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  * Horrible macros to enable use of code that was meant to be C-specific
 178  *   (and which push struct onto type) in C++; without these, C++ code
 179  *   that uses these macros in the context of a class will blow up
 180  *   due to "struct" being preprended to "type" by the macros, causing
 181  *   inconsistent use of tags.
 182  *
 183  * This approach is necessary because these are macros; we have to use
 184  *   these on a per-macro basis (because the queues are implemented as
 185  *   macros, disabling this warning in the scope of the header file is
 186  *   insufficient), whuch means we can't use #pragma, and have to use
 187  *   _Pragma.  We only need to use these for the queue macros that
 188  *   prepend "struct" to "type" and will cause C++ to blow up.
 189  */
 190 #if defined(__clang__) && defined(__cplusplus)
 191 #define __MISMATCH_TAGS_PUSH                                            \
 192         _Pragma("clang diagnostic push")                                \
 193         _Pragma("clang diagnostic ignored \"-Wmismatched-tags\"")
 194 #define __MISMATCH_TAGS_POP                                             \
 195         _Pragma("clang diagnostic pop")
 196 #else
 197 #define __MISMATCH_TAGS_PUSH
 198 #define __MISMATCH_TAGS_POP
 199 #endif
 200
 201 /*
 202  * Singly-linked List declarations.
 203  */
 204 #define SLIST_HEAD(name, type)                                          \
 205 __MISMATCH_TAGS_PUSH                                                    \
 206 struct name {                                                           \
 207         struct type *slh_first; /* first element */                     \
 208 }                                                                       \
 209 __MISMATCH_TAGS_POP
 210
 211 #define SLIST_HEAD_INITIALIZER(head)                                    \
 212         { NULL }
 213
 214 #define SLIST_ENTRY(type)                                               \
 215 __MISMATCH_TAGS_PUSH                                                    \
 216 struct {                                                                \
 217         struct type *sle_next;  /* next element */                      \
 218 }                                                                       \
 219 __MISMATCH_TAGS_POP
 220
 221 /*
 222  * Singly-linked List functions.
 223  */
 224 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 225
 226 #define SLIST_FIRST(head)       ((head)->slh_first)
 227
 228 #define SLIST_FOREACH(var, head, field)                                 \
 229         for ((var) = SLIST_FIRST((head));                               \
 230             (var);                                                      \
 231             (var) = SLIST_NEXT((var), field))
 232
 233 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 234         for ((var) = SLIST_FIRST((head));                               \
 235             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 236             (var) = (tvar))
 237
 238 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
 239         for ((varp) = &SLIST_FIRST((head));                             \
 240             ((var) = *(varp)) != NULL;                                  \
 241             (varp) = &SLIST_NEXT((var), field))
 242
 243 #define SLIST_INIT(head) do {                                           \
 244         SLIST_FIRST((head)) = NULL;                                     \
 245 } while (0)
 246
 247 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 248         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
 249         SLIST_NEXT((slistelm), field) = (elm);                          \
 250 } while (0)
 251
 252 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 253         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
 254         SLIST_FIRST((head)) = (elm);                                    \
 255 } while (0)
 256
 257 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 258
 259 #define SLIST_REMOVE(head, elm, type, field)                            \
 260 __MISMATCH_TAGS_PUSH                                                    \
 261 do {                                                                    \
 262         if (SLIST_FIRST((head)) == (elm)) {                             \
 263                 SLIST_REMOVE_HEAD((head), field);                       \
 264         }                                                               \
 265         else {                                                          \
 266                 struct type *curelm = SLIST_FIRST((head));              \
 267                 while (SLIST_NEXT(curelm, field) != (elm))              \
 268                         curelm = SLIST_NEXT(curelm, field);             \
 269                 SLIST_REMOVE_AFTER(curelm, field);                      \
 270         }                                                               \
 271         TRASHIT((elm)->field.sle_next);                                 \
 272 } while (0)                                                             \
 273 __MISMATCH_TAGS_POP
 274
 275 #define SLIST_REMOVE_AFTER(elm, field) do {                             \
 276         SLIST_NEXT(elm, field) =                                        \
 277             SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
 278 } while (0)
 279
 280 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 281         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 282 } while (0)
 283
 284 /*
 285  * Singly-linked Tail queue declarations.
