1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#ifndef _SYS_QUEUE_H_
33#define _SYS_QUEUE_H_
34
35#include <sys/cdefs.h>
36
37/*
38 * This file defines four types of data structures: singly-linked lists,
39 * singly-linked tail queues, lists and tail queues.
40 *
41 * A singly-linked list is headed by a single forward pointer. The elements
42 * are singly linked for minimum space and pointer manipulation overhead at
43 * the expense of O(n) removal for arbitrary elements. New elements can be
44 * added to the list after an existing element or at the head of the list.
45 * Elements being removed from the head of the list should use the explicit
46 * macro for this purpose for optimum efficiency. A singly-linked list may
47 * only be traversed in the forward direction. Singly-linked lists are ideal
48 * for applications with large datasets and few or no removals or for
49 * implementing a LIFO queue.
50 *
51 * A singly-linked tail queue is headed by a pair of pointers, one to the
52 * head of the list and the other to the tail of the list. The elements are
53 * singly linked for minimum space and pointer manipulation overhead at the
54 * expense of O(n) removal for arbitrary elements. New elements can be added
55 * to the list after an existing element, at the head of the list, or at the
56 * end of the list. Elements being removed from the head of the tail queue
57 * should use the explicit macro for this purpose for optimum efficiency.
58 * A singly-linked tail queue may only be traversed in the forward direction.
59 * Singly-linked tail queues are ideal for applications with large datasets
60 * and few or no removals or for implementing a FIFO queue.
61 *
62 * A list is headed by a single forward pointer (or an array of forward
63 * pointers for a hash table header). The elements are doubly linked
64 * so that an arbitrary element can be removed without a need to
65 * traverse the list. New elements can be added to the list before
66 * or after an existing element or at the head of the list. A list
67 * may be traversed in either direction.
68 *
69 * A tail queue is headed by a pair of pointers, one to the head of the
70 * list and the other to the tail of the list. The elements are doubly
71 * linked so that an arbitrary element can be removed without a need to
72 * traverse the list. New elements can be added to the list before or
73 * after an existing element, at the head of the list, or at the end of
74 * the list. A tail queue may be traversed in either direction.
75 *
76 * For details on the use of these macros, see the queue(3) manual page.
77 *
78 * Below is a summary of implemented functions where:
79 * + means the macro is available
80 * - means the macro is not available
81 * s means the macro is available but is slow (runs in O(n) time)
82 *
83 * SLIST LIST STAILQ TAILQ
84 * _HEAD + + + +
85 * _CLASS_HEAD + + + +
86 * _HEAD_INITIALIZER + + + +
87 * _ENTRY + + + +
88 * _CLASS_ENTRY + + + +
89 * _INIT + + + +
90 * _EMPTY + + + +
91 * _END + + + +
92 * _FIRST + + + +
93 * _NEXT + + + +
94 * _PREV - + - +
95 * _LAST - - + +
96 * _LAST_FAST - - - +
97 * _FOREACH + + + +
98 * _FOREACH_FROM + + + +
99 * _FOREACH_SAFE + + + +
100 * _FOREACH_FROM_SAFE + + + +
101 * _FOREACH_REVERSE - - - +
102 * _FOREACH_REVERSE_FROM - - - +
103 * _FOREACH_REVERSE_SAFE - - - +
104 * _FOREACH_REVERSE_FROM_SAFE - - - +
105 * _INSERT_HEAD + + + +
106 * _INSERT_BEFORE - + - +
107 * _INSERT_AFTER + + + +
108 * _INSERT_TAIL - - + +
109 * _CONCAT s s + +
110 * _REMOVE_AFTER + - + -
111 * _REMOVE_HEAD + + + +
112 * _REMOVE s + s +
113 * _REPLACE - + - +
114 * _SPLIT_AFTER + + + +
115 * _SWAP + + + +
116 *
117 */
118#ifdef QUEUE_MACRO_DEBUG
119#warn Use QUEUE_MACRO_DEBUG_xxx instead (TRACE, TRASH and/or ASSERTIONS)
120#define QUEUE_MACRO_DEBUG_TRACE
121#define QUEUE_MACRO_DEBUG_TRASH
122#endif
123#ifdef QUEUE_MACRO_DEBUG_TRACE
124/* Store the last 2 places the queue element or head was altered */
125struct qm_trace {
126 unsigned long lastline;
127 unsigned long prevline;
128 const char *lastfile;
129 const char *prevfile;
130};
131
132#define TRACEBUF struct qm_trace trace;
133#define TRACEBUF_INITIALIZER { __LINE__, 0, __FILE__, NULL } ,
134
135#define QMD_TRACE_HEAD(head) do { \
136 (head)->trace.prevline = (head)->trace.lastline; \
137 (head)->trace.prevfile = (head)->trace.lastfile; \
138 (head)->trace.lastline = __LINE__; \
139 (head)->trace.lastfile = __FILE__; \
140} while (0)
141
142#define QMD_TRACE_ELEM(elem) do { \
143 (elem)->trace.prevline = (elem)->trace.lastline; \
144 (elem)->trace.prevfile = (elem)->trace.lastfile; \
145 (elem)->trace.lastline = __LINE__; \
146 (elem)->trace.lastfile = __FILE__; \
147} while (0)
148
149#else /* !QUEUE_MACRO_DEBUG_TRACE */
150#define QMD_TRACE_ELEM(elem)
151#define QMD_TRACE_HEAD(head)
152#define TRACEBUF
153#define TRACEBUF_INITIALIZER
154#endif /* QUEUE_MACRO_DEBUG_TRACE */
155
156#ifdef QUEUE_MACRO_DEBUG_TRASH
157#define QMD_SAVELINK(name, link) void **name = (void *)&(link)
158#define TRASHIT(x) do {(x) = (void *)-1;} while (0)
159#define QMD_IS_TRASHED(x) ((x) == (void *)(intptr_t)-1)
160#else /* !QUEUE_MACRO_DEBUG_TRASH */
161#define QMD_SAVELINK(name, link)
162#define TRASHIT(x)
163#define QMD_IS_TRASHED(x) 0
164#endif /* QUEUE_MACRO_DEBUG_TRASH */
165
166#if defined(QUEUE_MACRO_DEBUG_ASSERTIONS) && \
167 defined(QUEUE_MACRO_NO_DEBUG_ASSERTIONS)
168#error Both QUEUE_MACRO_DEBUG_ASSERTIONS and QUEUE_MACRO_NO_DEBUG_ASSERTIONS defined
169#endif
170
171/*
172 * Automatically define QUEUE_MACRO_DEBUG_ASSERTIONS when compiling the kernel
173 * with INVARIANTS, if not already defined and not prevented by presence of
174 * QUEUE_MACRO_NO_DEBUG_ASSERTIONS.
