2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1991, 1993
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31 * @(#)queue.h 8.5 (Berkeley) 8/20/94
38 #include <sys/cdefs.h>
41 * This file defines four types of data structures: singly-linked lists,
42 * singly-linked tail queues, lists and tail queues.
44 * A singly-linked list is headed by a single forward pointer. The elements
45 * are singly linked for minimum space and pointer manipulation overhead at
46 * the expense of O(n) removal for arbitrary elements. New elements can be
47 * added to the list after an existing element or at the head of the list.
48 * Elements being removed from the head of the list should use the explicit
49 * macro for this purpose for optimum efficiency. A singly-linked list may
50 * only be traversed in the forward direction. Singly-linked lists are ideal
51 * for applications with large datasets and few or no removals or for
52 * implementing a LIFO queue.
54 * A singly-linked tail queue is headed by a pair of pointers, one to the
55 * head of the list and the other to the tail of the list. The elements are
56 * singly linked for minimum space and pointer manipulation overhead at the
57 * expense of O(n) removal for arbitrary elements. New elements can be added
58 * to the list after an existing element, at the head of the list, or at the
59 * end of the list. Elements being removed from the head of the tail queue
60 * should use the explicit macro for this purpose for optimum efficiency.
61 * A singly-linked tail queue may only be traversed in the forward direction.
62 * Singly-linked tail queues are ideal for applications with large datasets
63 * and few or no removals or for implementing a FIFO queue.
65 * A list is headed by a single forward pointer (or an array of forward
66 * pointers for a hash table header). The elements are doubly linked
67 * so that an arbitrary element can be removed without a need to
68 * traverse the list. New elements can be added to the list before
69 * or after an existing element or at the head of the list. A list
70 * may be traversed in either direction.
72 * A tail queue is headed by a pair of pointers, one to the head of the
73 * list and the other to the tail of the list. The elements are doubly
74 * linked so that an arbitrary element can be removed without a need to
75 * traverse the list. New elements can be added to the list before or
76 * after an existing element, at the head of the list, or at the end of
77 * the list. A tail queue may be traversed in either direction.
79 * For details on the use of these macros, see the queue(3) manual page.
81 * Below is a summary of implemented functions where:
82 * + means the macro is available
83 * - means the macro is not available
84 * s means the macro is available but is slow (runs in O(n) time)
86 * SLIST LIST STAILQ TAILQ
89 * _HEAD_INITIALIZER + + + +
91 * _CLASS_ENTRY + + + +
100 * _FOREACH_FROM + + + +
101 * _FOREACH_SAFE + + + +
102 * _FOREACH_FROM_SAFE + + + +
103 * _FOREACH_REVERSE - - - +
104 * _FOREACH_REVERSE_FROM - - - +
105 * _FOREACH_REVERSE_SAFE - - - +
106 * _FOREACH_REVERSE_FROM_SAFE - - - +
107 * _INSERT_HEAD + + + +
108 * _INSERT_BEFORE - + - +
109 * _INSERT_AFTER + + + +
110 * _INSERT_TAIL - - + +
112 * _REMOVE_AFTER + - + -
113 * _REMOVE_HEAD + - + -
118 #ifdef QUEUE_MACRO_DEBUG
119 #warn Use QUEUE_MACRO_DEBUG_TRACE and/or QUEUE_MACRO_DEBUG_TRASH
120 #define QUEUE_MACRO_DEBUG_TRACE
121 #define QUEUE_MACRO_DEBUG_TRASH
124 #ifdef QUEUE_MACRO_DEBUG_TRACE
125 /* Store the last 2 places the queue element or head was altered */
127 unsigned long lastline;
128 unsigned long prevline;
129 const char *lastfile;
130 const char *prevfile;
133 #define TRACEBUF struct qm_trace trace;
134 #define TRACEBUF_INITIALIZER { __LINE__, 0, __FILE__, NULL } ,
136 #define QMD_TRACE_HEAD(head) do { \
137 (head)->trace.prevline = (head)->trace.lastline; \
138 (head)->trace.prevfile = (head)->trace.lastfile; \
139 (head)->trace.lastline = __LINE__; \
140 (head)->trace.lastfile = __FILE__; \
143 #define QMD_TRACE_ELEM(elem) do { \
144 (elem)->trace.prevline = (elem)->trace.lastline; \
145 (elem)->trace.prevfile = (elem)->trace.lastfile; \
146 (elem)->trace.lastline = __LINE__; \
147 (elem)->trace.lastfile = __FILE__; \
150 #else /* !QUEUE_MACRO_DEBUG_TRACE */
151 #define QMD_TRACE_ELEM(elem)
152 #define QMD_TRACE_HEAD(head)
154 #define TRACEBUF_INITIALIZER
155 #endif /* QUEUE_MACRO_DEBUG_TRACE */
157 #ifdef QUEUE_MACRO_DEBUG_TRASH
158 #define QMD_SAVELINK(name, link) void **name = (void *)&(link)
159 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
160 #define QMD_IS_TRASHED(x) ((x) == (void *)(intptr_t)-1)
161 #else /* !QUEUE_MACRO_DEBUG_TRASH */
162 #define QMD_SAVELINK(name, link)
164 #define QMD_IS_TRASHED(x) 0
165 #endif /* QUEUE_MACRO_DEBUG_TRASH */
169 * In C++ there can be structure lists and class lists:
171 #define QUEUE_TYPEOF(type) type
173 #define QUEUE_TYPEOF(type) struct type
177 * Singly-linked List declarations.
