1 /* SPDX-License-Identifier: BSD-3-Clause
3 * Copyright (c) 1991, 1993
4 * The Regents of the University of California. All rights reserved.
11 * This file defines four types of data structures: singly-linked lists,
12 * singly-linked tail queues, lists and tail queues.
14 * A singly-linked list is headed by a single forward pointer. The elements
15 * are singly linked for minimum space and pointer manipulation overhead at
16 * the expense of O(n) removal for arbitrary elements. New elements can be
17 * added to the list after an existing element or at the head of the list.
18 * Elements being removed from the head of the list should use the explicit
19 * macro for this purpose for optimum efficiency. A singly-linked list may
20 * only be traversed in the forward direction. Singly-linked lists are ideal
21 * for applications with large datasets and few or no removals or for
22 * implementing a LIFO queue.
24 * A singly-linked tail queue is headed by a pair of pointers, one to the
25 * head of the list and the other to the tail of the list. The elements are
26 * singly linked for minimum space and pointer manipulation overhead at the
27 * expense of O(n) removal for arbitrary elements. New elements can be added
28 * to the list after an existing element, at the head of the list, or at the
29 * end of the list. Elements being removed from the head of the tail queue
30 * should use the explicit macro for this purpose for optimum efficiency.
31 * A singly-linked tail queue may only be traversed in the forward direction.
32 * Singly-linked tail queues are ideal for applications with large datasets
33 * and few or no removals or for implementing a FIFO queue.
35 * A list is headed by a single forward pointer (or an array of forward
36 * pointers for a hash table header). The elements are doubly linked
37 * so that an arbitrary element can be removed without a need to
38 * traverse the list. New elements can be added to the list before
39 * or after an existing element or at the head of the list. A list
40 * may be traversed in either direction.
42 * A tail queue is headed by a pair of pointers, one to the head of the
43 * list and the other to the tail of the list. The elements are doubly
44 * linked so that an arbitrary element can be removed without a need to
45 * traverse the list. New elements can be added to the list before or
46 * after an existing element, at the head of the list, or at the end of
47 * the list. A tail queue may be traversed in either direction.
49 * For details on the use of these macros, see the queue(3) manual page.
51 * Below is a summary of implemented functions where:
52 * + means the macro is available
53 * - means the macro is not available
54 * s means the macro is available but is slow (runs in O(n) time)
56 * SLIST LIST STAILQ TAILQ
59 * _HEAD_INITIALIZER + + + +
61 * _CLASS_ENTRY + + + +
70 * _FOREACH_FROM + + + +
71 * _FOREACH_SAFE + + + +
72 * _FOREACH_FROM_SAFE + + + +
73 * _FOREACH_REVERSE - - - +
74 * _FOREACH_REVERSE_FROM - - - +
75 * _FOREACH_REVERSE_SAFE - - - +
76 * _FOREACH_REVERSE_FROM_SAFE - - - +
77 * _INSERT_HEAD + + + +
78 * _INSERT_BEFORE - + - +
79 * _INSERT_AFTER + + + +
80 * _INSERT_TAIL - - + +
82 * _REMOVE_AFTER + - + -
83 * _REMOVE_HEAD + - + -
88 #ifdef QUEUE_MACRO_DEBUG
89 #warn Use QUEUE_MACRO_DEBUG_TRACE and/or QUEUE_MACRO_DEBUG_TRASH
90 #define QUEUE_MACRO_DEBUG_TRACE
91 #define QUEUE_MACRO_DEBUG_TRASH
94 #ifdef QUEUE_MACRO_DEBUG_TRACE
95 /* Store the last 2 places the queue element or head was altered */
97 unsigned long lastline;
98 unsigned long prevline;
100 const char *prevfile;
103 #define TRACEBUF struct qm_trace trace;
104 #define TRACEBUF_INITIALIZER { __LINE__, 0, __FILE__, NULL } ,
106 #define QMD_TRACE_HEAD(head) do { \
107 (head)->trace.prevline = (head)->trace.lastline; \
108 (head)->trace.prevfile = (head)->trace.lastfile; \
109 (head)->trace.lastline = __LINE__; \
110 (head)->trace.lastfile = __FILE__; \
113 #define QMD_TRACE_ELEM(elem) do { \
114 (elem)->trace.prevline = (elem)->trace.lastline; \
115 (elem)->trace.prevfile = (elem)->trace.lastfile; \
116 (elem)->trace.lastline = __LINE__; \
117 (elem)->trace.lastfile = __FILE__; \
120 #else /* !QUEUE_MACRO_DEBUG_TRACE */
121 #define QMD_TRACE_ELEM(elem)
122 #define QMD_TRACE_HEAD(head)
124 #define TRACEBUF_INITIALIZER
125 #endif /* QUEUE_MACRO_DEBUG_TRACE */
127 #ifdef QUEUE_MACRO_DEBUG_TRASH
128 #define QMD_SAVELINK(name, link) void **name = (void *)&(link)
129 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
130 #define QMD_IS_TRASHED(x) ((x) == (void *)(intptr_t)-1)
131 #else /* !QUEUE_MACRO_DEBUG_TRASH */
132 #define QMD_SAVELINK(name, link)
134 #define QMD_IS_TRASHED(x) 0
135 #endif /* QUEUE_MACRO_DEBUG_TRASH */
139 * In C++ there can be structure lists and class lists:
141 #define QUEUE_TYPEOF(type) type
143 #define QUEUE_TYPEOF(type) struct type
147 * Singly-linked List declarations.
