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queue.h
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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  * @(#)queue.h 8.5 (Berkeley) 8/20/94
32  * $FreeBSD$
33  */
34 
35 #ifndef _SYS_QUEUE_H_
36 #define _SYS_QUEUE_H_
37 
38 /*
39  * This file defines four types of data structures: singly-linked lists,
40  * singly-linked tail queues, lists and tail queues.
41  *
42  * A singly-linked list is headed by a single forward pointer. The elements
43  * are singly linked for minimum space and pointer manipulation overhead at
44  * the expense of O(n) removal for arbitrary elements. New elements can be
45  * added to the list after an existing element or at the head of the list.
46  * Elements being removed from the head of the list should use the explicit
47  * macro for this purpose for optimum efficiency. A singly-linked list may
48  * only be traversed in the forward direction. Singly-linked lists are ideal
49  * for applications with large datasets and few or no removals or for
50  * implementing a LIFO queue.
51  *
52  * A singly-linked tail queue is headed by a pair of pointers, one to the
53  * head of the list and the other to the tail of the list. The elements are
54  * singly linked for minimum space and pointer manipulation overhead at the
55  * expense of O(n) removal for arbitrary elements. New elements can be added
56  * to the list after an existing element, at the head of the list, or at the
57  * end of the list. Elements being removed from the head of the tail queue
58  * should use the explicit macro for this purpose for optimum efficiency.
59  * A singly-linked tail queue may only be traversed in the forward direction.
60  * Singly-linked tail queues are ideal for applications with large datasets
61  * and few or no removals or for implementing a FIFO queue.
62  *
63  * A list is headed by a single forward pointer (or an array of forward
64  * pointers for a hash table header). The elements are doubly linked
65  * so that an arbitrary element can be removed without a need to
66  * traverse the list. New elements can be added to the list before
67  * or after an existing element or at the head of the list. A list
68  * may be traversed in either direction.
69  *
70  * A tail queue is headed by a pair of pointers, one to the head of the
71  * list and the other to the tail of the list. The elements are doubly
72  * linked so that an arbitrary element can be removed without a need to
73  * traverse the list. New elements can be added to the list before or
74  * after an existing element, at the head of the list, or at the end of
75  * the list. A tail queue may be traversed in either direction.
76  *
77  * For details on the use of these macros, see the queue(3) manual page.
78  *
79  * Below is a summary of implemented functions where:
80  * + means the macro is available
81  * - means the macro is not available
82  * s means the macro is available but is slow (runs in O(n) time)
83  *
84  * SLIST LIST STAILQ TAILQ
85  * _HEAD + + + +
86  * _CLASS_HEAD + + + +
87  * _HEAD_INITIALIZER + + + +
88  * _ENTRY + + + +
89  * _CLASS_ENTRY + + + +
90  * _INIT + + + +
91  * _EMPTY + + + +
92  * _END + + + +
93  * _FIRST + + + +
94  * _NEXT + + + +
95  * _PREV - + - +
96  * _LAST - - + +
97  * _LAST_FAST - - - +
98  * _FOREACH + + + +
99  * _FOREACH_FROM + + + +
100  * _FOREACH_SAFE + + + +
101  * _FOREACH_FROM_SAFE + + + +
102  * _FOREACH_REVERSE - - - +
103  * _FOREACH_REVERSE_FROM - - - +
104  * _FOREACH_REVERSE_SAFE - - - +
105  * _FOREACH_REVERSE_FROM_SAFE - - - +
106  * _INSERT_HEAD + + + +
107  * _INSERT_BEFORE - + - +
108  * _INSERT_AFTER + + + +
109  * _INSERT_TAIL - - + +
110  * _CONCAT s s + +
111  * _REMOVE_AFTER + - + -
112  * _REMOVE_HEAD + - + -
113  * _REMOVE s + s +
114  * _SWAP + + + +
115  *
116  */
117 #ifdef QUEUE_MACRO_DEBUG
118 #warn Use QUEUE_MACRO_DEBUG_TRACE and/or QUEUE_MACRO_DEBUG_TRASH
119 #define QUEUE_MACRO_DEBUG_TRACE
120 #define QUEUE_MACRO_DEBUG_TRASH
121 #endif
122 
123 #ifdef QUEUE_MACRO_DEBUG_TRACE
124 /* Store the last 2 places the queue element or head was altered */
125 struct 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 #ifdef __cplusplus
167 /*
168  * In C++ there can be structure lists and class lists:
169  */
170 #define QUEUE_TYPEOF(type) type
171 #else
172 #define QUEUE_TYPEOF(type) struct type
173 #endif
174 
175 /*
176  * Singly-linked List declarations.
