drl/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  * 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 1.69 2008/05/22 14:40:03 ed 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_NEXT                 +       -       +       -
 101  * _REMOVE                      +       +       +       +
 102  *
 103  */
 104 #ifdef 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_REMOVE_NEXT(head, curelm, field);                 \
 200         }                                                               \
 201         TRASHIT((elm)->field.sle_next);                                 \
 202 } while (0)
 203
 204 #define SLIST_REMOVE_NEXT(head, elm, field) do {                                \
 205         SLIST_NEXT(elm, field) =                                        \
 206             SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
 207 } while (0)
 208
 209 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 210         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 211 } while (0)
 212
 213 /*
 214  * Singly-linked Tail queue declarations.
 215  */
 216 #define STAILQ_HEAD(name, type)                                         \
 217 struct name {                                                           \
 218         struct type *stqh_first;/* first element */                     \
 219         struct type **stqh_last;/* addr of last next element */         \
 220 }
 221
 222 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 223         { NULL, &(head).stqh_first }
 224
 225 #define STAILQ_ENTRY(type)                                              \
 226 struct {                                                                \
 227         struct type *stqe_next; /* next element */                      \
 228 }
 229
 230 /*
 231  * Singly-linked Tail queue functions.
 232  */
 233 #define STAILQ_CONCAT(head1, head2) do {                                \
 234         if (!STAILQ_EMPTY((head2))) {                                   \
 235                 *(head1)->stqh_last = (head2)->stqh_first;              \
 236                 (head1)->stqh_last = (head2)->stqh_last;                \
 237                 STAILQ_INIT((head2));                                   \
 238         }                                                               \
 239 } while (0)
 240
 241 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 242
 243 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 244
 245 #define STAILQ_FOREACH(var, head, field)                                \
 246         for((var) = STAILQ_FIRST((head));                               \
 247            (var);                                                       \
 248            (var) = STAILQ_NEXT((var), field))
 249
 250
 251 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
 252         for ((var) = STAILQ_FIRST((head));                              \
 253             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 254             (var) = (tvar))
 255
 256 #define STAILQ_INIT(head) do {                                          \
 257         STAILQ_FIRST((head)) = NULL;                                    \
 258         (head)->stqh_last = &STAILQ_FIRST((head));                      \
 259 } while (0)
 260
 261 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 262         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 263                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 264         STAILQ_NEXT((tqelm), field) = (elm);                            \
 265 } while (0)
 266
 267 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 268         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
 269                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 270         STAILQ_FIRST((head)) = (elm);                                   \
 271 } while (0)
 272
 273 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 274         STAILQ_NEXT((elm), field) = NULL;                               \
 275         *(head)->stqh_last = (elm);                                     \
 276         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
 277 } while (0)
 278
 279 #define STAILQ_LAST(head, type, field)                                  \
 280         (STAILQ_EMPTY((head)) ?                                         \
 281                 NULL :                                                  \
 282                 ((struct type *)(void *)                                \
 283                 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
 284
 285 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 286
 287 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 288         if (STAILQ_FIRST((head)) == (elm)) {                            \
 289                 STAILQ_REMOVE_HEAD((head), field);                      \
 290         }                                                               \
 291         else {                                                          \
 292                 struct type *curelm = STAILQ_FIRST((head));             \
 293                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 294                         curelm = STAILQ_NEXT(curelm, field);            \
 295                 STAILQ_REMOVE_NEXT(head, 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 #define STAILQ_REMOVE_NEXT(head, elm, field) do {                       \
 307         if ((STAILQ_NEXT(elm, field) =                                  \
 308              STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
 309                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 310 } while (0)
 311
 312 /*
 313  * List declarations.
 314  */
 315 #define LIST_HEAD(name, type)                                           \
 316 struct name {                                                           \
 317         struct type *lh_first;  /* first element */                     \
 318 }
 319
 320 #define LIST_HEAD_INITIALIZER(head)                                     \
 321         { NULL }
 322
 323 #define LIST_ENTRY(type)                                                \
 324 struct {                                                                \
 325         struct type *le_next;   /* next element */                      \
 326         struct type **le_prev;  /* address of previous next element */  \
 327 }
 328
 329 /*
 330  * List functions.