149 #define SLIST_HEAD(name, type) \
151 struct type *slh_first; /* first element */ \
154 #define SLIST_CLASS_HEAD(name, type) \
156 class type *slh_first; /* first element */ \
159 #define SLIST_HEAD_INITIALIZER(head) \
162 #define SLIST_ENTRY(type) \
164 struct type *sle_next; /* next element */ \
167 #define SLIST_CLASS_ENTRY(type) \
169 class type *sle_next; /* next element */ \
173 * Singly-linked List functions.
175 #if (defined(_KERNEL) && defined(INVARIANTS))
176 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm) do { \
177 if (*(prevp) != (elm)) \
178 panic("Bad prevptr *(%p) == %p != %p", \
179 (prevp), *(prevp), (elm)); \
182 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm)
185 #define SLIST_CONCAT(head1, head2, type, field) do { \
186 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1); \
187 if (curelm == NULL) { \
188 if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL) \
190 } else if (SLIST_FIRST(head2) != NULL) { \
191 while (SLIST_NEXT(curelm, field) != NULL) \
192 curelm = SLIST_NEXT(curelm, field); \
193 SLIST_NEXT(curelm, field) = SLIST_FIRST(head2); \
198 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
200 #define SLIST_FIRST(head) ((head)->slh_first)
202 #define SLIST_FOREACH(var, head, field) \
203 for ((var) = SLIST_FIRST((head)); \
205 (var) = SLIST_NEXT((var), field))
207 #define SLIST_FOREACH_FROM(var, head, field) \
208 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
210 (var) = SLIST_NEXT((var), field))
212 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
213 for ((var) = SLIST_FIRST((head)); \
214 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
217 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
218 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
219 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
222 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
223 for ((varp) = &SLIST_FIRST((head)); \
224 ((var) = *(varp)) != NULL; \
225 (varp) = &SLIST_NEXT((var), field))
227 #define SLIST_INIT(head) do { \
228 SLIST_FIRST((head)) = NULL; \
231 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
232 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
233 SLIST_NEXT((slistelm), field) = (elm); \
236 #define SLIST_INSERT_HEAD(head, elm, field) do { \
237 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
238 SLIST_FIRST((head)) = (elm); \
241 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
243 #define SLIST_REMOVE(head, elm, type, field) do { \
244 QMD_SAVELINK(oldnext, (elm)->field.sle_next); \
245 if (SLIST_FIRST((head)) == (elm)) { \
246 SLIST_REMOVE_HEAD((head), field); \
249 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head); \
250 while (SLIST_NEXT(curelm, field) != (elm)) \
251 curelm = SLIST_NEXT(curelm, field); \
252 SLIST_REMOVE_AFTER(curelm, field); \
257 #define SLIST_REMOVE_AFTER(elm, field) do { \
258 SLIST_NEXT(elm, field) = \
259 SLIST_NEXT(SLIST_NEXT(elm, field), field); \
262 #define SLIST_REMOVE_HEAD(head, field) do { \
263 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
266 #define SLIST_REMOVE_PREVPTR(prevp, elm, field) do { \
267 QMD_SLIST_CHECK_PREVPTR(prevp, elm); \
268 *(prevp) = SLIST_NEXT(elm, field); \
269 TRASHIT((elm)->field.sle_next); \
272 #define SLIST_SWAP(head1, head2, type) do { \
273 QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1); \
274 SLIST_FIRST(head1) = SLIST_FIRST(head2); \
275 SLIST_FIRST(head2) = swap_first; \
279 * Singly-linked Tail queue declarations.
