sys/sys/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  * 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 1.68 2006/10/24 11:20:29 ru 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 #ifdef QUEUE_MACRO_DEBUG
 104 /* Store the last 2 places the queue element or head was altered */
 105 struct qm_trace {
 106         char * lastfile;
 107         int lastline;
 108         char * prevfile;
 109         int prevline;
 110 };
 111
 112 #define TRACEBUF        struct qm_trace trace;
 113 #define TRASHIT(x)      do {(x) = (void *)-1;} while (0)
 114
 115 #define QMD_TRACE_HEAD(head) do {                                       \
 116         (head)->trace.prevline = (head)->trace.lastline;                \
 117         (head)->trace.prevfile = (head)->trace.lastfile;                \
 118         (head)->trace.lastline = __LINE__;                              \
 119         (head)->trace.lastfile = __FILE__;                              \
 120 } while (0)
 121
 122 #define QMD_TRACE_ELEM(elem) do {                                       \
 123         (elem)->trace.prevline = (elem)->trace.lastline;                \
 124         (elem)->trace.prevfile = (elem)->trace.lastfile;                \
 125         (elem)->trace.lastline = __LINE__;                              \
 126         (elem)->trace.lastfile = __FILE__;                              \
 127 } while (0)
 128
 129 #else
 130 #define QMD_TRACE_ELEM(elem)
 131 #define QMD_TRACE_HEAD(head)
 132 #define TRACEBUF
 133 #define TRASHIT(x)
 134 #endif  /* QUEUE_MACRO_DEBUG */
 135
 136 /*
 137  * Singly-linked List declarations.
 138  */
 139 #define SLIST_HEAD(name, type)                                          \
 140 struct name {                                                           \
 141         struct type *slh_first; /* first element */                     \
 142 }
 143
 144 #define SLIST_HEAD_INITIALIZER(head)                                    \
 145         { NULL }
 146
 147 #if defined( _WIN32 ) && defined(SLIST_ENTRY)
 148 #undef SLIST_ENTRY
 149 #endif
 150 #define SLIST_ENTRY(type)                                               \
 151 struct {                                                                \
 152         struct type *sle_next;  /* next element */                      \
 153 }
 154
 155 /*
 156  * Singly-linked List functions.
 157  */
 158 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 159
 160 #define SLIST_FIRST(head)       ((head)->slh_first)
 161
 162 #define SLIST_FOREACH(var, head, field)                                 \
 163         for ((var) = SLIST_FIRST((head));                               \
 164             (var);                                                      \
 165             (var) = SLIST_NEXT((var), field))
 166
 167 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 168         for ((var) = SLIST_FIRST((head));                               \
 169             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 170             (var) = (tvar))
 171
 172 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
 173         for ((varp) = &SLIST_FIRST((head));                             \
 174             ((var) = *(varp)) != NULL;                                  \
 175             (varp) = &SLIST_NEXT((var), field))
 176
 177 #define SLIST_INIT(head) do {                                           \
 178         SLIST_FIRST((head)) = NULL;                                     \
 179 } while (0)
 180
 181 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 182         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
 183         SLIST_NEXT((slistelm), field) = (elm);                          \
 184 } while (0)
 185
 186 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 187         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
 188         SLIST_FIRST((head)) = (elm);                                    \
 189 } while (0)
 190
 191 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 192
 193 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 194         if (SLIST_FIRST((head)) == (elm)) {                             \
 195                 SLIST_REMOVE_HEAD((head), field);                       \
 196         }                                                               \
 197         else {                                                          \
 198                 struct type *curelm = SLIST_FIRST((head));              \
 199                 while (SLIST_NEXT(curelm, field) != (elm))              \
 200                         curelm = SLIST_NEXT(curelm, field);             \
 201                 SLIST_NEXT(curelm, field) =                             \
 202                     SLIST_NEXT(SLIST_NEXT(curelm, field), field);       \
 203         }                                                               \
 204         TRASHIT((elm)->field.sle_next);                                 \
 205 } while (0)
 206
 207 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 208         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 209 } while (0)
 210
 211 /*
 212  * Singly-linked Tail queue declarations.
 213  */
 214 #define STAILQ_HEAD(name, type)                                         \
 215 struct name {                                                           \
 216         struct type *stqh_first;/* first element */                     \
 217         struct type **stqh_last;/* addr of last next element */         \
 218 }
 219
 220 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 221         { NULL, &(head).stqh_first }
 222
 223 #define STAILQ_ENTRY(type)                                              \
 224 struct {                                                                \
 225         struct type *stqe_next; /* next element */                      \
 226 }
 227
 228 /*
 229  * Singly-linked Tail queue functions.
