sys/sys/queue.h

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  30  * $FreeBSD$
  31  */
  32
  33 #ifndef _SYS_QUEUE_H_
  34 #define _SYS_QUEUE_H_
  35
  36 #include <sys/cdefs.h>
  37
  38 /*
  39  * This file defines four types of data structures: singly-linked lists,
  40  * singly-linked tail queues, lists and tail queues.
  41  *
  42  * A singly-linked list is headed by a single forward pointer. The elements
  43  * are singly linked for minimum space and pointer manipulation overhead at
  44  * the expense of O(n) removal for arbitrary elements. New elements can be
  45  * added to the list after an existing element or at the head of the list.
  46  * Elements being removed from the head of the list should use the explicit
  47  * macro for this purpose for optimum efficiency. A singly-linked list may
  48  * only be traversed in the forward direction.  Singly-linked lists are ideal
  49  * for applications with large datasets and few or no removals or for
  50  * implementing a LIFO queue.
  51  *
  52  * A singly-linked tail queue is headed by a pair of pointers, one to the
  53  * head of the list and the other to the tail of the list. The elements are
  54  * singly linked for minimum space and pointer manipulation overhead at the
  55  * expense of O(n) removal for arbitrary elements. New elements can be added
  56  * to the list after an existing element, at the head of the list, or at the
  57  * end of the list. Elements being removed from the head of the tail queue
  58  * should use the explicit macro for this purpose for optimum efficiency.
  59  * A singly-linked tail queue may only be traversed in the forward direction.
  60  * Singly-linked tail queues are ideal for applications with large datasets
  61  * and few or no removals or for implementing a FIFO queue.
  62  *
  63  * A list is headed by a single forward pointer (or an array of forward
  64  * pointers for a hash table header). The elements are doubly linked
  65  * so that an arbitrary element can be removed without a need to
  66  * traverse the list. New elements can be added to the list before
  67  * or after an existing element or at the head of the list. A list
  68  * may be traversed in either direction.
  69  *
  70  * A tail queue is headed by a pair of pointers, one to the head of the
  71  * list and the other to the tail of the list. The elements are doubly
  72  * linked so that an arbitrary element can be removed without a need to
  73  * traverse the list. New elements can be added to the list before or
  74  * after an existing element, at the head of the list, or at the end of
  75  * the list. A tail queue may be traversed in either direction.
  76  *
  77  * For details on the use of these macros, see the queue(3) manual page.
  78  *
  79  * Below is a summary of implemented functions where:
  80  *  +  means the macro is available
  81  *  -  means the macro is not available
  82  *  s  means the macro is available but is slow (runs in O(n) time)
  83  *
  84  *                              SLIST   LIST    STAILQ  TAILQ
  85  * _HEAD                        +       +       +       +
  86  * _CLASS_HEAD                  +       +       +       +
  87  * _HEAD_INITIALIZER            +       +       +       +
  88  * _ENTRY                       +       +       +       +
  89  * _CLASS_ENTRY                 +       +       +       +
  90  * _INIT                        +       +       +       +
  91  * _EMPTY                       +       +       +       +
  92  * _FIRST                       +       +       +       +
  93  * _NEXT                        +       +       +       +
  94  * _PREV                        -       +       -       +
  95  * _LAST                        -       -       +       +
  96  * _FOREACH                     +       +       +       +
  97  * _FOREACH_FROM                +       +       +       +
  98  * _FOREACH_SAFE                +       +       +       +
  99  * _FOREACH_FROM_SAFE           +       +       +       +
 100  * _FOREACH_REVERSE             -       -       -       +
 101  * _FOREACH_REVERSE_FROM        -       -       -       +
 102  * _FOREACH_REVERSE_SAFE        -       -       -       +
 103  * _FOREACH_REVERSE_FROM_SAFE   -       -       -       +