175 */
176#if !defined(QUEUE_MACRO_DEBUG_ASSERTIONS) && \
177 !defined(QUEUE_MACRO_NO_DEBUG_ASSERTIONS) && \
178 (defined(_KERNEL) && defined(INVARIANTS))
179#define QUEUE_MACRO_DEBUG_ASSERTIONS
180#endif
181
182/*
183 * If queue assertions are enabled, provide default definitions for QMD_PANIC()
184 * and QMD_ASSERT() if undefined.
185 */
186#ifdef QUEUE_MACRO_DEBUG_ASSERTIONS
187#ifndef QMD_PANIC
188#if defined(_KERNEL) || defined(_STANDALONE)
189/*
190 * On _STANDALONE, either <stand.h> or the headers using <sys/queue.h> provide
191 * a declaration or macro for panic().
192 */
193#ifdef _KERNEL
194#include <sys/kassert.h>
195#endif
196#define QMD_PANIC(fmt, ...) do { \
197 panic(fmt, ##__VA_ARGS__); \
198} while (0)
199#else /* !(_KERNEL || _STANDALONE) */
200#include <stdio.h>
201#include <stdlib.h>
202#define QMD_PANIC(fmt, ...) do { \
203 fprintf(stderr, fmt "\n", ##__VA_ARGS__); \
204 abort(); \
205} while (0)
206#endif /* _KERNEL || _STANDALONE */
207#endif /* !QMD_PANIC */
208
209#ifndef QMD_ASSERT
210#define QMD_ASSERT(expression, fmt, ...) do { \
211 if (__predict_false(!(expression))) \
212 QMD_PANIC("%s:%u: %s: " fmt, \
213 __FILE__, __LINE__, __func__, ##__VA_ARGS__); \
214} while (0)
215#endif /* !QMD_ASSERT */
216#else /* !QUEUE_MACRO_DEBUG_ASSERTIONS */
217#undef QMD_ASSERT
218#define QMD_ASSERT(test, fmt, ...) do {} while (0)
219#endif /* QUEUE_MACRO_DEBUG_ASSERTIONS */
220
221
222#ifdef __cplusplus
223/*
224 * In C++ there can be structure lists and class lists:
225 */
226#define QUEUE_TYPEOF(type) type
227#else
228#define QUEUE_TYPEOF(type) struct type
229#endif
230
231/*
232 * Singly-linked List declarations.
233 */
234
235#define SLIST_HEAD(name, type) \
236struct name { \
237 struct type *slh_first; /* first element */ \
238}
239
240#define SLIST_CLASS_HEAD(name, type) \
241struct name { \
242 class type *slh_first; /* first element */ \
243}
244
245#define SLIST_HEAD_INITIALIZER(head) \
246 { NULL }
247
248#define SLIST_ENTRY(type) \
249struct { \
250 struct type *sle_next; /* next element */ \
251}
252
253#define SLIST_CLASS_ENTRY(type) \
254struct { \
255 class type *sle_next; /* next element */ \
256}
257
258/*
259 * Singly-linked List functions.