 286  */
 287 #define STAILQ_HEAD(name, type)                                         \
 288 __MISMATCH_TAGS_PUSH                                                    \
 289 struct name {                                                           \
 290         struct type *stqh_first;/* first element */                     \
 291         struct type **stqh_last;/* addr of last next element */         \
 292 }                                                                       \
 293 __MISMATCH_TAGS_POP
 294
 295 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 296         { NULL, &(head).stqh_first }
 297
 298 #define STAILQ_ENTRY(type)                                              \
 299 __MISMATCH_TAGS_PUSH                                                    \
 300 struct {                                                                \
 301         struct type *stqe_next; /* next element */                      \
 302 }                                                                       \
 303 __MISMATCH_TAGS_POP
 304
 305 /*
 306  * Singly-linked Tail queue functions.
 307  */
 308 #define STAILQ_CONCAT(head1, head2) do {                                \
 309         if (!STAILQ_EMPTY((head2))) {                                   \
 310                 *(head1)->stqh_last = (head2)->stqh_first;              \
 311                 (head1)->stqh_last = (head2)->stqh_last;                \
 312                 STAILQ_INIT((head2));                                   \
 313         }                                                               \
 314 } while (0)
 315
 316 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 317
 318 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 319
 320 #define STAILQ_FOREACH(var, head, field)                                \
 321         for((var) = STAILQ_FIRST((head));                               \
 322            (var);                                                       \
 323            (var) = STAILQ_NEXT((var), field))
 324
 325
 326 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
 327         for ((var) = STAILQ_FIRST((head));                              \
 328             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 329             (var) = (tvar))
 330
 331 #define STAILQ_INIT(head) do {                                          \
 332         STAILQ_FIRST((head)) = NULL;                                    \
 333         (head)->stqh_last = &STAILQ_FIRST((head));                      \
 334 } while (0)
 335
 336 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 337         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 338                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 339         STAILQ_NEXT((tqelm), field) = (elm);                            \
 340 } while (0)
 341
 342 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 343         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
 344                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 345         STAILQ_FIRST((head)) = (elm);                                   \
 346 } while (0)
 347
 348 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 349         STAILQ_NEXT((elm), field) = NULL;                               \
 350         *(head)->stqh_last = (elm);                                     \
 351         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
 352 } while (0)
 353
 354 #define STAILQ_LAST(head, type, field)                                  \
 355 __MISMATCH_TAGS_PUSH                                                    \
 356         (STAILQ_EMPTY((head)) ?                                         \
 357                 NULL :                                                  \
 358                 ((struct type *)(void *)                                \
 359                 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))\
 360 __MISMATCH_TAGS_POP
 361
 362 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 363
 364 #define STAILQ_REMOVE(head, elm, type, field)                           \
 365 __MISMATCH_TAGS_PUSH                                                    \
 366 do {                                                                    \
 367         if (STAILQ_FIRST((head)) == (elm)) {                            \
 368                 STAILQ_REMOVE_HEAD((head), field);                      \
 369         }                                                               \
 370         else {                                                          \
 371                 struct type *curelm = STAILQ_FIRST((head));             \
 372                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 373                         curelm = STAILQ_NEXT(curelm, field);            \
 374                 STAILQ_REMOVE_AFTER(head, curelm, field);               \
 375         }                                                               \
 376         TRASHIT((elm)->field.stqe_next);                                \
 377 } while (0)                                                             \
 378 __MISMATCH_TAGS_POP
 379
 380 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 381         if ((STAILQ_FIRST((head)) =                                     \
 382              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
 383                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 384 } while (0)
 385
 386 #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {                 \
 387        if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \
 388                (head)->stqh_last = &STAILQ_FIRST((head));              \
 389 } while (0)
 390
 391 #define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
 392         if ((STAILQ_NEXT(elm, field) =                                  \
 393              STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
 394                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 395 } while (0)
 396
 397 #define STAILQ_SWAP(head1, head2, type)                                 \
 398 __MISMATCH_TAGS_PUSH                                                    \
 399 do {                                                                    \
 400         struct type *swap_first = STAILQ_FIRST(head1);                  \
 401         struct type **swap_last = (head1)->stqh_last;                   \
 402         STAILQ_FIRST(head1) = STAILQ_FIRST(head2);                      \
 403         (head1)->stqh_last = (head2)->stqh_last;                        \
 404         STAILQ_FIRST(head2) = swap_first;                               \
 405         (head2)->stqh_last = swap_last;                                 \
 406         if (STAILQ_EMPTY(head1))                                        \
 407                 (head1)->stqh_last = &STAILQ_FIRST(head1);              \
 408         if (STAILQ_EMPTY(head2))                                        \
 409                 (head2)->stqh_last = &STAILQ_FIRST(head2);              \
 410 } while (0)                                                             \
 411 __MISMATCH_TAGS_POP
 412
 413
 414 /*
 415  * List declarations.
