lwext4/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 #ifdef __cplusplus
  37 extern "C" {
  38 #endif
  39
  40 #include "ext4_config.h"
  41
  42 /*
  43  * This file defines four types of data structures: singly-linked lists,
  44  * singly-linked tail queues, lists and tail queues.
  45  *
  46  * A singly-linked list is headed by a single forward pointer. The elements
  47  * are singly linked for minimum space and pointer manipulation overhead at
  48  * the expense of O(n) removal for arbitrary elements. New elements can be
  49  * added to the list after an existing element or at the head of the list.
  50  * Elements being removed from the head of the list should use the explicit
  51  * macro for this purpose for optimum efficiency. A singly-linked list may
  52  * only be traversed in the forward direction.  Singly-linked lists are ideal
  53  * for applications with large datasets and few or no removals or for
  54  * implementing a LIFO queue.
  55  *
  56  * A singly-linked tail queue is headed by a pair of pointers, one to the
  57  * head of the list and the other to the tail of the list. The elements are
  58  * singly linked for minimum space and pointer manipulation overhead at the
  59  * expense of O(n) removal for arbitrary elements. New elements can be added
  60  * to the list after an existing element, at the head of the list, or at the
  61  * end of the list. Elements being removed from the head of the tail queue
  62  * should use the explicit macro for this purpose for optimum efficiency.
  63  * A singly-linked tail queue may only be traversed in the forward direction.
  64  * Singly-linked tail queues are ideal for applications with large datasets
  65  * and few or no removals or for implementing a FIFO queue.
  66  *
  67  * A list is headed by a single forward pointer (or an array of forward
  68  * pointers for a hash table header). The elements are doubly linked
  69  * so that an arbitrary element can be removed without a need to
  70  * traverse the list. New elements can be added to the list before
  71  * or after an existing element or at the head of the list. A list
  72  * may be traversed in either direction.
  73  *
  74  * A tail queue is headed by a pair of pointers, one to the head of the
  75  * list and the other to the tail of the list. The elements are doubly
  76  * linked so that an arbitrary element can be removed without a need to
  77  * traverse the list. New elements can be added to the list before or
  78  * after an existing element, at the head of the list, or at the end of
  79  * the list. A tail queue may be traversed in either direction.
  80  *
  81  * For details on the use of these macros, see the queue(3) manual page.
  82  *
  83  *
  84  *                              SLIST   LIST    STAILQ  TAILQ
  85  * _HEAD                        +       +       +       +
  86  * _HEAD_INITIALIZER            +       +       +       +
  87  * _ENTRY                       +       +       +       +
  88  * _INIT                        +       +       +       +
  89  * _EMPTY                       +       +       +       +
  90  * _FIRST                       +       +       +       +
  91  * _NEXT                        +       +       +       +
  92  * _PREV                        -       +       -       +
  93  * _LAST                        -       -       +       +
  94  * _FOREACH                     +       +       +       +
  95  * _FOREACH_FROM                +       +       +       +
  96  * _FOREACH_SAFE                +       +       +       +
  97  * _FOREACH_FROM_SAFE           +       +       +       +
  98  * _FOREACH_REVERSE             -       -       -       +
  99  * _FOREACH_REVERSE_FROM        -       -       -       +
 100  * _FOREACH_REVERSE_SAFE        -       -       -       +
 101  * _FOREACH_REVERSE_FROM_SAFE   -       -       -       +
 102  * _INSERT_HEAD                 +       +       +       +
 103  * _INSERT_BEFORE               -       +       -       +
 104  * _INSERT_AFTER                +       +       +       +
 105  * _INSERT_TAIL                 -       -       +       +
 106  * _CONCAT                      -       -       +       +
 107  * _REMOVE_AFTER                +       -       +       -
 108  * _REMOVE_HEAD                 +       -       +       -
 109  * _REMOVE                      +       +       +       +
 110  * _SWAP                        +       +       +       +
 111  *
 112  */
 113 #ifdef QUEUE_MACRO_DEBUG
 114 /* Store the last 2 places the queue element or head was altered */
 115 struct qm_trace {
 116         unsigned long    lastline;
 117         unsigned long    prevline;
 118         const char      *lastfile;
 119         const char      *prevfile;
 120 };
 121
 122 #define TRACEBUF        struct qm_trace trace;
 123 #define TRACEBUF_INITIALIZER    { __LINE__, 0, __FILE__, NULL } ,
 124 #define TRASHIT(x)      do {(x) = (void *)-1;} while (0)
 125 #define QMD_SAVELINK(name, link)        void **name = (void *)&(link)
 126
 127 #define QMD_TRACE_HEAD(head) do {                                       \
 128         (head)->trace.prevline = (head)->trace.lastline;                \
 129         (head)->trace.prevfile = (head)->trace.lastfile;                \
 130         (head)->trace.lastline = __LINE__;                              \