281 #define STAILQ_HEAD(name, type) \
283 struct type *stqh_first;/* first element */ \
284 struct type **stqh_last;/* addr of last next element */ \
287 #define STAILQ_CLASS_HEAD(name, type) \
289 class type *stqh_first; /* first element */ \
290 class type **stqh_last; /* addr of last next element */ \
293 #define STAILQ_HEAD_INITIALIZER(head) \
294 { NULL, &(head).stqh_first }
296 #define STAILQ_ENTRY(type) \
298 struct type *stqe_next; /* next element */ \
301 #define STAILQ_CLASS_ENTRY(type) \
303 class type *stqe_next; /* next element */ \
307 * Singly-linked Tail queue functions.
309 #define STAILQ_CONCAT(head1, head2) do { \
310 if (!STAILQ_EMPTY((head2))) { \
311 *(head1)->stqh_last = (head2)->stqh_first; \
312 (head1)->stqh_last = (head2)->stqh_last; \
313 STAILQ_INIT((head2)); \
317 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
319 #define STAILQ_FIRST(head) ((head)->stqh_first)
321 #define STAILQ_FOREACH(var, head, field) \
322 for((var) = STAILQ_FIRST((head)); \
324 (var) = STAILQ_NEXT((var), field))
326 #define STAILQ_FOREACH_FROM(var, head, field) \
327 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
329 (var) = STAILQ_NEXT((var), field))
331 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
332 for ((var) = STAILQ_FIRST((head)); \
333 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
336 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
337 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
338 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
341 #define STAILQ_INIT(head) do { \
342 STAILQ_FIRST((head)) = NULL; \
343 (head)->stqh_last = &STAILQ_FIRST((head)); \
346 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
347 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
348 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
349 STAILQ_NEXT((tqelm), field) = (elm); \
352 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
353 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
354 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
355 STAILQ_FIRST((head)) = (elm); \
358 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
359 STAILQ_NEXT((elm), field) = NULL; \
360 *(head)->stqh_last = (elm); \
361 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
364 #define STAILQ_LAST(head, type, field) \
365 (STAILQ_EMPTY((head)) ? NULL : \
366 __containerof((head)->stqh_last, \
367 QUEUE_TYPEOF(type), field.stqe_next))
369 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
371 #define STAILQ_REMOVE(head, elm, type, field) do { \
372 QMD_SAVELINK(oldnext, (elm)->field.stqe_next); \
373 if (STAILQ_FIRST((head)) == (elm)) { \
374 STAILQ_REMOVE_HEAD((head), field); \
377 QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head); \
378 while (STAILQ_NEXT(curelm, field) != (elm)) \
379 curelm = STAILQ_NEXT(curelm, field); \
380 STAILQ_REMOVE_AFTER(head, curelm, field); \
385 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \
386 if ((STAILQ_NEXT(elm, field) = \
387 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
388 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
391 #define STAILQ_REMOVE_HEAD(head, field) do { \
392 if ((STAILQ_FIRST((head)) = \
393 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
394 (head)->stqh_last = &STAILQ_FIRST((head)); \
397 #define STAILQ_SWAP(head1, head2, type) do { \
398 QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1); \
399 QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last; \
400 STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
401 (head1)->stqh_last = (head2)->stqh_last; \
402 STAILQ_FIRST(head2) = swap_first; \
403 (head2)->stqh_last = swap_last; \
404 if (STAILQ_EMPTY(head1)) \
405 (head1)->stqh_last = &STAILQ_FIRST(head1); \
406 if (STAILQ_EMPTY(head2)) \
407 (head2)->stqh_last = &STAILQ_FIRST(head2); \
414 #define LIST_HEAD(name, type) \
416 struct type *lh_first; /* first element */ \
419 #define LIST_CLASS_HEAD(name, type) \
421 class type *lh_first; /* first element */ \
424 #define LIST_HEAD_INITIALIZER(head) \
427 #define LIST_ENTRY(type) \
429 struct type *le_next; /* next element */ \
430 struct type **le_prev; /* address of previous next element */ \
433 #define LIST_CLASS_ENTRY(type) \
435 class type *le_next; /* next element */ \
436 class type **le_prev; /* address of previous next element */ \
443 #if (defined(_KERNEL) && defined(INVARIANTS))
445 * QMD_LIST_CHECK_HEAD(LIST_HEAD *head, LIST_ENTRY NAME)
447 * If the list is non-empty, validates that the first element of the list
448 * points back at 'head.'
