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  * $FreeBSD$
  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_AFTER                +       -       +       -
 100  * _REMOVE_HEAD                 +       -       +       -
 101  * _REMOVE                      +       +       +       +
 102  * _SWAP                        +       +       +       +
 103  *
 104  */
 105 #ifdef QUEUE_MACRO_DEBUG
 106 /* Store the last 2 places the queue element or head was altered */
 107 struct qm_trace {
 108         char * lastfile;
 109         int lastline;
 110         char * prevfile;
 111         int prevline;
 112 };
 113
 114 #define TRACEBUF        struct qm_trace trace;
 115 #define TRASHIT(x)      do {(x) = (void *)-1;} while (0)
 116 #define QMD_SAVELINK(name, link)        void **name = (void *)&(link)
 117
 118 #define QMD_TRACE_HEAD(head) do {                                       \
 119         (head)->trace.prevline = (head)->trace.lastline;                \
 120         (head)->trace.prevfile = (head)->trace.lastfile;                \
 121         (head)->trace.lastline = __LINE__;                              \
 122         (head)->trace.lastfile = __FILE__;                              \
 123 } while (0)
 124
 125 #define QMD_TRACE_ELEM(elem) do {                                       \
 126         (elem)->trace.prevline = (elem)->trace.lastline;                \
 127         (elem)->trace.prevfile = (elem)->trace.lastfile;                \
 128         (elem)->trace.lastline = __LINE__;                              \
 129         (elem)->trace.lastfile = __FILE__;                              \
 130 } while (0)
 131
 132 #else
 133 #define QMD_TRACE_ELEM(elem)
 134 #define QMD_TRACE_HEAD(head)
 135 #define QMD_SAVELINK(name, link)
 136 #define TRACEBUF
 137 #define TRASHIT(x)
 138 #endif  /* QUEUE_MACRO_DEBUG */
 139
 140 /*
 141  * Singly-linked List declarations.
 142  */
 143 #define SLIST_HEAD(name, type)                                          \
 144 struct name {                                                           \
 145         struct type *slh_first; /* first element */                     \
 146 }
 147
 148 #define SLIST_HEAD_INITIALIZER(head)                                    \
 149         { NULL }
 150
 151 #define SLIST_ENTRY(type)                                               \
 152 struct {                                                                \
 153         struct type *sle_next;  /* next element */                      \
 154 }
 155
 156 /*
 157  * Singly-linked List functions.
 158  */
 159 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 160
 161 #define SLIST_FIRST(head)       ((head)->slh_first)
 162
 163 #define SLIST_FOREACH(var, head, field)                                 \
 164         for ((var) = SLIST_FIRST((head));                               \
 165             (var);                                                      \
 166             (var) = SLIST_NEXT((var), field))
 167
 168 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 169         for ((var) = SLIST_FIRST((head));                               \
 170             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 171             (var) = (tvar))
 172
 173 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
 174         for ((varp) = &SLIST_FIRST((head));                             \
 175             ((var) = *(varp)) != NULL;                                  \
 176             (varp) = &SLIST_NEXT((var), field))
 177
 178 #define SLIST_INIT(head) do {                                           \
 179         SLIST_FIRST((head)) = NULL;                                     \
 180 } while (0)
 181
 182 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 183         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
 184         SLIST_NEXT((slistelm), field) = (elm);                          \
 185 } while (0)
 186
 187 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 188         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
 189         SLIST_FIRST((head)) = (elm);                                    \
 190 } while (0)
 191
 192 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 193
 194 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 195         QMD_SAVELINK(oldnext, (elm)->field.sle_next);                   \
 196         if (SLIST_FIRST((head)) == (elm)) {                             \
 197                 SLIST_REMOVE_HEAD((head), field);                       \
 198         }                                                               \
 199         else {                                                          \
 200                 struct type *curelm = SLIST_FIRST((head));              \
 201                 while (SLIST_NEXT(curelm, field) != (elm))              \
 202                         curelm = SLIST_NEXT(curelm, field);             \
 203                 SLIST_REMOVE_AFTER(curelm, field);                      \
 204         }                                                               \
 205         TRASHIT(*oldnext);                                              \
 206 } while (0)
 207
 208 #define SLIST_REMOVE_AFTER(elm, field) do {                             \
 209         SLIST_NEXT(elm, field) =                                        \
 210             SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
 211 } while (0)
 212
 213 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 214         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 215 } while (0)
 216
 217 #define SLIST_SWAP(head1, head2, type) do {                             \
 218         struct type *swap_first = SLIST_FIRST(head1);                   \
 219         SLIST_FIRST(head1) = SLIST_FIRST(head2);                        \
 220         SLIST_FIRST(head2) = swap_first;                                \
 221 } while (0)
 222
 223 /*
 224  * Singly-linked Tail queue declarations.