179 #define SLIST_HEAD(name, type) \
181 struct type *slh_first; /* first element */ \
184 #define SLIST_CLASS_HEAD(name, type) \
186 class type *slh_first; /* first element */ \
189 #define SLIST_HEAD_INITIALIZER(head) \
192 #define SLIST_ENTRY(type) \
194 struct type *sle_next; /* next element */ \
197 #define SLIST_CLASS_ENTRY(type) \
199 class type *sle_next; /* next element */ \
203 * Singly-linked List functions.
205 #if (defined(_KERNEL) && defined(INVARIANTS))
206 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm) do { \
207 if (*(prevp) != (elm)) \
208 panic("Bad prevptr *(%p) == %p != %p", \
209 (prevp), *(prevp), (elm)); \
212 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm)
215 #define SLIST_CONCAT(head1, head2, type, field) do { \
216 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1); \
217 if (curelm == NULL) { \
218 if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL) \
220 } else if (SLIST_FIRST(head2) != NULL) { \
221 while (SLIST_NEXT(curelm, field) != NULL) \
222 curelm = SLIST_NEXT(curelm, field); \
223 SLIST_NEXT(curelm, field) = SLIST_FIRST(head2); \
228 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
230 #define SLIST_FIRST(head) ((head)->slh_first)
232 #define SLIST_FOREACH(var, head, field) \
233 for ((var) = SLIST_FIRST((head)); \
235 (var) = SLIST_NEXT((var), field))
237 #define SLIST_FOREACH_FROM(var, head, field) \
238 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
240 (var) = SLIST_NEXT((var), field))
242 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
243 for ((var) = SLIST_FIRST((head)); \
244 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
247 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
248 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
249 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
252 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
253 for ((varp) = &SLIST_FIRST((head)); \
254 ((var) = *(varp)) != NULL; \
255 (varp) = &SLIST_NEXT((var), field))
257 #define SLIST_INIT(head) do { \
258 SLIST_FIRST((head)) = NULL; \
261 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
262 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
263 SLIST_NEXT((slistelm), field) = (elm); \
266 #define SLIST_INSERT_HEAD(head, elm, field) do { \
267 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
268 SLIST_FIRST((head)) = (elm); \
271 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
273 #define SLIST_REMOVE(head, elm, type, field) do { \
274 QMD_SAVELINK(oldnext, (elm)->field.sle_next); \
275 if (SLIST_FIRST((head)) == (elm)) { \
276 SLIST_REMOVE_HEAD((head), field); \
279 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head); \
280 while (SLIST_NEXT(curelm, field) != (elm)) \
281 curelm = SLIST_NEXT(curelm, field); \
282 SLIST_REMOVE_AFTER(curelm, field); \
287 #define SLIST_REMOVE_AFTER(elm, field) do { \
288 SLIST_NEXT(elm, field) = \
289 SLIST_NEXT(SLIST_NEXT(elm, field), field); \
292 #define SLIST_REMOVE_HEAD(head, field) do { \
293 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
296 #define SLIST_REMOVE_PREVPTR(prevp, elm, field) do { \
297 QMD_SLIST_CHECK_PREVPTR(prevp, elm); \
298 *(prevp) = SLIST_NEXT(elm, field); \
299 TRASHIT((elm)->field.sle_next); \
302 #define SLIST_SWAP(head1, head2, type) do { \
303 QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1); \
304 SLIST_FIRST(head1) = SLIST_FIRST(head2); \
305 SLIST_FIRST(head2) = swap_first; \
309 * Singly-linked Tail queue declarations.
