bsd/sys/queue.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*-
  29  * Copyright (c) 1991, 1993
  30  *      The Regents of the University of California.  All rights reserved.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 4. Neither the name of the University nor the names of its contributors
  41  *    may be used to endorse or promote products derived from this software
  42  *    without specific prior written permission.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  45  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  48  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54  * SUCH DAMAGE.
  55  *
  56  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  57  */
  58
  59 #ifndef _SYS_QUEUE_H_
  60 #define _SYS_QUEUE_H_
  61
  62 /*
  63  * This file defines five types of data structures: singly-linked lists,
  64  * singly-linked tail queues, lists, tail queues, and circular queues.
  65  *
  66  * A singly-linked list is headed by a single forward pointer. The elements
  67  * are singly linked for minimum space and pointer manipulation overhead at
  68  * the expense of O(n) removal for arbitrary elements. New elements can be
  69  * added to the list after an existing element or at the head of the list.
  70  * Elements being removed from the head of the list should use the explicit
  71  * macro for this purpose for optimum efficiency. A singly-linked list may
  72  * only be traversed in the forward direction.  Singly-linked lists are ideal
  73  * for applications with large datasets and few or no removals or for
  74  * implementing a LIFO queue.
  75  *
  76  * A singly-linked tail queue is headed by a pair of pointers, one to the
  77  * head of the list and the other to the tail of the list. The elements are
  78  * singly linked for minimum space and pointer manipulation overhead at the
  79  * expense of O(n) removal for arbitrary elements. New elements can be added
  80  * to the list after an existing element, at the head of the list, or at the
  81  * end of the list. Elements being removed from the head of the tail queue
  82  * should use the explicit macro for this purpose for optimum efficiency.
  83  * A singly-linked tail queue may only be traversed in the forward direction.
  84  * Singly-linked tail queues are ideal for applications with large datasets
  85  * and few or no removals or for implementing a FIFO queue.
  86  *
  87  * A list is headed by a single forward pointer (or an array of forward
  88  * pointers for a hash table header). The elements are doubly linked
  89  * so that an arbitrary element can be removed without a need to
  90  * traverse the list. New elements can be added to the list before
  91  * or after an existing element or at the head of the list. A list
  92  * may only be traversed in the forward direction.
  93  *
  94  * A tail queue is headed by a pair of pointers, one to the head of the
  95  * list and the other to the tail of the list. The elements are doubly
  96  * linked so that an arbitrary element can be removed without a need to
  97  * traverse the list. New elements can be added to the list before or
  98  * after an existing element, at the head of the list, or at the end of
  99  * the list. A tail queue may be traversed in either direction.
 100  *
 101  * A circle queue is headed by a pair of pointers, one to the head of the
 102  * list and the other to the tail of the list. The elements are doubly
 103  * linked so that an arbitrary element can be removed without a need to
 104  * traverse the list. New elements can be added to the list before or after
 105  * an existing element, at the head of the list, or at the end of the list.
 106  * A circle queue may be traversed in either direction, but has a more
 107  * complex end of list detection.
 108  * Note that circle queues are deprecated, because, as the removal log
 109  * in FreeBSD states, "CIRCLEQs are a disgrace to everything Knuth taught
 110  * us in Volume 1 Chapter 2. [...] Use TAILQ instead, it provides the same
 111  * functionality." Code using them will continue to compile, but they
 112  * are no longer documented on the man page.
 113  *
 114  * For details on the use of these macros, see the queue(3) manual page.