 225  */
 226 #define STAILQ_HEAD(name, type)                                         \
 227 struct name {                                                           \
 228         struct type *stqh_first;/* first element */                     \
 229         struct type **stqh_last;/* addr of last next element */         \
 230 }
 231
 232 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 233         { NULL, &(head).stqh_first }
 234
 235 #define STAILQ_ENTRY(type)                                              \
 236 struct {                                                                \
 237         struct type *stqe_next; /* next element */                      \
 238 }
 239
 240 /*
 241  * Singly-linked Tail queue functions.
 242  */
 243 #define STAILQ_CONCAT(head1, head2) do {                                \
 244         if (!STAILQ_EMPTY((head2))) {                                   \
 245                 *(head1)->stqh_last = (head2)->stqh_first;              \
 246                 (head1)->stqh_last = (head2)->stqh_last;                \
 247                 STAILQ_INIT((head2));                                   \
 248         }                                                               \
 249 } while (0)
 250
 251 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 252
 253 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 254
 255 #define STAILQ_FOREACH(var, head, field)                                \
 256         for((var) = STAILQ_FIRST((head));                               \
 257            (var);                                                       \
 258            (var) = STAILQ_NEXT((var), field))
 259
 260
 261 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
 262         for ((var) = STAILQ_FIRST((head));                              \
 263             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 264             (var) = (tvar))
 265
 266 #define STAILQ_INIT(head) do {                                          \
 267         STAILQ_FIRST((head)) = NULL;                                    \
 268         (head)->stqh_last = &STAILQ_FIRST((head));                      \
 269 } while (0)
 270
 271 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 272         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 273                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 274         STAILQ_NEXT((tqelm), field) = (elm);                            \
 275 } while (0)
 276
 277 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 278         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
 279                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 280         STAILQ_FIRST((head)) = (elm);                                   \
 281 } while (0)
 282
 283 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 284         STAILQ_NEXT((elm), field) = NULL;                               \
 285         *(head)->stqh_last = (elm);                                     \
 286         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
 287 } while (0)
 288
 289 #define STAILQ_LAST(head, type, field)                                  \
 290         (STAILQ_EMPTY((head)) ?                                         \
 291                 NULL :                                                  \
 292                 ((struct type *)(void *)                                \
 293                 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
 294
 295 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 296
 297 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 298         QMD_SAVELINK(oldnext, (elm)->field.stqe_next);                  \
 299         if (STAILQ_FIRST((head)) == (elm)) {                            \
 300                 STAILQ_REMOVE_HEAD((head), field);                      \
 301         }                                                               \
 302         else {                                                          \
 303                 struct type *curelm = STAILQ_FIRST((head));             \
 304                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 305                         curelm = STAILQ_NEXT(curelm, field);            \
 306                 STAILQ_REMOVE_AFTER(head, curelm, field);               \
 307         }                                                               \
 308         TRASHIT(*oldnext);                                              \
 309 } while (0)
 310
 311 #define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
 312         if ((STAILQ_NEXT(elm, field) =                                  \
 313              STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
 314                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 315 } while (0)
 316
 317 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 318         if ((STAILQ_FIRST((head)) =                                     \
 319              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
 320                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 321 } while (0)
 322
 323 #define STAILQ_SWAP(head1, head2, type) do {                            \
 324         struct type *swap_first = STAILQ_FIRST(head1);                  \
 325         struct type **swap_last = (head1)->stqh_last;                   \
 326         STAILQ_FIRST(head1) = STAILQ_FIRST(head2);                      \
 327         (head1)->stqh_last = (head2)->stqh_last;                        \
 328         STAILQ_FIRST(head2) = swap_first;                               \
 329         (head2)->stqh_last = swap_last;                                 \
 330         if (STAILQ_EMPTY(head1))                                        \
 331                 (head1)->stqh_last = &STAILQ_FIRST(head1);              \
 332         if (STAILQ_EMPTY(head2))                                        \
 333                 (head2)->stqh_last = &STAILQ_FIRST(head2);              \
 334 } while (0)
 335
 336
 337 /*
 338  * List declarations.
