bsd/sys/queue.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1991, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  *
  54  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  55  */
  56
  57 #ifndef _SYS_QUEUE_H_
  58 #define _SYS_QUEUE_H_
  59
  60 /*
  61  * This file defines five types of data structures: singly-linked lists,
  62  * slingly-linked tail queues, lists, tail queues, and circular queues.
  63  *
  64  * A singly-linked list is headed by a single forward pointer. The elements
  65  * are singly linked for minimum space and pointer manipulation overhead at
  66  * the expense of O(n) removal for arbitrary elements. New elements can be
  67  * added to the list after an existing element or at the head of the list.
  68  * Elements being removed from the head of the list should use the explicit
  69  * macro for this purpose for optimum efficiency. A singly-linked list may
  70  * only be traversed in the forward direction.  Singly-linked lists are ideal
  71  * for applications with large datasets and few or no removals or for
  72  * implementing a LIFO queue.
  73  *
  74  * A singly-linked tail queue is headed by a pair of pointers, one to the
  75  * head of the list and the other to the tail of the list. The elements are
  76  * singly linked for minimum space and pointer manipulation overhead at the
  77  * expense of O(n) removal for arbitrary elements. New elements can be added
  78  * to the list after an existing element, at the head of the list, or at the
  79  * end of the list. Elements being removed from the head of the tail queue
  80  * should use the explicit macro for this purpose for optimum efficiency.
  81  * A singly-linked tail queue may only be traversed in the forward direction.
  82  * Singly-linked tail queues are ideal for applications with large datasets
  83  * and few or no removals or for implementing a FIFO queue.
  84  *
  85  * A list is headed by a single forward pointer (or an array of forward
  86  * pointers for a hash table header). The elements are doubly linked
  87  * so that an arbitrary element can be removed without a need to
  88  * traverse the list. New elements can be added to the list before
  89  * or after an existing element or at the head of the list. A list
  90  * may only be traversed in the forward direction.
  91  *
  92  * A tail queue is headed by a pair of pointers, one to the head of the
  93  * list and the other to the tail of the list. The elements are doubly
  94  * linked so that an arbitrary element can be removed without a need to
  95  * traverse the list. New elements can be added to the list before or
  96  * after an existing element, at the head of the list, or at the end of
  97  * the list. A tail queue may only be traversed in the forward direction.
  98  *
  99  * A circle queue is headed by a pair of pointers, one to the head of the
 100  * list and the other to the tail of the list. The elements are doubly
 101  * linked so that an arbitrary element can be removed without a need to
 102  * traverse the list. New elements can be added to the list before or after
 103  * an existing element, at the head of the list, or at the end of the list.
 104  * A circle queue may be traversed in either direction, but has a more
 105  * complex end of list detection.
 106  *
 107  * For details on the use of these macros, see the queue(3) manual page.
 108  *
 109  *
 110  *                      SLIST   LIST    STAILQ  TAILQ   CIRCLEQ
 111  * _HEAD                +       +       +       +       +
 112  * _ENTRY               +       +       +       +       +
 113  * _INIT                +       +       +       +       +
 114  * _EMPTY               +       +       +       +       +
 115  * _FIRST               +       +       +       +       +
 116  * _NEXT                +       +       +       +       +
 117  * _PREV                -       -       -       +       +
 118  * _LAST                -       -       +       +       +
 119  * _FOREACH             +       +       -       +       +
 120  * _INSERT_HEAD         +       +       +       +       +
 121  * _INSERT_BEFORE       -       +       -       +       +
 122  * _INSERT_AFTER        +       +       +       +       +
 123  * _INSERT_TAIL         -       -       +       +       +
 124  * _REMOVE_HEAD         +       -       +       -       -
 125  * _REMOVE              +       +       +       +       +
 126  *
 127  */
 128
 129 /*
 130  * Singly-linked List definitions.
 131  */
 132 #define SLIST_HEAD(name, type)                                          \
 133 struct name {                                                           \
 134         struct type *slh_first; /* first element */                     \
 135 }
 136
 137 #define SLIST_ENTRY(type)                                               \
 138 struct {                                                                \
 139         struct type *sle_next;  /* next element */                      \
 140 }
 141
 142 /*
 143  * Singly-linked List functions.