 230  */
 231 #define STAILQ_CONCAT(head1, head2) do {                                \
 232         if (!STAILQ_EMPTY((head2))) {                                   \
 233                 *(head1)->stqh_last = (head2)->stqh_first;              \
 234                 (head1)->stqh_last = (head2)->stqh_last;                \
 235                 STAILQ_INIT((head2));                                   \
 236         }                                                               \
 237 } while (0)
 238
 239 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 240
 241 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 242
 243 #define STAILQ_FOREACH(var, head, field)                                \
 244         for((var) = STAILQ_FIRST((head));                               \
 245            (var);                                                       \
 246            (var) = STAILQ_NEXT((var), field))
 247
 248
 249 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
 250         for ((var) = STAILQ_FIRST((head));                              \
 251             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 252             (var) = (tvar))
 253
 254 #define STAILQ_INIT(head) do {                                          \
 255         STAILQ_FIRST((head)) = NULL;                                    \
 256         (head)->stqh_last = &STAILQ_FIRST((head));                      \
 257 } while (0)
 258
 259 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 260         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 261                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 262         STAILQ_NEXT((tqelm), field) = (elm);                            \
 263 } while (0)
 264
 265 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 266         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
 267                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 268         STAILQ_FIRST((head)) = (elm);                                   \
 269 } while (0)
 270
 271 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 272         STAILQ_NEXT((elm), field) = NULL;                               \
 273         *(head)->stqh_last = (elm);                                     \
 274         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
 275 } while (0)
 276
 277 #define STAILQ_LAST(head, type, field)                                  \
 278         (STAILQ_EMPTY((head)) ?                                         \
 279                 NULL :                                                  \
 280                 ((struct type *)(void *)                                \
 281                 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
 282
 283 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 284
 285 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 286         if (STAILQ_FIRST((head)) == (elm)) {                            \
 287                 STAILQ_REMOVE_HEAD((head), field);                      \
 288         }                                                               \
 289         else {                                                          \
 290                 struct type *curelm = STAILQ_FIRST((head));             \
 291                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 292                         curelm = STAILQ_NEXT(curelm, field);            \
 293                 if ((STAILQ_NEXT(curelm, field) =                       \
 294                      STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
 295                         (head)->stqh_last = &STAILQ_NEXT((curelm), field);\
 296         }                                                               \
 297         TRASHIT((elm)->field.stqe_next);                                \
 298 } while (0)
 299
 300 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 301         if ((STAILQ_FIRST((head)) =                                     \
 302              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
 303                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 304 } while (0)
 305
 306 #ifndef LIST_HEAD
 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 #if (defined(_KERNEL) && defined(INVARIANTS))
 329 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 330         if (LIST_FIRST((head)) != NULL &&                               \
 331             LIST_FIRST((head))->field.le_prev !=                        \
 332              &LIST_FIRST((head)))                                       \
 333                 panic("Bad list head %p first->prev != head", (head));  \
 334 } while (0)
 335
 336 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 337         if (LIST_NEXT((elm), field) != NULL &&                          \
 338             LIST_NEXT((elm), field)->field.le_prev !=                   \
 339              &((elm)->field.le_next))                                   \
 340                 panic("Bad link elm %p next->prev != elm", (elm));      \
 341 } while (0)
 342
 343 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 344         if (*(elm)->field.le_prev != (elm))                             \
 345                 panic("Bad link elm %p prev->next != elm", (elm));      \
 346 } while (0)
 347 #else
 348 #define QMD_LIST_CHECK_HEAD(head, field)
 349 #define QMD_LIST_CHECK_NEXT(elm, field)
 350 #define QMD_LIST_CHECK_PREV(elm, field)
 351 #endif /* (_KERNEL && INVARIANTS) */
 352
 353 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 354
 355 #define LIST_FIRST(head)        ((head)->lh_first)
 356
 357 #define LIST_FOREACH(var, head, field)                                  \
 358         for ((var) = LIST_FIRST((head));                                \
 359             (var);                                                      \
 360             (var) = LIST_NEXT((var), field))
 361
 362 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 363         for ((var) = LIST_FIRST((head));                                \
 364             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 365             (var) = (tvar))
 366
 367 #define LIST_INIT(head) do {                                            \
 368         LIST_FIRST((head)) = NULL;                                      \
 369 } while (0)
 370
