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6 * modification, are permitted provided that the following conditions
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19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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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 #define SLIST_ENTRY(type) \
149 struct type *sle_next; /* next element */ \
153 * Singly-linked List functions.
155 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
157 #define SLIST_FIRST(head) ((head)->slh_first)
159 #define SLIST_FOREACH(var, head, field) \
160 for ((var) = SLIST_FIRST((head)); \
162 (var) = SLIST_NEXT((var), field))
164 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
165 for ((var) = SLIST_FIRST((head)); \
166 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
169 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
170 for ((varp) = &SLIST_FIRST((head)); \
171 ((var) = *(varp)) != NULL; \
172 (varp) = &SLIST_NEXT((var), field))
174 #define SLIST_INIT(head) do { \
175 SLIST_FIRST((head)) = NULL; \
178 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
179 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
180 SLIST_NEXT((slistelm), field) = (elm); \
183 #define SLIST_INSERT_HEAD(head, elm, field) do { \
184 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
185 SLIST_FIRST((head)) = (elm); \
188 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
190 #define SLIST_REMOVE(head, elm, type, field) do { \
191 if (SLIST_FIRST((head)) == (elm)) { \
192 SLIST_REMOVE_HEAD((head), field); \
195 struct type *curelm = SLIST_FIRST((head)); \
196 while (SLIST_NEXT(curelm, field) != (elm)) \
197 curelm = SLIST_NEXT(curelm, field); \
198 SLIST_NEXT(curelm, field) = \
199 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
201 TRASHIT((elm)->field.sle_next); \
204 #define SLIST_REMOVE_HEAD(head, field) do { \
205 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
209 * Singly-linked Tail queue declarations.
211 #define STAILQ_HEAD(name, type) \
213 struct type *stqh_first;/* first element */ \
214 struct type **stqh_last;/* addr of last next element */ \
217 #define STAILQ_HEAD_INITIALIZER(head) \
218 { NULL, &(head).stqh_first }
220 #define STAILQ_ENTRY(type) \
222 struct type *stqe_next; /* next element */ \
226 * Singly-linked Tail queue functions.
228 #define STAILQ_CONCAT(head1, head2) do { \
229 if (!STAILQ_EMPTY((head2))) { \
230 *(head1)->stqh_last = (head2)->stqh_first; \
231 (head1)->stqh_last = (head2)->stqh_last; \
232 STAILQ_INIT((head2)); \
236 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
238 #define STAILQ_FIRST(head) ((head)->stqh_first)
240 #define STAILQ_FOREACH(var, head, field) \
241 for((var) = STAILQ_FIRST((head)); \
243 (var) = STAILQ_NEXT((var), field))
246 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
247 for ((var) = STAILQ_FIRST((head)); \
248 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
251 #define STAILQ_INIT(head) do { \
252 STAILQ_FIRST((head)) = NULL; \
253 (head)->stqh_last = &STAILQ_FIRST((head)); \
256 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
257 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
258 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
259 STAILQ_NEXT((tqelm), field) = (elm); \
262 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
263 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
264 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
265 STAILQ_FIRST((head)) = (elm); \
268 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
269 STAILQ_NEXT((elm), field) = NULL; \
270 *(head)->stqh_last = (elm); \
271 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
274 #define STAILQ_LAST(head, type, field) \
275 (STAILQ_EMPTY((head)) ? \
277 ((struct type *)(void *) \
278 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
280 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
282 #define STAILQ_REMOVE(head, elm, type, field) do { \