260 */
261
262#define QMD_SLIST_CHECK_PREVPTR(prevp, elm) \
263 QMD_ASSERT(*(prevp) == (elm), \
264 "Bad prevptr *(%p) == %p != %p", \
265 (prevp), *(prevp), (elm))
266
267#define SLIST_ASSERT_EMPTY(head) \
268 QMD_ASSERT(SLIST_EMPTY((head)), \
269 "slist %p is not empty", (head))
270
271#define SLIST_ASSERT_NONEMPTY(head) \
272 QMD_ASSERT(!SLIST_EMPTY((head)), \
273 "slist %p is empty", (head))
274
275#define SLIST_CONCAT(head1, head2, type, field) do { \
276 QUEUE_TYPEOF(type) *_Curelm = SLIST_FIRST(head1); \
277 if (_Curelm == NULL) { \
278 if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL) \
279 SLIST_INIT(head2); \
280 } else if (SLIST_FIRST(head2) != NULL) { \
281 while (SLIST_NEXT(_Curelm, field) != NULL) \
282 _Curelm = SLIST_NEXT(_Curelm, field); \
283 SLIST_NEXT(_Curelm, field) = SLIST_FIRST(head2); \
284 SLIST_INIT(head2); \
285 } \
286} while (0)
287
288#define SLIST_EMPTY(head) ((head)->slh_first == NULL)
289
290#define SLIST_EMPTY_ATOMIC(head) \
291 (atomic_load_ptr(&(head)->slh_first) == NULL)
292
293#define SLIST_FIRST(head) ((head)->slh_first)
294
295#define SLIST_FOREACH(var, head, field) \
296 for ((var) = SLIST_FIRST((head)); \
297 (var); \
298 (var) = SLIST_NEXT((var), field))
299
300#define SLIST_FOREACH_FROM(var, head, field) \
301 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
302 (var); \
303 (var) = SLIST_NEXT((var), field))
304
305#define SLIST_FOREACH_SAFE(var, head, field, tvar) \
306 for ((var) = SLIST_FIRST((head)); \
307 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
308 (var) = (tvar))
309
310#define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
311 for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
312 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
313 (var) = (tvar))
314
315#define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
316 for ((varp) = &SLIST_FIRST((head)); \
317 ((var) = *(varp)) != NULL; \
318 (varp) = &SLIST_NEXT((var), field))
319
320#define SLIST_INIT(head) do { \
321 SLIST_FIRST((head)) = NULL; \
322} while (0)
323
324#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
325 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
326 SLIST_NEXT((slistelm), field) = (elm); \
327} while (0)
328
329#define SLIST_INSERT_HEAD(head, elm, field) do { \
330 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
331 SLIST_FIRST((head)) = (elm); \
332} while (0)
333
334#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
335
336#define SLIST_REMOVE(head, elm, type, field) do { \
337 if (SLIST_FIRST((head)) == (elm)) { \
338 SLIST_REMOVE_HEAD((head), field); \
339 } \
340 else { \
341 QUEUE_TYPEOF(type) *_Curelm = SLIST_FIRST(head); \
342 while (SLIST_NEXT(_Curelm, field) != (elm)) \
343 _Curelm = SLIST_NEXT(_Curelm, field); \
344 SLIST_REMOVE_AFTER(_Curelm, field); \
345 } \
346} while (0)
347
348#define SLIST_REMOVE_AFTER(elm, field) do { \
349 QMD_SAVELINK(_Oldnext, SLIST_NEXT(elm, field)->field.sle_next); \
350 SLIST_NEXT(elm, field) = \
351 SLIST_NEXT(SLIST_NEXT(elm, field), field); \
352 TRASHIT(*_Oldnext); \
353} while (0)
354
355#define SLIST_REMOVE_HEAD(head, field) do { \
356 QMD_SAVELINK(_Oldnext, SLIST_FIRST(head)->field.sle_next); \
357 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
358 TRASHIT(*_Oldnext); \
359} while (0)
360
361#define SLIST_REMOVE_PREVPTR(prevp, elm, field) do { \
362 QMD_SLIST_CHECK_PREVPTR(prevp, elm); \
363 *(prevp) = SLIST_NEXT(elm, field); \
364 TRASHIT((elm)->field.sle_next); \
365} while (0)
366
367#define SLIST_SPLIT_AFTER(head, elm, rest, field) do { \
368 SLIST_ASSERT_NONEMPTY((head)); \
369 SLIST_FIRST((rest)) = SLIST_NEXT((elm), field); \
370 SLIST_NEXT((elm), field) = NULL; \
371} while (0)
372
373#define SLIST_SWAP(head1, head2, type) do { \
374 QUEUE_TYPEOF(type) *_Swap_first = SLIST_FIRST(head1); \
375 SLIST_FIRST(head1) = SLIST_FIRST(head2); \
376 SLIST_FIRST(head2) = _Swap_first; \
377} while (0)
378
379#define SLIST_END(head) NULL
380
381/*
382 * Singly-linked Tail queue declarations.
383 */
384
385#define STAILQ_HEAD(name, type) \
386struct name { \
387 struct type *stqh_first;/* first element */ \
388 struct type **stqh_last;/* addr of last next element */ \
389}
390
391#define STAILQ_CLASS_HEAD(name, type) \
392struct name { \
393 class type *stqh_first; /* first element */ \
394 class type **stqh_last; /* addr of last next element */ \
395}
396
397#define STAILQ_HEAD_INITIALIZER(head) \
398 { NULL, &(head).stqh_first }
399
400#define STAILQ_ENTRY(type) \
401struct { \
402 struct type *stqe_next; /* next element */ \
403}
404
405#define STAILQ_CLASS_ENTRY(type) \
406struct { \
407 class type *stqe_next; /* next element */ \
408}
409
410/*
411 * Singly-linked Tail queue functions.
412 */
413
414/*
415 * QMD_STAILQ_CHECK_EMPTY(STAILQ_HEAD *head)
416 *
417 * Validates that the stailq head's pointer to the last element's next pointer
418 * actually points to the head's first element pointer field.
419 */
420#define QMD_STAILQ_CHECK_EMPTY(head) \
421 QMD_ASSERT((head)->stqh_last == &(head)->stqh_first, \
422 "Empty stailq %p->stqh_last is %p, " \
423 "not head's first field address", \
424 (head), (head)->stqh_last)
425
426/*
427 * QMD_STAILQ_CHECK_TAIL(STAILQ_HEAD *head)
428 *
429 * Validates that the stailq's last element's next pointer is NULL.
