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1 /*
2  * Copyright (c) 2022 FuZhou Lockzhiner Electronic Co., Ltd. All rights reserved.
3  * Copyright (c) 1991, 1993
4  *  The Regents of the University of California.  All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 4. Neither the name of the University nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  *
30  *  @(#)queue.h 8.5 (Berkeley) 8/20/94
31  * $FreeBSD: releng/10.1/sys/sys/queue.h 251887 2013-06-18 02:57:56Z lstewart $
32  */
33 
34 #ifndef _SYS_QUEUE_H
35 #define _SYS_QUEUE_H
36 
37 #include "sys/defs.h"
38 
39 /*
40  * This file defines four types of data structures: singly-linked lists,
41  * singly-linked tail queues, lists and tail queues.
42  *
43  * A singly-linked list is headed by a single forward pointer. The elements
44  * are singly linked for minimum space and pointer manipulation overhead at
45  * the expense of O(n) removal for arbitrary elements. New elements can be
46  * added to the list after an existing element or at the head of the list.
47  * Elements being removed from the head of the list should use the explicit
48  * macro for this purpose for optimum efficiency. A singly-linked list may
49  * only be traversed in the forward direction.  Singly-linked lists are ideal
50  * for applications with large datasets and few or no removals or for
51  * implementing a LIFO queue.
52  *
53  * A singly-linked tail queue is headed by a pair of pointers, one to the
54  * head of the list and the other to the tail of the list. The elements are
55  * singly linked for minimum space and pointer manipulation overhead at the
56  * expense of O(n) removal for arbitrary elements. New elements can be added
57  * to the list after an existing element, at the head of the list, or at the
58  * end of the list. Elements being removed from the head of the tail queue
59  * should use the explicit macro for this purpose for optimum efficiency.
60  * A singly-linked tail queue may only be traversed in the forward direction.
61  * Singly-linked tail queues are ideal for applications with large datasets
62  * and few or no removals or for implementing a FIFO queue.
63  *
64  * A list is headed by a single forward pointer (or an array of forward
65  * pointers for a hash table header). The elements are doubly linked
66  * so that an arbitrary element can be removed without a need to
67  * traverse the list. New elements can be added to the list before
68  * or after an existing element or at the head of the list. A list
69  * may be traversed in either direction.
70  *
71  * A tail queue is headed by a pair of pointers, one to the head of the
72  * list and the other to the tail of the list. The elements are doubly
73  * linked so that an arbitrary element can be removed without a need to
74  * traverse the list. New elements can be added to the list before or
75  * after an existing element, at the head of the list, or at the end of
76  * the list. A tail queue may be traversed in either direction.
77  *
78  * For details on the use of these macros, see the queue(3) manual page.
79  *
80  *
81  *              SLIST   LIST    STAILQ  TAILQ
82  * _HEAD            +   +   +   +
83  * _HEAD_INITIALIZER        +   +   +   +
84  * _ENTRY           +   +   +   +
85  * _INIT            +   +   +   +
86  * _EMPTY           +   +   +   +
87  * _FIRST           +   +   +   +
88  * _NEXT            +   +   +   +
89  * _PREV            -   +   -   +
90  * _LAST            -   -   +   +
91  * _FOREACH         +   +   +   +
92  * _FOREACH_FROM        +   +   +   +
93  * _FOREACH_SAFE        +   +   +   +
94  * _FOREACH_FROM_SAFE       +   +   +   +
95  * _FOREACH_REVERSE     -   -   -   +
96  * _FOREACH_REVERSE_FROM    -   -   -   +
97  * _FOREACH_REVERSE_SAFE    -   -   -   +
98  * _FOREACH_REVERSE_FROM_SAFE   -   -   -   +
99  * _INSERT_HEAD         +   +   +   +
100  * _INSERT_BEFORE       -   +   -   +
101  * _INSERT_AFTER        +   +   +   +
102  * _INSERT_TAIL         -   -   +   +
103  * _CONCAT          -   -   +   +
104  * _REMOVE_AFTER        +   -   +   -
105  * _REMOVE_HEAD         +   -   +   -
106  * _REMOVE          +   +   +   +
107  * _SWAP            +   +   +   +
108  *
109  */
110 #ifdef QUEUE_MACRO_DEBUG
111 /* Store the last 2 places the queue element or head was altered */
112 struct qm_trace {
113     unsigned long    lastline;
114     unsigned long    prevline;
115     const char  *lastfile;
116     const char  *prevfile;
117 };
118 
119 #define TRACEBUF    struct qm_trace trace;
120 #define TRACEBUF_INITIALIZER    { __FILE__, __LINE__, NULL, 0 } ,
121 #define TRASHIT(x)  do { (x) = (void *)-1; } while (0)
122 #define QMD_SAVELINK(name, link)    void **name = (void *)&(link)