 339  */
 340 #define LIST_HEAD(name, type)                                           \
 341 struct name {                                                           \
 342         struct type *lh_first;  /* first element */                     \
 343 }
 344
 345 #define LIST_HEAD_INITIALIZER(head)                                     \
 346         { NULL }
 347
 348 #define LIST_ENTRY(type)                                                \
 349 struct {                                                                \
 350         struct type *le_next;   /* next element */                      \
 351         struct type **le_prev;  /* address of previous next element */  \
 352 }
 353
 354 /*
 355  * List functions.
 356  */
 357
 358 #if (defined(_KERNEL) && defined(INVARIANTS))
 359 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 360         if (LIST_FIRST((head)) != NULL &&                               \
 361             LIST_FIRST((head))->field.le_prev !=                        \
 362              &LIST_FIRST((head)))                                       \
 363                 panic("Bad list head %p first->prev != head", (head));  \
 364 } while (0)
 365
 366 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 367         if (LIST_NEXT((elm), field) != NULL &&                          \
 368             LIST_NEXT((elm), field)->field.le_prev !=                   \
 369              &((elm)->field.le_next))                                   \
 370                 panic("Bad link elm %p next->prev != elm", (elm));      \
 371 } while (0)
 372
 373 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 374         if (*(elm)->field.le_prev != (elm))                             \
 375                 panic("Bad link elm %p prev->next != elm", (elm));      \
 376 } while (0)
 377 #else
 378 #define QMD_LIST_CHECK_HEAD(head, field)
 379 #define QMD_LIST_CHECK_NEXT(elm, field)
 380 #define QMD_LIST_CHECK_PREV(elm, field)
 381 #endif /* (_KERNEL && INVARIANTS) */
 382
 383 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 384
 385 #define LIST_FIRST(head)        ((head)->lh_first)
 386
 387 #define LIST_FOREACH(var, head, field)                                  \
 388         for ((var) = LIST_FIRST((head));                                \
 389             (var);                                                      \
 390             (var) = LIST_NEXT((var), field))
 391
 392 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 393         for ((var) = LIST_FIRST((head));                                \
 394             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 395             (var) = (tvar))
 396
 397 #define LIST_INIT(head) do {                                            \
 398         LIST_FIRST((head)) = NULL;                                      \
 399 } while (0)
 400
 401 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 402         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 403         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 404                 LIST_NEXT((listelm), field)->field.le_prev =            \
 405                     &LIST_NEXT((elm), field);                           \
 406         LIST_NEXT((listelm), field) = (elm);                            \
 407         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 408 } while (0)
 409
 410 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 411         QMD_LIST_CHECK_PREV(listelm, field);                            \
 412         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 413         LIST_NEXT((elm), field) = (listelm);                            \
 414         *(listelm)->field.le_prev = (elm);                              \
 415         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 416 } while (0)
 417
 418 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 419         QMD_LIST_CHECK_HEAD((head), field);                             \
 420         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 421                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 422         LIST_FIRST((head)) = (elm);                                     \
 423         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 424 } while (0)
 425
 426 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 427
 428 #define LIST_REMOVE(elm, field) do {                                    \
 429         QMD_SAVELINK(oldnext, (elm)->field.le_next);                    \
 430         QMD_SAVELINK(oldprev, (elm)->field.le_prev);                    \
 431         QMD_LIST_CHECK_NEXT(elm, field);                                \
 432         QMD_LIST_CHECK_PREV(elm, field);                                \
 433         if (LIST_NEXT((elm), field) != NULL)                            \
 434                 LIST_NEXT((elm), field)->field.le_prev =                \
 435                     (elm)->field.le_prev;                               \
 436         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 437         TRASHIT(*oldnext);                                              \
 438         TRASHIT(*oldprev);                                              \
 439 } while (0)
 440
 441 #define LIST_SWAP(head1, head2, type, field) do {                       \
 442         struct type *swap_tmp = LIST_FIRST((head1));                    \
 443         LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
 444         LIST_FIRST((head2)) = swap_tmp;                                 \
 445         if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
 446                 swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
 447         if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
 448                 swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
 449 } while (0)
 450
 451 /*
 452  * Tail queue declarations.