 115  *
 116  *
 117  *                              SLIST   LIST    STAILQ  TAILQ   CIRCLEQ
 118  * _HEAD                        +       +       +       +       +
 119  * _HEAD_INITIALIZER            +       +       +       +       -
 120  * _ENTRY                       +       +       +       +       +
 121  * _INIT                        +       +       +       +       +
 122  * _EMPTY                       +       +       +       +       +
 123  * _FIRST                       +       +       +       +       +
 124  * _NEXT                        +       +       +       +       +
 125  * _PREV                        -       -       -       +       +
 126  * _LAST                        -       -       +       +       +
 127  * _FOREACH                     +       +       +       +       +
 128  * _FOREACH_SAFE                +       +       +       +       -
 129  * _FOREACH_REVERSE             -       -       -       +       -
 130  * _FOREACH_REVERSE_SAFE        -       -       -       +       -
 131  * _INSERT_HEAD                 +       +       +       +       +
 132  * _INSERT_BEFORE               -       +       -       +       +
 133  * _INSERT_AFTER                +       +       +       +       +
 134  * _INSERT_TAIL                 -       -       +       +       +
 135  * _CONCAT                      -       -       +       +       -
 136  * _REMOVE_AFTER                +       -       +       -       -
 137  * _REMOVE_HEAD                 +       -       +       -       -
 138  * _REMOVE_HEAD_UNTIL           -       -       +       -       -
 139  * _REMOVE                      +       +       +       +       +
 140  * _SWAP                        -       +       +       +       -
 141  *
 142  */
 143 #ifdef QUEUE_MACRO_DEBUG
 144 /* Store the last 2 places the queue element or head was altered */
 145 struct qm_trace {
 146         char * lastfile;
 147         int lastline;
 148         char * prevfile;
 149         int prevline;
 150 };
 151
 152 #define TRACEBUF        struct qm_trace trace;
 153 #define TRASHIT(x)      do {(x) = (void *)-1;} while (0)
 154
 155 #define QMD_TRACE_HEAD(head) do {                                       \
 156         (head)->trace.prevline = (head)->trace.lastline;                \
 157         (head)->trace.prevfile = (head)->trace.lastfile;                \
 158         (head)->trace.lastline = __LINE__;                              \
 159         (head)->trace.lastfile = __FILE__;                              \
 160 } while (0)
 161
 162 #define QMD_TRACE_ELEM(elem) do {                                       \
 163         (elem)->trace.prevline = (elem)->trace.lastline;                \
 164         (elem)->trace.prevfile = (elem)->trace.lastfile;                \
 165         (elem)->trace.lastline = __LINE__;                              \
 166         (elem)->trace.lastfile = __FILE__;                              \
 167 } while (0)
 168
 169 #else
 170 #define QMD_TRACE_ELEM(elem)
 171 #define QMD_TRACE_HEAD(head)
 172 #define TRACEBUF
 173 #define TRASHIT(x)
 174 #endif  /* QUEUE_MACRO_DEBUG */
 175
 176 /*
 177  * Singly-linked List declarations.
 178  */
 179 #define SLIST_HEAD(name, type)                                          \
 180 struct name {                                                           \
 181         struct type *slh_first; /* first element */                     \
 182 }
 183
 184 #define SLIST_HEAD_INITIALIZER(head)                                    \
 185         { NULL }
 186
 187 #define SLIST_ENTRY(type)                                               \
 188 struct {                                                                \
 189         struct type *sle_next;  /* next element */                      \
 190 }
 191
 192 /*
 193  * Singly-linked List functions.
 194  */
 195 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 196
 197 #define SLIST_FIRST(head)       ((head)->slh_first)
 198
 199 #define SLIST_FOREACH(var, head, field)                                 \
 200         for ((var) = SLIST_FIRST((head));                               \
 201             (var);                                                      \
 202             (var) = SLIST_NEXT((var), field))
 203
 204 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 205         for ((var) = SLIST_FIRST((head));                               \
 206             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 207             (var) = (tvar))
 208
 209 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
 210         for ((varp) = &SLIST_FIRST((head));                             \
 211             ((var) = *(varp)) != NULL;                                  \
 212             (varp) = &SLIST_NEXT((var), field))
 213
 214 #define SLIST_INIT(head) do {                                           \
 215         SLIST_FIRST((head)) = NULL;                                     \
 216 } while (0)
 217
 218 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 219         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
 220         SLIST_NEXT((slistelm), field) = (elm);                          \
 221 } while (0)
 222
 223 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 224         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
 225         SLIST_FIRST((head)) = (elm);                                    \
 226 } while (0)
 227
 228 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 229
 230 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 231         if (SLIST_FIRST((head)) == (elm)) {                             \
 232                 SLIST_REMOVE_HEAD((head), field);                       \
 233         }                                                               \
 234         else {                                                          \
 235                 struct type *curelm = SLIST_FIRST((head));              \
 236                 while (SLIST_NEXT(curelm, field) != (elm))              \
 237                         curelm = SLIST_NEXT(curelm, field);             \
 238                 SLIST_REMOVE_AFTER(curelm, field);                      \
 239         }                                                               \
 240         TRASHIT((elm)->field.sle_next);                                 \
 241 } while (0)
 242
 243 #define SLIST_REMOVE_AFTER(elm, field) do {                             \
 244         SLIST_NEXT(elm, field) =                                        \
 245             SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
 246 } while (0)
 247
 248 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 249         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 250 } while (0)
 251
 252 /*
 253  * Singly-linked Tail queue declarations.