 131         (head)->trace.lastfile = __FILE__;                              \
 132 } while (0)
 133
 134 #define QMD_TRACE_ELEM(elem) do {                                       \
 135         (elem)->trace.prevline = (elem)->trace.lastline;                \
 136         (elem)->trace.prevfile = (elem)->trace.lastfile;                \
 137         (elem)->trace.lastline = __LINE__;                              \
 138         (elem)->trace.lastfile = __FILE__;                              \
 139 } while (0)
 140
 141 #else
 142 #define QMD_TRACE_ELEM(elem)
 143 #define QMD_TRACE_HEAD(head)
 144 #define QMD_SAVELINK(name, link)
 145 #define TRACEBUF
 146 #define TRACEBUF_INITIALIZER
 147 #define TRASHIT(x)
 148 #endif  /* QUEUE_MACRO_DEBUG */
 149
 150 /*
 151  * Singly-linked List declarations.
 152  */
 153 #define SLIST_HEAD(name, type)                                          \
 154 struct name {                                                           \
 155         struct type *slh_first; /* first element */                     \
 156 }
 157
 158 #define SLIST_HEAD_INITIALIZER(head)                                    \
 159         { NULL }
 160
 161 #define SLIST_ENTRY(type)                                               \
 162 struct {                                                                \
 163         struct type *sle_next;  /* next element */                      \
 164 }
 165
 166 /*
 167  * Singly-linked List functions.
 168  */
 169 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 170
 171 #define SLIST_FIRST(head)       ((head)->slh_first)
 172
 173 #define SLIST_FOREACH(var, head, field)                                 \
 174         for ((var) = SLIST_FIRST((head));                               \
 175             (var);                                                      \
 176             (var) = SLIST_NEXT((var), field))
 177
 178 #define SLIST_FOREACH_FROM(var, head, field)                            \
 179         for ((var) = ((var) ? (var) : SLIST_FIRST((head)));             \
 180             (var);                                                      \
 181             (var) = SLIST_NEXT((var), field))
 182
 183 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 184         for ((var) = SLIST_FIRST((head));                               \
 185             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 186             (var) = (tvar))
 187
 188 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar)                 \
 189         for ((var) = ((var) ? (var) : SLIST_FIRST((head)));             \
 190             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 191             (var) = (tvar))
 192
 193 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
 194         for ((varp) = &SLIST_FIRST((head));                             \
 195             ((var) = *(varp)) != NULL;                                  \
 196             (varp) = &SLIST_NEXT((var), field))
 197
 198 #define SLIST_INIT(head) do {                                           \
 199         SLIST_FIRST((head)) = NULL;                                     \
 200 } while (0)
 201
 202 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 203         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
 204         SLIST_NEXT((slistelm), field) = (elm);                          \
 205 } while (0)
 206
 207 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 208         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
 209         SLIST_FIRST((head)) = (elm);                                    \
 210 } while (0)
 211
 212 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 213
 214 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 215         QMD_SAVELINK(oldnext, (elm)->field.sle_next);                   \
 216         if (SLIST_FIRST((head)) == (elm)) {                             \
 217                 SLIST_REMOVE_HEAD((head), field);                       \
 218         }                                                               \
 219         else {                                                          \
 220                 struct type *curelm = SLIST_FIRST((head));              \
 221                 while (SLIST_NEXT(curelm, field) != (elm))              \
 222                         curelm = SLIST_NEXT(curelm, field);             \
 223                 SLIST_REMOVE_AFTER(curelm, field);                      \
 224         }                                                               \
 225         TRASHIT(*oldnext);                                              \
 226 } while (0)
 227
 228 #define SLIST_REMOVE_AFTER(elm, field) do {                             \
 229         SLIST_NEXT(elm, field) =                                        \
 230             SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
 231 } while (0)
 232
 233 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 234         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 235 } while (0)
 236
 237 #define SLIST_SWAP(head1, head2, type) do {                             \
 238         struct type *swap_first = SLIST_FIRST(head1);                   \
 239         SLIST_FIRST(head1) = SLIST_FIRST(head2);                        \
 240         SLIST_FIRST(head2) = swap_first;                                \
 241 } while (0)
 242
 243 /*
 244  * Singly-linked Tail queue declarations.