430 */
431#define QMD_STAILQ_CHECK_TAIL(head) \
432 QMD_ASSERT(*(head)->stqh_last == NULL, \
433 "Stailq %p last element's next pointer is " \
434 "%p, not NULL", (head), *(head)->stqh_last)
435
436#define STAILQ_ASSERT_EMPTY(head) \
437 QMD_ASSERT(STAILQ_EMPTY((head)), \
438 "stailq %p is not empty", (head))
439
440#define STAILQ_ASSERT_NONEMPTY(head) \
441 QMD_ASSERT(!STAILQ_EMPTY((head)), \
442 "stailq %p is empty", (head))
443
444#define STAILQ_CONCAT(head1, head2) do { \
445 if (!STAILQ_EMPTY((head2))) { \
446 *(head1)->stqh_last = (head2)->stqh_first; \
447 (head1)->stqh_last = (head2)->stqh_last; \
448 STAILQ_INIT((head2)); \
449 } \
450} while (0)
451
452#define STAILQ_EMPTY(head) ({ \
453 if (STAILQ_FIRST(head) == NULL) \
454 QMD_STAILQ_CHECK_EMPTY(head); \
455 STAILQ_FIRST(head) == NULL; \
456})
457
458#define STAILQ_EMPTY_ATOMIC(head) \
459 (atomic_load_ptr(&(head)->stqh_first) == NULL)
460
461#define STAILQ_FIRST(head) ((head)->stqh_first)
462
463#define STAILQ_FOREACH(var, head, field) \
464 for((var) = STAILQ_FIRST((head)); \
465 (var); \
466 (var) = STAILQ_NEXT((var), field))
467
468#define STAILQ_FOREACH_FROM(var, head, field) \
469 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
470 (var); \
471 (var) = STAILQ_NEXT((var), field))
472
473#define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
474 for ((var) = STAILQ_FIRST((head)); \
475 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
476 (var) = (tvar))
477
478#define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
479 for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
480 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
481 (var) = (tvar))
482
483#define STAILQ_INIT(head) do { \
484 STAILQ_FIRST((head)) = NULL; \
485 (head)->stqh_last = &STAILQ_FIRST((head)); \
486} while (0)
487
488#define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
489 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
490 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
491 STAILQ_NEXT((tqelm), field) = (elm); \
492} while (0)
493
494#define STAILQ_INSERT_HEAD(head, elm, field) do { \
495 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
496 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
497 STAILQ_FIRST((head)) = (elm); \
498} while (0)
499
500#define STAILQ_INSERT_TAIL(head, elm, field) do { \
501 QMD_STAILQ_CHECK_TAIL(head); \
502 STAILQ_NEXT((elm), field) = NULL; \
503 *(head)->stqh_last = (elm); \
504 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
505} while (0)
506
507#define STAILQ_LAST(head, type, field) \
508 (STAILQ_EMPTY((head)) ? NULL : \
509 __containerof((head)->stqh_last, \
510 QUEUE_TYPEOF(type), field.stqe_next))
511
512#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
513
514#define STAILQ_REMOVE(head, elm, type, field) do { \
515 QMD_SAVELINK(_Oldnext, (elm)->field.stqe_next); \
516 if (STAILQ_FIRST((head)) == (elm)) { \
517 STAILQ_REMOVE_HEAD((head), field); \
518 } \
519 else { \
520 QUEUE_TYPEOF(type) *_Curelm = STAILQ_FIRST(head); \
521 while (STAILQ_NEXT(_Curelm, field) != (elm)) \
522 _Curelm = STAILQ_NEXT(_Curelm, field); \
523 STAILQ_REMOVE_AFTER(head, _Curelm, field); \
524 } \
525 TRASHIT(*_Oldnext); \
526} while (0)
527
528#define STAILQ_REMOVE_AFTER(head, elm, field) do { \
529 if ((STAILQ_NEXT(elm, field) = \
530 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
531 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
532} while (0)
533
534#define STAILQ_REMOVE_HEAD(head, field) do { \
535 if ((STAILQ_FIRST((head)) = \
536 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
537 (head)->stqh_last = &STAILQ_FIRST((head)); \
538} while (0)
539
540#define STAILQ_SPLIT_AFTER(head, elm, rest, field) do { \
541 STAILQ_ASSERT_NONEMPTY((head)); \
542 QMD_STAILQ_CHECK_TAIL((head)); \
543 if (STAILQ_NEXT((elm), field) == NULL) \
544 /* 'elm' is the last element in 'head'. */ \
545 STAILQ_INIT((rest)); \
546 else { \
547 STAILQ_FIRST((rest)) = STAILQ_NEXT((elm), field); \
548 (rest)->stqh_last = (head)->stqh_last; \
549 STAILQ_NEXT((elm), field) = NULL; \
550 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
551 } \
552} while (0)
553
554#define STAILQ_SWAP(head1, head2, type) do { \
555 QUEUE_TYPEOF(type) *_Swap_first = STAILQ_FIRST(head1); \
556 QUEUE_TYPEOF(type) **_Swap_last = (head1)->stqh_last; \
557 STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
558 (head1)->stqh_last = (head2)->stqh_last; \
559 STAILQ_FIRST(head2) = _Swap_first; \
560 (head2)->stqh_last = _Swap_last; \
561 if (STAILQ_FIRST(head1) == NULL) \
562 (head1)->stqh_last = &STAILQ_FIRST(head1); \
563 if (STAILQ_FIRST(head2) == NULL) \
564 (head2)->stqh_last = &STAILQ_FIRST(head2); \
565} while (0)
566
567#define STAILQ_REVERSE(head, type, field) do { \
568 if (STAILQ_EMPTY(head)) \
569 break; \
570 QUEUE_TYPEOF(type) *_Var, *_Varp, *_Varn; \
571 for (_Var = STAILQ_FIRST(head), _Varp = NULL; \
572 _Var != NULL;) { \
573 _Varn = STAILQ_NEXT(_Var, field); \
574 STAILQ_NEXT(_Var, field) = _Varp; \
575 _Varp = _Var; \
576 _Var = _Varn; \
577 } \
578 (head)->stqh_last = &STAILQ_NEXT(STAILQ_FIRST(head), field); \
579 (head)->stqh_first = _Varp; \
580} while (0)
581
582#define STAILQ_END(head) NULL
583
584
585/*
586 * List declarations.