 254  */
 255 #define STAILQ_HEAD(name, type)                                         \
 256 struct name {                                                           \
 257         struct type *stqh_first;/* first element */                     \
 258         struct type **stqh_last;/* addr of last next element */         \
 259 }
 260
 261 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 262         { NULL, &(head).stqh_first }
 263
 264 #define STAILQ_ENTRY(type)                                              \
 265 struct {                                                                \
 266         struct type *stqe_next; /* next element */                      \
 267 }
 268
 269 /*
 270  * Singly-linked Tail queue functions.
 271  */
 272 #define STAILQ_CONCAT(head1, head2) do {                                \
 273         if (!STAILQ_EMPTY((head2))) {                                   \
 274                 *(head1)->stqh_last = (head2)->stqh_first;              \
 275                 (head1)->stqh_last = (head2)->stqh_last;                \
 276                 STAILQ_INIT((head2));                                   \
 277         }                                                               \
 278 } while (0)
 279
 280 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 281
 282 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 283
 284 #define STAILQ_FOREACH(var, head, field)                                \
 285         for((var) = STAILQ_FIRST((head));                               \
 286            (var);                                                       \
 287            (var) = STAILQ_NEXT((var), field))
 288
 289
 290 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
 291         for ((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)) ?                                         \
 320                 NULL :                                                  \
 321                 ((struct type *)(void *)                                \
 322                 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
 323
 324 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 325
 326 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 327         if (STAILQ_FIRST((head)) == (elm)) {                            \
 328                 STAILQ_REMOVE_HEAD((head), field);                      \
 329         }                                                               \
 330         else {                                                          \
 331                 struct type *curelm = STAILQ_FIRST((head));             \
 332                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 333                         curelm = STAILQ_NEXT(curelm, field);            \
 334                 STAILQ_REMOVE_AFTER(head, curelm, field);               \
 335         }                                                               \
 336         TRASHIT((elm)->field.stqe_next);                                \
 337 } while (0)
 338
 339 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 340         if ((STAILQ_FIRST((head)) =                                     \
 341              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
 342                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 343 } while (0)
 344
 345 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {                 \
 346        if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
 347                (head)->stqh_last = &STAILQ_FIRST((head));              \
 348 } while (0)
 349
 350 #define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
 351         if ((STAILQ_NEXT(elm, field) =                                  \
 352              STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
 353                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 354 } while (0)
 355
 356 #define STAILQ_SWAP(head1, head2, type) do {                            \
 357         struct type *swap_first = STAILQ_FIRST(head1);                  \
 358         struct type **swap_last = (head1)->stqh_last;                   \
 359         STAILQ_FIRST(head1) = STAILQ_FIRST(head2);                      \
 360         (head1)->stqh_last = (head2)->stqh_last;                        \
 361         STAILQ_FIRST(head2) = swap_first;                               \
 362         (head2)->stqh_last = swap_last;                                 \
 363         if (STAILQ_EMPTY(head1))                                        \
 364                 (head1)->stqh_last = &STAILQ_FIRST(head1);              \
 365         if (STAILQ_EMPTY(head2))                                        \
 366                 (head2)->stqh_last = &STAILQ_FIRST(head2);              \
 367 } while (0)
 368
 369
 370 /*
 371  * List declarations.