 104  * _INSERT_HEAD                 +       +       +       +
 105  * _INSERT_BEFORE               -       +       -       +
 106  * _INSERT_AFTER                +       +       +       +
 107  * _INSERT_TAIL                 -       -       +       +
 108  * _CONCAT                      s       s       +       +
 109  * _REMOVE_AFTER                +       -       +       -
 110  * _REMOVE_HEAD                 +       -       +       -
 111  * _REMOVE                      s       +       s       +
 112  * _SWAP                        +       +       +       +
 113  *
 114  */
 115 #ifdef QUEUE_MACRO_DEBUG
 116 #warn Use QUEUE_MACRO_DEBUG_TRACE and/or QUEUE_MACRO_DEBUG_TRASH
 117 #define QUEUE_MACRO_DEBUG_TRACE
 118 #define QUEUE_MACRO_DEBUG_TRASH
 119 #endif
 120
 121 #ifdef QUEUE_MACRO_DEBUG_TRACE
 122 /* Store the last 2 places the queue element or head was altered */
 123 struct qm_trace {
 124         unsigned long    lastline;
 125         unsigned long    prevline;
 126         const char      *lastfile;
 127         const char      *prevfile;
 128 };
 129
 130 #define TRACEBUF        struct qm_trace trace;
 131 #define TRACEBUF_INITIALIZER    { __LINE__, 0, __FILE__, NULL } ,
 132
 133 #define QMD_TRACE_HEAD(head) do {                                       \
 134         (head)->trace.prevline = (head)->trace.lastline;                \
 135         (head)->trace.prevfile = (head)->trace.lastfile;                \
 136         (head)->trace.lastline = __LINE__;                              \
 137         (head)->trace.lastfile = __FILE__;                              \
 138 } while (0)
 139
 140 #define QMD_TRACE_ELEM(elem) do {                                       \
 141         (elem)->trace.prevline = (elem)->trace.lastline;                \
 142         (elem)->trace.prevfile = (elem)->trace.lastfile;                \
 143         (elem)->trace.lastline = __LINE__;                              \
 144         (elem)->trace.lastfile = __FILE__;                              \
 145 } while (0)
 146
 147 #else   /* !QUEUE_MACRO_DEBUG_TRACE */
 148 #define QMD_TRACE_ELEM(elem)
 149 #define QMD_TRACE_HEAD(head)
 150 #define TRACEBUF
 151 #define TRACEBUF_INITIALIZER
 152 #endif  /* QUEUE_MACRO_DEBUG_TRACE */
 153
 154 #ifdef QUEUE_MACRO_DEBUG_TRASH
 155 #define TRASHIT(x)              do {(x) = (void *)-1;} while (0)
 156 #define QMD_IS_TRASHED(x)       ((x) == (void *)(intptr_t)-1)
 157 #else   /* !QUEUE_MACRO_DEBUG_TRASH */
 158 #define TRASHIT(x)
 159 #define QMD_IS_TRASHED(x)       0
 160 #endif  /* QUEUE_MACRO_DEBUG_TRASH */
 161
 162 #if defined(QUEUE_MACRO_DEBUG_TRACE) || defined(QUEUE_MACRO_DEBUG_TRASH)
 163 #define QMD_SAVELINK(name, link)        void **name = (void *)&(link)
 164 #else   /* !QUEUE_MACRO_DEBUG_TRACE && !QUEUE_MACRO_DEBUG_TRASH */
 165 #define QMD_SAVELINK(name, link)
 166 #endif  /* QUEUE_MACRO_DEBUG_TRACE || QUEUE_MACRO_DEBUG_TRASH */
 167
 168 #ifdef __cplusplus
 169 /*
 170  * In C++ there can be structure lists and class lists:
 171  */
 172 #define QUEUE_TYPEOF(type) type
 173 #else
 174 #define QUEUE_TYPEOF(type) struct type
 175 #endif
 176
 177 /*
 178  * Singly-linked List declarations.
 179  */
 180 #define SLIST_HEAD(name, type)                                          \
 181 struct name {                                                           \
 182         struct type *slh_first; /* first element */                     \
 183 }
 184
 185 #define SLIST_CLASS_HEAD(name, type)                                    \
 186 struct name {                                                           \
 187         class type *slh_first;  /* first element */                     \
 188 }
 189
 190 #define SLIST_HEAD_INITIALIZER(head)                                    \
 191         { NULL }
 192
 193 #define SLIST_ENTRY(type)                                               \
 194 struct {                                                                \
 195         struct type *sle_next;  /* next element */                      \
 196 }
 197
 198 #define SLIST_CLASS_ENTRY(type)                                         \
 199 struct {                                                                \
 200         class type *sle_next;           /* next element */              \
 201 }
 202
 203 /*
 204  * Singly-linked List functions.