 144  */
 145 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 146
 147 #define SLIST_FIRST(head)       ((head)->slh_first)
 148
 149 #define SLIST_FOREACH(var, head, field)                                 \
 150         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 151
 152 #define SLIST_INIT(head) {                                              \
 153         (head)->slh_first = NULL;                                       \
 154 }
 155
 156 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 157         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 158         (slistelm)->field.sle_next = (elm);                             \
 159 } while (0)
 160
 161 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 162         (elm)->field.sle_next = (head)->slh_first;                      \
 163         (head)->slh_first = (elm);                                      \
 164 } while (0)
 165
 166 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 167
 168 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 169         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 170 } while (0)
 171
 172 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 173         if ((head)->slh_first == (elm)) {                               \
 174                 SLIST_REMOVE_HEAD((head), field);                       \
 175         }                                                               \
 176         else {                                                          \
 177                 struct type *curelm = (head)->slh_first;                \
 178                 while( curelm->field.sle_next != (elm) )                \
 179                         curelm = curelm->field.sle_next;                \
 180                 curelm->field.sle_next =                                \
 181                     curelm->field.sle_next->field.sle_next;             \
 182         }                                                               \
 183 } while (0)
 184
 185 /*
 186  * Singly-linked Tail queue definitions.
 187  */
 188 #define STAILQ_HEAD(name, type)                                         \
 189 struct name {                                                           \
 190         struct type *stqh_first;/* first element */                     \
 191         struct type **stqh_last;/* addr of last next element */         \
 192 }
 193
 194 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 195         { NULL, &(head).stqh_first }
 196
 197 #define STAILQ_ENTRY(type)                                              \
 198 struct {                                                                \
 199         struct type *stqe_next; /* next element */                      \
 200 }
 201
 202 /*
 203  * Singly-linked Tail queue functions.
 204  */
 205 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
 206
 207 #define STAILQ_INIT(head) do {                                          \
 208         (head)->stqh_first = NULL;                                      \
 209         (head)->stqh_last = &(head)->stqh_first;                        \
 210 } while (0)
 211
 212 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 213 #define STAILQ_LAST(head)       (*(head)->stqh_last)
 214
 215 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 216         if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)      \
 217                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 218         (head)->stqh_first = (elm);                                     \
 219 } while (0)
 220
 221 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 222         (elm)->field.stqe_next = NULL;                                  \
 223         *(head)->stqh_last = (elm);                                     \
 224         (head)->stqh_last = &(elm)->field.stqe_next;                    \
 225 } while (0)
 226
 227 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 228         if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
 229                 (head)->stqh_last = &(elm)->field.stqe_next;            \
 230         (tqelm)->field.stqe_next = (elm);                               \
 231 } while (0)
 232
 233 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 234
 235 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 236         if (((head)->stqh_first =                                       \
 237              (head)->stqh_first->field.stqe_next) == NULL)              \
 238                 (head)->stqh_last = &(head)->stqh_first;                \
 239 } while (0)
 240
 241 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {                 \
 242         if (((head)->stqh_first = (elm)->field.stqe_next) == NULL)      \
 243                 (head)->stqh_last = &(head)->stqh_first;                \
 244 } while (0)
 245
 246
 247 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 248         if ((head)->stqh_first == (elm)) {                              \
 249                 STAILQ_REMOVE_HEAD(head, field);                        \
 250         }                                                               \
 251         else {                                                          \
 252                 struct type *curelm = (head)->stqh_first;               \
 253                 while( curelm->field.stqe_next != (elm) )               \
 254                         curelm = curelm->field.stqe_next;               \
 255                 if((curelm->field.stqe_next =                           \
 256                     curelm->field.stqe_next->field.stqe_next) == NULL)  \
 257                         (head)->stqh_last = &(curelm)->field.stqe_next; \
 258         }                                                               \
 259 } while (0)
 260
 261 /*
 262  * List definitions.
 263  */
 264 #define LIST_HEAD(name, type)                                           \
 265 struct name {                                                           \
 266         struct type *lh_first;  /* first element */                     \
 267 }
 268
 269 #define LIST_HEAD_INITIALIZER(head)                                     \
 270         { NULL }
 271
 272 #define LIST_ENTRY(type)                                                \
 273 struct {                                                                \
 274         struct type *le_next;   /* next element */                      \
 275         struct type **le_prev;  /* address of previous next element */  \
 276 }
 277
 278 /*
 279  * List functions.