 416  */
 417 #define LIST_HEAD(name, type)                                           \
 418 __MISMATCH_TAGS_PUSH                                                    \
 419 struct name {                                                           \
 420         struct type *lh_first;  /* first element */                     \
 421 }                                                                       \
 422 __MISMATCH_TAGS_POP
 423
 424 #define LIST_HEAD_INITIALIZER(head)                                     \
 425         { NULL }
 426
 427 #define LIST_ENTRY(type)                                                \
 428 __MISMATCH_TAGS_PUSH                                                    \
 429 struct {                                                                \
 430         struct type *le_next;   /* next element */                      \
 431         struct type **le_prev;  /* address of previous next element */  \
 432 }                                                                       \
 433 __MISMATCH_TAGS_POP
 434
 435 /*
 436  * List functions.
 437  */
 438
 439 #if (defined(_KERNEL) && defined(INVARIANTS)) || defined(QUEUE_MACRO_DEBUG)
 440 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 441         if (LIST_FIRST((head)) != NULL &&                               \
 442             LIST_FIRST((head))->field.le_prev !=                        \
 443              &LIST_FIRST((head)))                                       \
 444                 panic("Bad list head %p first->prev != head", (head));  \
 445 } while (0)
 446
 447 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 448         if (LIST_NEXT((elm), field) != NULL &&                          \
 449             LIST_NEXT((elm), field)->field.le_prev !=                   \
 450              &((elm)->field.le_next))                                   \
 451                 panic("Bad link elm %p next->prev != elm", (elm));      \
 452 } while (0)
 453
 454 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 455         if (*(elm)->field.le_prev != (elm))                             \
 456                 panic("Bad link elm %p prev->next != elm", (elm));      \
 457 } while (0)
 458 #else
 459 #define QMD_LIST_CHECK_HEAD(head, field)
 460 #define QMD_LIST_CHECK_NEXT(elm, field)
 461 #define QMD_LIST_CHECK_PREV(elm, field)
 462 #endif /* (_KERNEL && INVARIANTS) || QUEUE_MACRO_DEBUG */
 463
 464 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 465
 466 #define LIST_FIRST(head)        ((head)->lh_first)
 467
 468 #define LIST_FOREACH(var, head, field)                                  \
 469         for ((var) = LIST_FIRST((head));                                \
 470             (var);                                                      \
 471             (var) = LIST_NEXT((var), field))
 472
 473 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 474         for ((var) = LIST_FIRST((head));                                \
 475             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 476             (var) = (tvar))
 477
 478 #define LIST_INIT(head) do {                                            \
 479         LIST_FIRST((head)) = NULL;                                      \
 480 } while (0)
 481
 482 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 483         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 484         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 485                 LIST_NEXT((listelm), field)->field.le_prev =            \
 486                     &LIST_NEXT((elm), field);                           \
 487         LIST_NEXT((listelm), field) = (elm);                            \
 488         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 489 } while (0)
 490
 491 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 492         QMD_LIST_CHECK_PREV(listelm, field);                            \
 493         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 494         LIST_NEXT((elm), field) = (listelm);                            \
 495         *(listelm)->field.le_prev = (elm);                              \
 496         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 497 } while (0)
 498
 499 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 500         QMD_LIST_CHECK_HEAD((head), field);                             \
 501         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 502                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 503         LIST_FIRST((head)) = (elm);                                     \
 504         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 505 } while (0)
 506
 507 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 508
 509 #define LIST_REMOVE(elm, field) do {                                    \
 510         QMD_LIST_CHECK_NEXT(elm, field);                                \
 511         QMD_LIST_CHECK_PREV(elm, field);                                \
 512         if (LIST_NEXT((elm), field) != NULL)                            \
 513                 LIST_NEXT((elm), field)->field.le_prev =                \
 514                     (elm)->field.le_prev;                               \
 515         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 516         TRASHIT((elm)->field.le_next);                                  \
 517         TRASHIT((elm)->field.le_prev);                                  \
 518 } while (0)
 519
 520 #define LIST_SWAP(head1, head2, type, field)                            \
 521 __MISMATCH_TAGS_PUSH                                                    \