 245  */
 246 #define STAILQ_HEAD(name, type)                                         \
 247 struct name {                                                           \
 248         struct type *stqh_first;/* first element */                     \
 249         struct type **stqh_last;/* addr of last next element */         \
 250 }
 251
 252 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 253         { NULL, &(head).stqh_first }
 254
 255 #define STAILQ_ENTRY(type)                                              \
 256 struct {                                                                \
 257         struct type *stqe_next; /* next element */                      \
 258 }
 259
 260 /*
 261  * Singly-linked Tail queue functions.
 262  */
 263 #define STAILQ_CONCAT(head1, head2) do {                                \
 264         if (!STAILQ_EMPTY((head2))) {                                   \
 265                 *(head1)->stqh_last = (head2)->stqh_first;              \
 266                 (head1)->stqh_last = (head2)->stqh_last;                \
 267                 STAILQ_INIT((head2));                                   \
 268         }                                                               \
 269 } while (0)
 270
 271 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 272
 273 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 274
 275 #define STAILQ_FOREACH(var, head, field)                                \
 276         for((var) = STAILQ_FIRST((head));                               \
 277            (var);                                                       \
 278            (var) = STAILQ_NEXT((var), field))
 279
 280 #define STAILQ_FOREACH_FROM(var, head, field)                           \
 281         for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));            \
 282            (var);                                                       \
 283            (var) = STAILQ_NEXT((var), field))
 284
 285 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
 286         for ((var) = STAILQ_FIRST((head));                              \
 287             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 288             (var) = (tvar))
 289
 290 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)                \
 291         for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));            \
 292             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 293             (var) = (tvar))
 294
 295 #define STAILQ_INIT(head) do {                                          \
 296         STAILQ_FIRST((head)) = NULL;                                    \
 297         (head)->stqh_last = &STAILQ_FIRST((head));                      \
 298 } while (0)
 299
 300 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 301         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 302                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 303         STAILQ_NEXT((tqelm), field) = (elm);                            \
 304 } while (0)
 305
 306 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 307         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
 308                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 309         STAILQ_FIRST((head)) = (elm);                                   \
 310 } while (0)
 311
 312 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 313         STAILQ_NEXT((elm), field) = NULL;                               \
 314         *(head)->stqh_last = (elm);                                     \
 315         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
 316 } while (0)
 317
 318 #define STAILQ_LAST(head, type, field)                                  \
 319         (STAILQ_EMPTY((head)) ? NULL :                                  \
 320             __containerof((head)->stqh_last, struct type, field.stqe_next))
 321
 322 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 323
 324 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 325         QMD_SAVELINK(oldnext, (elm)->field.stqe_next);                  \
 326         if (STAILQ_FIRST((head)) == (elm)) {                            \
 327                 STAILQ_REMOVE_HEAD((head), field);                      \
 328         }                                                               \
 329         else {                                                          \
 330                 struct type *curelm = STAILQ_FIRST((head));             \
 331                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 332                         curelm = STAILQ_NEXT(curelm, field);            \
 333                 STAILQ_REMOVE_AFTER(head, curelm, field);               \
 334         }                                                               \
 335         TRASHIT(*oldnext);                                              \
 336 } while (0)
 337
 338 #define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
 339         if ((STAILQ_NEXT(elm, field) =                                  \
 340              STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
 341                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 342 } while (0)
 343
 344 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 345         if ((STAILQ_FIRST((head)) =                                     \
 346              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
 347                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 348 } while (0)
 349
 350 #define STAILQ_SWAP(head1, head2, type) do {                            \
 351         struct type *swap_first = STAILQ_FIRST(head1);                  \
 352         struct type **swap_last = (head1)->stqh_last;                   \
 353         STAILQ_FIRST(head1) = STAILQ_FIRST(head2);                      \
 354         (head1)->stqh_last = (head2)->stqh_last;                        \
 355         STAILQ_FIRST(head2) = swap_first;                               \
 356         (head2)->stqh_last = swap_last;                                 \
 357         if (STAILQ_EMPTY(head1))                                        \
 358                 (head1)->stqh_last = &STAILQ_FIRST(head1);              \
 359         if (STAILQ_EMPTY(head2))                                        \
 360                 (head2)->stqh_last = &STAILQ_FIRST(head2);              \
 361 } while (0)
 362
 363
 364 /*
 365  * List declarations.