 331  */
 332
 333 #if (defined(_KERNEL) && defined(INVARIANTS))
 334 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 335         if (LIST_FIRST((head)) != NULL &&                               \
 336             LIST_FIRST((head))->field.le_prev !=                        \
 337              &LIST_FIRST((head)))                                       \
 338                 panic("Bad list head %p first->prev != head", (head));  \
 339 } while (0)
 340
 341 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 342         if (LIST_NEXT((elm), field) != NULL &&                          \
 343             LIST_NEXT((elm), field)->field.le_prev !=                   \
 344              &((elm)->field.le_next))                                   \
 345                 panic("Bad link elm %p next->prev != elm", (elm));      \
 346 } while (0)
 347
 348 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 349         if (*(elm)->field.le_prev != (elm))                             \
 350                 panic("Bad link elm %p prev->next != elm", (elm));      \
 351 } while (0)
 352 #else
 353 #define QMD_LIST_CHECK_HEAD(head, field)
 354 #define QMD_LIST_CHECK_NEXT(elm, field)
 355 #define QMD_LIST_CHECK_PREV(elm, field)
 356 #endif /* (_KERNEL && INVARIANTS) */
 357
 358 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 359
 360 #define LIST_FIRST(head)        ((head)->lh_first)
 361
 362 #define LIST_FOREACH(var, head, field)                                  \
 363         for ((var) = LIST_FIRST((head));                                \
 364             (var);                                                      \
 365             (var) = LIST_NEXT((var), field))
 366
 367 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 368         for ((var) = LIST_FIRST((head));                                \
 369             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 370             (var) = (tvar))
 371
 372 #define LIST_INIT(head) do {                                            \
 373         LIST_FIRST((head)) = NULL;                                      \
 374 } while (0)
 375
 376 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 377         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 378         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 379                 LIST_NEXT((listelm), field)->field.le_prev =            \
 380                     &LIST_NEXT((elm), field);                           \
 381         LIST_NEXT((listelm), field) = (elm);                            \
 382         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 383 } while (0)
 384
 385 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 386         QMD_LIST_CHECK_PREV(listelm, field);                            \
 387         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 388         LIST_NEXT((elm), field) = (listelm);                            \
 389         *(listelm)->field.le_prev = (elm);                              \
 390         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 391 } while (0)
 392
 393 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 394         QMD_LIST_CHECK_HEAD((head), field);                             \
 395         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 396                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 397         LIST_FIRST((head)) = (elm);                                     \
 398         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 399 } while (0)
 400
 401 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 402
 403 #define LIST_REMOVE(elm, field) do {                                    \
 404         QMD_LIST_CHECK_NEXT(elm, field);                                \
 405         QMD_LIST_CHECK_PREV(elm, field);                                \
 406         if (LIST_NEXT((elm), field) != NULL)                            \
 407                 LIST_NEXT((elm), field)->field.le_prev =                \
 408                     (elm)->field.le_prev;                               \
 409         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 410         TRASHIT((elm)->field.le_next);                                  \
 411         TRASHIT((elm)->field.le_prev);                                  \
 412 } while (0)
 413
 414 /*
 415  * Tail queue declarations.
 416  */
 417 #define TAILQ_HEAD(name, type)                                          \
 418 struct name {                                                           \
 419         struct type *tqh_first; /* first element */                     \
 420         struct type **tqh_last; /* addr of last next element */         \
 421         TRACEBUF                                                        \
 422 }
 423
 424 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 425         { NULL, &(head).tqh_first }
 426
 427 #define TAILQ_ENTRY(type)                                               \
 428 struct {                                                                \
 429         struct type *tqe_next;  /* next element */                      \
 430         struct type **tqe_prev; /* address of previous next element */  \
 431         TRACEBUF                                                        \
 432 }
 433
 434 /*
 435  * Tail queue functions.
 436  */
 437 #if (defined(_KERNEL) && defined(INVARIANTS))
 438 #define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
 439         if (!TAILQ_EMPTY(head) &&                                       \
 440             TAILQ_FIRST((head))->field.tqe_prev !=                      \
 441              &TAILQ_FIRST((head)))                                      \
 442                 panic("Bad tailq head %p first->prev != head", (head)); \
 443 } while (0)
 444
 445 #define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
 446         if (*(head)->tqh_last != NULL)                                  \
 447                 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
 448 } while (0)
 449
 450 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
 451         if (TAILQ_NEXT((elm), field) != NULL &&                         \
 452             TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
 453              &((elm)->field.tqe_next))                                  \
 454                 panic("Bad link elm %p next->prev != elm", (elm));      \
 455 } while (0)
 456
 457 #define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
 458         if (*(elm)->field.tqe_prev != (elm))                            \
 459                 panic("Bad link elm %p prev->next != elm", (elm));      \
 460 } while (0)
 461 #else
 462 #define QMD_TAILQ_CHECK_HEAD(head, field)
 463 #define QMD_TAILQ_CHECK_TAIL(head, headname)
 464 #define QMD_TAILQ_CHECK_NEXT(elm, field)
 465 #define QMD_TAILQ_CHECK_PREV(elm, field)
 466 #endif /* (_KERNEL && INVARIANTS) */
 467
 468 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 469         if (!TAILQ_EMPTY(head2)) {                                      \
 470                 *(head1)->tqh_last = (head2)->tqh_first;                \
 471                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 472                 (head1)->tqh_last = (head2)->tqh_last;                  \
 473                 TAILQ_INIT((head2));                                    \
 474                 QMD_TRACE_HEAD(head1);                                  \
