2 * Copyright (c) 1991, 1993
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29 * @(#)queue.h 8.5 (Berkeley) 8/20/94
40 #include "ext4_config.h"
43 * This file defines four types of data structures: singly-linked lists,
44 * singly-linked tail queues, lists and tail queues.
46 * A singly-linked list is headed by a single forward pointer. The elements
47 * are singly linked for minimum space and pointer manipulation overhead at
48 * the expense of O(n) removal for arbitrary elements. New elements can be
49 * added to the list after an existing element or at the head of the list.
50 * Elements being removed from the head of the list should use the explicit
51 * macro for this purpose for optimum efficiency. A singly-linked list may
52 * only be traversed in the forward direction. Singly-linked lists are ideal
53 * for applications with large datasets and few or no removals or for
54 * implementing a LIFO queue.
56 * A singly-linked tail queue is headed by a pair of pointers, one to the
57 * head of the list and the other to the tail of the list. The elements are
58 * singly linked for minimum space and pointer manipulation overhead at the
59 * expense of O(n) removal for arbitrary elements. New elements can be added
60 * to the list after an existing element, at the head of the list, or at the
61 * end of the list. Elements being removed from the head of the tail queue
62 * should use the explicit macro for this purpose for optimum efficiency.
63 * A singly-linked tail queue may only be traversed in the forward direction.
64 * Singly-linked tail queues are ideal for applications with large datasets
65 * and few or no removals or for implementing a FIFO queue.
67 * A list is headed by a single forward pointer (or an array of forward
68 * pointers for a hash table header). The elements are doubly linked
69 * so that an arbitrary element can be removed without a need to
70 * traverse the list. New elements can be added to the list before
71 * or after an existing element or at the head of the list. A list
72 * may be traversed in either direction.
74 * A tail queue is headed by a pair of pointers, one to the head of the
75 * list and the other to the tail of the list. The elements are doubly
76 * linked so that an arbitrary element can be removed without a need to
77 * traverse the list. New elements can be added to the list before or
78 * after an existing element, at the head of the list, or at the end of
79 * the list. A tail queue may be traversed in either direction.
81 * For details on the use of these macros, see the queue(3) manual page.
84 * SLIST LIST STAILQ TAILQ
86 * _HEAD_INITIALIZER + + + +
95 * _FOREACH_FROM + + + +
96 * _FOREACH_SAFE + + + +
97 * _FOREACH_FROM_SAFE + + + +
98 * _FOREACH_REVERSE - - - +
99 * _FOREACH_REVERSE_FROM - - - +
100 * _FOREACH_REVERSE_SAFE - - - +
101 * _FOREACH_REVERSE_FROM_SAFE - - - +
102 * _INSERT_HEAD + + + +
103 * _INSERT_BEFORE - + - +
104 * _INSERT_AFTER + + + +
105 * _INSERT_TAIL - - + +
107 * _REMOVE_AFTER + - + -
108 * _REMOVE_HEAD + - + -
113 #ifdef QUEUE_MACRO_DEBUG
114 /* Store the last 2 places the queue element or head was altered */
116 unsigned long lastline;
117 unsigned long prevline;
118 const char *lastfile;
119 const char *prevfile;
122 #define TRACEBUF struct qm_trace trace;
123 #define TRACEBUF_INITIALIZER { __LINE__, 0, __FILE__, NULL } ,
124 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
125 #define QMD_SAVELINK(name, link) void **name = (void *)&(link)
127 #define QMD_TRACE_HEAD(head) do { \
128 (head)->trace.prevline = (head)->trace.lastline; \
129 (head)->trace.prevfile = (head)->trace.lastfile; \
130 (head)->trace.lastline = __LINE__; \
131 (head)->trace.lastfile = __FILE__; \
134 #define QMD_TRACE_ELEM(elem) do { \
135 (elem)->trace.prevline = (elem)->trace.lastline; \
136 (elem)->trace.prevfile = (elem)->trace.lastfile; \
137 (elem)->trace.lastline = __LINE__; \
138 (elem)->trace.lastfile = __FILE__; \
142 #define QMD_TRACE_ELEM(elem)
143 #define QMD_TRACE_HEAD(head)
144 #define QMD_SAVELINK(name, link)
146 #define TRACEBUF_INITIALIZER
148 #endif /* QUEUE_MACRO_DEBUG */
151 * Singly-linked List declarations.