177  */
178 #define SLIST_HEAD(name, type) \
179 struct name { \
180  struct type *slh_first; /* first element */ \
181 }
182 
183 #define SLIST_CLASS_HEAD(name, type) \
184 struct name { \
185  class type *slh_first; /* first element */ \
186 }
187 
188 #define SLIST_HEAD_INITIALIZER(head) \
189  { NULL }
190 
191 #define SLIST_ENTRY(type) \
192 struct { \
193  struct type *sle_next; /* next element */ \
194 }
195 
196 #define SLIST_CLASS_ENTRY(type) \
197 struct { \
198  class type *sle_next; /* next element */ \
199 }
200 
201 /*
202  * Singly-linked List functions.
203  */
204 #if (defined(_KERNEL) && defined(INVARIANTS))
205 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm) do { \
206  if (*(prevp) != (elm)) \
207  panic("Bad prevptr *(%p) == %p != %p", \
208  (prevp), *(prevp), (elm)); \
209 } while (0)
210 #else
211 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm)
212 #endif
213 
214 #define SLIST_CONCAT(head1, head2, type, field) do { \
215  QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1); \
216  if (curelm == NULL) { \
217  if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL) \
218  SLIST_INIT(head2); \
219  } else if (SLIST_FIRST(head2) != NULL) { \
220  while (SLIST_NEXT(curelm, field) != NULL) \
221  curelm = SLIST_NEXT(curelm, field); \
222  SLIST_NEXT(curelm, field) = SLIST_FIRST(head2); \
223  SLIST_INIT(head2); \
224  } \
225 } while (0)
226 
227 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
228 
229 #define SLIST_FIRST(head) ((head)->slh_first)
230 
231 #define SLIST_FOREACH(var, head, field) \
232  for ((var) = SLIST_FIRST((head)); \
233  (var); \
234  (var) = SLIST_NEXT((var), field))
235 
236 #define SLIST_FOREACH_FROM(var, head, field) \
237  for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
238  (var); \
239  (var) = SLIST_NEXT((var), field))
240 
241 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
242  for ((var) = SLIST_FIRST((head)); \
243  (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
244  (var) = (tvar))
245 
246 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
247  for ((var) = ((var) ? (var) : SLIST_FIRST((head))); \
248  (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
249  (var) = (tvar))
250 
251 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
252  for ((varp) = &SLIST_FIRST((head)); \
253  ((var) = *(varp)) != NULL; \
254  (varp) = &SLIST_NEXT((var), field))
255 
256 #define SLIST_INIT(head) do { \
257  SLIST_FIRST((head)) = NULL; \
258 } while (0)
259 
260 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
261  SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
262  SLIST_NEXT((slistelm), field) = (elm); \
263 } while (0)
264 
265 #define SLIST_INSERT_HEAD(head, elm, field) do { \
266  SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
267  SLIST_FIRST((head)) = (elm); \
268 } while (0)
269 
270 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
271 
272 #define SLIST_REMOVE(head, elm, type, field) do { \
273  QMD_SAVELINK(oldnext, (elm)->field.sle_next); \
274  if (SLIST_FIRST((head)) == (elm)) { \
275  SLIST_REMOVE_HEAD((head), field); \
276  } \
277  else { \
278  QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head); \
279  while (SLIST_NEXT(curelm, field) != (elm)) \
280  curelm = SLIST_NEXT(curelm, field); \
281  SLIST_REMOVE_AFTER(curelm, field); \
282  } \
283  TRASHIT(*oldnext); \
284 } while (0)
285 
286 #define SLIST_REMOVE_AFTER(elm, field) do { \
287  SLIST_NEXT(elm, field) = \
288  SLIST_NEXT(SLIST_NEXT(elm, field), field); \
289 } while (0)
290 
291 #define SLIST_REMOVE_HEAD(head, field) do { \
292  SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
293 } while (0)
294 
295 #define SLIST_REMOVE_PREVPTR(prevp, elm, field) do { \
296  QMD_SLIST_CHECK_PREVPTR(prevp, elm); \
297  *(prevp) = SLIST_NEXT(elm, field); \
298  TRASHIT((elm)->field.sle_next); \
299 } while (0)
300 
301 #define SLIST_SWAP(head1, head2, type) do { \
302  QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1); \
303  SLIST_FIRST(head1) = SLIST_FIRST(head2); \
304  SLIST_FIRST(head2) = swap_first; \
305 } while (0)
306 
307 #define SLIST_END(head) NULL
308 
309 /*
310  * Singly-linked Tail queue declarations.