123 
124 #define QMD_TRACE_HEAD(head) do {                   \
125     (head)->trace.prevline = (head)->trace.lastline;        \
126     (head)->trace.prevfile = (head)->trace.lastfile;        \
127     (head)->trace.lastline = __LINE__;              \
128     (head)->trace.lastfile = __FILE__;              \
129 } while (0)
130 
131 #define QMD_TRACE_ELEM(elem) do {                   \
132     (elem)->trace.prevline = (elem)->trace.lastline;        \
133     (elem)->trace.prevfile = (elem)->trace.lastfile;        \
134     (elem)->trace.lastline = __LINE__;              \
135     (elem)->trace.lastfile = __FILE__;              \
136 } while (0)
137 
138 #else
139 #define QMD_TRACE_ELEM(elem)
140 #define QMD_TRACE_HEAD(head)
141 #define QMD_SAVELINK(name, link)
142 #define TRACEBUF
143 #define TRACEBUF_INITIALIZER
144 #define TRASHIT(x)
145 #endif  /* QUEUE_MACRO_DEBUG */
146 
147 /*
148  * Singly-linked List declarations.
149  */
150 #define SLIST_HEAD(name, type)                      \
151 struct name {                               \
152     struct type *slh_first; /* first element */         \
153 }
154 
155 #define SLIST_HEAD_INITIALIZER(head)                    \
156     { NULL }
157 
158 #define SLIST_ENTRY(type)                       \
159 struct {                                \
160     struct type *sle_next;  /* next element */          \
161 }
162 
163 /*
164  * Singly-linked List functions.
165  */
166 #define SLIST_EMPTY(head)   ((head)->slh_first == NULL)
167 
168 #define SLIST_FIRST(head)   ((head)->slh_first)
169 
170 #define SLIST_FOREACH(var, head, field)                 \
171     for ((var) = SLIST_FIRST((head));               \
172         (var);                          \
173         (var) = SLIST_NEXT((var), field))
174 
175 #define SLIST_FOREACH_FROM(var, head, field)                \
176     for ((var) = ((var) ? (var) : SLIST_FIRST((head)));     \
177         (var);                          \
178         (var) = SLIST_NEXT((var), field))
179 
180 #define SLIST_FOREACH_SAFE(var, head, field, tvar)          \
181     for ((var) = SLIST_FIRST((head));               \
182         (var) && ((tvar) = SLIST_NEXT((var), field), 1);        \
183         (var) = (tvar))
184 
185 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar)         \
186     for ((var) = ((var) ? (var) : SLIST_FIRST((head)));     \
187         (var) && ((tvar) = SLIST_NEXT((var), field), 1);        \
188         (var) = (tvar))
189 
190 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)           \
191     for ((varp) = &SLIST_FIRST((head));             \
192         ((var) = *(varp)) != NULL;                  \
193         (varp) = &SLIST_NEXT((var), field))
194 
195 #define SLIST_INIT(head) do {                       \
196     SLIST_FIRST((head)) = NULL;                 \
197 } while (0)
198 
199 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {           \
200     SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);   \
201     SLIST_NEXT((slistelm), field) = (elm);              \
202 } while (0)
203 
204 #define SLIST_INSERT_HEAD(head, elm, field) do {            \
205     SLIST_NEXT((elm), field) = SLIST_FIRST((head));         \
206     SLIST_FIRST((head)) = (elm);                    \
207 } while (0)
208 
209 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
210 
211 #define SLIST_REMOVE(head, elm, type, field) do {           \
212     QMD_SAVELINK(oldnext, (elm)->field.sle_next);           \
213     if (SLIST_FIRST((head)) == (elm)) {             \
214         SLIST_REMOVE_HEAD((head), field);           \
215     }                               \
216     else {                              \
217         struct type *curelm = SLIST_FIRST((head));      \
218         while (SLIST_NEXT(curelm, field) != (elm))      \
219             curelm = SLIST_NEXT(curelm, field);     \
220         SLIST_REMOVE_AFTER(curelm, field);          \
221     }                               \
222     TRASHIT(*oldnext);                      \
223 } while (0)
224 
225 #define SLIST_REMOVE_AFTER(elm, field) do {             \
226     SLIST_NEXT(elm, field) =                    \
227         SLIST_NEXT(SLIST_NEXT(elm, field), field);          \
228 } while (0)
229 
230 #define SLIST_REMOVE_HEAD(head, field) do {             \
231     SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
232 } while (0)
233 
234 #define SLIST_SWAP(head1, head2, type) do {             \
235     struct type *swap_first = SLIST_FIRST(head1);           \
236     SLIST_FIRST(head1) = SLIST_FIRST(head2);            \
237     SLIST_FIRST(head2) = swap_first;                \
238 } while (0)
239 
240 /*
241  * Singly-linked Tail queue declarations.
