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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)queue.h 8.5 (Berkeley) 8/20/94 34 * $FreeBSD: src/sys/sys/queue.h,v 1.32.2.7 2002/04/17 14:21:02 des Exp $ 35 * $DragonFly: src/sys/sys/queue.h,v 1.4 2003/11/09 02:22:37 dillon Exp $ 36 */ 37 38 #ifndef _SYS_QUEUE_H_ 39 #define _SYS_QUEUE_H_ 40 41 #ifndef _MACHINE_STDINT_H_ 42 #include <machine/stdint.h> /* for __offsetof */ 43 #endif 44 45 /* 46 * This file defines five types of data structures: singly-linked lists, 47 * singly-linked tail queues, lists, tail queues, and circular queues. 48 * 49 * A singly-linked list is headed by a single forward pointer. The elements 50 * are singly linked for minimum space and pointer manipulation overhead at 51 * the expense of O(n) removal for arbitrary elements. New elements can be 52 * added to the list after an existing element or at the head of the list. 53 * Elements being removed from the head of the list should use the explicit 54 * macro for this purpose for optimum efficiency. A singly-linked list may 55 * only be traversed in the forward direction. Singly-linked lists are ideal 56 * for applications with large datasets and few or no removals or for 57 * implementing a LIFO queue. 58 * 59 * A singly-linked tail queue is headed by a pair of pointers, one to the 60 * head of the list and the other to the tail of the list. The elements are 61 * singly linked for minimum space and pointer manipulation overhead at the 62 * expense of O(n) removal for arbitrary elements. New elements can be added 63 * to the list after an existing element, at the head of the list, or at the 64 * end of the list. Elements being removed from the head of the tail queue 65 * should use the explicit macro for this purpose for optimum efficiency. 66 * A singly-linked tail queue may only be traversed in the forward direction. 67 * Singly-linked tail queues are ideal for applications with large datasets 68 * and few or no removals or for implementing a FIFO queue. 69 * 70 * A list is headed by a single forward pointer (or an array of forward 71 * pointers for a hash table header). The elements are doubly linked 72 * 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 74 * or after an existing element or at the head of the list. A list 75 * may only be traversed in the forward direction. 76 * 77 * A tail queue is headed by a pair of pointers, one to the head of the 78 * list and the other to the tail of the list. The elements are doubly 79 * linked so that an arbitrary element can be removed without a need to 80 * traverse the list. New elements can be added to the list before or 81 * after an existing element, at the head of the list, or at the end of 82 * the list. A tail queue may be traversed in either direction. 83 * 84 * A circle queue is headed by a pair of pointers, one to the head of the 85 * list and the other to the tail of the list. The elements are doubly 86 * linked so that an arbitrary element can be removed without a need to 87 * traverse the list. New elements can be added to the list before or after 88 * an existing element, at the head of the list, or at the end of the list. 89 * A circle queue may be traversed in either direction, but has a more 90 * complex end of list detection. 91 * 92 * For details on the use of these macros, see the queue(3) manual page. 93 * 94 * 95 * SLIST LIST STAILQ TAILQ CIRCLEQ 96 * _HEAD + + + + + 97 * _HEAD_INITIALIZER + + + + + 98 * _ENTRY + + + + + 99 * _INIT + + + + + 100 * _EMPTY + + + + + 101 * _FIRST + + + + + 102 * _NEXT + + + + + 103 * _PREV - - - + + 104 * _LAST - - + + + 105 * _FOREACH + + + + + 106 * _FOREACH_REVERSE - - - + + 107 * _INSERT_HEAD + + + + + 108 * _INSERT_BEFORE - + - + + 109 * _INSERT_AFTER + + + + + 110 * _INSERT_TAIL - - + + + 111 * _REMOVE_HEAD + - + - - 112 * _REMOVE + + + + + 113 * 114 */ 115 116 /* 117 * Singly-linked List declarations. 118 */ 119 #define SLIST_HEAD(name, type) \ 120 struct name { \ 121 struct type *slh_first; /* first element */ \ 122 } 123 124 #define SLIST_HEAD_INITIALIZER(head) \ 125 { NULL } 126 127 #define SLIST_ENTRY(type) \ 128 struct { \ 129 struct type *sle_next; /* next element */ \ 130 } 131 132 /* 133 * Singly-linked List functions. 