311 #define STAILQ_HEAD(name, type) \
313 struct type *stqh_first;/* first element */ \
314 struct type **stqh_last;/* addr of last next element */ \
317 #define STAILQ_CLASS_HEAD(name, type) \
319 class type *stqh_first; /* first element */ \
320 class type **stqh_last; /* addr of last next element */ \
323 #define STAILQ_HEAD_INITIALIZER(head) \
324 { NULL, &(head).stqh_first }
326 #define STAILQ_ENTRY(type) \
328 struct type *stqe_next; /* next element */ \
331 #define STAILQ_CLASS_ENTRY(type) \
333 class type *stqe_next; /* next element */ \
337 * Singly-linked Tail queue functions.
339 #define STAILQ_CONCAT(head1, head2) do { \
340 if (!STAILQ_EMPTY((head2))) { \
341 *(head1)->stqh_last = (head2)->stqh_first; \
342 (head1)->stqh_last = (head2)->stqh_last; \
343 STAILQ_INIT((head2)); \
347 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
349 #define STAILQ_FIRST(head) ((head)->stqh_first)
351 #define STAILQ_FOREACH(var, head, field) \
352 for((var) = STAILQ_FIRST((head)); \
354 (var) = STAILQ_NEXT((var), field))
356 #define STAILQ_FOREACH_FROM(var, head, field) \
357 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
359 (var) = STAILQ_NEXT((var), field))
361 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
362 for ((var) = STAILQ_FIRST((head)); \
363 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
366 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
367 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
368 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
371 #define STAILQ_INIT(head) do { \
372 STAILQ_FIRST((head)) = NULL; \
373 (head)->stqh_last = &STAILQ_FIRST((head)); \
376 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
377 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
378 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
379 STAILQ_NEXT((tqelm), field) = (elm); \
382 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
383 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
384 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
385 STAILQ_FIRST((head)) = (elm); \
388 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
389 STAILQ_NEXT((elm), field) = NULL; \
390 *(head)->stqh_last = (elm); \
391 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
394 #define STAILQ_LAST(head, type, field) \
395 (STAILQ_EMPTY((head)) ? NULL : \
396 __containerof((head)->stqh_last, \
397 QUEUE_TYPEOF(type), field.stqe_next))
399 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
401 #define STAILQ_REMOVE(head, elm, type, field) do { \
402 QMD_SAVELINK(oldnext, (elm)->field.stqe_next); \
403 if (STAILQ_FIRST((head)) == (elm)) { \
404 STAILQ_REMOVE_HEAD((head), field); \
407 QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head); \
408 while (STAILQ_NEXT(curelm, field) != (elm)) \
409 curelm = STAILQ_NEXT(curelm, field); \
410 STAILQ_REMOVE_AFTER(head, curelm, field); \
415 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \
416 if ((STAILQ_NEXT(elm, field) = \
417 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
418 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
421 #define STAILQ_REMOVE_HEAD(head, field) do { \
422 if ((STAILQ_FIRST((head)) = \
423 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
424 (head)->stqh_last = &STAILQ_FIRST((head)); \
427 #define STAILQ_SWAP(head1, head2, type) do { \
428 QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1); \
429 QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last; \
430 STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
431 (head1)->stqh_last = (head2)->stqh_last; \
432 STAILQ_FIRST(head2) = swap_first; \
433 (head2)->stqh_last = swap_last; \
434 if (STAILQ_EMPTY(head1)) \
435 (head1)->stqh_last = &STAILQ_FIRST(head1); \
436 if (STAILQ_EMPTY(head2)) \
437 (head2)->stqh_last = &STAILQ_FIRST(head2); \
443 #define LIST_HEAD(name, type) \
445 struct type *lh_first; /* first element */ \
448 #define LIST_CLASS_HEAD(name, type) \
450 class type *lh_first; /* first element */ \
453 #define LIST_HEAD_INITIALIZER(head) \
456 #define LIST_ENTRY(type) \
458 struct type *le_next; /* next element */ \
459 struct type **le_prev; /* address of previous next element */ \
462 #define LIST_CLASS_ENTRY(type) \
464 class type *le_next; /* next element */ \
465 class type **le_prev; /* address of previous next element */ \
472 #if (defined(_KERNEL) && defined(INVARIANTS))
474 * QMD_LIST_CHECK_HEAD(LIST_HEAD *head, LIST_ENTRY NAME)
476 * If the list is non-empty, validates that the first element of the list
477 * points back at 'head.'