242  */
243 #define STAILQ_HEAD(name, type)                                 \
244 struct name {                                                   \
245     struct type *stqh_first; /* first element */                \
246     struct type **stqh_last; /* addr of last next element */    \
247 }
248 
249 #define STAILQ_HEAD_INITIALIZER(head)                   \
250     { NULL, &(head).stqh_first }
251 
252 #define STAILQ_ENTRY(type)                      \
253 struct {                                \
254     struct type *stqe_next; /* next element */          \
255 }
256 
257 /*
258  * Singly-linked Tail queue functions.
259  */
260 #define STAILQ_CONCAT(head1, head2) do {                \
261     if (!STAILQ_EMPTY((head2))) {                   \
262         *(head1)->stqh_last = (head2)->stqh_first;      \
263         (head1)->stqh_last = (head2)->stqh_last;        \
264         STAILQ_INIT((head2));                   \
265     }                               \
266 } while (0)
267 
268 #define STAILQ_EMPTY(head)  ((head)->stqh_first == NULL)
269 
270 #define STAILQ_FIRST(head)  ((head)->stqh_first)
271 
272 #define STAILQ_FOREACH(var, head, field)                \
273     for ((var) = STAILQ_FIRST((head));               \
274        (var);                           \
275        (var) = STAILQ_NEXT((var), field))
276 
277 #define STAILQ_FOREACH_FROM(var, head, field)               \
278     for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));        \
279        (var);                           \
280        (var) = STAILQ_NEXT((var), field))
281 
282 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)         \
283     for ((var) = STAILQ_FIRST((head));              \
284         (var) && ((tvar) = STAILQ_NEXT((var), field), 1);       \
285         (var) = (tvar))
286 
287 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)        \
288     for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));        \
289         (var) && ((tvar) = STAILQ_NEXT((var), field), 1);       \
290         (var) = (tvar))
291 
292 #define STAILQ_INIT(head) do {                      \
293     STAILQ_FIRST((head)) = NULL;                    \
294     (head)->stqh_last = &STAILQ_FIRST((head));          \
295 } while (0)
296 
297 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {       \
298     if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL) \
299         (head)->stqh_last = &STAILQ_NEXT((elm), field);     \
300     STAILQ_NEXT((tqelm), field) = (elm);                \
301 } while (0)
302 
303 #define STAILQ_INSERT_HEAD(head, elm, field) do {           \
304     if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
305         (head)->stqh_last = &STAILQ_NEXT((elm), field);     \
306     STAILQ_FIRST((head)) = (elm);                   \
307 } while (0)
308 
309 #define STAILQ_INSERT_TAIL(head, elm, field) do {           \
310     STAILQ_NEXT((elm), field) = NULL;               \
311     *(head)->stqh_last = (elm);                 \
312     (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
313 } while (0)
314 
315 #define STAILQ_LAST(head, type, field)                  \
316     (STAILQ_EMPTY((head)) ? NULL : __containerof((head)->stqh_last, struct type, (field).stqe_next))
317 
318 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
319 
320 #define STAILQ_REMOVE(head, elm, type, field) do {          \
321     QMD_SAVELINK(oldnext, (elm)->field.stqe_next);          \
322     if (STAILQ_FIRST((head)) == (elm)) {                \
323         STAILQ_REMOVE_HEAD((head), field);          \
324     }                               \
325     else {                              \
326         struct type *curelm = STAILQ_FIRST((head));     \
327         while (STAILQ_NEXT(curelm, field) != (elm))     \
328             curelm = STAILQ_NEXT(curelm, field);        \
329         STAILQ_REMOVE_AFTER(head, curelm, field);       \
330     }                               \