134 */ 135 #define SLIST_EMPTY(head) ((head)->slh_first == NULL) 136 137 #define SLIST_FIRST(head) ((head)->slh_first) 138 139 #define SLIST_FOREACH(var, head, field) \ 140 for ((var) = SLIST_FIRST((head)); \ 141 (var); \ 142 (var) = SLIST_NEXT((var), field)) 143 144 #define SLIST_INIT(head) do { \ 145 SLIST_FIRST((head)) = NULL; \ 146 } while (0) 147 148 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 149 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \ 150 SLIST_NEXT((slistelm), field) = (elm); \ 151 } while (0) 152 153 #define SLIST_INSERT_HEAD(head, elm, field) do { \ 154 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \ 155 SLIST_FIRST((head)) = (elm); \ 156 } while (0) 157 158 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 159 160 #define SLIST_REMOVE(head, elm, type, field) do { \ 161 if (SLIST_FIRST((head)) == (elm)) { \ 162 SLIST_REMOVE_HEAD((head), field); \ 163 } \ 164 else { \ 165 struct type *curelm = SLIST_FIRST((head)); \ 166 while (SLIST_NEXT(curelm, field) != (elm)) \ 167 curelm = SLIST_NEXT(curelm, field); \ 168 SLIST_NEXT(curelm, field) = \ 169 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \ 170 } \ 171 } while (0) 172 173 #define SLIST_REMOVE_HEAD(head, field) do { \ 174 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \ 175 } while (0) 176 177 /* 178 * Singly-linked Tail queue declarations. 179 */ 180 #define STAILQ_HEAD(name, type) \ 181 struct name { \ 182 struct type *stqh_first;/* first element */ \ 183 struct type **stqh_last;/* addr of last next element */ \ 184 } 185 186 #define STAILQ_HEAD_INITIALIZER(head) \ 187 { NULL, &(head).stqh_first } 188 189 #define STAILQ_ENTRY(type) \ 190 struct { \ 191 struct type *stqe_next; /* next element */ \ 192 } 193 194 /* 195 * Singly-linked Tail queue functions. 196 */ 197 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 198 199 #define STAILQ_FIRST(head) ((head)->stqh_first) 200 201 #define STAILQ_FOREACH(var, head, field) \ 202 for((var) = STAILQ_FIRST((head)); \ 203 (var); \ 204 (var) = STAILQ_NEXT((var), field)) 205 206 #define STAILQ_INIT(head) do { \ 207 STAILQ_FIRST((head)) = NULL; \ 208 (head)->stqh_last = &STAILQ_FIRST((head)); \ 209 } while (0) 210 211 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \ 212 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\ 213 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 214 STAILQ_NEXT((tqelm), field) = (elm); \ 215 } while (0) 216 217 #define STAILQ_INSERT_HEAD(head, elm, field) do { \ 218 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \ 219 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 220 STAILQ_FIRST((head)) = (elm); \ 221 } while (0) 222 223 #define STAILQ_INSERT_TAIL(head, elm, field) do { \ 224 STAILQ_NEXT((elm), field) = NULL; \ 225 *(head)->stqh_last = (elm); \ 226 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 227 } while (0) 228 229 #define STAILQ_LAST(head, type, field) \ 230 (STAILQ_EMPTY(head) ? \ 231 NULL : \ 232 ((struct type *) \ 233 ((char *)((head)->stqh_last) - __offsetof(struct type, field)))) 234 235 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 236 237 #define STAILQ_REMOVE(head, elm, type, field) do { \ 238 if (STAILQ_FIRST((head)) == (elm)) { \ 239 STAILQ_REMOVE_HEAD(head, field); \ 240 } \ 241 else { \ 242 struct type *curelm = STAILQ_FIRST((head)); \ 243 while (STAILQ_NEXT(curelm, field) != (elm)) \ 244 curelm = STAILQ_NEXT(curelm, field); \ 245 if ((STAILQ_NEXT(curelm, field) = \ 246 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\ 247 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\ 248 } \ 249 } while (0) 250 251 #define STAILQ_REMOVE_HEAD(head, field) do { \ 252 if ((STAILQ_FIRST((head)) = \ 253 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \ 254 (head)->stqh_last = &STAILQ_FIRST((head)); \ 255 } while (0) 256 257 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \ 258 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \ 259 (head)->stqh_last = &STAILQ_FIRST((head)); \ 260 } while (0) 261 262 /* 263 * List declarations. 264 */ 265 #define LIST_HEAD(name, type) \ 266 struct name { \ 267 struct type *lh_first; /* first element */ \ 268 } 269 270 #define LIST_HEAD_INITIALIZER(head) \ 271 { NULL } 272 273 #define LIST_ENTRY(type) \ 274 struct { \ 275 struct type *le_next; /* next element */ \ 276 struct type **le_prev; /* address of previous next element */ \ 277 } 278 279 /* 280 * List functions. 