 453  */
 454 #define TAILQ_HEAD(name, type)                                          \
 455 struct name {                                                           \
 456         struct type *tqh_first; /* first element */                     \
 457         struct type **tqh_last; /* addr of last next element */         \
 458         TRACEBUF                                                        \
 459 }
 460
 461 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 462         { NULL, &(head).tqh_first }
 463
 464 #define TAILQ_ENTRY(type)                                               \
 465 struct {                                                                \
 466         struct type *tqe_next;  /* next element */                      \
 467         struct type **tqe_prev; /* address of previous next element */  \
 468         TRACEBUF                                                        \
 469 }
 470
 471 /*
 472  * Tail queue functions.
 473  */
 474 #if (defined(_KERNEL) && defined(INVARIANTS))
 475 #define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
 476         if (!TAILQ_EMPTY(head) &&                                       \
 477             TAILQ_FIRST((head))->field.tqe_prev !=                      \
 478              &TAILQ_FIRST((head)))                                      \
 479                 panic("Bad tailq head %p first->prev != head", (head)); \
 480 } while (0)
 481
 482 #define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
 483         if (*(head)->tqh_last != NULL)                                  \
 484                 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
 485 } while (0)
 486
 487 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
 488         if (TAILQ_NEXT((elm), field) != NULL &&                         \
 489             TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
 490              &((elm)->field.tqe_next))                                  \
 491                 panic("Bad link elm %p next->prev != elm", (elm));      \
 492 } while (0)
 493
 494 #define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
 495         if (*(elm)->field.tqe_prev != (elm))                            \
 496                 panic("Bad link elm %p prev->next != elm", (elm));      \
 497 } while (0)
 498 #else
 499 #define QMD_TAILQ_CHECK_HEAD(head, field)
 500 #define QMD_TAILQ_CHECK_TAIL(head, headname)
 501 #define QMD_TAILQ_CHECK_NEXT(elm, field)
 502 #define QMD_TAILQ_CHECK_PREV(elm, field)
 503 #endif /* (_KERNEL && INVARIANTS) */
 504
 505 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 506         if (!TAILQ_EMPTY(head2)) {                                      \
 507                 *(head1)->tqh_last = (head2)->tqh_first;                \
 508                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 509                 (head1)->tqh_last = (head2)->tqh_last;                  \
 510                 TAILQ_INIT((head2));                                    \
 511                 QMD_TRACE_HEAD(head1);                                  \
 512                 QMD_TRACE_HEAD(head2);                                  \
 513         }                                                               \
 514 } while (0)
 515
 516 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 517
 518 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 519
 520 #define TAILQ_FOREACH(var, head, field)                                 \
 521         for ((var) = TAILQ_FIRST((head));                               \
 522             (var);                                                      \
 523             (var) = TAILQ_NEXT((var), field))
 524
 525 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 526         for ((var) = TAILQ_FIRST((head));                               \
 527             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 528             (var) = (tvar))
 529
 530 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 531         for ((var) = TAILQ_LAST((head), headname);                      \
 532             (var);                                                      \
 533             (var) = TAILQ_PREV((var), headname, field))
 534
 535 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 536         for ((var) = TAILQ_LAST((head), headname);                      \
 537             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 538             (var) = (tvar))
 539
 540 #define TAILQ_INIT(head) do {                                           \
 541         TAILQ_FIRST((head)) = NULL;                                     \
 542         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 543         QMD_TRACE_HEAD(head);                                           \
 544 } while (0)
 545
 546 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 547         QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
 548         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 549                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 550                     &TAILQ_NEXT((elm), field);                          \
 551         else {                                                          \
 552                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 553                 QMD_TRACE_HEAD(head);                                   \