311  */
312 #define STAILQ_HEAD(name, type) \
313 struct name { \
314  struct type *stqh_first;/* first element */ \
315  struct type **stqh_last;/* addr of last next element */ \
316 }
317 
318 #define STAILQ_CLASS_HEAD(name, type) \
319 struct name { \
320  class type *stqh_first; /* first element */ \
321  class type **stqh_last; /* addr of last next element */ \
322 }
323 
324 #define STAILQ_HEAD_INITIALIZER(head) \
325  { NULL, &(head).stqh_first }
326 
327 #define STAILQ_ENTRY(type) \
328 struct { \
329  struct type *stqe_next; /* next element */ \
330 }
331 
332 #define STAILQ_CLASS_ENTRY(type) \
333 struct { \
334  class type *stqe_next; /* next element */ \
335 }
336 
337 /*
338  * Singly-linked Tail queue functions.
339  */
340 #define STAILQ_CONCAT(head1, head2) do { \
341  if (!STAILQ_EMPTY((head2))) { \
342  *(head1)->stqh_last = (head2)->stqh_first; \
343  (head1)->stqh_last = (head2)->stqh_last; \
344  STAILQ_INIT((head2)); \
345  } \
346 } while (0)
347 
348 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
349 
350 #define STAILQ_FIRST(head) ((head)->stqh_first)
351 
352 #define STAILQ_FOREACH(var, head, field) \
353  for((var) = STAILQ_FIRST((head)); \
354  (var); \
355  (var) = STAILQ_NEXT((var), field))
356 
357 #define STAILQ_FOREACH_FROM(var, head, field) \
358  for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
359  (var); \
360  (var) = STAILQ_NEXT((var), field))
361 
362 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
363  for ((var) = STAILQ_FIRST((head)); \
364  (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
365  (var) = (tvar))
366 
367 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
368  for ((var) = ((var) ? (var) : STAILQ_FIRST((head))); \
369  (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
370  (var) = (tvar))
371 
372 #define STAILQ_INIT(head) do { \
373  STAILQ_FIRST((head)) = NULL; \
374  (head)->stqh_last = &STAILQ_FIRST((head)); \
375 } while (0)
376 
377 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
378  if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
379  (head)->stqh_last = &STAILQ_NEXT((elm), field); \
380  STAILQ_NEXT((tqelm), field) = (elm); \
381 } while (0)
382 
383 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
384  if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
385  (head)->stqh_last = &STAILQ_NEXT((elm), field); \
386  STAILQ_FIRST((head)) = (elm); \
387 } while (0)
388 
389 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
390  STAILQ_NEXT((elm), field) = NULL; \
391  *(head)->stqh_last = (elm); \
392  (head)->stqh_last = &STAILQ_NEXT((elm), field); \
393 } while (0)
394 
395 #define STAILQ_LAST(head, type, field) \
396  (STAILQ_EMPTY((head)) ? NULL : \
397  __containerof((head)->stqh_last, \
398  QUEUE_TYPEOF(type), field.stqe_next))
399 
400 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
401 
402 #define STAILQ_REMOVE(head, elm, type, field) do { \
403  QMD_SAVELINK(oldnext, (elm)->field.stqe_next); \
404  if (STAILQ_FIRST((head)) == (elm)) { \
405  STAILQ_REMOVE_HEAD((head), field); \
406  } \
407  else { \
408  QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head); \
409  while (STAILQ_NEXT(curelm, field) != (elm)) \
410  curelm = STAILQ_NEXT(curelm, field); \
411  STAILQ_REMOVE_AFTER(head, curelm, field); \
412  } \
413  TRASHIT(*oldnext); \
414 } while (0)
415 
416 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \
417  if ((STAILQ_NEXT(elm, field) = \
418  STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
419  (head)->stqh_last = &STAILQ_NEXT((elm), field); \
420 } while (0)
421 
422 #define STAILQ_REMOVE_HEAD(head, field) do { \
423  if ((STAILQ_FIRST((head)) = \
424  STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
425  (head)->stqh_last = &STAILQ_FIRST((head)); \
426 } while (0)
427 
428 #define STAILQ_SWAP(head1, head2, type) do { \
429  QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1); \
430  QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last; \
431  STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
432  (head1)->stqh_last = (head2)->stqh_last; \
433  STAILQ_FIRST(head2) = swap_first; \
434  (head2)->stqh_last = swap_last; \
435  if (STAILQ_EMPTY(head1)) \
436  (head1)->stqh_last = &STAILQ_FIRST(head1); \
437  if (STAILQ_EMPTY(head2)) \
438  (head2)->stqh_last = &STAILQ_FIRST(head2); \
439 } while (0)
440 
441 #define STAILQ_END(head) NULL
442 
443 
444 /*
445  * List declarations.