450 #define QMD_LIST_CHECK_HEAD(head, field) do { \
451 if (LIST_FIRST((head)) != NULL && \
452 LIST_FIRST((head))->field.le_prev != \
453 &LIST_FIRST((head))) \
454 panic("Bad list head %p first->prev != head", (head)); \
458 * QMD_LIST_CHECK_NEXT(TYPE *elm, LIST_ENTRY NAME)
460 * If an element follows 'elm' in the list, validates that the next element
461 * points back at 'elm.'
463 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
464 if (LIST_NEXT((elm), field) != NULL && \
465 LIST_NEXT((elm), field)->field.le_prev != \
466 &((elm)->field.le_next)) \
467 panic("Bad link elm %p next->prev != elm", (elm)); \
471 * QMD_LIST_CHECK_PREV(TYPE *elm, LIST_ENTRY NAME)
473 * Validates that the previous element (or head of the list) points to 'elm.'
475 #define QMD_LIST_CHECK_PREV(elm, field) do { \
476 if (*(elm)->field.le_prev != (elm)) \
477 panic("Bad link elm %p prev->next != elm", (elm)); \
480 #define QMD_LIST_CHECK_HEAD(head, field)
481 #define QMD_LIST_CHECK_NEXT(elm, field)
482 #define QMD_LIST_CHECK_PREV(elm, field)
483 #endif /* (_KERNEL && INVARIANTS) */
485 #define LIST_CONCAT(head1, head2, type, field) do { \
486 QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1); \
487 if (curelm == NULL) { \
488 if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) { \
489 LIST_FIRST(head2)->field.le_prev = \
490 &LIST_FIRST((head1)); \
493 } else if (LIST_FIRST(head2) != NULL) { \
494 while (LIST_NEXT(curelm, field) != NULL) \
495 curelm = LIST_NEXT(curelm, field); \
496 LIST_NEXT(curelm, field) = LIST_FIRST(head2); \
497 LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
502 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
504 #define LIST_FIRST(head) ((head)->lh_first)
506 #define LIST_FOREACH(var, head, field) \
507 for ((var) = LIST_FIRST((head)); \
509 (var) = LIST_NEXT((var), field))
511 #define LIST_FOREACH_FROM(var, head, field) \
512 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
514 (var) = LIST_NEXT((var), field))
516 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
517 for ((var) = LIST_FIRST((head)); \
518 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
521 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
522 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
523 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
526 #define LIST_INIT(head) do { \
527 LIST_FIRST((head)) = NULL; \
530 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
531 QMD_LIST_CHECK_NEXT(listelm, field); \
532 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
533 LIST_NEXT((listelm), field)->field.le_prev = \
534 &LIST_NEXT((elm), field); \
535 LIST_NEXT((listelm), field) = (elm); \
536 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
539 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
540 QMD_LIST_CHECK_PREV(listelm, field); \
541 (elm)->field.le_prev = (listelm)->field.le_prev; \
542 LIST_NEXT((elm), field) = (listelm); \
543 *(listelm)->field.le_prev = (elm); \
544 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
547 #define LIST_INSERT_HEAD(head, elm, field) do { \
548 QMD_LIST_CHECK_HEAD((head), field); \
549 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
550 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
551 LIST_FIRST((head)) = (elm); \
552 (elm)->field.le_prev = &LIST_FIRST((head)); \
555 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
557 #define LIST_PREV(elm, head, type, field) \
558 ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL : \
559 __containerof((elm)->field.le_prev, \
560 QUEUE_TYPEOF(type), field.le_next))
562 #define LIST_REMOVE(elm, field) do { \
563 QMD_SAVELINK(oldnext, (elm)->field.le_next); \
564 QMD_SAVELINK(oldprev, (elm)->field.le_prev); \
565 QMD_LIST_CHECK_NEXT(elm, field); \
566 QMD_LIST_CHECK_PREV(elm, field); \
567 if (LIST_NEXT((elm), field) != NULL) \
568 LIST_NEXT((elm), field)->field.le_prev = \
569 (elm)->field.le_prev; \
570 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
575 #define LIST_SWAP(head1, head2, type, field) do { \
576 QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1); \
577 LIST_FIRST((head1)) = LIST_FIRST((head2)); \
578 LIST_FIRST((head2)) = swap_tmp; \
579 if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
580 swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
581 if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
582 swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
586 * Tail queue declarations.