331     TRASHIT(*oldnext);                      \
332 } while (0)
333 
334 #define STAILQ_REMOVE_AFTER(head, elm, field) do {          \
335     if ((STAILQ_NEXT(elm, field) =                  \
336          STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)  \
337         (head)->stqh_last = &STAILQ_NEXT((elm), field);     \
338 } while (0)
339 
340 #define STAILQ_REMOVE_HEAD(head, field) do {                \
341     if ((STAILQ_FIRST((head)) =                 \
342          STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)     \
343         (head)->stqh_last = &STAILQ_FIRST((head));      \
344 } while (0)
345 
346 #define STAILQ_SWAP(head1, head2, type) do {                \
347     struct type *swap_first = STAILQ_FIRST(head1);          \
348     struct type **swap_last = (head1)->stqh_last;           \
349     STAILQ_FIRST(head1) = STAILQ_FIRST(head2);          \
350     (head1)->stqh_last = (head2)->stqh_last;            \
351     STAILQ_FIRST(head2) = swap_first;               \
352     (head2)->stqh_last = swap_last;                 \
353     if (STAILQ_EMPTY(head1))                    \
354         (head1)->stqh_last = &STAILQ_FIRST(head1);      \
355     if (STAILQ_EMPTY(head2))                    \
356         (head2)->stqh_last = &STAILQ_FIRST(head2);      \
357 } while (0)
358 
359 /*
360  * List declarations.
361  */
362 #define LIST_HEAD(name, type)                       \
363 struct name {                               \
364     struct type *lh_first;  /* first element */         \
365 }
366 
367 #define LIST_HEAD_INITIALIZER(head)                 \
368     { NULL }
369 
370 #define LIST_ENTRY(type)                        \
371 struct {                                \
372     struct type *le_next;   /* next element */          \
373     struct type **le_prev;  /* address of previous next element */  \
374 }
375 
376 /*
377  * List functions.
378  */
379 
380 #if (defined(_KERNEL) && defined(INVARIANTS))
381 #define QMD_LIST_CHECK_HEAD(head, field) do {               \
382     if (LIST_FIRST((head)) != NULL &&               \
383         LIST_FIRST((head))->field.le_prev !=            \
384          &LIST_FIRST((head)))                   \
385         panic("Bad list head %p first->prev != head", (head));  \
386 } while (0)
387 
388 #define QMD_LIST_CHECK_NEXT(elm, field) do {                \
389     if (LIST_NEXT((elm), field) != NULL &&              \
390         LIST_NEXT((elm), field)->field.le_prev !=           \
391          &((elm)->field.le_next))                   \
392             panic("Bad link elm %p next->prev != elm", (elm));  \
393 } while (0)
394 
395 #define QMD_LIST_CHECK_PREV(elm, field) do {                \
396     if (*(elm)->field.le_prev != (elm))             \
397         panic("Bad link elm %p prev->next != elm", (elm));  \
398 } while (0)
399 #else
400 #define QMD_LIST_CHECK_HEAD(head, field)
401 #define QMD_LIST_CHECK_NEXT(elm, field)
402 #define QMD_LIST_CHECK_PREV(elm, field)
403 #endif /* (_KERNEL && INVARIANTS) */
404 
405 #define LIST_EMPTY(head)    ((head)->lh_first == NULL)
406 
407 #define LIST_FIRST(head)    ((head)->lh_first)
408 
409 #define LIST_FOREACH(var, head, field)                  \
410     for ((var) = LIST_FIRST((head));                \
411         (var);                          \
412         (var) = LIST_NEXT((var), field))
413 
414 #define LIST_FOREACH_FROM(var, head, field)             \
415     for ((var) = ((var) ? (var) : LIST_FIRST((head)));      \
416         (var);                          \
417         (var) = LIST_NEXT((var), field))
418 
419 #define LIST_FOREACH_SAFE(var, head, field, tvar)           \
420     for ((var) = LIST_FIRST((head));                \
421         (var) && ((tvar) = LIST_NEXT((var), field), 1);     \
422         (var) = (tvar))
423 
424 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar)          \
425     for ((var) = ((var) ? (var) : LIST_FIRST((head)));      \