281 */ 282 283 #define LIST_EMPTY(head) ((head)->lh_first == NULL) 284 285 #define LIST_FIRST(head) ((head)->lh_first) 286 287 #define LIST_FOREACH(var, head, field) \ 288 for ((var) = LIST_FIRST((head)); \ 289 (var); \ 290 (var) = LIST_NEXT((var), field)) 291 292 #define LIST_INIT(head) do { \ 293 LIST_FIRST((head)) = NULL; \ 294 } while (0) 295 296 #define LIST_INSERT_AFTER(listelm, elm, field) do { \ 297 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\ 298 LIST_NEXT((listelm), field)->field.le_prev = \ 299 &LIST_NEXT((elm), field); \ 300 LIST_NEXT((listelm), field) = (elm); \ 301 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \ 302 } while (0) 303 304 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 305 (elm)->field.le_prev = (listelm)->field.le_prev; \ 306 LIST_NEXT((elm), field) = (listelm); \ 307 *(listelm)->field.le_prev = (elm); \ 308 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \ 309 } while (0) 310 311 #define LIST_INSERT_HEAD(head, elm, field) do { \ 312 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \ 313 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\ 314 LIST_FIRST((head)) = (elm); \ 315 (elm)->field.le_prev = &LIST_FIRST((head)); \ 316 } while (0) 317 318 #define LIST_NEXT(elm, field) ((elm)->field.le_next) 319 320 #define LIST_REMOVE(elm, field) do { \ 321 if (LIST_NEXT((elm), field) != NULL) \ 322 LIST_NEXT((elm), field)->field.le_prev = \ 323 (elm)->field.le_prev; \ 324 *(elm)->field.le_prev = LIST_NEXT((elm), field); \ 325 } while (0) 326 327 /* 328 * Tail queue declarations. 329 */ 330 #define TAILQ_HEAD(name, type) \ 331 struct name { \ 332 struct type *tqh_first; /* first element */ \ 333 struct type **tqh_last; /* addr of last next element */ \ 334 } 335 336 #define TAILQ_HEAD_INITIALIZER(head) \ 337 { NULL, &(head).tqh_first } 338 339 #define TAILQ_ENTRY(type) \ 340 struct { \ 341 struct type *tqe_next; /* next element */ \ 342 struct type **tqe_prev; /* address of previous next element */ \ 343 } 344 345 /* 346 * Tail queue functions. 347 */ 348 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 349 350 #define TAILQ_FIRST(head) ((head)->tqh_first) 351 352 #define TAILQ_FOREACH(var, head, field) \ 353 for ((var) = TAILQ_FIRST((head)); \ 354 (var); \ 355 (var) = TAILQ_NEXT((var), field)) 356 357 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ 358 for ((var) = TAILQ_LAST((head), headname); \ 359 (var); \ 360 (var) = TAILQ_PREV((var), headname, field)) 361 362 #define TAILQ_INIT(head) do { \ 363 TAILQ_FIRST((head)) = NULL; \ 364 (head)->tqh_last = &TAILQ_FIRST((head)); \ 365 } while (0) 366 367 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 368 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\ 369 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 370 &TAILQ_NEXT((elm), field); \ 371 else \ 372 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 373 TAILQ_NEXT((listelm), field) = (elm); \ 374 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \ 375 } while (0) 376 377 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 378 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 379 TAILQ_NEXT((elm), field) = (listelm); \ 380 *(listelm)->field.tqe_prev = (elm); \ 381 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \ 382 } while (0) 383 384 #define TAILQ_INSERT_HEAD(head, elm, field) do { \ 385 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \ 386 TAILQ_FIRST((head))->field.tqe_prev = \ 387 &TAILQ_NEXT((elm), field); \ 388 else \ 389 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 390 TAILQ_FIRST((head)) = (elm); \ 391 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \ 392 } while (0) 393 394 #define TAILQ_INSERT_TAIL(head, elm, field) do { \ 395 TAILQ_NEXT((elm), field) = NULL; \ 396 (elm)->field.tqe_prev = (head)->tqh_last; \ 397 *(head)->tqh_last = (elm); \ 398 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 399 } while (0) 400 401 #define TAILQ_LAST(head, headname) \ 402 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 403 404 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 405 406 #define TAILQ_PREV(elm, headname, field) \ 407 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 408 409 #define TAILQ_REMOVE(head, elm, field) do { \ 410 if ((TAILQ_NEXT((elm), field)) != NULL) \ 411 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 412 (elm)->field.tqe_prev; \ 413 else \ 414 (head)->tqh_last = (elm)->field.tqe_prev; \ 415 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \ 416 } while (0) 417 418 /* 419 * Circular queue declarations. 