 522 do {                                                                    \
 523         struct type *swap_tmp = LIST_FIRST((head1));                    \
 524         LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
 525         LIST_FIRST((head2)) = swap_tmp;                                 \
 526         if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
 527                 swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
 528         if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
 529                 swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
 530 } while (0)                                                             \
 531 __MISMATCH_TAGS_POP
 532
 533 /*
 534  * Tail queue declarations.
 535  */
 536 #define TAILQ_HEAD(name, type)                                          \
 537 __MISMATCH_TAGS_PUSH                                                    \
 538 struct name {                                                           \
 539         struct type *tqh_first; /* first element */                     \
 540         struct type **tqh_last; /* addr of last next element */         \
 541         TRACEBUF                                                        \
 542 }                                                                       \
 543 __MISMATCH_TAGS_POP
 544
 545 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 546         { NULL, &(head).tqh_first }
 547
 548 #define TAILQ_ENTRY(type)                                               \
 549 __MISMATCH_TAGS_PUSH                                                    \
 550 struct {                                                                \
 551         struct type *tqe_next;  /* next element */                      \
 552         struct type **tqe_prev; /* address of previous next element */  \
 553         TRACEBUF                                                        \
 554 }                                                                       \
 555 __MISMATCH_TAGS_POP
 556
 557 /*
 558  * Tail queue functions.
 559  */
 560 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 561         if (!TAILQ_EMPTY(head2)) {                                      \
 562                 *(head1)->tqh_last = (head2)->tqh_first;                \
 563                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 564                 (head1)->tqh_last = (head2)->tqh_last;                  \
 565                 TAILQ_INIT((head2));                                    \
 566                 QMD_TRACE_HEAD(head1);                                  \
 567                 QMD_TRACE_HEAD(head2);                                  \
 568         }                                                               \
 569 } while (0)
 570
 571 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 572
 573 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 574
 575 #define TAILQ_FOREACH(var, head, field)                                 \
 576         for ((var) = TAILQ_FIRST((head));                               \
 577             (var);                                                      \
 578             (var) = TAILQ_NEXT((var), field))
 579
 580 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 581         for ((var) = TAILQ_FIRST((head));                               \
 582             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 583             (var) = (tvar))
 584
 585 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 586         for ((var) = TAILQ_LAST((head), headname);                      \
 587             (var);                                                      \
 588             (var) = TAILQ_PREV((var), headname, field))
 589
 590 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 591         for ((var) = TAILQ_LAST((head), headname);                      \
 592             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 593             (var) = (tvar))
 594
 595 #define TAILQ_INIT(head) do {                                           \
 596         TAILQ_FIRST((head)) = NULL;                                     \
 597         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 598         QMD_TRACE_HEAD(head);                                           \
 599 } while (0)
 600
 601 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 602         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 603                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 604                     &TAILQ_NEXT((elm), field);                          \
 605         else {                                                          \
 606                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 607                 QMD_TRACE_HEAD(head);                                   \
 608         }                                                               \
 609         TAILQ_NEXT((listelm), field) = (elm);                           \
 610         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 611         QMD_TRACE_ELEM(&(elm)->field);                                  \
 612         QMD_TRACE_ELEM(&listelm->field);                                \
 613 } while (0)
 614
 615 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 616         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 617         TAILQ_NEXT((elm), field) = (listelm);                           \
 618         *(listelm)->field.tqe_prev = (elm);                             \
 619         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 620         QMD_TRACE_ELEM(&(elm)->field);                                  \