426         (var) && ((tvar) = LIST_NEXT((var), field), 1);     \
427         (var) = (tvar))
428 
429 #define LIST_INIT(head) do {                        \
430     LIST_FIRST((head)) = NULL;                  \
431 } while (0)
432 
433 #define LIST_INSERT_AFTER(listelm, elm, field) do {                         \
434     QMD_LIST_CHECK_NEXT(listelm, field);                                    \
435     if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)    \
436         LIST_NEXT((listelm), field)->field.le_prev =                        \
437             &LIST_NEXT((elm), field);                                       \
438     LIST_NEXT((listelm), field) = (elm);                                    \
439     (elm)->field.le_prev = &LIST_NEXT((listelm), field);                    \
440 } while (0)
441 
442 #define LIST_INSERT_BEFORE(listelm, elm, field) do {            \
443     QMD_LIST_CHECK_PREV(listelm, field);                \
444     (elm)->field.le_prev = (listelm)->field.le_prev;        \
445     LIST_NEXT((elm), field) = (listelm);                \
446     *(listelm)->field.le_prev = (elm);              \
447     (listelm)->field.le_prev = &LIST_NEXT((elm), field);        \
448 } while (0)
449 
450 #define LIST_INSERT_HEAD(head, elm, field) do {             \
451     QMD_LIST_CHECK_HEAD((head), field);             \
452     if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
453         LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field); \
454     LIST_FIRST((head)) = (elm);                 \
455     (elm)->field.le_prev = &LIST_FIRST((head));         \
456 } while (0)
457 
458 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
459 
460 #define LIST_PREV(elm, head, type, field)               \
461     ((elm)->field.le_prev == &LIST_FIRST((head)) ?      \
462     NULL : __containerof((elm)->(field).le_prev, struct type, (field).le_next))
463 
464 #define LIST_REMOVE(elm, field) do {                    \
465     QMD_SAVELINK(oldnext, (elm)->field.le_next);            \
466     QMD_SAVELINK(oldprev, (elm)->field.le_prev);            \
467     QMD_LIST_CHECK_NEXT(elm, field);                \
468     QMD_LIST_CHECK_PREV(elm, field);                \
469     if (LIST_NEXT((elm), field) != NULL)                \
470         LIST_NEXT((elm), field)->field.le_prev =        \
471             (elm)->field.le_prev;               \
472     *(elm)->field.le_prev = LIST_NEXT((elm), field);        \
473     TRASHIT(*oldnext);                      \
474     TRASHIT(*oldprev);                      \
475 } while (0)
476 
477 #define LIST_SWAP(head1, head2, type, field) do {           \
478     struct type *swap_tmp = LIST_FIRST((head1));            \
479     LIST_FIRST((head1)) = LIST_FIRST((head2));          \
480     LIST_FIRST((head2)) = swap_tmp;                 \
481     if ((swap_tmp = LIST_FIRST((head1))) != NULL)           \
482         swap_tmp->field.le_prev = &LIST_FIRST((head1));     \
483     if ((swap_tmp = LIST_FIRST((head2))) != NULL)           \
484         swap_tmp->field.le_prev = &LIST_FIRST((head2));     \
485 } while (0)
486 
487 /*
488  * Tail queue declarations.
489  */
490 #define TAILQ_HEAD(name, type)                      \
491 struct name {                               \
492     struct type *tqh_first; /* first element */         \
493     struct type **tqh_last; /* addr of last next element */     \
494     TRACEBUF                            \
495 }
496 
497 #define TAILQ_HEAD_INITIALIZER(head)                    \
498     { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
499 
500 #define TAILQ_ENTRY(type)                       \
501 struct {                                \
502     struct type *tqe_next;  /* next element */          \
503     struct type **tqe_prev; /* address of previous next element */  \
504     TRACEBUF                            \
505 }
506 
507 /*
508  * Tail queue functions.
