l4/pkg/libbsd/lib/contrib/include/bsd/queue.h

   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. 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 <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 *)(void *)                                \
 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 #if defined(__GNUC__) || defined(__INTEL_COMPILER)
 521
 522 static __inline void
 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
 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 /* !(__GNUC__ || __INTEL_COMPILER) */
 545
 546 void    insque(void *a, void *b);
 547 void    remque(void *a);
 548
 549 #endif /* __GNUC__ || __INTEL_COMPILER */
 550
 551 #endif /* _KERNEL */
 552
 553 #endif /* !_SYS_QUEUE_H */