 621         QMD_TRACE_ELEM(&listelm->field);                                \
 622 } while (0)
 623
 624 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 625         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 626                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 627                     &TAILQ_NEXT((elm), field);                          \
 628         else                                                            \
 629                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 630         TAILQ_FIRST((head)) = (elm);                                    \
 631         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 632         QMD_TRACE_HEAD(head);                                           \
 633         QMD_TRACE_ELEM(&(elm)->field);                                  \
 634 } while (0)
 635
 636 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 637         TAILQ_NEXT((elm), field) = NULL;                                \
 638         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 639         *(head)->tqh_last = (elm);                                      \
 640         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 641         QMD_TRACE_HEAD(head);                                           \
 642         QMD_TRACE_ELEM(&(elm)->field);                                  \
 643 } while (0)
 644
 645 #define TAILQ_LAST(head, headname)                                      \
 646 __MISMATCH_TAGS_PUSH                                                    \
 647         (*(((struct headname *)((head)->tqh_last))->tqh_last))          \
 648 __MISMATCH_TAGS_POP
 649
 650 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 651
 652 #define TAILQ_PREV(elm, headname, field)                                \
 653 __MISMATCH_TAGS_PUSH                                                    \
 654         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))     \
 655 __MISMATCH_TAGS_POP
 656
 657 #define TAILQ_REMOVE(head, elm, field) do {                             \
 658         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 659                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 660                     (elm)->field.tqe_prev;                              \
 661         else {                                                          \
 662                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 663                 QMD_TRACE_HEAD(head);                                   \
 664         }                                                               \
 665         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 666         TRASHIT((elm)->field.tqe_next);                                 \
 667         TRASHIT((elm)->field.tqe_prev);                                 \
 668         QMD_TRACE_ELEM(&(elm)->field);                                  \
 669 } while (0)
 670
 671 /*
 672  * Why did they switch to spaces for this one macro?
 673  */
 674 #define TAILQ_SWAP(head1, head2, type, field)                           \
 675 __MISMATCH_TAGS_PUSH                                                    \
 676 do {                                                                    \
 677         struct type *swap_first = (head1)->tqh_first;                   \
 678         struct type **swap_last = (head1)->tqh_last;                    \
 679         (head1)->tqh_first = (head2)->tqh_first;                        \
 680         (head1)->tqh_last = (head2)->tqh_last;                          \
 681         (head2)->tqh_first = swap_first;                                \
 682         (head2)->tqh_last = swap_last;                                  \
 683         if ((swap_first = (head1)->tqh_first) != NULL)                  \
 684                 swap_first->field.tqe_prev = &(head1)->tqh_first;       \
 685         else                                                            \
 686                 (head1)->tqh_last = &(head1)->tqh_first;                \
 687         if ((swap_first = (head2)->tqh_first) != NULL)                  \
 688                 swap_first->field.tqe_prev = &(head2)->tqh_first;       \
 689         else                                                            \
 690                 (head2)->tqh_last = &(head2)->tqh_first;                \
 691 } while (0)                                                             \
 692 __MISMATCH_TAGS_POP
 693
 694 /*
 695  * Circular queue definitions.
 696  */
 697 #define CIRCLEQ_HEAD(name, type)                                        \
 698 __MISMATCH_TAGS_PUSH                                                    \
 699 struct name {                                                           \
 700         struct type *cqh_first;         /* first element */             \
 701         struct type *cqh_last;          /* last element */              \
 702 }                                                                       \
 703 __MISMATCH_TAGS_POP
 704
 705 #define CIRCLEQ_ENTRY(type)                                             \
 706 __MISMATCH_TAGS_PUSH                                                    \
 707 struct {                                                                \
 708         struct type *cqe_next;          /* next element */              \
 709         struct type *cqe_prev;          /* previous element */          \
 710 }                                                                       \
 711 __MISMATCH_TAGS_POP
 712
 713 /*
 714  * Circular queue functions.