 372  */
 373 #define LIST_HEAD(name, type)                                           \
 374 struct name {                                                           \
 375         struct type *lh_first;  /* first element */                     \
 376 }
 377
 378 #define LIST_HEAD_INITIALIZER(head)                                     \
 379         { NULL }
 380
 381 #define LIST_ENTRY(type)                                                \
 382 struct {                                                                \
 383         struct type *le_next;   /* next element */                      \
 384         struct type **le_prev;  /* address of previous next element */  \
 385 }
 386
 387 /*
 388  * List functions.
 389  */
 390
 391 #if (defined(_KERNEL) && defined(INVARIANTS)) || defined(QUEUE_MACRO_DEBUG)
 392 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 393         if (LIST_FIRST((head)) != NULL &&                               \
 394             LIST_FIRST((head))->field.le_prev !=                        \
 395              &LIST_FIRST((head)))                                       \
 396                 panic("Bad list head %p first->prev != head", (head));  \
 397 } while (0)
 398
 399 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 400         if (LIST_NEXT((elm), field) != NULL &&                          \
 401             LIST_NEXT((elm), field)->field.le_prev !=                   \
 402              &((elm)->field.le_next))                                   \
 403                 panic("Bad link elm %p next->prev != elm", (elm));      \
 404 } while (0)
 405
 406 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 407         if (*(elm)->field.le_prev != (elm))                             \
 408                 panic("Bad link elm %p prev->next != elm", (elm));      \
 409 } while (0)
 410 #else
 411 #define QMD_LIST_CHECK_HEAD(head, field)
 412 #define QMD_LIST_CHECK_NEXT(elm, field)
 413 #define QMD_LIST_CHECK_PREV(elm, field)
 414 #endif /* (_KERNEL && INVARIANTS) || QUEUE_MACRO_DEBUG */
 415
 416 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 417
 418 #define LIST_FIRST(head)        ((head)->lh_first)
 419
 420 #define LIST_FOREACH(var, head, field)                                  \
 421         for ((var) = LIST_FIRST((head));                                \
 422             (var);                                                      \
 423             (var) = LIST_NEXT((var), field))
 424
 425 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 426         for ((var) = LIST_FIRST((head));                                \
 427             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 428             (var) = (tvar))
 429
 430 #define LIST_INIT(head) do {                                            \
 431         LIST_FIRST((head)) = NULL;                                      \
 432 } while (0)
 433
 434 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 435         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 436         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 437                 LIST_NEXT((listelm), field)->field.le_prev =            \
 438                     &LIST_NEXT((elm), field);                           \
 439         LIST_NEXT((listelm), field) = (elm);                            \
 440         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 441 } while (0)
 442
 443 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 444         QMD_LIST_CHECK_PREV(listelm, field);                            \
 445         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 446         LIST_NEXT((elm), field) = (listelm);                            \
 447         *(listelm)->field.le_prev = (elm);                              \
 448         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 449 } while (0)
 450
 451 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 452         QMD_LIST_CHECK_HEAD((head), field);                             \
 453         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 454                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 455         LIST_FIRST((head)) = (elm);                                     \
 456         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 457 } while (0)
 458
 459 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 460
 461 #define LIST_REMOVE(elm, field) do {                                    \
 462         QMD_LIST_CHECK_NEXT(elm, field);                                \
 463         QMD_LIST_CHECK_PREV(elm, field);                                \
 464         if (LIST_NEXT((elm), field) != NULL)                            \
 465                 LIST_NEXT((elm), field)->field.le_prev =                \
 466                     (elm)->field.le_prev;                               \
 467         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 468         TRASHIT((elm)->field.le_next);                                  \
 469         TRASHIT((elm)->field.le_prev);                                  \
 470 } while (0)
 471
 472 #define LIST_SWAP(head1, head2, type, field) do {                       \
 473         struct type *swap_tmp = LIST_FIRST((head1));                    \
 474         LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
 475         LIST_FIRST((head2)) = swap_tmp;                                 \
 476         if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
 477                 swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
 478         if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
 479                 swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
 480 } while (0)
 481
 482 /*
 483  * Tail queue declarations.