509  */
510 #if (defined(_KERNEL) && defined(INVARIANTS))
511 #define QMD_TAILQ_CHECK_HEAD(head, field) do {              \
512     if (!TAILQ_EMPTY(head) &&                   \
513         TAILQ_FIRST((head))->field.tqe_prev !=          \
514          &TAILQ_FIRST((head)))                  \
515         panic("Bad tailq head %p first->prev != head", (head)); \
516 } while (0)
517 
518 #define QMD_TAILQ_CHECK_TAIL(head, field) do {              \
519     if (*(head)->tqh_last != NULL)                  \
520             panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
521 } while (0)
522 
523 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {               \
524     if (TAILQ_NEXT((elm), field) != NULL &&             \
525         TAILQ_NEXT((elm), field)->field.tqe_prev !=         \
526          &((elm)->field.tqe_next))                  \
527         panic("Bad link elm %p next->prev != elm", (elm));  \
528 } while (0)
529 
530 #define QMD_TAILQ_CHECK_PREV(elm, field) do {               \
531     if (*(elm)->field.tqe_prev != (elm))                \
532         panic("Bad link elm %p prev->next != elm", (elm));  \
533 } while (0)
534 #else
535 #define QMD_TAILQ_CHECK_HEAD(head, field)
536 #define QMD_TAILQ_CHECK_TAIL(head, headname)
537 #define QMD_TAILQ_CHECK_NEXT(elm, field)
538 #define QMD_TAILQ_CHECK_PREV(elm, field)
539 #endif /* (_KERNEL && INVARIANTS) */
540 
541 #define TAILQ_CONCAT(head1, head2, field) do {              \
542     if (!TAILQ_EMPTY(head2)) {                  \
543         *(head1)->tqh_last = (head2)->tqh_first;        \
544         (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
545         (head1)->tqh_last = (head2)->tqh_last;          \
546         TAILQ_INIT((head2));                    \
547         QMD_TRACE_HEAD(head1);                  \
548         QMD_TRACE_HEAD(head2);                  \
549     }                               \
550 } while (0)
551 
552 #define TAILQ_EMPTY(head)   ((head)->tqh_first == NULL)
553 
554 #define TAILQ_FIRST(head)   ((head)->tqh_first)
555 
556 #define TAILQ_FOREACH(var, head, field)                 \
557     for ((var) = TAILQ_FIRST((head));               \
558         (var);                          \
559         (var) = TAILQ_NEXT((var), field))
560 
561 #define TAILQ_FOREACH_FROM(var, head, field)                \
562     for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));     \
563         (var);                          \
564         (var) = TAILQ_NEXT((var), field))
565 
566 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)          \
567     for ((var) = TAILQ_FIRST((head));               \
568         (var) && ((tvar) = TAILQ_NEXT((var), field), 1);        \
569         (var) = (tvar))
570 
571 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)         \
572     for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));     \
573         (var) && ((tvar) = TAILQ_NEXT((var), field), 1);        \
574         (var) = (tvar))
575 
576 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)       \
577     for ((var) = TAILQ_LAST((head), headname);          \
578         (var);                          \
579         (var) = TAILQ_PREV((var), headname, field))
580 
581 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field)      \
582     for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
583         (var);                          \
584         (var) = TAILQ_PREV((var), headname, field))
585 
586 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
587     for ((var) = TAILQ_LAST((head), headname);          \
588         (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
589         (var) = (tvar))
590 
591 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
592     for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
593         (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
594         (var) = (tvar))
595 
596 #define TAILQ_INIT(head) do {                       \
597     TAILQ_FIRST((head)) = NULL;                 \
598     (head)->tqh_last = &TAILQ_FIRST((head));            \
599     QMD_TRACE_HEAD(head);                       \
600 } while (0)
601 
602 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {      \
603     QMD_TAILQ_CHECK_NEXT(listelm, field);               \
604     if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL) \
605         TAILQ_NEXT((elm), field)->field.tqe_prev =      \
606             &TAILQ_NEXT((elm), field);              \