420 */ 421 #define CIRCLEQ_HEAD(name, type) \ 422 struct name { \ 423 struct type *cqh_first; /* first element */ \ 424 struct type *cqh_last; /* last element */ \ 425 } 426 427 #define CIRCLEQ_HEAD_INITIALIZER(head) \ 428 { (void *)&(head), (void *)&(head) } 429 430 #define CIRCLEQ_ENTRY(type) \ 431 struct { \ 432 struct type *cqe_next; /* next element */ \ 433 struct type *cqe_prev; /* previous element */ \ 434 } 435 436 /* 437 * Circular queue functions. 438 */ 439 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) 440 441 #define CIRCLEQ_FIRST(head) ((head)->cqh_first) 442 443 #define CIRCLEQ_FOREACH(var, head, field) \ 444 for ((var) = CIRCLEQ_FIRST((head)); \ 445 (var) != (void *)(head) || ((var) = NULL); \ 446 (var) = CIRCLEQ_NEXT((var), field)) 447 448 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ 449 for ((var) = CIRCLEQ_LAST((head)); \ 450 (var) != (void *)(head) || ((var) = NULL); \ 451 (var) = CIRCLEQ_PREV((var), field)) 452 453 #define CIRCLEQ_INIT(head) do { \ 454 CIRCLEQ_FIRST((head)) = (void *)(head); \ 455 CIRCLEQ_LAST((head)) = (void *)(head); \ 456 } while (0) 457 458 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ 459 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_NEXT((listelm), field); \ 460 CIRCLEQ_PREV((elm), field) = (listelm); \ 461 if (CIRCLEQ_NEXT((listelm), field) == (void *)(head)) \ 462 CIRCLEQ_LAST((head)) = (elm); \ 463 else \ 464 CIRCLEQ_PREV(CIRCLEQ_NEXT((listelm), field), field) = (elm);\ 465 CIRCLEQ_NEXT((listelm), field) = (elm); \ 466 } while (0) 467 468 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ 469 CIRCLEQ_NEXT((elm), field) = (listelm); \ 470 CIRCLEQ_PREV((elm), field) = CIRCLEQ_PREV((listelm), field); \ 471 if (CIRCLEQ_PREV((listelm), field) == (void *)(head)) \ 472 CIRCLEQ_FIRST((head)) = (elm); \ 473 else \ 474 CIRCLEQ_NEXT(CIRCLEQ_PREV((listelm), field), field) = (elm);\ 475 CIRCLEQ_PREV((listelm), field) = (elm); \ 476 } while (0) 477 478 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ 479 CIRCLEQ_NEXT((elm), field) = CIRCLEQ_FIRST((head)); \ 480 CIRCLEQ_PREV((elm), field) = (void *)(head); \ 481 if (CIRCLEQ_LAST((head)) == (void *)(head)) \ 482 CIRCLEQ_LAST((head)) = (elm); \ 483 else \ 484 CIRCLEQ_PREV(CIRCLEQ_FIRST((head)), field) = (elm); \ 485 CIRCLEQ_FIRST((head)) = (elm); \ 486 } while (0) 487 488 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ 489 CIRCLEQ_NEXT((elm), field) = (void *)(head); \ 490 CIRCLEQ_PREV((elm), field) = CIRCLEQ_LAST((head)); \ 491 if (CIRCLEQ_FIRST((head)) == (void *)(head)) \ 492 CIRCLEQ_FIRST((head)) = (elm); \ 493 else \ 494 CIRCLEQ_NEXT(CIRCLEQ_LAST((head)), field) = (elm); \ 495 CIRCLEQ_LAST((head)) = (elm); \ 496 } while (0) 497 498 #define CIRCLEQ_LAST(head) ((head)->cqh_last) 499 500 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next) 501 502 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev) 503 504 #define CIRCLEQ_REMOVE(head, elm, field) do { \ 505 if (CIRCLEQ_NEXT((elm), field) == (void *)(head)) \ 506 CIRCLEQ_LAST((head)) = CIRCLEQ_PREV((elm), field); \ 507 else \ 508 CIRCLEQ_PREV(CIRCLEQ_NEXT((elm), field), field) = \ 509 CIRCLEQ_PREV((elm), field); \ 510 if (CIRCLEQ_PREV((elm), field) == (void *)(head)) \ 511 CIRCLEQ_FIRST((head)) = CIRCLEQ_NEXT((elm), field); \ 512 else \ 513 CIRCLEQ_NEXT(CIRCLEQ_PREV((elm), field), field) = \ 514 CIRCLEQ_NEXT((elm), field); \ 515 } while (0) 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 #ifdef __GNUC__ 530 531 static __inline void 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 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__ */ 554 555 void insque (void *a, void *b); 556 void remque (void *a); 557 558 #endif /* __GNUC__ */ 559 560 #endif /* _KERNEL */ 561 562 #endif /* !_SYS_QUEUE_H_ */ 563