587 */
588
589#define LIST_HEAD(name, type) \
590struct name { \
591 struct type *lh_first; /* first element */ \
592}
593
594#define LIST_CLASS_HEAD(name, type) \
595struct name { \
596 class type *lh_first; /* first element */ \
597}
598
599#define LIST_HEAD_INITIALIZER(head) \
600 { NULL }
601
602#define LIST_ENTRY(type) \
603struct { \
604 struct type *le_next; /* next element */ \
605 struct type **le_prev; /* address of previous next element */ \
606}
607
608#define LIST_CLASS_ENTRY(type) \
609struct { \
610 class type *le_next; /* next element */ \
611 class type **le_prev; /* address of previous next element */ \
612}
613
614/*
615 * List functions.
616 */
617
618/*
619 * QMD_LIST_CHECK_HEAD(LIST_HEAD *head, LIST_ENTRY NAME)
620 *
621 * If the list is non-empty, validates that the first element of the list
622 * points back at 'head.'
623 */
624#define QMD_LIST_CHECK_HEAD(head, field) \
625 QMD_ASSERT(LIST_FIRST((head)) == NULL || \
626 LIST_FIRST((head))->field.le_prev == \
627 &LIST_FIRST((head)), \
628 "Bad list head %p first->prev != head", \
629 (head))
630
631/*
632 * QMD_LIST_CHECK_NEXT(TYPE *elm, LIST_ENTRY NAME)
633 *
634 * If an element follows 'elm' in the list, validates that the next element
635 * points back at 'elm.'
636 */
637#define QMD_LIST_CHECK_NEXT(elm, field) \
638 QMD_ASSERT(LIST_NEXT((elm), field) == NULL || \
639 LIST_NEXT((elm), field)->field.le_prev == \
640 &((elm)->field.le_next), \
641 "Bad link elm %p next->prev != elm", (elm))
642
643/*
644 * QMD_LIST_CHECK_PREV(TYPE *elm, LIST_ENTRY NAME)
645 *
646 * Validates that the previous element (or head of the list) points to 'elm.'
647 */
648#define QMD_LIST_CHECK_PREV(elm, field) \
649 QMD_ASSERT(*(elm)->field.le_prev == (elm), \
650 "Bad link elm %p prev->next != elm", (elm))
651
652#define LIST_ASSERT_EMPTY(head) \
653 QMD_ASSERT(LIST_EMPTY((head)), \
654 "list %p is not empty", (head))
655
656#define LIST_ASSERT_NONEMPTY(head) \
657 QMD_ASSERT(!LIST_EMPTY((head)), \
658 "list %p is empty", (head))
659
660#define LIST_CONCAT(head1, head2, type, field) do { \
661 QUEUE_TYPEOF(type) *_Curelm = LIST_FIRST(head1); \
662 if (_Curelm == NULL) { \
663 if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) { \
664 LIST_FIRST(head2)->field.le_prev = \
665 &LIST_FIRST((head1)); \
666 LIST_INIT(head2); \
667 } \
668 } else if (LIST_FIRST(head2) != NULL) { \
669 while (LIST_NEXT(_Curelm, field) != NULL) \
670 _Curelm = LIST_NEXT(_Curelm, field); \
671 LIST_NEXT(_Curelm, field) = LIST_FIRST(head2); \
672 LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(_Curelm, field);\
673 LIST_INIT(head2); \
674 } \
675} while (0)
676
677#define LIST_EMPTY(head) ((head)->lh_first == NULL)
678
679#define LIST_EMPTY_ATOMIC(head) \
680 (atomic_load_ptr(&(head)->lh_first) == NULL)
681
682#define LIST_FIRST(head) ((head)->lh_first)
683
684#define LIST_FOREACH(var, head, field) \
685 for ((var) = LIST_FIRST((head)); \
686 (var); \
687 (var) = LIST_NEXT((var), field))
688
689#define LIST_FOREACH_FROM(var, head, field) \
690 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
691 (var); \
692 (var) = LIST_NEXT((var), field))
693
694#define LIST_FOREACH_SAFE(var, head, field, tvar) \
695 for ((var) = LIST_FIRST((head)); \
696 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
697 (var) = (tvar))
698
699#define LIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
700 for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
701 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
702 (var) = (tvar))
703
704#define LIST_INIT(head) do { \
705 LIST_FIRST((head)) = NULL; \
706} while (0)
707
708#define LIST_INSERT_AFTER(listelm, elm, field) do { \
709 QMD_LIST_CHECK_NEXT(listelm, field); \
710 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
711 LIST_NEXT((listelm), field)->field.le_prev = \
712 &LIST_NEXT((elm), field); \
713 LIST_NEXT((listelm), field) = (elm); \
714 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
715} while (0)
716
717#define LIST_INSERT_BEFORE(listelm, elm, field) do { \