153 #define SLIST_HEAD(name, type) \
155 struct type *slh_first; /* first element */ \
158 #define SLIST_HEAD_INITIALIZER(head) \
161 #define SLIST_ENTRY(type) \
163 struct type *sle_next; /* next element */ \
167 * Singly-linked List functions.
169 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
171 #define SLIST_FIRST(head) ((head)->slh_first)
173 #define SLIST_FOREACH(var, head, field) \
174 for ((var) = SLIST_FIRST((head)); \
176 (var) = SLIST_NEXT((var), field))
178 #define SLIST_FOREACH_FROM(var, head, field) \
179 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
181 (var) = SLIST_NEXT((var), field))
183 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
184 for ((var) = SLIST_FIRST((head)); \
185 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
188 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
189 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
190 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
193 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
194 for ((varp) = &SLIST_FIRST((head)); \
195 ((var) = *(varp)) != NULL; \
196 (varp) = &SLIST_NEXT((var), field))
198 #define SLIST_INIT(head) do { \
199 SLIST_FIRST((head)) = NULL; \
202 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
203 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
204 SLIST_NEXT((slistelm), field) = (elm); \
207 #define SLIST_INSERT_HEAD(head, elm, field) do { \
208 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
209 SLIST_FIRST((head)) = (elm); \
212 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
214 #define SLIST_REMOVE(head, elm, type, field) do { \
215 QMD_SAVELINK(oldnext, (elm)->field.sle_next); \
216 if (SLIST_FIRST((head)) == (elm)) { \
217 SLIST_REMOVE_HEAD((head), field); \
220 struct type *curelm = SLIST_FIRST((head)); \
221 while (SLIST_NEXT(curelm, field) != (elm)) \
222 curelm = SLIST_NEXT(curelm, field); \
223 SLIST_REMOVE_AFTER(curelm, field); \
228 #define SLIST_REMOVE_AFTER(elm, field) do { \
229 SLIST_NEXT(elm, field) = \
230 SLIST_NEXT(SLIST_NEXT(elm, field), field); \
233 #define SLIST_REMOVE_HEAD(head, field) do { \
234 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
237 #define SLIST_SWAP(head1, head2, type) do { \
238 struct type *swap_first = SLIST_FIRST(head1); \
239 SLIST_FIRST(head1) = SLIST_FIRST(head2); \
240 SLIST_FIRST(head2) = swap_first; \
244 * Singly-linked Tail queue declarations.
246 #define STAILQ_HEAD(name, type) \
248 struct type *stqh_first;/* first element */ \
249 struct type **stqh_last;/* addr of last next element */ \
252 #define STAILQ_HEAD_INITIALIZER(head) \
253 { NULL, &(head).stqh_first }
255 #define STAILQ_ENTRY(type) \
257 struct type *stqe_next; /* next element */ \
261 * Singly-linked Tail queue functions.