283 if (STAILQ_FIRST((head)) == (elm)) { \
284 STAILQ_REMOVE_HEAD((head), field); \
287 struct type *curelm = STAILQ_FIRST((head)); \
288 while (STAILQ_NEXT(curelm, field) != (elm)) \
289 curelm = STAILQ_NEXT(curelm, field); \
290 if ((STAILQ_NEXT(curelm, field) = \
291 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
292 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
294 TRASHIT((elm)->field.stqe_next); \
297 #define STAILQ_REMOVE_HEAD(head, field) do { \
298 if ((STAILQ_FIRST((head)) = \
299 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
300 (head)->stqh_last = &STAILQ_FIRST((head)); \
307 #define LIST_HEAD(name, type) \
309 struct type *lh_first; /* first element */ \
312 #define LIST_HEAD_INITIALIZER(head) \
315 #define LIST_ENTRY(type) \
317 struct type *le_next; /* next element */ \
318 struct type **le_prev; /* address of previous next element */ \
325 #if (defined(_KERNEL) && defined(INVARIANTS))
326 #define QMD_LIST_CHECK_HEAD(head, field) do { \
327 if (LIST_FIRST((head)) != NULL && \
328 LIST_FIRST((head))->field.le_prev != \
329 &LIST_FIRST((head))) \
330 panic("Bad list head %p first->prev != head", (head)); \
333 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
334 if (LIST_NEXT((elm), field) != NULL && \
335 LIST_NEXT((elm), field)->field.le_prev != \
336 &((elm)->field.le_next)) \
337 panic("Bad link elm %p next->prev != elm", (elm)); \
340 #define QMD_LIST_CHECK_PREV(elm, field) do { \
341 if (*(elm)->field.le_prev != (elm)) \
342 panic("Bad link elm %p prev->next != elm", (elm)); \
345 #define QMD_LIST_CHECK_HEAD(head, field)
346 #define QMD_LIST_CHECK_NEXT(elm, field)
347 #define QMD_LIST_CHECK_PREV(elm, field)
348 #endif /* (_KERNEL && INVARIANTS) */
350 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
352 #define LIST_FIRST(head) ((head)->lh_first)
354 #define LIST_FOREACH(var, head, field) \
355 for ((var) = LIST_FIRST((head)); \
357 (var) = LIST_NEXT((var), field))
359 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
360 for ((var) = LIST_FIRST((head)); \
361 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
364 #define LIST_INIT(head) do { \
365 LIST_FIRST((head)) = NULL; \
368 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
369 QMD_LIST_CHECK_NEXT(listelm, field); \
370 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
371 LIST_NEXT((listelm), field)->field.le_prev = \
372 &LIST_NEXT((elm), field); \
373 LIST_NEXT((listelm), field) = (elm); \
374 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
377 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
378 QMD_LIST_CHECK_PREV(listelm, field); \
379 (elm)->field.le_prev = (listelm)->field.le_prev; \
380 LIST_NEXT((elm), field) = (listelm); \
381 *(listelm)->field.le_prev = (elm); \
382 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
385 #define LIST_INSERT_HEAD(head, elm, field) do { \
386 QMD_LIST_CHECK_HEAD((head), field); \
387 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
388 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
389 LIST_FIRST((head)) = (elm); \
390 (elm)->field.le_prev = &LIST_FIRST((head)); \
393 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
395 #define LIST_REMOVE(elm, field) do { \
396 QMD_LIST_CHECK_NEXT(elm, field); \
397 QMD_LIST_CHECK_PREV(elm, field); \
398 if (LIST_NEXT((elm), field) != NULL) \
399 LIST_NEXT((elm), field)->field.le_prev = \
400 (elm)->field.le_prev; \
401 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
402 TRASHIT((elm)->field.le_next); \
403 TRASHIT((elm)->field.le_prev); \
405 #endif /* LIST_HEAD */
408 * Tail queue declarations.
410 #define TAILQ_HEAD(name, type) \
412 struct type *tqh_first; /* first element */ \
413 struct type **tqh_last; /* addr of last next element */ \
417 #define TAILQ_HEAD_INITIALIZER(head) \
418 { NULL, &(head).tqh_first }
420 #define TAILQ_ENTRY(type) \
422 struct type *tqe_next; /* next element */ \
423 struct type **tqe_prev; /* address of previous next element */ \
428 * Tail queue functions.