 205  */
 206 #if (defined(_KERNEL) && defined(INVARIANTS))
 207 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm) do {                        \
 208         if (*(prevp) != (elm))                                          \
 209                 panic("Bad prevptr *(%p) == %p != %p",                  \
 210                     (prevp), *(prevp), (elm));                          \
 211 } while (0)
 212 #else
 213 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm)
 214 #endif
 215
 216 #define SLIST_CONCAT(head1, head2, type, field) do {                    \
 217         QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1);                \
 218         if (curelm == NULL) {                                           \
 219                 if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL)  \
 220                         SLIST_INIT(head2);                              \
 221         } else if (SLIST_FIRST(head2) != NULL) {                        \
 222                 while (SLIST_NEXT(curelm, field) != NULL)               \
 223                         curelm = SLIST_NEXT(curelm, field);             \
 224                 SLIST_NEXT(curelm, field) = SLIST_FIRST(head2);         \
 225                 SLIST_INIT(head2);                                      \
 226         }                                                               \
 227 } while (0)
 228
 229 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 230
 231 #define SLIST_FIRST(head)       ((head)->slh_first)
 232
 233 #define SLIST_FOREACH(var, head, field)                                 \
 234         for ((var) = SLIST_FIRST((head));                               \
 235             (var);                                                      \
 236             (var) = SLIST_NEXT((var), field))
 237
 238 #define SLIST_FOREACH_FROM(var, head, field)                            \
 239         for ((var) = ((var) ? (var) : SLIST_FIRST((head)));             \
 240             (var);                                                      \
 241             (var) = SLIST_NEXT((var), field))
 242
 243 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 244         for ((var) = SLIST_FIRST((head));                               \
 245             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 246             (var) = (tvar))
 247
 248 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar)                 \
 249         for ((var) = ((var) ? (var) : SLIST_FIRST((head)));             \
 250             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 251             (var) = (tvar))
 252
 253 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
 254         for ((varp) = &SLIST_FIRST((head));                             \
 255             ((var) = *(varp)) != NULL;                                  \
 256             (varp) = &SLIST_NEXT((var), field))
 257
 258 #define SLIST_INIT(head) do {                                           \
 259         SLIST_FIRST((head)) = NULL;                                     \
 260 } while (0)
 261
 262 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 263         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
 264         SLIST_NEXT((slistelm), field) = (elm);                          \
 265 } while (0)
 266
 267 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 268         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
 269         SLIST_FIRST((head)) = (elm);                                    \
 270 } while (0)
 271
 272 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 273
 274 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 275         QMD_SAVELINK(oldnext, (elm)->field.sle_next);                   \
 276         if (SLIST_FIRST((head)) == (elm)) {                             \
 277                 SLIST_REMOVE_HEAD((head), field);                       \
 278         }                                                               \
 279         else {                                                          \
 280                 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head);         \
 281                 while (SLIST_NEXT(curelm, field) != (elm))              \
 282                         curelm = SLIST_NEXT(curelm, field);             \
 283                 SLIST_REMOVE_AFTER(curelm, field);                      \
 284         }                                                               \
 285         TRASHIT(*oldnext);                                              \
 286 } while (0)
 287
 288 #define SLIST_REMOVE_AFTER(elm, field) do {                             \
 289         SLIST_NEXT(elm, field) =                                        \
 290             SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
 291 } while (0)
 292
 293 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 294         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 295 } while (0)
 296
 297 #define SLIST_REMOVE_PREVPTR(prevp, elm, field) do {                    \
 298         QMD_SLIST_CHECK_PREVPTR(prevp, elm);                            \
 299         *(prevp) = SLIST_NEXT(elm, field);                              \
 300         TRASHIT((elm)->field.sle_next);                                 \
 301 } while (0)
 302
 303 #define SLIST_SWAP(head1, head2, type) do {                             \
 304         QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1);            \
 305         SLIST_FIRST(head1) = SLIST_FIRST(head2);                        \
 306         SLIST_FIRST(head2) = swap_first;                                \
 307 } while (0)
 308
 309 /*
 310  * Singly-linked Tail queue declarations.
 311  */
 312 #define STAILQ_HEAD(name, type)                                         \
 313 struct name {                                                           \
 314         struct type *stqh_first;/* first element */                     \
 315         struct type **stqh_last;/* addr of last next element */         \
 316 }
 317
 318 #define STAILQ_CLASS_HEAD(name, type)                                   \
 319 struct name {                                                           \
 320         class type *stqh_first; /* first element */                     \
 321         class type **stqh_last; /* addr of last next element */         \
 322 }
 323
 324 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 325         { NULL, &(head).stqh_first }
 326
 327 #define STAILQ_ENTRY(type)                                              \
 328 struct {                                                                \
 329         struct type *stqe_next; /* next element */                      \
 330 }
 331
 332 #define STAILQ_CLASS_ENTRY(type)                                        \
 333 struct {                                                                \
 334         class type *stqe_next;  /* next element */                      \
 335 }
 336
 337 /*
 338  * Singly-linked Tail queue functions.