263 #define STAILQ_CONCAT(head1, head2) do { \
264 if (!STAILQ_EMPTY((head2))) { \
265 *(head1)->stqh_last = (head2)->stqh_first; \
266 (head1)->stqh_last = (head2)->stqh_last; \
267 STAILQ_INIT((head2)); \
271 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
273 #define STAILQ_FIRST(head) ((head)->stqh_first)
275 #define STAILQ_FOREACH(var, head, field) \
276 for((var) = STAILQ_FIRST((head)); \
278 (var) = STAILQ_NEXT((var), field))
280 #define STAILQ_FOREACH_FROM(var, head, field) \
281 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
283 (var) = STAILQ_NEXT((var), field))
285 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
286 for ((var) = STAILQ_FIRST((head)); \
287 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
290 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
291 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
292 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
295 #define STAILQ_INIT(head) do { \
296 STAILQ_FIRST((head)) = NULL; \
297 (head)->stqh_last = &STAILQ_FIRST((head)); \
300 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
301 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
302 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
303 STAILQ_NEXT((tqelm), field) = (elm); \
306 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
307 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
308 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
309 STAILQ_FIRST((head)) = (elm); \
312 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
313 STAILQ_NEXT((elm), field) = NULL; \
314 *(head)->stqh_last = (elm); \
315 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
318 #define STAILQ_LAST(head, type, field) \
319 (STAILQ_EMPTY((head)) ? NULL : \
320 __containerof((head)->stqh_last, struct type, field.stqe_next))
322 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
324 #define STAILQ_REMOVE(head, elm, type, field) do { \
325 QMD_SAVELINK(oldnext, (elm)->field.stqe_next); \
326 if (STAILQ_FIRST((head)) == (elm)) { \
327 STAILQ_REMOVE_HEAD((head), field); \
330 struct type *curelm = STAILQ_FIRST((head)); \
331 while (STAILQ_NEXT(curelm, field) != (elm)) \
332 curelm = STAILQ_NEXT(curelm, field); \
333 STAILQ_REMOVE_AFTER(head, curelm, field); \
338 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \
339 if ((STAILQ_NEXT(elm, field) = \
340 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
341 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
344 #define STAILQ_REMOVE_HEAD(head, field) do { \
345 if ((STAILQ_FIRST((head)) = \
346 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
347 (head)->stqh_last = &STAILQ_FIRST((head)); \
350 #define STAILQ_SWAP(head1, head2, type) do { \
351 struct type *swap_first = STAILQ_FIRST(head1); \
352 struct type **swap_last = (head1)->stqh_last; \
353 STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
354 (head1)->stqh_last = (head2)->stqh_last; \
355 STAILQ_FIRST(head2) = swap_first; \
356 (head2)->stqh_last = swap_last; \
357 if (STAILQ_EMPTY(head1)) \
358 (head1)->stqh_last = &STAILQ_FIRST(head1); \
359 if (STAILQ_EMPTY(head2)) \
360 (head2)->stqh_last = &STAILQ_FIRST(head2); \
367 #define LIST_HEAD(name, type) \
369 struct type *lh_first; /* first element */ \
372 #define LIST_HEAD_INITIALIZER(head) \
375 #define LIST_ENTRY(type) \
377 struct type *le_next; /* next element */ \
378 struct type **le_prev; /* address of previous next element */ \
385 #if (defined(_KERNEL) && defined(INVARIANTS))
386 #define QMD_LIST_CHECK_HEAD(head, field) do { \
387 if (LIST_FIRST((head)) != NULL && \
388 LIST_FIRST((head))->field.le_prev != \
389 &LIST_FIRST((head))) \
390 panic("Bad list head %p first->prev != head", (head)); \
393 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
394 if (LIST_NEXT((elm), field) != NULL && \
395 LIST_NEXT((elm), field)->field.le_prev != \
396 &((elm)->field.le_next)) \
397 panic("Bad link elm %p next->prev != elm", (elm)); \
400 #define QMD_LIST_CHECK_PREV(elm, field) do { \
401 if (*(elm)->field.le_prev != (elm)) \
402 panic("Bad link elm %p prev->next != elm", (elm)); \
405 #define QMD_LIST_CHECK_HEAD(head, field)
406 #define QMD_LIST_CHECK_NEXT(elm, field)
407 #define QMD_LIST_CHECK_PREV(elm, field)
408 #endif /* (_KERNEL && INVARIANTS) */
410 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
412 #define LIST_FIRST(head) ((head)->lh_first)
414 #define LIST_FOREACH(var, head, field) \
415 for ((var) = LIST_FIRST((head)); \
417 (var) = LIST_NEXT((var), field))