 715  */
 716 #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
 717
 718 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
 719
 720 #define CIRCLEQ_FOREACH(var, head, field)                               \
 721         for((var) = (head)->cqh_first;                                  \
 722             (var) != (void *)(head);                                    \
 723             (var) = (var)->field.cqe_next)
 724
 725 #define CIRCLEQ_INIT(head) do {                                         \
 726         (head)->cqh_first = (void *)(head);                             \
 727         (head)->cqh_last = (void *)(head);                              \
 728 } while (0)
 729
 730 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 731         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 732         (elm)->field.cqe_prev = (listelm);                              \
 733         if ((listelm)->field.cqe_next == (void *)(head))                \
 734                 (head)->cqh_last = (elm);                               \
 735         else                                                            \
 736                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 737         (listelm)->field.cqe_next = (elm);                              \
 738 } while (0)
 739
 740 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 741         (elm)->field.cqe_next = (listelm);                              \
 742         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 743         if ((listelm)->field.cqe_prev == (void *)(head))                \
 744                 (head)->cqh_first = (elm);                              \
 745         else                                                            \
 746                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 747         (listelm)->field.cqe_prev = (elm);                              \
 748 } while (0)
 749
 750 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 751         (elm)->field.cqe_next = (head)->cqh_first;                      \
 752         (elm)->field.cqe_prev = (void *)(head);                         \
 753         if ((head)->cqh_last == (void *)(head))                         \
 754                 (head)->cqh_last = (elm);                               \
 755         else                                                            \
 756                 (head)->cqh_first->field.cqe_prev = (elm);              \
 757         (head)->cqh_first = (elm);                                      \
 758 } while (0)
 759
 760 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 761         (elm)->field.cqe_next = (void *)(head);                         \
 762         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 763         if ((head)->cqh_first == (void *)(head))                        \
 764                 (head)->cqh_first = (elm);                              \
 765         else                                                            \
 766                 (head)->cqh_last->field.cqe_next = (elm);               \
 767         (head)->cqh_last = (elm);                                       \
 768 } while (0)
 769
 770 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
 771
 772 #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
 773
 774 #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
 775
 776 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 777         if ((elm)->field.cqe_next == (void *)(head))                    \
 778                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 779         else                                                            \
 780                 (elm)->field.cqe_next->field.cqe_prev =                 \
 781                     (elm)->field.cqe_prev;                              \
 782         if ((elm)->field.cqe_prev == (void *)(head))                    \
 783                 (head)->cqh_first = (elm)->field.cqe_next;              \
 784         else                                                            \
 785                 (elm)->field.cqe_prev->field.cqe_next =                 \
 786                     (elm)->field.cqe_next;                              \
 787 } while (0)
 788
 789 #ifdef _KERNEL
 790
 791 #if NOTFB31
 792
 793 /*
 794  * XXX insque() and remque() are an old way of handling certain queues.
 795  * They bogusly assumes that all queue heads look alike.
 796  */
 797
 798 struct quehead {
 799         struct quehead *qh_link;
 800         struct quehead *qh_rlink;
 801 };
 802
 803 #ifdef __GNUC__
 804
 805 static __inline void
 806 insque(void *a, void *b)
 807 {
 808         struct quehead *element = (struct quehead *)a,
 809                  *head = (struct quehead *)b;
 810
 811         element->qh_link = head->qh_link;
 812         element->qh_rlink = head;
 813         head->qh_link = element;
 814         element->qh_link->qh_rlink = element;
 815 }
 816
 817 static __inline void
 818 remque(void *a)
 819 {
 820         struct quehead *element = (struct quehead *)a;
 821
 822         element->qh_link->qh_rlink = element->qh_rlink;
 823         element->qh_rlink->qh_link = element->qh_link;
 824         element->qh_rlink = 0;
 825 }
 826
 827 #else /* !__GNUC__ */
 828
 829 void    insque(void *a, void *b);
 830 void    remque(void *a);
 831
 832 #endif /* __GNUC__ */
 833
 834 #endif
 835 #endif /* _KERNEL */
 836
 837 #endif /* !_SYS_QUEUE_H_ */