 366  */
 367 #define LIST_HEAD(name, type)                                           \
 368 struct name {                                                           \
 369         struct type *lh_first;  /* first element */                     \
 370 }
 371
 372 #define LIST_HEAD_INITIALIZER(head)                                     \
 373         { NULL }
 374
 375 #define LIST_ENTRY(type)                                                \
 376 struct {                                                                \
 377         struct type *le_next;   /* next element */                      \
 378         struct type **le_prev;  /* address of previous next element */  \
 379 }
 380
 381 /*
 382  * List functions.
 383  */
 384
 385 #if (defined(_KERNEL) && defined(INVARIANTS))
 386 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 387         if (LIST_FIRST((head)) != NULL &&                               \
 388             LIST_FIRST((head))->field.le_prev !=                        \
 389              &LIST_FIRST((head)))                                       \
 390                 panic("Bad list head %p first->prev != head", (head));  \
 391 } while (0)
 392
 393 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 394         if (LIST_NEXT((elm), field) != NULL &&                          \
 395             LIST_NEXT((elm), field)->field.le_prev !=                   \
 396              &((elm)->field.le_next))                                   \
 397                 panic("Bad link elm %p next->prev != elm", (elm));      \
 398 } while (0)
 399
 400 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 401         if (*(elm)->field.le_prev != (elm))                             \
 402                 panic("Bad link elm %p prev->next != elm", (elm));      \
 403 } while (0)
 404 #else
 405 #define QMD_LIST_CHECK_HEAD(head, field)
 406 #define QMD_LIST_CHECK_NEXT(elm, field)
 407 #define QMD_LIST_CHECK_PREV(elm, field)
 408 #endif /* (_KERNEL && INVARIANTS) */
 409
 410 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 411
 412 #define LIST_FIRST(head)        ((head)->lh_first)
 413
 414 #define LIST_FOREACH(var, head, field)                                  \
 415         for ((var) = LIST_FIRST((head));                                \
 416             (var);                                                      \
 417             (var) = LIST_NEXT((var), field))
 418
 419 #define LIST_FOREACH_FROM(var, head, field)                             \
 420         for ((var) = ((var) ? (var) : LIST_FIRST((head)));              \
 421             (var);                                                      \
 422             (var) = LIST_NEXT((var), field))
 423
 424 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 425         for ((var) = LIST_FIRST((head));                                \
 426             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 427             (var) = (tvar))
 428
 429 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar)                  \
 430         for ((var) = ((var) ? (var) : LIST_FIRST((head)));              \
 431             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 432             (var) = (tvar))
 433
 434 #define LIST_INIT(head) do {                                            \
 435         LIST_FIRST((head)) = NULL;                                      \
 436 } while (0)
 437
 438 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 439         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 440         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 441                 LIST_NEXT((listelm), field)->field.le_prev =            \
 442                     &LIST_NEXT((elm), field);                           \
 443         LIST_NEXT((listelm), field) = (elm);                            \
 444         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 445 } while (0)
 446
 447 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 448         QMD_LIST_CHECK_PREV(listelm, field);                            \
 449         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 450         LIST_NEXT((elm), field) = (listelm);                            \
 451         *(listelm)->field.le_prev = (elm);                              \
 452         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 453 } while (0)
 454
 455 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 456         QMD_LIST_CHECK_HEAD((head), field);                             \
 457         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 458                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 459         LIST_FIRST((head)) = (elm);                                     \
 460         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 461 } while (0)
 462
 463 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 464
 465 #define LIST_PREV(elm, head, type, field)                               \
 466         ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :           \
 467             __containerof((elm)->field.le_prev, struct type, field.le_next))
 468
 469 #define LIST_REMOVE(elm, field) do {                                    \
 470         QMD_SAVELINK(oldnext, (elm)->field.le_next);                    \
 471         QMD_SAVELINK(oldprev, (elm)->field.le_prev);                    \
 472         QMD_LIST_CHECK_NEXT(elm, field);                                \
 473         QMD_LIST_CHECK_PREV(elm, field);                                \
 474         if (LIST_NEXT((elm), field) != NULL)                            \
 475                 LIST_NEXT((elm), field)->field.le_prev =                \
 476                     (elm)->field.le_prev;                               \
 477         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 478         TRASHIT(*oldnext);                                              \
 479         TRASHIT(*oldprev);                                              \
 480 } while (0)
 481
 482 #define LIST_SWAP(head1, head2, type, field) do {                       \
 483         struct type *swap_tmp = LIST_FIRST((head1));                    \
 484         LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
 485         LIST_FIRST((head2)) = swap_tmp;                                 \
 486         if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
 487                 swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
 488         if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
 489                 swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
 490 } while (0)
 491
 492 /*
 493  * Tail queue declarations.