479 #define QMD_LIST_CHECK_HEAD(head, field) do { \
480 if (LIST_FIRST((head)) != NULL && \
481 LIST_FIRST((head))->field.le_prev != \
482 &LIST_FIRST((head))) \
483 panic("Bad list head %p first->prev != head", (head)); \
487 * QMD_LIST_CHECK_NEXT(TYPE *elm, LIST_ENTRY NAME)
489 * If an element follows 'elm' in the list, validates that the next element
490 * points back at 'elm.'
492 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
493 if (LIST_NEXT((elm), field) != NULL && \
494 LIST_NEXT((elm), field)->field.le_prev != \
495 &((elm)->field.le_next)) \
496 panic("Bad link elm %p next->prev != elm", (elm)); \
500 * QMD_LIST_CHECK_PREV(TYPE *elm, LIST_ENTRY NAME)
502 * Validates that the previous element (or head of the list) points to 'elm.'
504 #define QMD_LIST_CHECK_PREV(elm, field) do { \
505 if (*(elm)->field.le_prev != (elm)) \
506 panic("Bad link elm %p prev->next != elm", (elm)); \
509 #define QMD_LIST_CHECK_HEAD(head, field)
510 #define QMD_LIST_CHECK_NEXT(elm, field)
511 #define QMD_LIST_CHECK_PREV(elm, field)
512 #endif /* (_KERNEL && INVARIANTS) */
514 #define LIST_CONCAT(head1, head2, type, field) do { \
515 QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1); \
516 if (curelm == NULL) { \
517 if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) { \
518 LIST_FIRST(head2)->field.le_prev = \
519 &LIST_FIRST((head1)); \
522 } else if (LIST_FIRST(head2) != NULL) { \
523 while (LIST_NEXT(curelm, field) != NULL) \
524 curelm = LIST_NEXT(curelm, field); \
525 LIST_NEXT(curelm, field) = LIST_FIRST(head2); \
526 LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
531 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
533 #define LIST_FIRST(head) ((head)->lh_first)
535 #define LIST_FOREACH(var, head, field) \
536 for ((var) = LIST_FIRST((head)); \
538 (var) = LIST_NEXT((var), field))
540 #define LIST_FOREACH_FROM(var, head, field) \
541 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
543 (var) = LIST_NEXT((var), field))
545 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
546 for ((var) = LIST_FIRST((head)); \
547 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
550 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
551 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
552 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
555 #define LIST_INIT(head) do { \
556 LIST_FIRST((head)) = NULL; \
559 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
560 QMD_LIST_CHECK_NEXT(listelm, field); \
561 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
562 LIST_NEXT((listelm), field)->field.le_prev = \
563 &LIST_NEXT((elm), field); \
564 LIST_NEXT((listelm), field) = (elm); \
565 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
568 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
569 QMD_LIST_CHECK_PREV(listelm, field); \
570 (elm)->field.le_prev = (listelm)->field.le_prev; \
571 LIST_NEXT((elm), field) = (listelm); \
572 *(listelm)->field.le_prev = (elm); \
573 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
576 #define LIST_INSERT_HEAD(head, elm, field) do { \
577 QMD_LIST_CHECK_HEAD((head), field); \
578 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
579 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
580 LIST_FIRST((head)) = (elm); \
581 (elm)->field.le_prev = &LIST_FIRST((head)); \
584 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
586 #define LIST_PREV(elm, head, type, field) \
587 ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL : \
588 __containerof((elm)->field.le_prev, \
589 QUEUE_TYPEOF(type), field.le_next))
591 #define LIST_REMOVE(elm, field) do { \
592 QMD_SAVELINK(oldnext, (elm)->field.le_next); \
593 QMD_SAVELINK(oldprev, (elm)->field.le_prev); \
594 QMD_LIST_CHECK_NEXT(elm, field); \
595 QMD_LIST_CHECK_PREV(elm, field); \
596 if (LIST_NEXT((elm), field) != NULL) \
597 LIST_NEXT((elm), field)->field.le_prev = \
598 (elm)->field.le_prev; \
599 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
604 #define LIST_SWAP(head1, head2, type, field) do { \
605 QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1); \
606 LIST_FIRST((head1)) = LIST_FIRST((head2)); \
607 LIST_FIRST((head2)) = swap_tmp; \
608 if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
609 swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
610 if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
611 swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
615 * Tail queue declarations.
