1 /*
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)queue.h 8.5 (Berkeley) 8/20/94
30 * $FreeBSD: src/sys/sys/queue.h,v 1.58 2004/04/07 04:19:49 imp Exp $
31 */
32
33 #ifndef _SYS_QUEUE_H_
34 #define _SYS_QUEUE_H_
35
36 #include <stddef.h>
37
38 #ifndef offsetof
39 #define offsetof(type, field) ((size_t)(&((type *)0)->field))
40 #endif
41
42 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
43 for ((var) = STAILQ_FIRST((head)); \
44 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
45 (var) = (tvar))
46
47 /*
48 * This file defines four types of data structures: singly-linked lists,
49 * singly-linked tail queues, lists and tail queues.
50 *
51 * A singly-linked list is headed by a single forward pointer. The elements
52 * are singly linked for minimum space and pointer manipulation overhead at
53 * the expense of O(n) removal for arbitrary elements. New elements can be
54 * added to the list after an existing element or at the head of the list.
55 * Elements being removed from the head of the list should use the explicit
56 * macro for this purpose for optimum efficiency. A singly-linked list may
57 * only be traversed in the forward direction. Singly-linked lists are ideal
58 * for applications with large datasets and few or no removals or for
59 * implementing a LIFO queue.
60 *
61 * A singly-linked tail queue is headed by a pair of pointers, one to the
62 * head of the list and the other to the tail of the list. The elements are
63 * singly linked for minimum space and pointer manipulation overhead at the
64 * expense of O(n) removal for arbitrary elements. New elements can be added
65 * to the list after an existing element, at the head of the list, or at the
66 * end of the list. Elements being removed from the head of the tail queue
67 * should use the explicit macro for this purpose for optimum efficiency.
68 * A singly-linked tail queue may only be traversed in the forward direction.
69 * Singly-linked tail queues are ideal for applications with large datasets
70 * and few or no removals or for implementing a FIFO queue.
71 *
72 * A list is headed by a single forward pointer (or an array of forward
73 * pointers for a hash table header). The elements are doubly linked
74 * so that an arbitrary element can be removed without a need to
75 * traverse the list. New elements can be added to the list before
76 * or after an existing element or at the head of the list. A list
77 * may only be traversed in the forward direction.
78 *
79 * A tail queue is headed by a pair of pointers, one to the head of the
80 * list and the other to the tail of the list. The elements are doubly
81 * linked so that an arbitrary element can be removed without a need to
82 * traverse the list. New elements can be added to the list before or
83 * after an existing element, at the head of the list, or at the end of
84 * the list. A tail queue may be traversed in either direction.
85 *
86 * For details on the use of these macros, see the queue(3) manual page.
87 *
88 *
89 * SLIST LIST STAILQ TAILQ
90 * _HEAD + + + +
91 * _HEAD_INITIALIZER + + + +
92 * _ENTRY + + + +
93 * _INIT + + + +
94 * _EMPTY + + + +
95 * _FIRST + + + +
96 * _NEXT + + + +
97 * _PREV - - - +
98 * _LAST - - + +
99 * _FOREACH + + + +
100 * _FOREACH_SAFE + + + +
101 * _FOREACH_REVERSE - - - +
102 * _FOREACH_REVERSE_SAFE - - - +
103 * _INSERT_HEAD + + + +
104 * _INSERT_BEFORE - + - +
105 * _INSERT_AFTER + + + +
106 * _INSERT_TAIL - - + +
107 * _CONCAT - - + +
108 * _REMOVE_HEAD + - + -
109 * _REMOVE + + + +
110 *
111 */
112 #define QUEUE_MACRO_DEBUG 0
113 #if QUEUE_MACRO_DEBUG
114 /* Store the last 2 places the queue element or head was altered */
115 struct qm_trace {
116 char * lastfile;
117 int lastline;
118 char * prevfile;
119 int prevline;
120 };
121
122 #define TRACEBUF struct qm_trace trace;
123 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
124
125 #define QMD_TRACE_HEAD(head) do { \
126 (head)->trace.prevline = (head)->trace.lastline; \
127 (head)->trace.prevfile = (head)->trace.lastfile; \
128 (head)->trace.lastline = __LINE__; \
129 (head)->trace.lastfile = __FILE__; \
130 } while (0)
131
132 #define QMD_TRACE_ELEM(elem) do { \
133 (elem)->trace.prevline = (elem)->trace.lastline; \
134 (elem)->trace.prevfile = (elem)->trace.lastfile; \
135 (elem)->trace.lastline = __LINE__; \
136 (elem)->trace.lastfile = __FILE__; \
137 } while (0)
138
139 #else
140 #define QMD_TRACE_ELEM(elem)
141 #define QMD_TRACE_HEAD(head)
142 #define TRACEBUF
143 #define TRASHIT(x)
144 #endif /* QUEUE_MACRO_DEBUG */
145
146 /*
147 * Singly-linked List declarations.