446  */
447 #define LIST_HEAD(name, type) \
448 struct name { \
449  struct type *lh_first; /* first element */ \
450 }
451 
452 #define LIST_CLASS_HEAD(name, type) \
453 struct name { \
454  class type *lh_first; /* first element */ \
455 }
456 
457 #define LIST_HEAD_INITIALIZER(head) \
458  { NULL }
459 
460 #define LIST_ENTRY(type) \
461 struct { \
462  struct type *le_next; /* next element */ \
463  struct type **le_prev; /* address of previous next element */ \
464 }
465 
466 #define LIST_CLASS_ENTRY(type) \
467 struct { \
468  class type *le_next; /* next element */ \
469  class type **le_prev; /* address of previous next element */ \
470 }
471 
472 /*
473  * List functions.
474  */
475 
476 #if (defined(_KERNEL) && defined(INVARIANTS))
477 /*
478  * QMD_LIST_CHECK_HEAD(LIST_HEAD *head, LIST_ENTRY NAME)
479  *
480  * If the list is non-empty, validates that the first element of the list
481  * points back at 'head.'
482  */
483 #define QMD_LIST_CHECK_HEAD(head, field) do { \
484  if (LIST_FIRST((head)) != NULL && \
485  LIST_FIRST((head))->field.le_prev != \
486  &LIST_FIRST((head))) \
487  panic("Bad list head %p first->prev != head", (head)); \
488 } while (0)
489 
490 /*
491  * QMD_LIST_CHECK_NEXT(TYPE *elm, LIST_ENTRY NAME)
492  *
493  * If an element follows 'elm' in the list, validates that the next element
494  * points back at 'elm.'
495  */
496 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
497  if (LIST_NEXT((elm), field) != NULL && \
498  LIST_NEXT((elm), field)->field.le_prev != \
499  &((elm)->field.le_next)) \
500  panic("Bad link elm %p next->prev != elm", (elm)); \
501 } while (0)
502 
503 /*
504  * QMD_LIST_CHECK_PREV(TYPE *elm, LIST_ENTRY NAME)
505  *
506  * Validates that the previous element (or head of the list) points to 'elm.'