 280  */
 281
 282 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
 283
 284 #define LIST_FIRST(head)        ((head)->lh_first)
 285
 286 #define LIST_FOREACH(var, head, field)                                  \
 287         for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
 288
 289 #define LIST_INIT(head) do {                                            \
 290         (head)->lh_first = NULL;                                        \
 291 } while (0)
 292
 293 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 294         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 295                 (listelm)->field.le_next->field.le_prev =               \
 296                     &(elm)->field.le_next;                              \
 297         (listelm)->field.le_next = (elm);                               \
 298         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 299 } while (0)
 300
 301 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 302         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 303         (elm)->field.le_next = (listelm);                               \
 304         *(listelm)->field.le_prev = (elm);                              \
 305         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 306 } while (0)
 307
 308 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 309         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 310                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 311         (head)->lh_first = (elm);                                       \
 312         (elm)->field.le_prev = &(head)->lh_first;                       \
 313 } while (0)
 314
 315 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 316
 317 #define LIST_REMOVE(elm, field) do {                                    \
 318         if ((elm)->field.le_next != NULL)                               \
 319                 (elm)->field.le_next->field.le_prev =                   \
 320                     (elm)->field.le_prev;                               \
 321         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 322 } while (0)
 323
 324 /*
 325  * Tail queue definitions.
 326  */
 327 #define TAILQ_HEAD(name, type)                                          \
 328 struct name {                                                           \
 329         struct type *tqh_first; /* first element */                     \
 330         struct type **tqh_last; /* addr of last next element */         \
 331 }
 332
 333 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 334         { NULL, &(head).tqh_first }
 335
 336 #define TAILQ_ENTRY(type)                                               \
 337 struct {                                                                \
 338         struct type *tqe_next;  /* next element */                      \
 339         struct type **tqe_prev; /* address of previous next element */  \
 340 }
 341
 342 /*
 343  * Tail queue functions.
 344  */
 345 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
 346
 347 #define TAILQ_FOREACH(var, head, field)                                 \
 348         for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))
 349
 350 #define TAILQ_FOREACH_REVERSE(var, head, field, headname)                                       \
 351         for (var = TAILQ_LAST(head, headname);                 \
 352                var; var = TAILQ_PREV(var, headname, field))
 353
 354 #define TAILQ_FIRST(head) ((head)->tqh_first)
 355
 356 #define TAILQ_LAST(head, headname) \
 357         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 358
 359 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 360
 361 #define TAILQ_PREV(elm, headname, field) \
 362         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 363
 364 #define TAILQ_INIT(head) do {                                           \
 365         (head)->tqh_first = NULL;                                       \
 366         (head)->tqh_last = &(head)->tqh_first;                          \
 367 } while (0)
 368
 369 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 370         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 371                 (head)->tqh_first->field.tqe_prev =                     \
 372                     &(elm)->field.tqe_next;                             \
 373         else                                                            \
 374                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 375         (head)->tqh_first = (elm);                                      \
 376         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 377 } while (0)
 378
 379 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 380         (elm)->field.tqe_next = NULL;                                   \
 381         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 382         *(head)->tqh_last = (elm);                                      \
 383         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 384 } while (0)
 385
 386 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 387         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 388                 (elm)->field.tqe_next->field.tqe_prev =                 \
 389                     &(elm)->field.tqe_next;                             \
 390         else                                                            \
 391                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 392         (listelm)->field.tqe_next = (elm);                              \
 393         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 394 } while (0)
 395
 396 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 397         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 398         (elm)->field.tqe_next = (listelm);                              \
 399         *(listelm)->field.tqe_prev = (elm);                             \
 400         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 401 } while (0)
 402
 403 #define TAILQ_REMOVE(head, elm, field) do {                             \
 404         if (((elm)->field.tqe_next) != NULL)                            \
 405                 (elm)->field.tqe_next->field.tqe_prev =                 \
 406                     (elm)->field.tqe_prev;                              \
 407         else                                                            \
 408                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 409         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 410 } while (0)
 411
 412 /*
 413  * Circular queue definitions.