148 */
149 #define SLIST_HEAD(name, type) \
150 struct name { \
151 struct type *slh_first; /* first element */ \
152 }
153
154 #define SLIST_HEAD_INITIALIZER(head) \
155 { NULL }
156
157 #define SLIST_ENTRY(type) \
158 struct { \
159 struct type *sle_next; /* next element */ \
160 }
161
162 /*
163 * Singly-linked List functions.
164 */
165 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
166
167 #define SLIST_FIRST(head) ((head)->slh_first)
168
169 #define SLIST_FOREACH(var, head, field) \
170 for ((var) = SLIST_FIRST((head)); \
171 (var); \
172 (var) = SLIST_NEXT((var), field))
173
174 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
175 for ((var) = SLIST_FIRST((head)); \
176 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
177 (var) = (tvar))
178
179 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
180 for ((varp) = &SLIST_FIRST((head)); \
181 ((var) = *(varp)) != NULL; \
182 (varp) = &SLIST_NEXT((var), field))
183
184 #define SLIST_INIT(head) do { \
185 SLIST_FIRST((head)) = NULL; \
186 } while (0)
187
188 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
189 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
190 SLIST_NEXT((slistelm), field) = (elm); \
191 } while (0)
192
193 #define SLIST_INSERT_HEAD(head, elm, field) do { \
194 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
195 SLIST_FIRST((head)) = (elm); \
196 } while (0)
197
198 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
199
200 #define SLIST_REMOVE(head, elm, type, field) do { \
201 if (SLIST_FIRST((head)) == (elm)) { \
202 SLIST_REMOVE_HEAD((head), field); \
203 } \
204 else { \
205 struct type *curelm = SLIST_FIRST((head)); \
206 while (SLIST_NEXT(curelm, field) != (elm)) \
207 curelm = SLIST_NEXT(curelm, field); \
208 SLIST_NEXT(curelm, field) = \
209 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
210 } \
211 } while (0)
212
213 #define SLIST_REMOVE_HEAD(head, field) do { \
214 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
215 } while (0)
216
217 /*
218 * Singly-linked Tail queue declarations.
219 */
220 #define STAILQ_HEAD(name, type) \
221 struct name { \
222 struct type *stqh_first;/* first element */ \
223 struct type **stqh_last;/* addr of last next element */ \
224 }
225
226 #define STAILQ_HEAD_INITIALIZER(head) \
227 { NULL, &(head).stqh_first }
228
229 #define STAILQ_ENTRY(type) \
230 struct { \
231 struct type *stqe_next; /* next element */ \
232 }
233
234 /*
235 * Singly-linked Tail queue functions.
236 */
237 #define STAILQ_CONCAT(head1, head2) do { \
238 if (!STAILQ_EMPTY((head2))) { \
239 *(head1)->stqh_last = (head2)->stqh_first; \
240 (head1)->stqh_last = (head2)->stqh_last; \
241 STAILQ_INIT((head2)); \
242 } \
243 } while (0)
244
245 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
246
247 #define STAILQ_FIRST(head) ((head)->stqh_first)
248
249 #define STAILQ_FOREACH(var, head, field) \
250 for((var) = STAILQ_FIRST((head)); \
251 (var); \
252 (var) = STAILQ_NEXT((var), field))
253
254
255 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
256 for ((var) = STAILQ_FIRST((head)); \
257 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
258 (var) = (tvar))
259
260 #define STAILQ_INIT(head) do { \
261 STAILQ_FIRST((head)) = NULL; \
262 (head)->stqh_last = &STAILQ_FIRST((head)); \
263 } while (0)
264
265 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
266 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
267 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
268 STAILQ_NEXT((tqelm), field) = (elm); \
269 } while (0)
270
271 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
272 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
273 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
274 STAILQ_FIRST((head)) = (elm); \
275 } while (0)
276
277 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
278 STAILQ_NEXT((elm), field) = NULL; \
279 *(head)->stqh_last = (elm); \
280 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
281 } while (0)
282
283 #define STAILQ_LAST(head, type, field) \
284 (STAILQ_EMPTY((head)) ? \
285 NULL : \
286 ((struct type *) \
287 ((char *)((head)->stqh_last) - offsetof(struct type, field))))
288
289 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
290
291 #define STAILQ_REMOVE(head, elm, type, field) do { \
292 if (STAILQ_FIRST((head)) == (elm)) { \
293 STAILQ_REMOVE_HEAD((head), field); \
294 } \
295 else { \
296 struct type *curelm = STAILQ_FIRST((head)); \
297 while (STAILQ_NEXT(curelm, field) != (elm)) \
298 curelm = STAILQ_NEXT(curelm, field); \
299 if ((STAILQ_NEXT(curelm, field) = \
300 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
301 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
302 } \
303 } while (0)
304
305 #define STAILQ_REMOVE_HEAD(head, field) do { \
306 if ((STAILQ_FIRST((head)) = \
307 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
308 (head)->stqh_last = &STAILQ_FIRST((head)); \
309 } while (0)
310
311 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
312 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
313 (head)->stqh_last = &STAILQ_FIRST((head)); \
314 } while (0)
315
316 /*
317 * List declarations.