507  */
508 #define QMD_LIST_CHECK_PREV(elm, field) do { \
509  if (*(elm)->field.le_prev != (elm)) \
510  panic("Bad link elm %p prev->next != elm", (elm)); \
511 } while (0)
512 #else
513 #define QMD_LIST_CHECK_HEAD(head, field)
514 #define QMD_LIST_CHECK_NEXT(elm, field)
515 #define QMD_LIST_CHECK_PREV(elm, field)
516 #endif /* (_KERNEL && INVARIANTS) */
517 
518 #define LIST_CONCAT(head1, head2, type, field) do { \
519  QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1); \
520  if (curelm == NULL) { \
521  if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) { \
522  LIST_FIRST(head2)->field.le_prev = \
523  &LIST_FIRST((head1)); \
524  LIST_INIT(head2); \
525  } \
526  } else if (LIST_FIRST(head2) != NULL) { \
527  while (LIST_NEXT(curelm, field) != NULL) \
528  curelm = LIST_NEXT(curelm, field); \
529  LIST_NEXT(curelm, field) = LIST_FIRST(head2); \
530  LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
531  LIST_INIT(head2); \
532  } \
533 } while (0)
534 
535 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
536 
537 #define LIST_FIRST(head) ((head)->lh_first)
538 
539 #define LIST_FOREACH(var, head, field) \
540  for ((var) = LIST_FIRST((head)); \
541  (var); \
542  (var) = LIST_NEXT((var), field))
543 
544 #define LIST_FOREACH_FROM(var, head, field) \
545  for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
546  (var); \
547  (var) = LIST_NEXT((var), field))
548 
549 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
550  for ((var) = LIST_FIRST((head)); \
551  (var) && ((tvar) = LIST_NEXT((var), field), 1); \
552  (var) = (tvar))
553 
554 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar) \
555  for ((var) = ((var) ? (var) : LIST_FIRST((head))); \
556  (var) && ((tvar) = LIST_NEXT((var), field), 1); \
557  (var) = (tvar))
558 
559 #define LIST_INIT(head) do { \
560  LIST_FIRST((head)) = NULL; \
561 } while (0)
562 
563 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
564  QMD_LIST_CHECK_NEXT(listelm, field); \
565  if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
566  LIST_NEXT((listelm), field)->field.le_prev = \
567  &LIST_NEXT((elm), field); \
568  LIST_NEXT((listelm), field) = (elm); \
569  (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
570 } while (0)
571 
572 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
573  QMD_LIST_CHECK_PREV(listelm, field); \
574  (elm)->field.le_prev = (listelm)->field.le_prev; \
575  LIST_NEXT((elm), field) = (listelm); \
576  *(listelm)->field.le_prev = (elm); \
577  (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
578 } while (0)
579 
580 #define LIST_INSERT_HEAD(head, elm, field) do { \
581  QMD_LIST_CHECK_HEAD((head), field); \
582  if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
583  LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
584  LIST_FIRST((head)) = (elm); \
585  (elm)->field.le_prev = &LIST_FIRST((head)); \
586 } while (0)
587 
588 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
589 
590 #define LIST_PREV(elm, head, type, field) \
591  ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL : \
592  __containerof((elm)->field.le_prev, \
593  QUEUE_TYPEOF(type), field.le_next))
594 
595 #define LIST_REMOVE(elm, field) do { \
596  QMD_SAVELINK(oldnext, (elm)->field.le_next); \
597  QMD_SAVELINK(oldprev, (elm)->field.le_prev); \
598  QMD_LIST_CHECK_NEXT(elm, field); \
599  QMD_LIST_CHECK_PREV(elm, field); \
600  if (LIST_NEXT((elm), field) != NULL) \
601  LIST_NEXT((elm), field)->field.le_prev = \
602  (elm)->field.le_prev; \
603  *(elm)->field.le_prev = LIST_NEXT((elm), field); \
604  TRASHIT(*oldnext); \
605  TRASHIT(*oldprev); \
606 } while (0)
607 
608 #define LIST_SWAP(head1, head2, type, field) do { \
609  QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1); \
610  LIST_FIRST((head1)) = LIST_FIRST((head2)); \
611  LIST_FIRST((head2)) = swap_tmp; \
612  if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
613  swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
614  if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
615  swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
616 } while (0)
617 
618 #define LIST_END(head) NULL
619 
620 /*
621  * Tail queue declarations.
622  */
623 #define TAILQ_HEAD(name, type) \
624 struct name { \
625  struct type *tqh_first; /* first element */ \
626  struct type **tqh_last; /* addr of last next element */ \
627  TRACEBUF \
628 }
629 
630 #define TAILQ_CLASS_HEAD(name, type) \
631 struct name { \
632  class type *tqh_first; /* first element */ \
633  class type **tqh_last; /* addr of last next element */ \
634  TRACEBUF \
635 }
636 
637 #define TAILQ_HEAD_INITIALIZER(head) \
638  { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
639 
640 #define TAILQ_ENTRY(type) \
641 struct { \
642  struct type *tqe_next; /* next element */ \
643  struct type **tqe_prev; /* address of previous next element */ \
644  TRACEBUF \
645 }
646 
647 #define TAILQ_CLASS_ENTRY(type) \
648 struct { \
649  class type *tqe_next; /* next element */ \
650  class type **tqe_prev; /* address of previous next element */ \
651  TRACEBUF \
652 }
653 
654 /*
655  * Tail queue functions.
