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 1.60.2.1 2005/08/16 22:41:39 phk Exp $
31 */
32
33 #ifndef _SYS_QUEUE_H_
34 #define _SYS_QUEUE_H_
35
36 #include <sys/cdefs.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 only be traversed in the forward 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 *
80 * SLIST LIST STAILQ TAILQ
81 * _HEAD + + + +
82 * _HEAD_INITIALIZER + + + +
83 * _ENTRY + + + +
84 * _INIT + + + +
85 * _EMPTY + + + +
86 * _FIRST + + + +
87 * _NEXT + + + +
88 * _PREV - - - +
89 * _LAST - - + +
90 * _FOREACH + + + +
91 * _FOREACH_SAFE + + + +
92 * _FOREACH_REVERSE - - - +
93 * _FOREACH_REVERSE_SAFE - - - +
94 * _INSERT_HEAD + + + +
95 * _INSERT_BEFORE - + - +
96 * _INSERT_AFTER + + + +
97 * _INSERT_TAIL - - + +
98 * _CONCAT - - + +
99 * _REMOVE_HEAD + - + -
100 * _REMOVE + + + +
101 *
102 */
103 #define QUEUE_MACRO_DEBUG 0
104 #if QUEUE_MACRO_DEBUG
105 /* Store the last 2 places the queue element or head was altered */
106 struct qm_trace {
107 char * lastfile;
108 int lastline;
109 char * prevfile;
110 int prevline;
111 };
112
113 #define TRACEBUF struct qm_trace trace;
114 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
115
116 #define QMD_TRACE_HEAD(head) do { \
117 (head)->trace.prevline = (head)->trace.lastline; \
118 (head)->trace.prevfile = (head)->trace.lastfile; \
119 (head)->trace.lastline = __LINE__; \
120 (head)->trace.lastfile = __FILE__; \
121 } while (0)
122
123 #define QMD_TRACE_ELEM(elem) do { \
124 (elem)->trace.prevline = (elem)->trace.lastline; \
125 (elem)->trace.prevfile = (elem)->trace.lastfile; \
126 (elem)->trace.lastline = __LINE__; \
127 (elem)->trace.lastfile = __FILE__; \
128 } while (0)
129
130 #else
131 #define QMD_TRACE_ELEM(elem)
132 #define QMD_TRACE_HEAD(head)
133 #define TRACEBUF
134 #define TRASHIT(x)
135 #endif /* QUEUE_MACRO_DEBUG */
136
137 /*
138 * Singly-linked List declarations.
139 */
140 #define SLIST_HEAD(name, type) \
141 struct name { \
142 struct type *slh_first; /* first element */ \
143 }
144
145 #define SLIST_HEAD_INITIALIZER(head) \
146 { NULL }
147
148 #define SLIST_ENTRY(type) \
149 struct { \
150 struct type *sle_next; /* next element */ \
151 }
152
153 /*
154 * Singly-linked List functions.
155 */
156 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
157
158 #define SLIST_FIRST(head) ((head)->slh_first)
159
160 #define SLIST_FOREACH(var, head, field) \
161 for ((var) = SLIST_FIRST((head)); \
162 (var); \
163 (var) = SLIST_NEXT((var), field))
164
165 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
166 for ((var) = SLIST_FIRST((head)); \
167 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
168 (var) = (tvar))
169
170 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
171 for ((varp) = &SLIST_FIRST((head)); \
172 ((var) = *(varp)) != NULL; \
173 (varp) = &SLIST_NEXT((var), field))
174
175 #define SLIST_INIT(head) do { \
176 SLIST_FIRST((head)) = NULL; \
177 } while (0)
178
179 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
180 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
181 SLIST_NEXT((slistelm), field) = (elm); \
182 } while (0)
183
184 #define SLIST_INSERT_HEAD(head, elm, field) do { \
185 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
186 SLIST_FIRST((head)) = (elm); \
187 } while (0)
188
189 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
190
191 #define SLIST_REMOVE(head, elm, type, field) do { \
192 if (SLIST_FIRST((head)) == (elm)) { \
193 SLIST_REMOVE_HEAD((head), field); \
194 } \
195 else { \
196 struct type *curelm = SLIST_FIRST((head)); \
197 while (SLIST_NEXT(curelm, field) != (elm)) \
198 curelm = SLIST_NEXT(curelm, field); \
199 SLIST_NEXT(curelm, field) = \
200 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \
201 } \
202 } while (0)
203
204 #define SLIST_REMOVE_HEAD(head, field) do { \
205 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
206 } while (0)
207
208 /*
209 * Singly-linked Tail queue declarations.
210 */
211 #define STAILQ_HEAD(name, type) \
212 struct name { \
213 struct type *stqh_first;/* first element */ \
214 struct type **stqh_last;/* addr of last next element */ \
215 }
216
217 #define STAILQ_HEAD_INITIALIZER(head) \
218 { NULL, &(head).stqh_first }
219
220 #define STAILQ_ENTRY(type) \
221 struct { \
222 struct type *stqe_next; /* next element */ \
223 }
224
225 /*
226 * Singly-linked Tail queue functions.