718 QMD_LIST_CHECK_PREV(listelm, field); \
719 (elm)->field.le_prev = (listelm)->field.le_prev; \
720 LIST_NEXT((elm), field) = (listelm); \
721 *(listelm)->field.le_prev = (elm); \
722 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
723} while (0)
724
725#define LIST_INSERT_HEAD(head, elm, field) do { \
726 QMD_LIST_CHECK_HEAD((head), field); \
727 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
728 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
729 LIST_FIRST((head)) = (elm); \
730 (elm)->field.le_prev = &LIST_FIRST((head)); \
731} while (0)
732
733#define LIST_NEXT(elm, field) ((elm)->field.le_next)
734
735#define LIST_PREV(elm, head, type, field) \
736 ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL : \
737 __containerof((elm)->field.le_prev, \
738 QUEUE_TYPEOF(type), field.le_next))
739
740#define LIST_REMOVE_HEAD(head, field) \
741 LIST_REMOVE(LIST_FIRST(head), field)
742
743#define LIST_REMOVE(elm, field) do { \
744 QMD_SAVELINK(_Oldnext, (elm)->field.le_next); \
745 QMD_SAVELINK(_Oldprev, (elm)->field.le_prev); \
746 QMD_LIST_CHECK_NEXT(elm, field); \
747 QMD_LIST_CHECK_PREV(elm, field); \
748 if (LIST_NEXT((elm), field) != NULL) \
749 LIST_NEXT((elm), field)->field.le_prev = \
750 (elm)->field.le_prev; \
751 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
752 TRASHIT(*_Oldnext); \
753 TRASHIT(*_Oldprev); \
754} while (0)
755
756#define LIST_REPLACE(elm, elm2, field) do { \
757 QMD_SAVELINK(_Oldnext, (elm)->field.le_next); \
758 QMD_SAVELINK(_Oldprev, (elm)->field.le_prev); \
759 QMD_LIST_CHECK_NEXT(elm, field); \
760 QMD_LIST_CHECK_PREV(elm, field); \
761 LIST_NEXT((elm2), field) = LIST_NEXT((elm), field); \
762 if (LIST_NEXT((elm2), field) != NULL) \
763 LIST_NEXT((elm2), field)->field.le_prev = \
764 &(elm2)->field.le_next; \
765 (elm2)->field.le_prev = (elm)->field.le_prev; \
766 *(elm2)->field.le_prev = (elm2); \
767 TRASHIT(*_Oldnext); \
768 TRASHIT(*_Oldprev); \
769} while (0)
770
771#define LIST_SPLIT_AFTER(head, elm, rest, field) do { \
772 LIST_ASSERT_NONEMPTY((head)); \
773 if (LIST_NEXT((elm), field) == NULL) \
774 /* 'elm' is the last element in 'head'. */ \
775 LIST_INIT((rest)); \
776 else { \
777 LIST_FIRST((rest)) = LIST_NEXT((elm), field); \
778 LIST_NEXT((elm), field)->field.le_prev = \
779 &LIST_FIRST((rest)); \
780 LIST_NEXT((elm), field) = NULL; \
781 } \
782} while (0)
783
784#define LIST_SWAP(head1, head2, type, field) do { \
785 QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1); \
786 LIST_FIRST((head1)) = LIST_FIRST((head2)); \
787 LIST_FIRST((head2)) = swap_tmp; \
788 if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
789 swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
790 if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
791 swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
792} while (0)
793
794#define LIST_END(head) NULL
795
796/*
797 * Tail queue declarations.
798 */
799
800#define TAILQ_HEAD(name, type) \
801struct name { \
802 struct type *tqh_first; /* first element */ \
803 struct type **tqh_last; /* addr of last next element */ \
804 TRACEBUF \
805}
806
807#define TAILQ_CLASS_HEAD(name, type) \
808struct name { \
809 class type *tqh_first; /* first element */ \
810 class type **tqh_last; /* addr of last next element */ \
811 TRACEBUF \
812}
813
814#define TAILQ_HEAD_INITIALIZER(head) \
815 { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
816
817#define TAILQ_ENTRY(type) \
818struct { \
819 struct type *tqe_next; /* next element */ \
820 struct type **tqe_prev; /* address of previous next element */ \
821 TRACEBUF \
822}
823
824#define TAILQ_CLASS_ENTRY(type) \
825struct { \
826 class type *tqe_next; /* next element */ \
827 class type **tqe_prev; /* address of previous next element */ \
828 TRACEBUF \
829}
830
831/*
832 * Tail queue functions.
833 */
834
835/*
836 * QMD_TAILQ_CHECK_HEAD(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
837 *
838 * If the tailq is non-empty, validates that the first element of the tailq
839 * points back at 'head.'