607     else {                              \
608         (head)->tqh_last = &TAILQ_NEXT((elm), field);       \
609         QMD_TRACE_HEAD(head);                   \
610     }                               \
611     TAILQ_NEXT((listelm), field) = (elm);               \
612     (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);      \
613     QMD_TRACE_ELEM(&(elm)->field);                  \
614     QMD_TRACE_ELEM(&(listelm)->field);                \
615 } while (0)
616 
617 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {           \
618     QMD_TAILQ_CHECK_PREV(listelm, field);               \
619     (elm)->field.tqe_prev = (listelm)->field.tqe_prev;      \
620     TAILQ_NEXT((elm), field) = (listelm);               \
621     *(listelm)->field.tqe_prev = (elm);             \
622     (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);      \
623     QMD_TRACE_ELEM(&(elm)->field);                  \
624     QMD_TRACE_ELEM(&(listelm)->field);                \
625 } while (0)
626 
627 #define TAILQ_INSERT_HEAD(head, elm, field) do {            \
628     QMD_TAILQ_CHECK_HEAD(head, field);              \
629     if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
630         TAILQ_FIRST((head))->field.tqe_prev =           \
631             &TAILQ_NEXT((elm), field);              \
632     else                                \
633         (head)->tqh_last = &TAILQ_NEXT((elm), field);       \
634     TAILQ_FIRST((head)) = (elm);                    \
635     (elm)->field.tqe_prev = &TAILQ_FIRST((head));           \
636     QMD_TRACE_HEAD(head);                       \
637     QMD_TRACE_ELEM(&(elm)->field);                  \
638 } while (0)
639 
640 #define TAILQ_INSERT_TAIL(head, elm, field) do {            \
641     QMD_TAILQ_CHECK_TAIL(head, field);              \
642     TAILQ_NEXT((elm), field) = NULL;                \
643     (elm)->field.tqe_prev = (head)->tqh_last;           \
644     *(head)->tqh_last = (elm);                  \
645     (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
646     QMD_TRACE_HEAD(head);                       \
647     QMD_TRACE_ELEM(&(elm)->field);                  \
648 } while (0)
649 
650 #define TAILQ_LAST(head, headname)                  \
651     (*(((struct headname *)((head)->tqh_last))->tqh_last))
652 
653 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
654 
655 #define TAILQ_PREV(elm, headname, field)                \
656     (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
657 
658 #define TAILQ_REMOVE(head, elm, field) do {             \
659     QMD_SAVELINK(oldnext, (elm)->field.tqe_next);           \
660     QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);           \
661     QMD_TAILQ_CHECK_NEXT(elm, field);               \
662     QMD_TAILQ_CHECK_PREV(elm, field);               \
663     if ((TAILQ_NEXT((elm), field)) != NULL)             \
664         TAILQ_NEXT((elm), field)->field.tqe_prev =      \
665             (elm)->field.tqe_prev;              \
666     else {                              \
667         (head)->tqh_last = (elm)->field.tqe_prev;       \
668         QMD_TRACE_HEAD(head);                   \
669     }                               \
670     *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);      \
671     TRASHIT(*oldnext);                      \
672     TRASHIT(*oldprev);                      \
673     QMD_TRACE_ELEM(&(elm)->field);                  \
674 } while (0)
675 
676 #define TAILQ_SWAP(head1, head2, type, field) do {          \
677     struct type *swap_first = (head1)->tqh_first;           \
678     struct type **swap_last = (head1)->tqh_last;            \
679     (head1)->tqh_first = (head2)->tqh_first;            \
680     (head1)->tqh_last = (head2)->tqh_last;              \
681     (head2)->tqh_first = swap_first;                \
682     (head2)->tqh_last = swap_last;                  \
683     if ((swap_first = (head1)->tqh_first) != NULL)          \
684         swap_first->field.tqe_prev = &(head1)->tqh_first;   \
685     else                                \
686         (head1)->tqh_last = &(head1)->tqh_first;        \
687     if ((swap_first = (head2)->tqh_first) != NULL)          \
688         swap_first->field.tqe_prev = &(head2)->tqh_first;   \
689     else                                \
690         (head2)->tqh_last = &(head2)->tqh_first;        \
691 } while (0)
692 
693 #endif /* !_SYS_QUEUE_H */
694