419 #define LIST_FOREACH_FROM(var, head, field) \
420 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
422 (var) = LIST_NEXT((var), field))
424 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
425 for ((var) = LIST_FIRST((head)); \
426 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
429 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
430 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
431 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
434 #define LIST_INIT(head) do { \
435 LIST_FIRST((head)) = NULL; \
438 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
439 QMD_LIST_CHECK_NEXT(listelm, field); \
440 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
441 LIST_NEXT((listelm), field)->field.le_prev = \
442 &LIST_NEXT((elm), field); \
443 LIST_NEXT((listelm), field) = (elm); \
444 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
447 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
448 QMD_LIST_CHECK_PREV(listelm, field); \
449 (elm)->field.le_prev = (listelm)->field.le_prev; \
450 LIST_NEXT((elm), field) = (listelm); \
451 *(listelm)->field.le_prev = (elm); \
452 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
455 #define LIST_INSERT_HEAD(head, elm, field) do { \
456 QMD_LIST_CHECK_HEAD((head), field); \
457 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
458 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
459 LIST_FIRST((head)) = (elm); \
460 (elm)->field.le_prev = &LIST_FIRST((head)); \
463 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
465 #define LIST_PREV(elm, head, type, field) \
466 ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL : \
467 __containerof((elm)->field.le_prev, struct type, field.le_next))
469 #define LIST_REMOVE(elm, field) do { \
470 QMD_SAVELINK(oldnext, (elm)->field.le_next); \
471 QMD_SAVELINK(oldprev, (elm)->field.le_prev); \
472 QMD_LIST_CHECK_NEXT(elm, field); \
473 QMD_LIST_CHECK_PREV(elm, field); \
474 if (LIST_NEXT((elm), field) != NULL) \
475 LIST_NEXT((elm), field)->field.le_prev = \
476 (elm)->field.le_prev; \
477 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
482 #define LIST_SWAP(head1, head2, type, field) do { \
483 struct type *swap_tmp = LIST_FIRST((head1)); \
484 LIST_FIRST((head1)) = LIST_FIRST((head2)); \
485 LIST_FIRST((head2)) = swap_tmp; \
486 if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
487 swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
488 if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
489 swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
493 * Tail queue declarations.
495 #define TAILQ_HEAD(name, type) \
497 struct type *tqh_first; /* first element */ \
498 struct type **tqh_last; /* addr of last next element */ \
502 #define TAILQ_HEAD_INITIALIZER(head) \
503 { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
505 #define TAILQ_ENTRY(type) \
507 struct type *tqe_next; /* next element */ \
508 struct type **tqe_prev; /* address of previous next element */ \
513 * Tail queue functions.
515 #if (defined(_KERNEL) && defined(INVARIANTS))
516 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
517 if (!TAILQ_EMPTY(head) && \
518 TAILQ_FIRST((head))->field.tqe_prev != \
519 &TAILQ_FIRST((head))) \
520 panic("Bad tailq head %p first->prev != head", (head)); \
523 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
524 if (*(head)->tqh_last != NULL) \
525 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
528 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
529 if (TAILQ_NEXT((elm), field) != NULL && \
530 TAILQ_NEXT((elm), field)->field.tqe_prev != \
531 &((elm)->field.tqe_next)) \
532 panic("Bad link elm %p next->prev != elm", (elm)); \
535 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
536 if (*(elm)->field.tqe_prev != (elm)) \
537 panic("Bad link elm %p prev->next != elm", (elm)); \
540 #define QMD_TAILQ_CHECK_HEAD(head, field)
541 #define QMD_TAILQ_CHECK_TAIL(head, headname)
542 #define QMD_TAILQ_CHECK_NEXT(elm, field)
543 #define QMD_TAILQ_CHECK_PREV(elm, field)
544 #endif /* (_KERNEL && INVARIANTS) */
546 #define TAILQ_CONCAT(head1, head2, field) do { \
547 if (!TAILQ_EMPTY(head2)) { \
548 *(head1)->tqh_last = (head2)->tqh_first; \
549 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
550 (head1)->tqh_last = (head2)->tqh_last; \
551 TAILQ_INIT((head2)); \
552 QMD_TRACE_HEAD(head1); \
553 QMD_TRACE_HEAD(head2); \
557 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
559 #define TAILQ_FIRST(head) ((head)->tqh_first)
561 #define TAILQ_FOREACH(var, head, field) \