588 #define TAILQ_HEAD(name, type) \
590 struct type *tqh_first; /* first element */ \
591 struct type **tqh_last; /* addr of last next element */ \
595 #define TAILQ_CLASS_HEAD(name, type) \
597 class type *tqh_first; /* first element */ \
598 class type **tqh_last; /* addr of last next element */ \
602 #define TAILQ_HEAD_INITIALIZER(head) \
603 { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
605 #define TAILQ_ENTRY(type) \
607 struct type *tqe_next; /* next element */ \
608 struct type **tqe_prev; /* address of previous next element */ \
612 #define TAILQ_CLASS_ENTRY(type) \
614 class type *tqe_next; /* next element */ \
615 class type **tqe_prev; /* address of previous next element */ \
620 * Tail queue functions.
622 #if (defined(_KERNEL) && defined(INVARIANTS))
624 * QMD_TAILQ_CHECK_HEAD(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
626 * If the tailq is non-empty, validates that the first element of the tailq
627 * points back at 'head.'
629 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
630 if (!TAILQ_EMPTY(head) && \
631 TAILQ_FIRST((head))->field.tqe_prev != \
632 &TAILQ_FIRST((head))) \
633 panic("Bad tailq head %p first->prev != head", (head)); \
637 * QMD_TAILQ_CHECK_TAIL(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
639 * Validates that the tail of the tailq is a pointer to pointer to NULL.
641 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
642 if (*(head)->tqh_last != NULL) \
643 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
647 * QMD_TAILQ_CHECK_NEXT(TYPE *elm, TAILQ_ENTRY NAME)
649 * If an element follows 'elm' in the tailq, validates that the next element
650 * points back at 'elm.'
652 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
653 if (TAILQ_NEXT((elm), field) != NULL && \
654 TAILQ_NEXT((elm), field)->field.tqe_prev != \
655 &((elm)->field.tqe_next)) \
656 panic("Bad link elm %p next->prev != elm", (elm)); \
660 * QMD_TAILQ_CHECK_PREV(TYPE *elm, TAILQ_ENTRY NAME)
662 * Validates that the previous element (or head of the tailq) points to 'elm.'
664 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
665 if (*(elm)->field.tqe_prev != (elm)) \
666 panic("Bad link elm %p prev->next != elm", (elm)); \
669 #define QMD_TAILQ_CHECK_HEAD(head, field)
670 #define QMD_TAILQ_CHECK_TAIL(head, headname)
671 #define QMD_TAILQ_CHECK_NEXT(elm, field)
672 #define QMD_TAILQ_CHECK_PREV(elm, field)
673 #endif /* (_KERNEL && INVARIANTS) */
675 #define TAILQ_CONCAT(head1, head2, field) do { \
676 if (!TAILQ_EMPTY(head2)) { \
677 *(head1)->tqh_last = (head2)->tqh_first; \
678 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
679 (head1)->tqh_last = (head2)->tqh_last; \
680 TAILQ_INIT((head2)); \
681 QMD_TRACE_HEAD(head1); \
682 QMD_TRACE_HEAD(head2); \
686 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
688 #define TAILQ_FIRST(head) ((head)->tqh_first)
690 #define TAILQ_FOREACH(var, head, field) \
691 for ((var) = TAILQ_FIRST((head)); \
693 (var) = TAILQ_NEXT((var), field))
695 #define TAILQ_FOREACH_FROM(var, head, field) \
696 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
698 (var) = TAILQ_NEXT((var), field))
700 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
701 for ((var) = TAILQ_FIRST((head)); \
702 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
705 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
706 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
707 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
710 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
711 for ((var) = TAILQ_LAST((head), headname); \
713 (var) = TAILQ_PREV((var), headname, field))
715 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field) \
716 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
718 (var) = TAILQ_PREV((var), headname, field))
720 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
721 for ((var) = TAILQ_LAST((head), headname); \
722 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
725 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
726 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