617 #define TAILQ_HEAD(name, type) \
619 struct type *tqh_first; /* first element */ \
620 struct type **tqh_last; /* addr of last next element */ \
624 #define TAILQ_CLASS_HEAD(name, type) \
626 class type *tqh_first; /* first element */ \
627 class type **tqh_last; /* addr of last next element */ \
631 #define TAILQ_HEAD_INITIALIZER(head) \
632 { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
634 #define TAILQ_ENTRY(type) \
636 struct type *tqe_next; /* next element */ \
637 struct type **tqe_prev; /* address of previous next element */ \
641 #define TAILQ_CLASS_ENTRY(type) \
643 class type *tqe_next; /* next element */ \
644 class type **tqe_prev; /* address of previous next element */ \
649 * Tail queue functions.
651 #if (defined(_KERNEL) && defined(INVARIANTS))
653 * QMD_TAILQ_CHECK_HEAD(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
655 * If the tailq is non-empty, validates that the first element of the tailq
656 * points back at 'head.'
658 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
659 if (!TAILQ_EMPTY(head) && \
660 TAILQ_FIRST((head))->field.tqe_prev != \
661 &TAILQ_FIRST((head))) \
662 panic("Bad tailq head %p first->prev != head", (head)); \
666 * QMD_TAILQ_CHECK_TAIL(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
668 * Validates that the tail of the tailq is a pointer to pointer to NULL.
670 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
671 if (*(head)->tqh_last != NULL) \
672 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
676 * QMD_TAILQ_CHECK_NEXT(TYPE *elm, TAILQ_ENTRY NAME)
678 * If an element follows 'elm' in the tailq, validates that the next element
679 * points back at 'elm.'
681 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
682 if (TAILQ_NEXT((elm), field) != NULL && \
683 TAILQ_NEXT((elm), field)->field.tqe_prev != \
684 &((elm)->field.tqe_next)) \
685 panic("Bad link elm %p next->prev != elm", (elm)); \
689 * QMD_TAILQ_CHECK_PREV(TYPE *elm, TAILQ_ENTRY NAME)
691 * Validates that the previous element (or head of the tailq) points to 'elm.'
693 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
694 if (*(elm)->field.tqe_prev != (elm)) \
695 panic("Bad link elm %p prev->next != elm", (elm)); \
698 #define QMD_TAILQ_CHECK_HEAD(head, field)
699 #define QMD_TAILQ_CHECK_TAIL(head, headname)
700 #define QMD_TAILQ_CHECK_NEXT(elm, field)
701 #define QMD_TAILQ_CHECK_PREV(elm, field)
702 #endif /* (_KERNEL && INVARIANTS) */
704 #define TAILQ_CONCAT(head1, head2, field) do { \
705 if (!TAILQ_EMPTY(head2)) { \
706 *(head1)->tqh_last = (head2)->tqh_first; \
707 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
708 (head1)->tqh_last = (head2)->tqh_last; \
709 TAILQ_INIT((head2)); \
710 QMD_TRACE_HEAD(head1); \
711 QMD_TRACE_HEAD(head2); \
715 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
717 #define TAILQ_FIRST(head) ((head)->tqh_first)
719 #define TAILQ_FOREACH(var, head, field) \
720 for ((var) = TAILQ_FIRST((head)); \
722 (var) = TAILQ_NEXT((var), field))
724 #define TAILQ_FOREACH_FROM(var, head, field) \
725 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
727 (var) = TAILQ_NEXT((var), field))
729 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
730 for ((var) = TAILQ_FIRST((head)); \
731 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
734 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
735 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
736 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
739 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
740 for ((var) = TAILQ_LAST((head), headname); \
742 (var) = TAILQ_PREV((var), headname, field))
744 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field) \
745 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
747 (var) = TAILQ_PREV((var), headname, field))
749 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
750 for ((var) = TAILQ_LAST((head), headname); \
751 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
754 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
755 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