318 */
319 #define LIST_HEAD(name, type) \
320 struct name { \
321 struct type *lh_first; /* first element */ \
322 }
323
324 #define LIST_HEAD_INITIALIZER(head) \
325 { NULL }
326
327 #define LIST_ENTRY(type) \
328 struct { \
329 struct type *le_next; /* next element */ \
330 struct type **le_prev; /* address of previous next element */ \
331 }
332
333 /*
334 * List functions.
335 */
336
337 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
338
339 #define LIST_FIRST(head) ((head)->lh_first)
340
341 #define LIST_FOREACH(var, head, field) \
342 for ((var) = LIST_FIRST((head)); \
343 (var); \
344 (var) = LIST_NEXT((var), field))
345
346 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
347 for ((var) = LIST_FIRST((head)); \
348 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
349 (var) = (tvar))
350
351 #define LIST_INIT(head) do { \
352 LIST_FIRST((head)) = NULL; \
353 } while (0)
354
355 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
356 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
357 LIST_NEXT((listelm), field)->field.le_prev = \
358 &LIST_NEXT((elm), field); \
359 LIST_NEXT((listelm), field) = (elm); \
360 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
361 } while (0)
362
363 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
364 (elm)->field.le_prev = (listelm)->field.le_prev; \
365 LIST_NEXT((elm), field) = (listelm); \
366 *(listelm)->field.le_prev = (elm); \
367 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
368 } while (0)
369
370 #define LIST_INSERT_HEAD(head, elm, field) do { \
371 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
372 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
373 LIST_FIRST((head)) = (elm); \
374 (elm)->field.le_prev = &LIST_FIRST((head)); \
375 } while (0)
376
377 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
378
379 #define LIST_REMOVE(elm, field) do { \
380 if (LIST_NEXT((elm), field) != NULL) \
381 LIST_NEXT((elm), field)->field.le_prev = \
382 (elm)->field.le_prev; \
383 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
384 } while (0)
385
386 /*
387 * Tail queue declarations.
388 */
389 #define TAILQ_HEAD(name, type) \
390 struct name { \
391 struct type *tqh_first; /* first element */ \
392 struct type **tqh_last; /* addr of last next element */ \
393 TRACEBUF \
394 }
395
396 #define TAILQ_HEAD_INITIALIZER(head) \
397 { NULL, &(head).tqh_first }
398
399 #define TAILQ_ENTRY(type) \
400 struct { \
401 struct type *tqe_next; /* next element */ \
402 struct type **tqe_prev; /* address of previous next element */ \
403 TRACEBUF \
404 }
405
406 /*
407 * Tail queue functions.