727 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
730 #define TAILQ_INIT(head) do { \
731 TAILQ_FIRST((head)) = NULL; \
732 (head)->tqh_last = &TAILQ_FIRST((head)); \
733 QMD_TRACE_HEAD(head); \
736 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
737 QMD_TAILQ_CHECK_NEXT(listelm, field); \
738 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
739 TAILQ_NEXT((elm), field)->field.tqe_prev = \
740 &TAILQ_NEXT((elm), field); \
742 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
743 QMD_TRACE_HEAD(head); \
745 TAILQ_NEXT((listelm), field) = (elm); \
746 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
747 QMD_TRACE_ELEM(&(elm)->field); \
748 QMD_TRACE_ELEM(&(listelm)->field); \
751 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
752 QMD_TAILQ_CHECK_PREV(listelm, field); \
753 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
754 TAILQ_NEXT((elm), field) = (listelm); \
755 *(listelm)->field.tqe_prev = (elm); \
756 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
757 QMD_TRACE_ELEM(&(elm)->field); \
758 QMD_TRACE_ELEM(&(listelm)->field); \
761 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
762 QMD_TAILQ_CHECK_HEAD(head, field); \
763 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
764 TAILQ_FIRST((head))->field.tqe_prev = \
765 &TAILQ_NEXT((elm), field); \
767 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
768 TAILQ_FIRST((head)) = (elm); \
769 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
770 QMD_TRACE_HEAD(head); \
771 QMD_TRACE_ELEM(&(elm)->field); \
774 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
775 QMD_TAILQ_CHECK_TAIL(head, field); \
776 TAILQ_NEXT((elm), field) = NULL; \
777 (elm)->field.tqe_prev = (head)->tqh_last; \
778 *(head)->tqh_last = (elm); \
779 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
780 QMD_TRACE_HEAD(head); \
781 QMD_TRACE_ELEM(&(elm)->field); \
784 #define TAILQ_LAST(head, headname) \
785 (*(((struct headname *)((head)->tqh_last))->tqh_last))
788 * The FAST function is fast in that it causes no data access other
789 * then the access to the head. The standard LAST function above
790 * will cause a data access of both the element you want and
791 * the previous element. FAST is very useful for instances when
792 * you may want to prefetch the last data element.
794 #define TAILQ_LAST_FAST(head, type, field) \
795 (TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last, QUEUE_TYPEOF(type), field.tqe_next))
797 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
799 #define TAILQ_PREV(elm, headname, field) \
800 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
802 #define TAILQ_PREV_FAST(elm, head, type, field) \
803 ((elm)->field.tqe_prev == &(head)->tqh_first ? NULL : \
804 __containerof((elm)->field.tqe_prev, QUEUE_TYPEOF(type), field.tqe_next))
806 #define TAILQ_REMOVE(head, elm, field) do { \
807 QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
808 QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
809 QMD_TAILQ_CHECK_NEXT(elm, field); \
810 QMD_TAILQ_CHECK_PREV(elm, field); \
811 if ((TAILQ_NEXT((elm), field)) != NULL) \
812 TAILQ_NEXT((elm), field)->field.tqe_prev = \
813 (elm)->field.tqe_prev; \
815 (head)->tqh_last = (elm)->field.tqe_prev; \
816 QMD_TRACE_HEAD(head); \
818 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
821 QMD_TRACE_ELEM(&(elm)->field); \
824 #define TAILQ_SWAP(head1, head2, type, field) do { \
825 QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first; \
826 QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last; \
827 (head1)->tqh_first = (head2)->tqh_first; \
828 (head1)->tqh_last = (head2)->tqh_last; \
829 (head2)->tqh_first = swap_first; \
830 (head2)->tqh_last = swap_last; \
831 if ((swap_first = (head1)->tqh_first) != NULL) \
832 swap_first->field.tqe_prev = &(head1)->tqh_first; \
834 (head1)->tqh_last = &(head1)->tqh_first; \
835 if ((swap_first = (head2)->tqh_first) != NULL) \
836 swap_first->field.tqe_prev = &(head2)->tqh_first; \
838 (head2)->tqh_last = &(head2)->tqh_first; \
841 #endif /* !_SYS_QUEUE_H_ */