227 */
228 #define STAILQ_CONCAT(head1, head2) do { \
229 if (!STAILQ_EMPTY((head2))) { \
230 *(head1)->stqh_last = (head2)->stqh_first; \
231 (head1)->stqh_last = (head2)->stqh_last; \
232 STAILQ_INIT((head2)); \
233 } \
234 } while (0)
235
236 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
237
238 #define STAILQ_FIRST(head) ((head)->stqh_first)
239
240 #define STAILQ_FOREACH(var, head, field) \
241 for((var) = STAILQ_FIRST((head)); \
242 (var); \
243 (var) = STAILQ_NEXT((var), field))
244
245
246 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
247 for ((var) = STAILQ_FIRST((head)); \
248 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
249 (var) = (tvar))
250
251 #define STAILQ_INIT(head) do { \
252 STAILQ_FIRST((head)) = NULL; \
253 (head)->stqh_last = &STAILQ_FIRST((head)); \
254 } while (0)
255
256 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
257 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
258 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
259 STAILQ_NEXT((tqelm), field) = (elm); \
260 } while (0)
261
262 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
263 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
264 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
265 STAILQ_FIRST((head)) = (elm); \
266 } while (0)
267
268 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
269 STAILQ_NEXT((elm), field) = NULL; \
270 *(head)->stqh_last = (elm); \
271 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
272 } while (0)
273
274 #define STAILQ_LAST(head, type, field) \
275 (STAILQ_EMPTY((head)) ? \
276 NULL : \
277 ((struct type *) \
278 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
279
280 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
281
282 #define STAILQ_REMOVE(head, elm, type, field) do { \
283 if (STAILQ_FIRST((head)) == (elm)) { \
284 STAILQ_REMOVE_HEAD((head), field); \
285 } \
286 else { \
287 struct type *curelm = STAILQ_FIRST((head)); \
288 while (STAILQ_NEXT(curelm, field) != (elm)) \
289 curelm = STAILQ_NEXT(curelm, field); \
290 if ((STAILQ_NEXT(curelm, field) = \
291 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
292 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
293 } \
294 } while (0)
295
296 #define STAILQ_REMOVE_HEAD(head, field) do { \
297 if ((STAILQ_FIRST((head)) = \
298 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
299 (head)->stqh_last = &STAILQ_FIRST((head)); \
300 } while (0)
301
302 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \
303 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
304 (head)->stqh_last = &STAILQ_FIRST((head)); \
305 } while (0)
306
307 /*
308 * List declarations.
309 */
310 #define LIST_HEAD(name, type) \
311 struct name { \
312 struct type *lh_first; /* first element */ \
313 }
314
315 #define LIST_HEAD_INITIALIZER(head) \
316 { NULL }
317
318 #define LIST_ENTRY(type) \
319 struct { \
320 struct type *le_next; /* next element */ \
321 struct type **le_prev; /* address of previous next element */ \
322 }
323
324 /*
325 * List functions.
326 */
327
328 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
329
330 #define LIST_FIRST(head) ((head)->lh_first)
331
332 #define LIST_FOREACH(var, head, field) \
333 for ((var) = LIST_FIRST((head)); \
334 (var); \
335 (var) = LIST_NEXT((var), field))
336
337 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
338 for ((var) = LIST_FIRST((head)); \
339 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
340 (var) = (tvar))
341
342 #define LIST_INIT(head) do { \
343 LIST_FIRST((head)) = NULL; \
344 } while (0)
345
346 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
347 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
348 LIST_NEXT((listelm), field)->field.le_prev = \
349 &LIST_NEXT((elm), field); \
350 LIST_NEXT((listelm), field) = (elm); \
351 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
352 } while (0)
353
354 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
355 (elm)->field.le_prev = (listelm)->field.le_prev; \
356 LIST_NEXT((elm), field) = (listelm); \
357 *(listelm)->field.le_prev = (elm); \
358 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
359 } while (0)
360
361 #define LIST_INSERT_HEAD(head, elm, field) do { \
362 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
363 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
364 LIST_FIRST((head)) = (elm); \
365 (elm)->field.le_prev = &LIST_FIRST((head)); \
366 } while (0)
367
368 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
369
370 #define LIST_REMOVE(elm, field) do { \
371 if (LIST_NEXT((elm), field) != NULL) \
372 LIST_NEXT((elm), field)->field.le_prev = \
373 (elm)->field.le_prev; \
374 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
375 } while (0)
376
377 /*
378 * Tail queue declarations.
379 */
380 #define TAILQ_HEAD(name, type) \
381 struct name { \
382 struct type *tqh_first; /* first element */ \
383 struct type **tqh_last; /* addr of last next element */ \
384 TRACEBUF \
385 }
386
387 #define TAILQ_HEAD_INITIALIZER(head) \
388 { NULL, &(head).tqh_first }
389
390 #define TAILQ_ENTRY(type) \
391 struct { \
392 struct type *tqe_next; /* next element */ \
393 struct type **tqe_prev; /* address of previous next element */ \
394 TRACEBUF \
395 }
396
397 /*
398 * Tail queue functions.