 494  */
 495 #define TAILQ_HEAD(name, type)                                          \
 496 struct name {                                                           \
 497         struct type *tqh_first; /* first element */                     \
 498         struct type **tqh_last; /* addr of last next element */         \
 499         TRACEBUF                                                        \
 500 }
 501
 502 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 503         { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
 504
 505 #define TAILQ_ENTRY(type)                                               \
 506 struct {                                                                \
 507         struct type *tqe_next;  /* next element */                      \
 508         struct type **tqe_prev; /* address of previous next element */  \
 509         TRACEBUF                                                        \
 510 }
 511
 512 /*
 513  * Tail queue functions.
 514  */
 515 #if (defined(_KERNEL) && defined(INVARIANTS))
 516 #define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
 517         if (!TAILQ_EMPTY(head) &&                                       \
 518             TAILQ_FIRST((head))->field.tqe_prev !=                      \
 519              &TAILQ_FIRST((head)))                                      \
 520                 panic("Bad tailq head %p first->prev != head", (head)); \
 521 } while (0)
 522
 523 #define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
 524         if (*(head)->tqh_last != NULL)                                  \
 525                 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
 526 } while (0)
 527
 528 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
 529         if (TAILQ_NEXT((elm), field) != NULL &&                         \
 530             TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
 531              &((elm)->field.tqe_next))                                  \
 532                 panic("Bad link elm %p next->prev != elm", (elm));      \
 533 } while (0)
 534
 535 #define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
 536         if (*(elm)->field.tqe_prev != (elm))                            \
 537                 panic("Bad link elm %p prev->next != elm", (elm));      \
 538 } while (0)
 539 #else
 540 #define QMD_TAILQ_CHECK_HEAD(head, field)
 541 #define QMD_TAILQ_CHECK_TAIL(head, headname)
 542 #define QMD_TAILQ_CHECK_NEXT(elm, field)
 543 #define QMD_TAILQ_CHECK_PREV(elm, field)
 544 #endif /* (_KERNEL && INVARIANTS) */
 545
 546 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 547         if (!TAILQ_EMPTY(head2)) {                                      \
 548                 *(head1)->tqh_last = (head2)->tqh_first;                \
 549                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 550                 (head1)->tqh_last = (head2)->tqh_last;                  \
 551                 TAILQ_INIT((head2));                                    \
 552                 QMD_TRACE_HEAD(head1);                                  \
 553                 QMD_TRACE_HEAD(head2);                                  \
 554         }                                                               \
 555 } while (0)
 556
 557 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 558
 559 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 560
 561 #define TAILQ_FOREACH(var, head, field)                                 \
 562         for ((var) = TAILQ_FIRST((head));                               \
 563             (var);                                                      \
 564             (var) = TAILQ_NEXT((var), field))
 565
 566 #define TAILQ_FOREACH_FROM(var, head, field)                            \
 567         for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));             \
 568             (var);                                                      \
 569             (var) = TAILQ_NEXT((var), field))
 570
 571 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 572         for ((var) = TAILQ_FIRST((head));                               \
 573             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 574             (var) = (tvar))
 575
 576 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)                 \
 577         for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));             \
 578             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 579             (var) = (tvar))
 580
 581 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 582         for ((var) = TAILQ_LAST((head), headname);                      \
 583             (var);                                                      \
 584             (var) = TAILQ_PREV((var), headname, field))
 585
 586 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field)          \
 587         for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
 588             (var);                                                      \
 589             (var) = TAILQ_PREV((var), headname, field))
 590
 591 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 592         for ((var) = TAILQ_LAST((head), headname);                      \
 593             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 594             (var) = (tvar))
 595
 596 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
 597         for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
 598             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 599             (var) = (tvar))
 600
 601 #define TAILQ_INIT(head) do {                                           \
 602         TAILQ_FIRST((head)) = NULL;                                     \
 603         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 604         QMD_TRACE_HEAD(head);                                           \
 605 } while (0)
 606
