quehead *)a,
596 *head = (struct quehead *)b;
598 element->qh_link = head->qh_link;
599 element->qh_rlink = head;
600 head->qh_link = element;
601 element->qh_link->qh_rlink = element;
607 struct quehead *element = (struct quehead *)a;
609 element->qh_link->qh_rlink = element->qh_rlink;
610 element->qh_rlink->qh_link = element->qh_link;
611 element->qh_rlink = 0;
614 #else /* !__CC_SUPPORTS___INLINE */
616 void insque(void *a, void *b);
617 void remque(void *a);
619 #endif /* __CC_SUPPORTS___INLINE */
623 #endif /* !_SYS_QUEUE_H_ */