408 */
409 #define TAILQ_CONCAT(head1, head2, field) do { \
410 if (!TAILQ_EMPTY(head2)) { \
411 *(head1)->tqh_last = (head2)->tqh_first; \
412 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
413 (head1)->tqh_last = (head2)->tqh_last; \
414 TAILQ_INIT((head2)); \
415 QMD_TRACE_HEAD(head); \
416 QMD_TRACE_HEAD(head2); \
417 } \
418 } while (0)
419
420 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
421
422 #define TAILQ_FIRST(head) ((head)->tqh_first)
423
424 #define TAILQ_FOREACH(var, head, field) \
425 for ((var) = TAILQ_FIRST((head)); \
426 (var); \
427 (var) = TAILQ_NEXT((var), field))
428
429 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
430 for ((var) = TAILQ_FIRST((head)); \
431 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
432 (var) = (tvar))
433
434 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
435 for ((var) = TAILQ_LAST((head), headname); \
436 (var); \
437 (var) = TAILQ_PREV((var), headname, field))
438
439 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
440 for ((var) = TAILQ_LAST((head), headname); \
441 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
442 (var) = (tvar))
443
444 #define TAILQ_INIT(head) do { \
445 TAILQ_FIRST((head)) = NULL; \
446 (head)->tqh_last = &TAILQ_FIRST((head)); \
447 QMD_TRACE_HEAD(head); \
448 } while (0)
449
450 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
451 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
452 TAILQ_NEXT((elm), field)->field.tqe_prev = \
453 &TAILQ_NEXT((elm), field); \
454 else { \
455 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
456 QMD_TRACE_HEAD(head); \
457 } \
458 TAILQ_NEXT((listelm), field) = (elm); \
459 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
460 QMD_TRACE_ELEM(&(elm)->field); \
461 QMD_TRACE_ELEM(&listelm->field); \
462 } while (0)
463
464 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
465 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
466 TAILQ_NEXT((elm), field) = (listelm); \
467 *(listelm)->field.tqe_prev = (elm); \
468 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
469 QMD_TRACE_ELEM(&(elm)->field); \
470 QMD_TRACE_ELEM(&listelm->field); \
471 } while (0)
472
473 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
474 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
475 TAILQ_FIRST((head))->field.tqe_prev = \
476 &TAILQ_NEXT((elm), field); \
477 else \
478 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
479 TAILQ_FIRST((head)) = (elm); \
480 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
481 QMD_TRACE_HEAD(head); \
482 QMD_TRACE_ELEM(&(elm)->field); \
483 } while (0)
484
485 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
486 TAILQ_NEXT((elm), field) = NULL; \
487 (elm)->field.tqe_prev = (head)->tqh_last; \
488 *(head)->tqh_last = (elm); \
489 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
490 QMD_TRACE_HEAD(head); \
491 QMD_TRACE_ELEM(&(elm)->field); \
492 } while (0)
493
494 #define TAILQ_LAST(head, headname) \
495 (*(((struct headname *)((head)->tqh_last))->tqh_last))
496
497 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
498
499 #define TAILQ_PREV(elm, headname, field) \
500 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
501
502 #define TAILQ_REMOVE(head, elm, field) do { \
503 if ((TAILQ_NEXT((elm), field)) != NULL) \
504 TAILQ_NEXT((elm), field)->field.tqe_prev = \
505 (elm)->field.tqe_prev; \
506 else { \
507 (head)->tqh_last = (elm)->field.tqe_prev; \
508 QMD_TRACE_HEAD(head); \
509 } \
510 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
511 TRASHIT((elm)->field.tqe_next); \
512 TRASHIT((elm)->field.tqe_prev); \
513 QMD_TRACE_ELEM(&(elm)->field); \
514 } while (0)
515
516
517 #ifdef _KERNEL
518
519 /*
520 * XXX insque() and remque() are an old way of handling certain queues.
521 * They bogusly assumes that all queue heads look alike.
522 */
523
524 struct quehead {
525 struct quehead *qh_link;
526 struct quehead *qh_rlink;
527 };
528
529 #if defined(__GNUC__) || defined(__INTEL_COMPILER)
530
531 static __inline void
insque(void * a,void * b)532 insque(void *a, void *b)
533 {
534 struct quehead *element = (struct quehead *)a,
535 *head = (struct quehead *)b;
536
537 element->qh_link = head->qh_link;
538 element->qh_rlink = head;
539 head->qh_link = element;
540 element->qh_link->qh_rlink = element;
541 }
542
543 static __inline void
remque(void * a)544 remque(void *a)
545 {
546 struct quehead *element = (struct quehead *)a;
547
548 element->qh_link->qh_rlink = element->qh_rlink;
549 element->qh_rlink->qh_link = element->qh_link;
550 element->qh_rlink = 0;
551 }
552
553 #else /* !(__GNUC__ || __INTEL_COMPILER) */
554
555 void insque(void *a, void *b);
556 void remque(void *a);
557
558 #endif /* __GNUC__ || __INTEL_COMPILER */
559
560 #endif /* _KERNEL */
561
562 #endif /* !_SYS_QUEUE_H_ */
563