430 #if (defined(_KERNEL) && defined(INVARIANTS))
431 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
432 if (!TAILQ_EMPTY(head) && \
433 TAILQ_FIRST((head))->field.tqe_prev != \
434 &TAILQ_FIRST((head))) \
435 panic("Bad tailq head %p first->prev != head", (head)); \
438 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
439 if (*(head)->tqh_last != NULL) \
440 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
443 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
444 if (TAILQ_NEXT((elm), field) != NULL && \
445 TAILQ_NEXT((elm), field)->field.tqe_prev != \
446 &((elm)->field.tqe_next)) \
447 panic("Bad link elm %p next->prev != elm", (elm)); \
450 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
451 if (*(elm)->field.tqe_prev != (elm)) \
452 panic("Bad link elm %p prev->next != elm", (elm)); \
455 #define QMD_TAILQ_CHECK_HEAD(head, field)
456 #define QMD_TAILQ_CHECK_TAIL(head, headname)
457 #define QMD_TAILQ_CHECK_NEXT(elm, field)
458 #define QMD_TAILQ_CHECK_PREV(elm, field)
459 #endif /* (_KERNEL && INVARIANTS) */
461 #define TAILQ_CONCAT(head1, head2, field) do { \
462 if (!TAILQ_EMPTY(head2)) { \
463 *(head1)->tqh_last = (head2)->tqh_first; \
464 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
465 (head1)->tqh_last = (head2)->tqh_last; \
466 TAILQ_INIT((head2)); \
467 QMD_TRACE_HEAD(head1); \
468 QMD_TRACE_HEAD(head2); \
472 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
474 #define TAILQ_FIRST(head) ((head)->tqh_first)
476 #define TAILQ_FOREACH(var, head, field) \
477 for ((var) = TAILQ_FIRST((head)); \
479 (var) = TAILQ_NEXT((var), field))
481 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
482 for ((var) = TAILQ_FIRST((head)); \
483 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
486 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
487 for ((var) = TAILQ_LAST((head), headname); \
489 (var) = TAILQ_PREV((var), headname, field))
491 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
492 for ((var) = TAILQ_LAST((head), headname); \
493 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
496 #define TAILQ_INIT(head) do { \
497 TAILQ_FIRST((head)) = NULL; \
498 (head)->tqh_last = &TAILQ_FIRST((head)); \
499 QMD_TRACE_HEAD(head); \
502 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
503 QMD_TAILQ_CHECK_NEXT(listelm, field); \
504 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
505 TAILQ_NEXT((elm), field)->field.tqe_prev = \
506 &TAILQ_NEXT((elm), field); \
508 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
509 QMD_TRACE_HEAD(head); \
511 TAILQ_NEXT((listelm), field) = (elm); \
512 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
513 QMD_TRACE_ELEM(&(elm)->field); \
514 QMD_TRACE_ELEM(&listelm->field); \
517 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
518 QMD_TAILQ_CHECK_PREV(listelm, field); \
519 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
520 TAILQ_NEXT((elm), field) = (listelm); \
521 *(listelm)->field.tqe_prev = (elm); \
522 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
523 QMD_TRACE_ELEM(&(elm)->field); \
524 QMD_TRACE_ELEM(&listelm->field); \
527 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
528 QMD_TAILQ_CHECK_HEAD(head, field); \
529 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
530 TAILQ_FIRST((head))->field.tqe_prev = \
531 &TAILQ_NEXT((elm), field); \
533 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
534 TAILQ_FIRST((head)) = (elm); \
535 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
536 QMD_TRACE_HEAD(head); \
537 QMD_TRACE_ELEM(&(elm)->field); \
540 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
541 QMD_TAILQ_CHECK_TAIL(head, field); \
542 TAILQ_NEXT((elm), field) = NULL; \
543 (elm)->field.tqe_prev = (head)->tqh_last; \
544 *(head)->tqh_last = (elm); \
545 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
546 QMD_TRACE_HEAD(head); \
547 QMD_TRACE_ELEM(&(elm)->field); \
550 #define TAILQ_LAST(head, headname) \
551 (*(((struct headname *)((head)->tqh_last))->tqh_last))
553 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
555 #define TAILQ_PREV(elm, headname, field) \
556 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
558 #define TAILQ_REMOVE(head, elm, field) do { \
559 QMD_TAILQ_CHECK_NEXT(elm, field); \
560 QMD_TAILQ_CHECK_PREV(elm, field); \
561 if ((TAILQ_NEXT((elm), field)) != NULL) \
562 TAILQ_NEXT((elm), field)->field.tqe_prev = \
563 (elm)->field.tqe_prev; \
565 (head)->tqh_last = (elm)->field.tqe_prev; \
566 QMD_TRACE_HEAD(head); \
568 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
569 TRASHIT((elm)->field.tqe_next); \
570 TRASHIT((elm)->field.tqe_prev); \
571 QMD_TRACE_ELEM(&(elm)->field); \
578 * XXX insque() and remque() are an old way of handling certain queues.
579 * They bogusly assumes that all queue heads look alike.
583 struct quehead *qh_link;
584 struct quehead *qh_rlink;
587 #ifdef __CC_SUPPORTS___INLINE
590 insque(void *a, void *b)
592 struct quehead *element = (struct quehead *)a,
593 *head = (struct quehead *)b;
595 element->qh_link = head->qh_link;
596 element->qh_rlink = head;
597 head->qh_link = element;
598 element->qh_link->qh_rlink = element;
604 struct quehead *element = (struct quehead *)a;
606 element->qh_link->qh_rlink = element->qh_rlink;
607 element->qh_rlink->qh_link = element->qh_link;
608 element->qh_rlink = 0;
611 #else /* !__CC_SUPPORTS___INLINE */
613 void insque(void *a, void *b);
614 void remque(void *a);
616 #endif /* __CC_SUPPORTS___INLINE */
620 #endif /* !_SYS_QUEUE_H_ */