 371 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 372         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 373         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 374                 LIST_NEXT((listelm), field)->field.le_prev =            \
 375                     &LIST_NEXT((elm), field);                           \
 376         LIST_NEXT((listelm), field) = (elm);                            \
 377         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 378 } while (0)
 379
 380 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 381         QMD_LIST_CHECK_PREV(listelm, field);                            \
 382         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 383         LIST_NEXT((elm), field) = (listelm);                            \
 384         *(listelm)->field.le_prev = (elm);                              \
 385         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 386 } while (0)
 387
 388 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 389         QMD_LIST_CHECK_HEAD((head), field);                             \
 390         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 391                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 392         LIST_FIRST((head)) = (elm);                                     \
 393         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 394 } while (0)
 395
 396 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 397
 398 #define LIST_REMOVE(elm, field) do {                                    \
 399         QMD_LIST_CHECK_NEXT(elm, field);                                \
 400         QMD_LIST_CHECK_PREV(elm, field);                                \
 401         if (LIST_NEXT((elm), field) != NULL)                            \
 402                 LIST_NEXT((elm), field)->field.le_prev =                \
 403                     (elm)->field.le_prev;                               \
 404         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 405         TRASHIT((elm)->field.le_next);                                  \
 406         TRASHIT((elm)->field.le_prev);                                  \
 407 } while (0)
 408 #endif /* LIST_HEAD */
 409
 410 /*
 411  * Tail queue declarations.
 412  */
 413 #define TAILQ_HEAD(name, type)                                          \
 414 struct name {                                                           \
 415         struct type *tqh_first; /* first element */                     \
 416         struct type **tqh_last; /* addr of last next element */         \
 417         TRACEBUF                                                        \
 418 }
 419
 420 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 421         { NULL, &(head).tqh_first }
 422
 423 #define TAILQ_ENTRY(type)                                               \
 424 struct {                                                                \
 425         struct type *tqe_next;  /* next element */                      \
 426         struct type **tqe_prev; /* address of previous next element */  \
 427         TRACEBUF                                                        \
 428 }
 429
 430 /*
 431  * Tail queue functions.
 432  */
 433 #if (defined(_KERNEL) && defined(INVARIANTS))
 434 #define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
 435         if (!TAILQ_EMPTY(head) &&                                       \
 436             TAILQ_FIRST((head))->field.tqe_prev !=                      \
 437              &TAILQ_FIRST((head)))                                      \
 438                 panic("Bad tailq head %p first->prev != head", (head)); \
 439 } while (0)
 440
 441 #define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
 442         if (*(head)->tqh_last != NULL)                                  \
 443                 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
 444 } while (0)
 445
 446 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
 447         if (TAILQ_NEXT((elm), field) != NULL &&                         \
 448             TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
 449              &((elm)->field.tqe_next))                                  \
 450                 panic("Bad link elm %p next->prev != elm", (elm));      \
 451 } while (0)
 452
 453 #define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
 454         if (*(elm)->field.tqe_prev != (elm))                            \
 455                 panic("Bad link elm %p prev->next != elm", (elm));      \
 456 } while (0)
 457 #else
 458 #define QMD_TAILQ_CHECK_HEAD(head, field)
 459 #define QMD_TAILQ_CHECK_TAIL(head, headname)
 460 #define QMD_TAILQ_CHECK_NEXT(elm, field)
 461 #define QMD_TAILQ_CHECK_PREV(elm, field)
 462 #endif /* (_KERNEL && INVARIANTS) */
 463
 464 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 465         if (!TAILQ_EMPTY(head2)) {                                      \
 466                 *(head1)->tqh_last = (head2)->tqh_first;                \
 467                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 468                 (head1)->tqh_last = (head2)->tqh_last;                  \
 469                 TAILQ_INIT((head2));                                    \
 470                 QMD_TRACE_HEAD(head1);                                  \
 471                 QMD_TRACE_HEAD(head2);                                  \
 472         }                                                               \
 473 } while (0)
 474
 475 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 476
 477 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 478
 479 #define TAILQ_FOREACH(var, head, field)                                 \
 480         for ((var) = TAILQ_FIRST((head));                               \
 481             (var);                                                      \
 482             (var) = TAILQ_NEXT((var), field))
 483
 484 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 485         for ((var) = TAILQ_FIRST((head));                               \
 486             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 487             (var) = (tvar))
 488
 489 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 490         for ((var) = TAILQ_LAST((head), headname);                      \
 491             (var);                                                      \