656  */
657 #if (defined(_KERNEL) && defined(INVARIANTS))
658 /*
659  * QMD_TAILQ_CHECK_HEAD(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
660  *
661  * If the tailq is non-empty, validates that the first element of the tailq
662  * points back at 'head.'
663  */
664 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
665  if (!TAILQ_EMPTY(head) && \
666  TAILQ_FIRST((head))->field.tqe_prev != \
667  &TAILQ_FIRST((head))) \
668  panic("Bad tailq head %p first->prev != head", (head)); \
669 } while (0)
670 
671 /*
672  * QMD_TAILQ_CHECK_TAIL(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
673  *
674  * Validates that the tail of the tailq is a pointer to pointer to NULL.
675  */
676 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
677  if (*(head)->tqh_last != NULL) \
678  panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
679 } while (0)
680 
681 /*
682  * QMD_TAILQ_CHECK_NEXT(TYPE *elm, TAILQ_ENTRY NAME)
683  *
684  * If an element follows 'elm' in the tailq, validates that the next element
685  * points back at 'elm.'
686  */
687 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
688  if (TAILQ_NEXT((elm), field) != NULL && \
689  TAILQ_NEXT((elm), field)->field.tqe_prev != \
690  &((elm)->field.tqe_next)) \
691  panic("Bad link elm %p next->prev != elm", (elm)); \
692 } while (0)
693 
694 /*
695  * QMD_TAILQ_CHECK_PREV(TYPE *elm, TAILQ_ENTRY NAME)
696  *
697  * Validates that the previous element (or head of the tailq) points to 'elm.'
698  */
699 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
700  if (*(elm)->field.tqe_prev != (elm)) \
701  panic("Bad link elm %p prev->next != elm", (elm)); \
702 } while (0)
703 #else
704 #define QMD_TAILQ_CHECK_HEAD(head, field)
705 #define QMD_TAILQ_CHECK_TAIL(head, headname)
706 #define QMD_TAILQ_CHECK_NEXT(elm, field)
707 #define QMD_TAILQ_CHECK_PREV(elm, field)
708 #endif /* (_KERNEL && INVARIANTS) */
709 
710 #define TAILQ_CONCAT(head1, head2, field) do { \
711  if (!TAILQ_EMPTY(head2)) { \
712  *(head1)->tqh_last = (head2)->tqh_first; \
713  (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
714  (head1)->tqh_last = (head2)->tqh_last; \
715  TAILQ_INIT((head2)); \
716  QMD_TRACE_HEAD(head1); \
717  QMD_TRACE_HEAD(head2); \
718  } \
719 } while (0)
720 
721 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
722 
723 #define TAILQ_FIRST(head) ((head)->tqh_first)
724 
725 #define TAILQ_FOREACH(var, head, field) \
726  for ((var) = TAILQ_FIRST((head)); \
727  (var); \
728  (var) = TAILQ_NEXT((var), field))
729 
730 #define TAILQ_FOREACH_FROM(var, head, field) \
731  for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
732  (var); \
733  (var) = TAILQ_NEXT((var), field))
734 
735 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
736  for ((var) = TAILQ_FIRST((head)); \
737  (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
738  (var) = (tvar))
739 
740 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar) \
741  for ((var) = ((var) ? (var) : TAILQ_FIRST((head))); \
742  (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
743  (var) = (tvar))
744 
745 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
746  for ((var) = TAILQ_LAST((head), headname); \
747  (var); \
748  (var) = TAILQ_PREV((var), headname, field))
749 
750 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field) \
751  for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
752  (var); \
753  (var) = TAILQ_PREV((var), headname, field))
754 
755 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
756  for ((var) = TAILQ_LAST((head), headname); \
757  (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
758  (var) = (tvar))
759 
760 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
761  for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname)); \
762  (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
763  (var) = (tvar))
764 
765 #define TAILQ_INIT(head) do { \
766  TAILQ_FIRST((head)) = NULL; \
767  (head)->tqh_last = &TAILQ_FIRST((head)); \
768  QMD_TRACE_HEAD(head); \
769 } while (0)
770 
771 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
772  QMD_TAILQ_CHECK_NEXT(listelm, field); \