562 for ((var) = TAILQ_FIRST((head)); \
564 (var) = TAILQ_NEXT((var), field))
566 #define TAILQ_FOREACH_FROM(var, head, field) \
567 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
569 (var) = TAILQ_NEXT((var), field))
571 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
572 for ((var) = TAILQ_FIRST((head)); \
573 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
576 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
577 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
578 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
581 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
582 for ((var) = TAILQ_LAST((head), headname); \
584 (var) = TAILQ_PREV((var), headname, field))
586 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field) \
587 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
589 (var) = TAILQ_PREV((var), headname, field))
591 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
592 for ((var) = TAILQ_LAST((head), headname); \
593 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
596 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
597 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
598 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
601 #define TAILQ_INIT(head) do { \
602 TAILQ_FIRST((head)) = NULL; \
603 (head)->tqh_last = &TAILQ_FIRST((head)); \
604 QMD_TRACE_HEAD(head); \
607 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
608 QMD_TAILQ_CHECK_NEXT(listelm, field); \
609 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
610 TAILQ_NEXT((elm), field)->field.tqe_prev = \
611 &TAILQ_NEXT((elm), field); \
613 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
614 QMD_TRACE_HEAD(head); \
616 TAILQ_NEXT((listelm), field) = (elm); \
617 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
618 QMD_TRACE_ELEM(&(elm)->field); \
619 QMD_TRACE_ELEM(&(listelm)->field); \
622 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
623 QMD_TAILQ_CHECK_PREV(listelm, field); \
624 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
625 TAILQ_NEXT((elm), field) = (listelm); \
626 *(listelm)->field.tqe_prev = (elm); \
627 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
628 QMD_TRACE_ELEM(&(elm)->field); \
629 QMD_TRACE_ELEM(&(listelm)->field); \
632 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
633 QMD_TAILQ_CHECK_HEAD(head, field); \
634 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
635 TAILQ_FIRST((head))->field.tqe_prev = \
636 &TAILQ_NEXT((elm), field); \
638 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
639 TAILQ_FIRST((head)) = (elm); \
640 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
641 QMD_TRACE_HEAD(head); \
642 QMD_TRACE_ELEM(&(elm)->field); \
645 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
646 QMD_TAILQ_CHECK_TAIL(head, field); \
647 TAILQ_NEXT((elm), field) = NULL; \
648 (elm)->field.tqe_prev = (head)->tqh_last; \
649 *(head)->tqh_last = (elm); \
650 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
651 QMD_TRACE_HEAD(head); \
652 QMD_TRACE_ELEM(&(elm)->field); \
655 #define TAILQ_LAST(head, headname) \
656 (*(((struct headname *)((head)->tqh_last))->tqh_last))
658 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
660 #define TAILQ_PREV(elm, headname, field) \
661 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
663 #define TAILQ_REMOVE(head, elm, field) do { \
664 QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
665 QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
666 QMD_TAILQ_CHECK_NEXT(elm, field); \
667 QMD_TAILQ_CHECK_PREV(elm, field); \
668 if ((TAILQ_NEXT((elm), field)) != NULL) \
669 TAILQ_NEXT((elm), field)->field.tqe_prev = \
670 (elm)->field.tqe_prev; \
672 (head)->tqh_last = (elm)->field.tqe_prev; \
673 QMD_TRACE_HEAD(head); \
675 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
678 QMD_TRACE_ELEM(&(elm)->field); \
681 #define TAILQ_SWAP(head1, head2, type, field) do { \
682 struct type *swap_first = (head1)->tqh_first; \
683 struct type **swap_last = (head1)->tqh_last; \
684 (head1)->tqh_first = (head2)->tqh_first; \
685 (head1)->tqh_last = (head2)->tqh_last; \
686 (head2)->tqh_first = swap_first; \
687 (head2)->tqh_last = swap_last; \
688 if ((swap_first = (head1)->tqh_first) != NULL) \
689 swap_first->field.tqe_prev = &(head1)->tqh_first; \
691 (head1)->tqh_last = &(head1)->tqh_first; \
692 if ((swap_first = (head2)->tqh_first) != NULL) \
693 swap_first->field.tqe_prev = &(head2)->tqh_first; \
695 (head2)->tqh_last = &(head2)->tqh_first; \
702 #endif /* !_SYS_QUEUE_H_ */