399 */
400 #define TAILQ_CONCAT(head1, head2, field) do { \
401 if (!TAILQ_EMPTY(head2)) { \
402 *(head1)->tqh_last = (head2)->tqh_first; \
403 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
404 (head1)->tqh_last = (head2)->tqh_last; \
405 TAILQ_INIT((head2)); \
406 QMD_TRACE_HEAD(head1); \
407 QMD_TRACE_HEAD(head2); \
408 } \
409 } while (0)
410
411 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
412
413 #define TAILQ_FIRST(head) ((head)->tqh_first)
414
415 #define TAILQ_FOREACH(var, head, field) \
416 for ((var) = TAILQ_FIRST((head)); \
417 (var); \
418 (var) = TAILQ_NEXT((var), field))
419
420 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
421 for ((var) = TAILQ_FIRST((head)); \
422 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
423 (var) = (tvar))
424
425 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
426 for ((var) = TAILQ_LAST((head), headname); \
427 (var); \
428 (var) = TAILQ_PREV((var), headname, field))
429
430 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
431 for ((var) = TAILQ_LAST((head), headname); \
432 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
433 (var) = (tvar))
434
435 #define TAILQ_INIT(head) do { \
436 TAILQ_FIRST((head)) = NULL; \
437 (head)->tqh_last = &TAILQ_FIRST((head)); \
438 QMD_TRACE_HEAD(head); \
439 } while (0)
440
441 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
442 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
443 TAILQ_NEXT((elm), field)->field.tqe_prev = \
444 &TAILQ_NEXT((elm), field); \
445 else { \
446 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
447 QMD_TRACE_HEAD(head); \
448 } \
449 TAILQ_NEXT((listelm), field) = (elm); \
450 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
451 QMD_TRACE_ELEM(&(elm)->field); \
452 QMD_TRACE_ELEM(&listelm->field); \
453 } while (0)
454
455 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
456 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
457 TAILQ_NEXT((elm), field) = (listelm); \
458 *(listelm)->field.tqe_prev = (elm); \
459 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
460 QMD_TRACE_ELEM(&(elm)->field); \
461 QMD_TRACE_ELEM(&listelm->field); \
462 } while (0)
463
464 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
465 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
466 TAILQ_FIRST((head))->field.tqe_prev = \
467 &TAILQ_NEXT((elm), field); \
468 else \
469 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
470 TAILQ_FIRST((head)) = (elm); \
471 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
472 QMD_TRACE_HEAD(head); \
473 QMD_TRACE_ELEM(&(elm)->field); \
474 } while (0)
475
476 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
477 TAILQ_NEXT((elm), field) = NULL; \
478 (elm)->field.tqe_prev = (head)->tqh_last; \
479 *(head)->tqh_last = (elm); \
480 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
481 QMD_TRACE_HEAD(head); \
482 QMD_TRACE_ELEM(&(elm)->field); \
483 } while (0)
484
485 #define TAILQ_LAST(head, headname) \
486 (*(((struct headname *)((head)->tqh_last))->tqh_last))
487
488 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
489
490 #define TAILQ_PREV(elm, headname, field) \
491 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
492
493 #define TAILQ_REMOVE(head, elm, field) do { \
494 if ((TAILQ_NEXT((elm), field)) != NULL) \
495 TAILQ_NEXT((elm), field)->field.tqe_prev = \
496 (elm)->field.tqe_prev; \
497 else { \
498 (head)->tqh_last = (elm)->field.tqe_prev; \
499 QMD_TRACE_HEAD(head); \
500 } \
501 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
502 TRASHIT((elm)->field.tqe_next); \
503 TRASHIT((elm)->field.tqe_prev); \
504 QMD_TRACE_ELEM(&(elm)->field); \
505 } while (0)
506
507
508 #ifdef _KERNEL
509
510 /*
511 * XXX insque() and remque() are an old way of handling certain queues.
512 * They bogusly assumes that all queue heads look alike.
513 */
514
515 struct quehead {
516 struct quehead *qh_link;
517 struct quehead *qh_rlink;
518 };
519
520 #ifdef __CC_SUPPORTS___INLINE
521
522 static __inline void
insque(void * a,void * b)523 insque(void *a, void *b)
524 {
525 struct quehead *element = (struct quehead *)a,
526 *head = (struct quehead *)b;
527
528 element->qh_link = head->qh_link;
529 element->qh_rlink = head;
530 head->qh_link = element;
531 element->qh_link->qh_rlink = element;
532 }
533
534 static __inline void
remque(void * a)535 remque(void *a)
536 {
537 struct quehead *element = (struct quehead *)a;
538
539 element->qh_link->qh_rlink = element->qh_rlink;
540 element->qh_rlink->qh_link = element->qh_link;
541 element->qh_rlink = 0;
542 }
543
544 #else /* !__CC_SUPPORTS___INLINE */
545
546 void insque(void *a, void *b);
547 void remque(void *a);
548
549 #endif /* __CC_SUPPORTS___INLINE */
550
551 #endif /* _KERNEL */
552
553 #endif /* _SYS_QUEUE_H_ */
554