 554         }                                                               \
 555         TAILQ_NEXT((listelm), field) = (elm);                           \
 556         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 557         QMD_TRACE_ELEM(&(elm)->field);                                  \
 558         QMD_TRACE_ELEM(&listelm->field);                                \
 559 } while (0)
 560
 561 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 562         QMD_TAILQ_CHECK_PREV(listelm, field);                           \
 563         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 564         TAILQ_NEXT((elm), field) = (listelm);                           \
 565         *(listelm)->field.tqe_prev = (elm);                             \
 566         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 567         QMD_TRACE_ELEM(&(elm)->field);                                  \
 568         QMD_TRACE_ELEM(&listelm->field);                                \
 569 } while (0)
 570
 571 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 572         QMD_TAILQ_CHECK_HEAD(head, field);                              \
 573         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 574                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 575                     &TAILQ_NEXT((elm), field);                          \
 576         else                                                            \
 577                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 578         TAILQ_FIRST((head)) = (elm);                                    \
 579         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 580         QMD_TRACE_HEAD(head);                                           \
 581         QMD_TRACE_ELEM(&(elm)->field);                                  \
 582 } while (0)
 583
 584 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 585         QMD_TAILQ_CHECK_TAIL(head, field);                              \
 586         TAILQ_NEXT((elm), field) = NULL;                                \
 587         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 588         *(head)->tqh_last = (elm);                                      \
 589         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 590         QMD_TRACE_HEAD(head);                                           \
 591         QMD_TRACE_ELEM(&(elm)->field);                                  \
 592 } while (0)
 593
 594 #define TAILQ_LAST(head, headname)                                      \
 595         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 596
 597 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 598
 599 #define TAILQ_PREV(elm, headname, field)                                \
 600         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 601
 602 #define TAILQ_REMOVE(head, elm, field) do {                             \
 603         QMD_SAVELINK(oldnext, (elm)->field.tqe_next);                   \
 604         QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);                   \
 605         QMD_TAILQ_CHECK_NEXT(elm, field);                               \
 606         QMD_TAILQ_CHECK_PREV(elm, field);                               \
 607         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 608                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 609                     (elm)->field.tqe_prev;                              \
 610         else {                                                          \
 611                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 612                 QMD_TRACE_HEAD(head);                                   \
 613         }                                                               \
 614         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 615         TRASHIT(*oldnext);                                              \
 616         TRASHIT(*oldprev);                                              \
 617         QMD_TRACE_ELEM(&(elm)->field);                                  \
 618 } while (0)
 619
 620 #define TAILQ_SWAP(head1, head2, type, field) do {                      \
 621         struct type *swap_first = (head1)->tqh_first;                   \
 622         struct type **swap_last = (head1)->tqh_last;                    \
 623         (head1)->tqh_first = (head2)->tqh_first;                        \
 624         (head1)->tqh_last = (head2)->tqh_last;                          \
 625         (head2)->tqh_first = swap_first;                                \
 626         (head2)->tqh_last = swap_last;                                  \
 627         if ((swap_first = (head1)->tqh_first) != NULL)                  \
 628                 swap_first->field.tqe_prev = &(head1)->tqh_first;       \
 629         else                                                            \
 630                 (head1)->tqh_last = &(head1)->tqh_first;                \
 631         if ((swap_first = (head2)->tqh_first) != NULL)                  \
 632                 swap_first->field.tqe_prev = &(head2)->tqh_first;       \
 633         else                                                            \
 634                 (head2)->tqh_last = &(head2)->tqh_first;                \
 635 } while (0)
 636
 637 #endif /* !_SYS_QUEUE_H_ */