 492             (var) = TAILQ_PREV((var), headname, field))
 493
 494 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 495         for ((var) = TAILQ_LAST((head), headname);                      \
 496             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 497             (var) = (tvar))
 498
 499 #define TAILQ_INIT(head) do {                                           \
 500         TAILQ_FIRST((head)) = NULL;                                     \
 501         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 502         QMD_TRACE_HEAD(head);                                           \
 503 } while (0)
 504
 505 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 506         QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
 507         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 508                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 509                     &TAILQ_NEXT((elm), field);                          \
 510         else {                                                          \
 511                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 512                 QMD_TRACE_HEAD(head);                                   \
 513         }                                                               \
 514         TAILQ_NEXT((listelm), field) = (elm);                           \
 515         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 516         QMD_TRACE_ELEM(&(elm)->field);                                  \
 517         QMD_TRACE_ELEM(&listelm->field);                                \
 518 } while (0)
 519
 520 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 521         QMD_TAILQ_CHECK_PREV(listelm, field);                           \
 522         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 523         TAILQ_NEXT((elm), field) = (listelm);                           \
 524         *(listelm)->field.tqe_prev = (elm);                             \
 525         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 526         QMD_TRACE_ELEM(&(elm)->field);                                  \
 527         QMD_TRACE_ELEM(&listelm->field);                                \
 528 } while (0)
 529
 530 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 531         QMD_TAILQ_CHECK_HEAD(head, field);                              \
 532         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 533                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 534                     &TAILQ_NEXT((elm), field);                          \
 535         else                                                            \
 536                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 537         TAILQ_FIRST((head)) = (elm);                                    \
 538         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 539         QMD_TRACE_HEAD(head);                                           \
 540         QMD_TRACE_ELEM(&(elm)->field);                                  \
 541 } while (0)
 542
 543 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 544         QMD_TAILQ_CHECK_TAIL(head, field);                              \
 545         TAILQ_NEXT((elm), field) = NULL;                                \
 546         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 547         *(head)->tqh_last = (elm);                                      \
 548         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 549         QMD_TRACE_HEAD(head);                                           \
 550         QMD_TRACE_ELEM(&(elm)->field);                                  \
 551 } while (0)
 552
 553 #define TAILQ_LAST(head, headname)                                      \
 554         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 555
 556 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 557
 558 #define TAILQ_PREV(elm, headname, field)                                \
 559         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 560
 561 #define TAILQ_REMOVE(head, elm, field) do {                             \
 562         QMD_TAILQ_CHECK_NEXT(elm, field);                               \
 563         QMD_TAILQ_CHECK_PREV(elm, field);                               \
 564         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 565                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 566                     (elm)->field.tqe_prev;                              \
 567         else {                                                          \
 568                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 569                 QMD_TRACE_HEAD(head);                                   \
 570         }                                                               \
 571         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 572         TRASHIT((elm)->field.tqe_next);                                 \
 573         TRASHIT((elm)->field.tqe_prev);                                 \
 574         QMD_TRACE_ELEM(&(elm)->field);                                  \
 575 } while (0)
 576
 577
 578 #ifdef _KERNEL
 579
 580 /*
 581  * XXX insque() and remque() are an old way of handling certain queues.
 582  * They bogusly assumes that all queue heads look alike.
 583  */
 584
 585 struct quehead {
 586         struct quehead *qh_link;
 587         struct quehead *qh_rlink;
 588 };
 589
 590 #ifdef __CC_SUPPORTS___INLINE
 591
 592 static __inline void
 593 insque(void *a, void *b)
 594 {
 595         struct quehead *element = (struct quehead *)a,
 596                  *head = (struct quehead *)b;
 597
 598         element->qh_link = head->qh_link;
 599         element->qh_rlink = head;
 600         head->qh_link = element;
 601         element->qh_link->qh_rlink = element;
 602 }
 603
 604 static __inline void
 605 remque(void *a)
 606 {
 607         struct quehead *element = (struct quehead *)a;
 608
 609         element->qh_link->qh_rlink = element->qh_rlink;
 610         element->qh_rlink->qh_link = element->qh_link;
 611         element->qh_rlink = 0;
 612 }
 613
 614 #else /* !__CC_SUPPORTS___INLINE */
 615
 616 void    insque(void *a, void *b);
 617 void    remque(void *a);
 618
 619 #endif /* __CC_SUPPORTS___INLINE */
 620
 621 #endif /* _KERNEL */
 622
 623 #endif /* !_SYS_QUEUE_H_ */