756 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
759 #define TAILQ_INIT(head) do { \
760 TAILQ_FIRST((head)) = NULL; \
761 (head)->tqh_last = &TAILQ_FIRST((head)); \
762 QMD_TRACE_HEAD(head); \
765 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
766 QMD_TAILQ_CHECK_NEXT(listelm, field); \
767 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
768 TAILQ_NEXT((elm), field)->field.tqe_prev = \
769 &TAILQ_NEXT((elm), field); \
771 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
772 QMD_TRACE_HEAD(head); \
774 TAILQ_NEXT((listelm), field) = (elm); \
775 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
776 QMD_TRACE_ELEM(&(elm)->field); \
777 QMD_TRACE_ELEM(&(listelm)->field); \
780 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
781 QMD_TAILQ_CHECK_PREV(listelm, field); \
782 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
783 TAILQ_NEXT((elm), field) = (listelm); \
784 *(listelm)->field.tqe_prev = (elm); \
785 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
786 QMD_TRACE_ELEM(&(elm)->field); \
787 QMD_TRACE_ELEM(&(listelm)->field); \
790 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
791 QMD_TAILQ_CHECK_HEAD(head, field); \
792 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
793 TAILQ_FIRST((head))->field.tqe_prev = \
794 &TAILQ_NEXT((elm), field); \
796 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
797 TAILQ_FIRST((head)) = (elm); \
798 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
799 QMD_TRACE_HEAD(head); \
800 QMD_TRACE_ELEM(&(elm)->field); \
803 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
804 QMD_TAILQ_CHECK_TAIL(head, field); \
805 TAILQ_NEXT((elm), field) = NULL; \
806 (elm)->field.tqe_prev = (head)->tqh_last; \
807 *(head)->tqh_last = (elm); \
808 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
809 QMD_TRACE_HEAD(head); \
810 QMD_TRACE_ELEM(&(elm)->field); \
813 #define TAILQ_LAST(head, headname) \
814 (*(((struct headname *)((head)->tqh_last))->tqh_last))
817 * The FAST function is fast in that it causes no data access other
818 * then the access to the head. The standard LAST function above
819 * will cause a data access of both the element you want and
820 * the previous element. FAST is very useful for instances when
821 * you may want to prefetch the last data element.
823 #define TAILQ_LAST_FAST(head, type, field) \
824 (TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last, QUEUE_TYPEOF(type), field.tqe_next))
826 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
828 #define TAILQ_PREV(elm, headname, field) \
829 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
831 #define TAILQ_PREV_FAST(elm, head, type, field) \
832 ((elm)->field.tqe_prev == &(head)->tqh_first ? NULL : \
833 __containerof((elm)->field.tqe_prev, QUEUE_TYPEOF(type), field.tqe_next))
835 #define TAILQ_REMOVE(head, elm, field) do { \
836 QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
837 QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
838 QMD_TAILQ_CHECK_NEXT(elm, field); \
839 QMD_TAILQ_CHECK_PREV(elm, field); \
840 if ((TAILQ_NEXT((elm), field)) != NULL) \
841 TAILQ_NEXT((elm), field)->field.tqe_prev = \
842 (elm)->field.tqe_prev; \
844 (head)->tqh_last = (elm)->field.tqe_prev; \
845 QMD_TRACE_HEAD(head); \
847 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
850 QMD_TRACE_ELEM(&(elm)->field); \
853 #define TAILQ_SWAP(head1, head2, type, field) do { \
854 QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first; \
855 QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last; \
856 (head1)->tqh_first = (head2)->tqh_first; \
857 (head1)->tqh_last = (head2)->tqh_last; \
858 (head2)->tqh_first = swap_first; \
859 (head2)->tqh_last = swap_last; \
860 if ((swap_first = (head1)->tqh_first) != NULL) \
861 swap_first->field.tqe_prev = &(head1)->tqh_first; \
863 (head1)->tqh_last = &(head1)->tqh_first; \
864 if ((swap_first = (head2)->tqh_first) != NULL) \
865 swap_first->field.tqe_prev = &(head2)->tqh_first; \
867 (head2)->tqh_last = &(head2)->tqh_first; \
870 #endif /* !_SYS_QUEUE_H_ */