 475                 QMD_TRACE_HEAD(head2);                                  \
 476         }                                                               \
 477 } while (0)
 478
 479 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 480
 481 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 482
 483 #define TAILQ_FOREACH(var, head, field)                                 \
 484         for ((var) = TAILQ_FIRST((head));                               \
 485             (var);                                                      \
 486             (var) = TAILQ_NEXT((var), field))
 487
 488 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 489         for ((var) = TAILQ_FIRST((head));                               \
 490             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 491             (var) = (tvar))
 492
 493 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 494         for ((var) = TAILQ_LAST((head), headname);                      \
 495             (var);                                                      \
 496             (var) = TAILQ_PREV((var), headname, field))
 497
 498 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 499         for ((var) = TAILQ_LAST((head), headname);                      \
 500             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 501             (var) = (tvar))
 502
 503 #define TAILQ_INIT(head) do {                                           \
 504         TAILQ_FIRST((head)) = NULL;                                     \
 505         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 506         QMD_TRACE_HEAD(head);                                           \
 507 } while (0)
 508
 509 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 510         QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
 511         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 512                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 513                     &TAILQ_NEXT((elm), field);                          \
 514         else {                                                          \
 515                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 516                 QMD_TRACE_HEAD(head);                                   \
 517         }                                                               \
 518         TAILQ_NEXT((listelm), field) = (elm);                           \
 519         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 520         QMD_TRACE_ELEM(&(elm)->field);                                  \
 521         QMD_TRACE_ELEM(&listelm->field);                                \
 522 } while (0)
 523
 524 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 525         QMD_TAILQ_CHECK_PREV(listelm, field);                           \
 526         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 527         TAILQ_NEXT((elm), field) = (listelm);                           \
 528         *(listelm)->field.tqe_prev = (elm);                             \
 529         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 530         QMD_TRACE_ELEM(&(elm)->field);                                  \
 531         QMD_TRACE_ELEM(&listelm->field);                                \
 532 } while (0)
 533
 534 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 535         QMD_TAILQ_CHECK_HEAD(head, field);                              \
 536         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 537                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 538                     &TAILQ_NEXT((elm), field);                          \
 539         else                                                            \
 540                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 541         TAILQ_FIRST((head)) = (elm);                                    \
 542         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 543         QMD_TRACE_HEAD(head);                                           \
 544         QMD_TRACE_ELEM(&(elm)->field);                                  \
 545 } while (0)
 546
 547 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 548         QMD_TAILQ_CHECK_TAIL(head, field);                              \
 549         TAILQ_NEXT((elm), field) = NULL;                                \
 550         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 551         *(head)->tqh_last = (elm);                                      \
 552         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 553         QMD_TRACE_HEAD(head);                                           \
 554         QMD_TRACE_ELEM(&(elm)->field);                                  \
 555 } while (0)
 556
 557 #define TAILQ_LAST(head, headname)                                      \
 558         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 559
 560 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 561
 562 #define TAILQ_PREV(elm, headname, field)                                \
 563         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 564
 565 #define TAILQ_REMOVE(head, elm, field) do {                             \
 566         QMD_TAILQ_CHECK_NEXT(elm, field);                               \
 567         QMD_TAILQ_CHECK_PREV(elm, field);                               \
 568         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 569                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 570                     (elm)->field.tqe_prev;                              \
 571         else {                                                          \
 572                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 573                 QMD_TRACE_HEAD(head);                                   \
 574         }                                                               \
 575         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 576         TRASHIT((elm)->field.tqe_next);                                 \
 577         TRASHIT((elm)->field.tqe_prev);                                 \
 578         QMD_TRACE_ELEM(&(elm)->field);                                  \
 579 } while (0)
 580
 581
 582 #ifdef _KERNEL
 583
 584 /*
 585  * XXX insque() and remque() are an old way of handling certain queues.
 586  * They bogusly assumes that all queue heads look alike.
 587  */
 588
 589 struct quehead {
 590         struct quehead *qh_link;
 591         struct quehead *qh_rlink;
 592 };
 593
 594 #ifdef __CC_SUPPORTS___INLINE
 595
 596 static __inline void
 597 insque(void *a, void *b)
 598 {
 599         struct quehead *element = (struct quehead *)a,
 600                  *head = (struct quehead *)b;
 601
 602         element->qh_link = head->qh_link;
 603         element->qh_rlink = head;
 604         head->qh_link = element;
 605         element->qh_link->qh_rlink = element;
 606 }
 607
 608 static __inline void
 609 remque(void *a)
 610 {
 611         struct quehead *element = (struct quehead *)a;
 612
 613         element->qh_link->qh_rlink = element->qh_rlink;
 614         element->qh_rlink->qh_link = element->qh_link;
 615         element->qh_rlink = 0;
 616 }
 617
 618 #else /* !__CC_SUPPORTS___INLINE */
 619
 620 void    insque(void *a, void *b);
 621 void    remque(void *a);
 622
 623 #endif /* __CC_SUPPORTS___INLINE */
 624
 625 #endif /* _KERNEL */
 626
 627 #endif /* !_SYS_QUEUE_H_ */