773  if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
774  TAILQ_NEXT((elm), field)->field.tqe_prev = \
775  &TAILQ_NEXT((elm), field); \
776  else { \
777  (head)->tqh_last = &TAILQ_NEXT((elm), field); \
778  QMD_TRACE_HEAD(head); \
779  } \
780  TAILQ_NEXT((listelm), field) = (elm); \
781  (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
782  QMD_TRACE_ELEM(&(elm)->field); \
783  QMD_TRACE_ELEM(&(listelm)->field); \
784 } while (0)
785 
786 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
787  QMD_TAILQ_CHECK_PREV(listelm, field); \
788  (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
789  TAILQ_NEXT((elm), field) = (listelm); \
790  *(listelm)->field.tqe_prev = (elm); \
791  (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
792  QMD_TRACE_ELEM(&(elm)->field); \
793  QMD_TRACE_ELEM(&(listelm)->field); \
794 } while (0)
795 
796 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
797  QMD_TAILQ_CHECK_HEAD(head, field); \
798  if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
799  TAILQ_FIRST((head))->field.tqe_prev = \
800  &TAILQ_NEXT((elm), field); \
801  else \
802  (head)->tqh_last = &TAILQ_NEXT((elm), field); \
803  TAILQ_FIRST((head)) = (elm); \
804  (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
805  QMD_TRACE_HEAD(head); \
806  QMD_TRACE_ELEM(&(elm)->field); \
807 } while (0)
808 
809 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
810  QMD_TAILQ_CHECK_TAIL(head, field); \
811  TAILQ_NEXT((elm), field) = NULL; \
812  (elm)->field.tqe_prev = (head)->tqh_last; \
813  *(head)->tqh_last = (elm); \
814  (head)->tqh_last = &TAILQ_NEXT((elm), field); \
815  QMD_TRACE_HEAD(head); \
816  QMD_TRACE_ELEM(&(elm)->field); \
817 } while (0)
818 
819 #define TAILQ_LAST(head, headname) \
820  (*(((struct headname *)((head)->tqh_last))->tqh_last))
821 
822 /*
823  * The FAST function is fast in that it causes no data access other
824  * then the access to the head. The standard LAST function above
825  * will cause a data access of both the element you want and
826  * the previous element. FAST is very useful for instances when
827  * you may want to prefetch the last data element.
828  */
829 #define TAILQ_LAST_FAST(head, type, field) \
830  (TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last, QUEUE_TYPEOF(type), field.tqe_next))
831 
832 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
833 
834 #define TAILQ_PREV(elm, headname, field) \
835  (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
836 
837 #define TAILQ_PREV_FAST(elm, head, type, field) \
838  ((elm)->field.tqe_prev == &(head)->tqh_first ? NULL : \
839  __containerof((elm)->field.tqe_prev, QUEUE_TYPEOF(type), field.tqe_next))
840 
841 #define TAILQ_REMOVE(head, elm, field) do { \
842  QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
843  QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
844  QMD_TAILQ_CHECK_NEXT(elm, field); \
845  QMD_TAILQ_CHECK_PREV(elm, field); \
846  if ((TAILQ_NEXT((elm), field)) != NULL) \
847  TAILQ_NEXT((elm), field)->field.tqe_prev = \
848  (elm)->field.tqe_prev; \
849  else { \
850  (head)->tqh_last = (elm)->field.tqe_prev; \
851  QMD_TRACE_HEAD(head); \
852  } \
853  *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
854  TRASHIT(*oldnext); \
855  TRASHIT(*oldprev); \
856  QMD_TRACE_ELEM(&(elm)->field); \
857 } while (0)
858 
859 #define TAILQ_SWAP(head1, head2, type, field) do { \
860  QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first; \
861  QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last; \
862  (head1)->tqh_first = (head2)->tqh_first; \
863  (head1)->tqh_last = (head2)->tqh_last; \
864  (head2)->tqh_first = swap_first; \
865  (head2)->tqh_last = swap_last; \
866  if ((swap_first = (head1)->tqh_first) != NULL) \
867  swap_first->field.tqe_prev = &(head1)->tqh_first; \
868  else \
869  (head1)->tqh_last = &(head1)->tqh_first; \
870  if ((swap_first = (head2)->tqh_first) != NULL) \
871  swap_first->field.tqe_prev = &(head2)->tqh_first; \
872  else \
873  (head2)->tqh_last = &(head2)->tqh_first; \
874 } while (0)
875 
876 #define TAILQ_END(head) NULL
877 
878 #endif /* !_SYS_QUEUE_H_ */