 484  */
 485 #define TAILQ_HEAD(name, type)                                          \
 486 struct name {                                                           \
 487         struct type *tqh_first; /* first element */                     \
 488         struct type **tqh_last; /* addr of last next element */         \
 489         TRACEBUF                                                        \
 490 }
 491
 492 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 493         { NULL, &(head).tqh_first }
 494
 495 #define TAILQ_ENTRY(type)                                               \
 496 struct {                                                                \
 497         struct type *tqe_next;  /* next element */                      \
 498         struct type **tqe_prev; /* address of previous next element */  \
 499         TRACEBUF                                                        \
 500 }
 501
 502 /*
 503  * Tail queue functions.
 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         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 548                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 549                     &TAILQ_NEXT((elm), field);                          \
 550         else {                                                          \
 551                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 552                 QMD_TRACE_HEAD(head);                                   \
 553         }                                                               \
 554         TAILQ_NEXT((listelm), field) = (elm);                           \
 555         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 556         QMD_TRACE_ELEM(&(elm)->field);                                  \
 557         QMD_TRACE_ELEM(&listelm->field);                                \
 558 } while (0)
 559
 560 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 561         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 562         TAILQ_NEXT((elm), field) = (listelm);                           \
 563         *(listelm)->field.tqe_prev = (elm);                             \
 564         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 565         QMD_TRACE_ELEM(&(elm)->field);                                  \
 566         QMD_TRACE_ELEM(&listelm->field);                                \
 567 } while (0)
 568
 569 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 570         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 571                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 572                     &TAILQ_NEXT((elm), field);                          \
 573         else                                                            \
 574                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 575         TAILQ_FIRST((head)) = (elm);                                    \
 576         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 577         QMD_TRACE_HEAD(head);                                           \
 578         QMD_TRACE_ELEM(&(elm)->field);                                  \
 579 } while (0)
 580
 581 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 582         TAILQ_NEXT((elm), field) = NULL;                                \
 583         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 584         *(head)->tqh_last = (elm);                                      \
 585         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 586         QMD_TRACE_HEAD(head);                                           \
 587         QMD_TRACE_ELEM(&(elm)->field);                                  \
 588 } while (0)
 589
 590 #define TAILQ_LAST(head, headname)                                      \
 591         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 592
 593 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 594
 595 #define TAILQ_PREV(elm, headname, field)                                \
 596         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 597
 598 #define TAILQ_REMOVE(head, elm, field) do {                             \
 599         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 600                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 601                     (elm)->field.tqe_prev;                              \
 602         else {                                                          \
 603                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 604                 QMD_TRACE_HEAD(head);                                   \
 605         }                                                               \
 606         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 607         TRASHIT((elm)->field.tqe_next);                                 \
 608         TRASHIT((elm)->field.tqe_prev);                                 \
 609         QMD_TRACE_ELEM(&(elm)->field);                                  \
 610 } while (0)
 611
 612 #define TAILQ_SWAP(head1, head2, type, field) do {                      \
 613         struct type *swap_first = (head1)->tqh_first;                   \
 614         struct type **swap_last = (head1)->tqh_last;                    \
 615         (head1)->tqh_first = (head2)->tqh_first;                        \
 616         (head1)->tqh_last = (head2)->tqh_last;                          \
 617         (head2)->tqh_first = swap_first;                                \
 618         (head2)->tqh_last = swap_last;                                  \
 619         if ((swap_first = (head1)->tqh_first) != NULL)                  \
 620                 swap_first->field.tqe_prev = &(head1)->tqh_first;       \
 621         else                                                            \
 622                 (head1)->tqh_last = &(head1)->tqh_first;                \
 623         if ((swap_first = (head2)->tqh_first) != NULL)                  \
 624                 swap_first->field.tqe_prev = &(head2)->tqh_first;       \
 625         else                                                            \
 626                 (head2)->tqh_last = &(head2)->tqh_first;                \
 627 } while (0)
 628
 629 /*
 630  * Circular queue definitions.
 631  */
 632 #define CIRCLEQ_HEAD(name, type)                                        \
 633 struct name {                                                           \
 634         struct type *cqh_first;         /* first element */             \
 635         struct type *cqh_last;          /* last element */              \
 636 }
 637
 638 #define CIRCLEQ_ENTRY(type)                                             \
 639 struct {                                                                \
 640         struct type *cqe_next;          /* next element */              \
 641         struct type *cqe_prev;          /* previous element */          \
 642 }
 643
 644 /*
 645  * Circular queue functions.