 607 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 608         QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
 609         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 610                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 611                     &TAILQ_NEXT((elm), field);                          \
 612         else {                                                          \
 613                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 614                 QMD_TRACE_HEAD(head);                                   \
 615         }                                                               \
 616         TAILQ_NEXT((listelm), field) = (elm);                           \
 617         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 618         QMD_TRACE_ELEM(&(elm)->field);                                  \
 619         QMD_TRACE_ELEM(&(listelm)->field);                              \
 620 } while (0)
 621
 622 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 623         QMD_TAILQ_CHECK_PREV(listelm, field);                           \
 624         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 625         TAILQ_NEXT((elm), field) = (listelm);                           \
 626         *(listelm)->field.tqe_prev = (elm);                             \
 627         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 628         QMD_TRACE_ELEM(&(elm)->field);                                  \
 629         QMD_TRACE_ELEM(&(listelm)->field);                              \
 630 } while (0)
 631
 632 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 633         QMD_TAILQ_CHECK_HEAD(head, field);                              \
 634         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 635                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 636                     &TAILQ_NEXT((elm), field);                          \
 637         else                                                            \
 638                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 639         TAILQ_FIRST((head)) = (elm);                                    \
 640         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 641         QMD_TRACE_HEAD(head);                                           \
 642         QMD_TRACE_ELEM(&(elm)->field);                                  \
 643 } while (0)
 644
 645 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 646         QMD_TAILQ_CHECK_TAIL(head, field);                              \
 647         TAILQ_NEXT((elm), field) = NULL;                                \
 648         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 649         *(head)->tqh_last = (elm);                                      \
 650         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 651         QMD_TRACE_HEAD(head);                                           \
 652         QMD_TRACE_ELEM(&(elm)->field);                                  \
 653 } while (0)
 654
 655 #define TAILQ_LAST(head, headname)                                      \
 656         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 657
 658 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 659
 660 #define TAILQ_PREV(elm, headname, field)                                \
 661         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 662
 663 #define TAILQ_REMOVE(head, elm, field) do {                             \
 664         QMD_SAVELINK(oldnext, (elm)->field.tqe_next);                   \
 665         QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);                   \
 666         QMD_TAILQ_CHECK_NEXT(elm, field);                               \
 667         QMD_TAILQ_CHECK_PREV(elm, field);                               \
 668         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 669                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 670                     (elm)->field.tqe_prev;                              \
 671         else {                                                          \
 672                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 673                 QMD_TRACE_HEAD(head);                                   \
 674         }                                                               \
 675         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 676         TRASHIT(*oldnext);                                              \
 677         TRASHIT(*oldprev);                                              \
 678         QMD_TRACE_ELEM(&(elm)->field);                                  \
 679 } while (0)
 680
 681 #define TAILQ_SWAP(head1, head2, type, field) do {                      \
 682         struct type *swap_first = (head1)->tqh_first;                   \
 683         struct type **swap_last = (head1)->tqh_last;                    \
 684         (head1)->tqh_first = (head2)->tqh_first;                        \
 685         (head1)->tqh_last = (head2)->tqh_last;                          \
 686         (head2)->tqh_first = swap_first;                                \
 687         (head2)->tqh_last = swap_last;                                  \
 688         if ((swap_first = (head1)->tqh_first) != NULL)                  \
 689                 swap_first->field.tqe_prev = &(head1)->tqh_first;       \
 690         else                                                            \
 691                 (head1)->tqh_last = &(head1)->tqh_first;                \
 692         if ((swap_first = (head2)->tqh_first) != NULL)                  \
 693                 swap_first->field.tqe_prev = &(head2)->tqh_first;       \
 694         else                                                            \
 695                 (head2)->tqh_last = &(head2)->tqh_first;                \
 696 } while (0)
 697
 698 #ifdef __cplusplus
 699 }
 700 #endif
 701
 702 #endif /* !_SYS_QUEUE_H_ */