840 */
841#define QMD_TAILQ_CHECK_HEAD(head, field) \
842 QMD_ASSERT(TAILQ_EMPTY(head) || \
843 TAILQ_FIRST((head))->field.tqe_prev == \
844 &TAILQ_FIRST((head)), \
845 "Bad tailq head %p first->prev != head", \
846 (head))
847
848/*
849 * QMD_TAILQ_CHECK_TAIL(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
850 *
851 * Validates that the tail of the tailq is a pointer to pointer to NULL.
852 */
853#define QMD_TAILQ_CHECK_TAIL(head, field) \
854 QMD_ASSERT(*(head)->tqh_last == NULL, \
855 "Bad tailq NEXT(%p->tqh_last) != NULL", \
856 (head))
857
858/*
859 * QMD_TAILQ_CHECK_NEXT(TYPE *elm, TAILQ_ENTRY NAME)
860 *
861 * If an element follows 'elm' in the tailq, validates that the next element
862 * points back at 'elm.'
863 */
864#define QMD_TAILQ_CHECK_NEXT(elm, field) \
865 QMD_ASSERT(TAILQ_NEXT((elm), field) == NULL || \
866 TAILQ_NEXT((elm), field)->field.tqe_prev == \
867 &((elm)->field.tqe_next), \
868 "Bad link elm %p next->prev != elm", (elm))
869
870/*
871 * QMD_TAILQ_CHECK_PREV(TYPE *elm, TAILQ_ENTRY NAME)
872 *
873 * Validates that the previous element (or head of the tailq) points to 'elm.'
874 */
875#define QMD_TAILQ_CHECK_PREV(elm, field) \
876 QMD_ASSERT(*(elm)->field.tqe_prev == (elm), \
877 "Bad link elm %p prev->next != elm", (elm))
878
879#define TAILQ_ASSERT_EMPTY(head) \
880 QMD_ASSERT(TAILQ_EMPTY((head)), \
881 "tailq %p is not empty", (head))
882
883#define TAILQ_ASSERT_NONEMPTY(head) \
884 QMD_ASSERT(!TAILQ_EMPTY((head)), \
885 "tailq %p is empty", (head))
886
887#define TAILQ_CONCAT(head1, head2, field) do { \
888 if (!TAILQ_EMPTY(head2)) { \
889 *(head1)->tqh_last = (head2)->tqh_first; \
890 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
891 (head1)->tqh_last = (head2)->tqh_last; \
892 TAILQ_INIT((head2)); \
893 QMD_TRACE_HEAD(head1); \
894 QMD_TRACE_HEAD(head2); \
895 } \
896} while (0)
897
898#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
899
900#define TAILQ_EMPTY_ATOMIC(head) \
901 (atomic_load_ptr(&(head)->tqh_first) == NULL)
902
903#define TAILQ_FIRST(head) ((head)->tqh_first)
904
905#define TAILQ_FOREACH(var, head, field) \
906 for ((var) = TAILQ_FIRST((head)); \
907 (var); \
908 (var) = TAILQ_NEXT((var), field))
909
910#define TAILQ_FOREACH_FROM(var, head, field) \
911 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
912 (var); \
913 (var) = TAILQ_NEXT((var), field))
914
915#define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
916 for ((var) = TAILQ_FIRST((head)); \
917 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
918 (var) = (tvar))
919
920#define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
921 for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
922 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
923 (var) = (tvar))
924
925#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
926 for ((var) = TAILQ_LAST((head), headname); \
927 (var); \
928 (var) = TAILQ_PREV((var), headname, field))
929
930#define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field) \
931 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
932 (var); \
933 (var) = TAILQ_PREV((var), headname, field))
934
935#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
936 for ((var) = TAILQ_LAST((head), headname); \
937 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
938 (var) = (tvar))
939
940#define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar)\
941 for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
942 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
943 (var) = (tvar))
944
945#define TAILQ_INIT(head) do { \
946 TAILQ_FIRST((head)) = NULL; \
947 (head)->tqh_last = &TAILQ_FIRST((head)); \
948 QMD_TRACE_HEAD(head); \
949} while (0)
950
951#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
952 QMD_TAILQ_CHECK_NEXT(listelm, field); \
953 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
954 TAILQ_NEXT((elm), field)->field.tqe_prev = \
955 &TAILQ_NEXT((elm), field); \
956 else { \
957 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
958 QMD_TRACE_HEAD(head); \
959 } \
960 TAILQ_NEXT((listelm), field) = (elm); \
961 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
962 QMD_TRACE_ELEM(&(elm)->field); \
963 QMD_TRACE_ELEM(&(listelm)->field); \
964} while (0)
965
966#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
967 QMD_TAILQ_CHECK_PREV(listelm, field); \
968 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
969 TAILQ_NEXT((elm), field) = (listelm); \
970 *(listelm)->field.tqe_prev = (elm); \
971 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
972 QMD_TRACE_ELEM(&(elm)->field); \
973 QMD_TRACE_ELEM(&(listelm)->field); \
974} while (0)
975
976#define TAILQ_INSERT_HEAD(head, elm, field) do { \
977 QMD_TAILQ_CHECK_HEAD(head, field); \
978 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
979 TAILQ_FIRST((head))->field.tqe_prev = \
980 &TAILQ_NEXT((elm), field); \
981 else \
982 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
983 TAILQ_FIRST((head)) = (elm); \
984 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
985 QMD_TRACE_HEAD(head); \
986 QMD_TRACE_ELEM(&(elm)->field); \
987} while (0)
988
989#define TAILQ_INSERT_TAIL(head, elm, field) do { \
990 QMD_TAILQ_CHECK_TAIL(head, field); \
991 TAILQ_NEXT((elm), field) = NULL; \
992 (elm)->field.tqe_prev = (head)->tqh_last; \
993 *(head)->tqh_last = (elm); \
994 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
995 QMD_TRACE_HEAD(head); \
996 QMD_TRACE_ELEM(&(elm)->field); \
997} while (0)
998
999#define TAILQ_LAST(head, headname) \
1000 (*(((struct headname *)((head)->tqh_last))->tqh_last))
1001
1002/*
1003 * The FAST function is fast in that it causes no data access other
1004 * then the access to the head. The standard LAST function above
1005 * will cause a data access of both the element you want and
1006 * the previous element. FAST is very useful for instances when
1007 * you may want to prefetch the last data element.