 646  */
 647 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
 648
 649 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
 650
 651 #define CIRCLEQ_FOREACH(var, head, field)                               \
 652         for((var) = (head)->cqh_first;                                  \
 653             (var) != (void *)(head);                                    \
 654             (var) = (var)->field.cqe_next)
 655
 656 #define CIRCLEQ_INIT(head) do {                                         \
 657         (head)->cqh_first = (void *)(head);                             \
 658         (head)->cqh_last = (void *)(head);                              \
 659 } while (0)
 660
 661 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 662         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 663         (elm)->field.cqe_prev = (listelm);                              \
 664         if ((listelm)->field.cqe_next == (void *)(head))                \
 665                 (head)->cqh_last = (elm);                               \
 666         else                                                            \
 667                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 668         (listelm)->field.cqe_next = (elm);                              \
 669 } while (0)
 670
 671 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 672         (elm)->field.cqe_next = (listelm);                              \
 673         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 674         if ((listelm)->field.cqe_prev == (void *)(head))                \
 675                 (head)->cqh_first = (elm);                              \
 676         else                                                            \
 677                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 678         (listelm)->field.cqe_prev = (elm);                              \
 679 } while (0)
 680
 681 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 682         (elm)->field.cqe_next = (head)->cqh_first;                      \
 683         (elm)->field.cqe_prev = (void *)(head);                         \
 684         if ((head)->cqh_last == (void *)(head))                         \
 685                 (head)->cqh_last = (elm);                               \
 686         else                                                            \
 687                 (head)->cqh_first->field.cqe_prev = (elm);              \
 688         (head)->cqh_first = (elm);                                      \
 689 } while (0)
 690
 691 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 692         (elm)->field.cqe_next = (void *)(head);                         \
 693         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 694         if ((head)->cqh_first == (void *)(head))                        \
 695                 (head)->cqh_first = (elm);                              \
 696         else                                                            \
 697                 (head)->cqh_last->field.cqe_next = (elm);               \
 698         (head)->cqh_last = (elm);                                       \
 699 } while (0)
 700
 701 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
 702
 703 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
 704
 705 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
 706
 707 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 708         if ((elm)->field.cqe_next == (void *)(head))                    \
 709                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 710         else                                                            \
 711                 (elm)->field.cqe_next->field.cqe_prev =                 \
 712                     (elm)->field.cqe_prev;                              \
 713         if ((elm)->field.cqe_prev == (void *)(head))                    \
 714                 (head)->cqh_first = (elm)->field.cqe_next;              \
 715         else                                                            \
 716                 (elm)->field.cqe_prev->field.cqe_next =                 \
 717                     (elm)->field.cqe_next;                              \
 718 } while (0)
 719
 720 #ifdef _KERNEL
 721
 722 #if NOTFB31
 723
 724 /*
 725  * XXX insque() and remque() are an old way of handling certain queues.
 726  * They bogusly assumes that all queue heads look alike.
 727  */
 728
 729 struct quehead {
 730         struct quehead *qh_link;
 731         struct quehead *qh_rlink;
 732 };
 733
 734 #ifdef __GNUC__
 735
 736 static __inline void
 737 insque(void *a, void *b)
 738 {
 739         struct quehead *element = (struct quehead *)a,
 740                  *head = (struct quehead *)b;
 741
 742         element->qh_link = head->qh_link;
 743         element->qh_rlink = head;
 744         head->qh_link = element;
 745         element->qh_link->qh_rlink = element;
 746 }
 747
 748 static __inline void
 749 remque(void *a)
 750 {
 751         struct quehead *element = (struct quehead *)a;
 752
 753         element->qh_link->qh_rlink = element->qh_rlink;
 754         element->qh_rlink->qh_link = element->qh_link;
 755         element->qh_rlink = 0;
 756 }
 757
 758 #else /* !__GNUC__ */
 759
 760 void    insque(void *a, void *b);
 761 void    remque(void *a);
 762
 763 #endif /* __GNUC__ */
 764
 765 #endif
 766 #endif /* _KERNEL */
 767
 768 #endif /* !_SYS_QUEUE_H_ */