 414  */
 415 #define CIRCLEQ_HEAD(name, type)                                        \
 416 struct name {                                                           \
 417         struct type *cqh_first;         /* first element */             \
 418         struct type *cqh_last;          /* last element */              \
 419 }
 420
 421 #define CIRCLEQ_ENTRY(type)                                             \
 422 struct {                                                                \
 423         struct type *cqe_next;          /* next element */              \
 424         struct type *cqe_prev;          /* previous element */          \
 425 }
 426
 427 /*
 428  * Circular queue functions.
 429  */
 430 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
 431
 432 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
 433
 434 #define CIRCLEQ_FOREACH(var, head, field)                               \
 435         for((var) = (head)->cqh_first;                                  \
 436             (var) != (void *)(head);                                    \
 437             (var) = (var)->field.cqe_next)
 438
 439 #define CIRCLEQ_INIT(head) do {                                         \
 440         (head)->cqh_first = (void *)(head);                             \
 441         (head)->cqh_last = (void *)(head);                              \
 442 } while (0)
 443
 444 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 445         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 446         (elm)->field.cqe_prev = (listelm);                              \
 447         if ((listelm)->field.cqe_next == (void *)(head))                \
 448                 (head)->cqh_last = (elm);                               \
 449         else                                                            \
 450                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 451         (listelm)->field.cqe_next = (elm);                              \
 452 } while (0)
 453
 454 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 455         (elm)->field.cqe_next = (listelm);                              \
 456         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 457         if ((listelm)->field.cqe_prev == (void *)(head))                \
 458                 (head)->cqh_first = (elm);                              \
 459         else                                                            \
 460                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 461         (listelm)->field.cqe_prev = (elm);                              \
 462 } while (0)
 463
 464 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 465         (elm)->field.cqe_next = (head)->cqh_first;                      \
 466         (elm)->field.cqe_prev = (void *)(head);                         \
 467         if ((head)->cqh_last == (void *)(head))                         \
 468                 (head)->cqh_last = (elm);                               \
 469         else                                                            \
 470                 (head)->cqh_first->field.cqe_prev = (elm);              \
 471         (head)->cqh_first = (elm);                                      \
 472 } while (0)
 473
 474 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 475         (elm)->field.cqe_next = (void *)(head);                         \
 476         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 477         if ((head)->cqh_first == (void *)(head))                        \
 478                 (head)->cqh_first = (elm);                              \
 479         else                                                            \
 480                 (head)->cqh_last->field.cqe_next = (elm);               \
 481         (head)->cqh_last = (elm);                                       \
 482 } while (0)
 483
 484 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
 485
 486 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
 487
 488 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
 489
 490 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 491         if ((elm)->field.cqe_next == (void *)(head))                    \
 492                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 493         else                                                            \
 494                 (elm)->field.cqe_next->field.cqe_prev =                 \
 495                     (elm)->field.cqe_prev;                              \
 496         if ((elm)->field.cqe_prev == (void *)(head))                    \
 497                 (head)->cqh_first = (elm)->field.cqe_next;              \
 498         else                                                            \
 499                 (elm)->field.cqe_prev->field.cqe_next =                 \
 500                     (elm)->field.cqe_next;                              \
 501 } while (0)
 502
 503 #ifdef KERNEL
 504
 505 #if NOTFB31
 506
 507 /*
 508  * XXX insque() and remque() are an old way of handling certain queues.
 509  * They bogusly assumes that all queue heads look alike.
 510  */
 511
 512 struct quehead {
 513         struct quehead *qh_link;
 514         struct quehead *qh_rlink;
 515 };
 516
 517 #ifdef  __GNUC__
 518
 519 static __inline void
 520 insque(void *a, void *b)
 521 {
 522         struct quehead *element = a, *head = b;
 523
 524         element->qh_link = head->qh_link;
 525         element->qh_rlink = head;
 526         head->qh_link = element;
 527         element->qh_link->qh_rlink = element;
 528 }
 529
 530 static __inline void
 531 remque(void *a)
 532 {
 533         struct quehead *element = a;
 534
 535         element->qh_link->qh_rlink = element->qh_rlink;
 536         element->qh_rlink->qh_link = element->qh_link;
 537         element->qh_rlink = 0;
 538 }
 539
 540 #else /* !__GNUC__ */
 541
 542 void    insque(void *a, void *b);
 543 void    remque(void *a);
 544
 545 #endif /* __GNUC__ */
 546
 547 #endif
 548 #endif /* KERNEL */
 549
 550 #endif /* !_SYS_QUEUE_H_ */