1008 */
1009#define TAILQ_LAST_FAST(head, type, field) \
1010 (TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last, QUEUE_TYPEOF(type), field.tqe_next))
1011
1012#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
1013
1014#define TAILQ_PREV(elm, headname, field) \
1015 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
1016
1017#define TAILQ_PREV_FAST(elm, head, type, field) \
1018 ((elm)->field.tqe_prev == &(head)->tqh_first ? NULL : \
1019 __containerof((elm)->field.tqe_prev, QUEUE_TYPEOF(type), field.tqe_next))
1020
1021#define TAILQ_REMOVE_HEAD(head, field) \
1022 TAILQ_REMOVE(head, TAILQ_FIRST(head), field)
1023
1024#define TAILQ_REMOVE(head, elm, field) do { \
1025 QMD_SAVELINK(_Oldnext, (elm)->field.tqe_next); \
1026 QMD_SAVELINK(_Oldprev, (elm)->field.tqe_prev); \
1027 QMD_TAILQ_CHECK_NEXT(elm, field); \
1028 QMD_TAILQ_CHECK_PREV(elm, field); \
1029 if ((TAILQ_NEXT((elm), field)) != NULL) \
1030 TAILQ_NEXT((elm), field)->field.tqe_prev = \
1031 (elm)->field.tqe_prev; \
1032 else { \
1033 (head)->tqh_last = (elm)->field.tqe_prev; \
1034 QMD_TRACE_HEAD(head); \
1035 } \
1036 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
1037 TRASHIT(*_Oldnext); \
1038 TRASHIT(*_Oldprev); \
1039 QMD_TRACE_ELEM(&(elm)->field); \
1040} while (0)
1041
1042#define TAILQ_REPLACE(head, elm, elm2, field) do { \
1043 QMD_SAVELINK(_Oldnext, (elm)->field.tqe_next); \
1044 QMD_SAVELINK(_Oldprev, (elm)->field.tqe_prev); \
1045 QMD_TAILQ_CHECK_NEXT(elm, field); \
1046 QMD_TAILQ_CHECK_PREV(elm, field); \
1047 TAILQ_NEXT((elm2), field) = TAILQ_NEXT((elm), field); \
1048 if (TAILQ_NEXT((elm2), field) != TAILQ_END(head)) \
1049 TAILQ_NEXT((elm2), field)->field.tqe_prev = \
1050 &(elm2)->field.tqe_next; \
1051 else \
1052 (head)->tqh_last = &(elm2)->field.tqe_next; \
1053 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
1054 *(elm2)->field.tqe_prev = (elm2); \
1055 TRASHIT(*_Oldnext); \
1056 TRASHIT(*_Oldprev); \
1057 QMD_TRACE_ELEM(&(elm)->field); \
1058} while (0)
1059
1060#define TAILQ_SPLIT_AFTER(head, elm, rest, field) do { \
1061 TAILQ_ASSERT_NONEMPTY((head)); \
1062 QMD_TAILQ_CHECK_TAIL((head), field); \
1063 if (TAILQ_NEXT((elm), field) == NULL) \
1064 /* 'elm' is the last element in 'head'. */ \
1065 TAILQ_INIT((rest)); \
1066 else { \
1067 TAILQ_FIRST((rest)) = TAILQ_NEXT((elm), field); \
1068 (rest)->tqh_last = (head)->tqh_last; \
1069 TAILQ_NEXT((elm), field)->field.tqe_prev = \
1070 &TAILQ_FIRST((rest)); \
1071 \
1072 TAILQ_NEXT((elm), field) = NULL; \
1073 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
1074 } \
1075} while (0)
1076
1077#define TAILQ_SWAP(head1, head2, type, field) do { \
1078 QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first; \
1079 QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last; \
1080 (head1)->tqh_first = (head2)->tqh_first; \
1081 (head1)->tqh_last = (head2)->tqh_last; \
1082 (head2)->tqh_first = swap_first; \
1083 (head2)->tqh_last = swap_last; \
1084 if ((swap_first = (head1)->tqh_first) != NULL) \
1085 swap_first->field.tqe_prev = &(head1)->tqh_first; \
1086 else \
1087 (head1)->tqh_last = &(head1)->tqh_first; \
1088 if ((swap_first = (head2)->tqh_first) != NULL) \
1089 swap_first->field.tqe_prev = &(head2)->tqh_first; \
1090 else \
1091 (head2)->tqh_last = &(head2)->tqh_first; \
1092} while (0)
1093
1094#define TAILQ_END(head) NULL
1095
1096#endif /* !_SYS_QUEUE_H_ */