 339  */
 340 #define STAILQ_CONCAT(head1, head2) do {                                \
 341         if (!STAILQ_EMPTY((head2))) {                                   \
 342                 *(head1)->stqh_last = (head2)->stqh_first;              \
 343                 (head1)->stqh_last = (head2)->stqh_last;                \
 344                 STAILQ_INIT((head2));                                   \
 345         }                                                               \
 346 } while (0)
 347
 348 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 349
 350 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 351
 352 #define STAILQ_FOREACH(var, head, field)                                \
 353         for((var) = STAILQ_FIRST((head));                               \
 354            (var);                                                       \
 355            (var) = STAILQ_NEXT((var), field))
 356
 357 #define STAILQ_FOREACH_FROM(var, head, field)                           \
 358         for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));            \
 359            (var);                                                       \
 360            (var) = STAILQ_NEXT((var), field))
 361
 362 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
 363         for ((var) = STAILQ_FIRST((head));                              \
 364             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 365             (var) = (tvar))
 366
 367 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)                \
 368         for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));            \
 369             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 370             (var) = (tvar))
 371
 372 #define STAILQ_INIT(head) do {                                          \
 373         STAILQ_FIRST((head)) = NULL;                                    \
 374         (head)->stqh_last = &STAILQ_FIRST((head));                      \
 375 } while (0)
 376
 377 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 378         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 379                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 380         STAILQ_NEXT((tqelm), field) = (elm);                            \
 381 } while (0)
 382
 383 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 384         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
 385                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 386         STAILQ_FIRST((head)) = (elm);                                   \
 387 } while (0)
 388
 389 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 390         STAILQ_NEXT((elm), field) = NULL;                               \
 391         *(head)->stqh_last = (elm);                                     \
 392         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
 393 } while (0)
 394
 395 #define STAILQ_LAST(head, type, field)                          \
 396         (STAILQ_EMPTY((head)) ? NULL :                          \
 397             __containerof((head)->stqh_last,                    \
 398             QUEUE_TYPEOF(type), field.stqe_next))
 399
 400 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 401
 402 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 403         QMD_SAVELINK(oldnext, (elm)->field.stqe_next);                  \
 404         if (STAILQ_FIRST((head)) == (elm)) {                            \
 405                 STAILQ_REMOVE_HEAD((head), field);                      \
 406         }                                                               \
 407         else {                                                          \
 408                 QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head);        \
 409                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 410                         curelm = STAILQ_NEXT(curelm, field);            \
 411                 STAILQ_REMOVE_AFTER(head, curelm, field);               \
 412         }                                                               \
 413         TRASHIT(*oldnext);                                              \
 414 } while (0)
 415
 416 #define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
 417         if ((STAILQ_NEXT(elm, field) =                                  \
 418              STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
 419                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 420 } while (0)
 421
 422 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 423         if ((STAILQ_FIRST((head)) =                                     \
 424              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
 425                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 426 } while (0)
 427
 428 #define STAILQ_SWAP(head1, head2, type) do {                            \
 429         QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1);           \
 430         QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last;            \
 431         STAILQ_FIRST(head1) = STAILQ_FIRST(head2);                      \
 432         (head1)->stqh_last = (head2)->stqh_last;                        \
 433         STAILQ_FIRST(head2) = swap_first;                               \
 434         (head2)->stqh_last = swap_last;                                 \
 435         if (STAILQ_EMPTY(head1))                                        \
 436                 (head1)->stqh_last = &STAILQ_FIRST(head1);              \
 437         if (STAILQ_EMPTY(head2))                                        \
 438                 (head2)->stqh_last = &STAILQ_FIRST(head2);              \
 439 } while (0)
 440
 441
 442 /*
 443  * List declarations.
 444  */
 445 #define LIST_HEAD(name, type)                                           \
 446 struct name {                                                           \
 447         struct type *lh_first;  /* first element */                     \
 448 }
 449
 450 #define LIST_CLASS_HEAD(name, type)                                     \
 451 struct name {                                                           \
 452         class type *lh_first;   /* first element */                     \
 453 }
 454
 455 #define LIST_HEAD_INITIALIZER(head)                                     \
 456         { NULL }
 457
 458 #define LIST_ENTRY(type)                                                \
 459 struct {                                                                \
 460         struct type *le_next;   /* next element */                      \
 461         struct type **le_prev;  /* address of previous next element */  \
 462 }
 463
 464 #define LIST_CLASS_ENTRY(type)                                          \
 465 struct {                                                                \
 466         class type *le_next;    /* next element */                      \
 467         class type **le_prev;   /* address of previous next element */  \
 468 }
 469
 470 /*
 471  * List functions.
 472  */
 473
 474 #if (defined(_KERNEL) && defined(INVARIANTS))
 475 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 476         if (LIST_FIRST((head)) != NULL &&                               \
 477             LIST_FIRST((head))->field.le_prev !=                        \
 478              &LIST_FIRST((head)))                                       \
 479                 panic("Bad list head %p first->prev != head", (head));  \
 480 } while (0)
 481
 482 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 483         if (LIST_NEXT((elm), field) != NULL &&                          \
 484             LIST_NEXT((elm), field)->field.le_prev !=                   \
 485              &((elm)->field.le_next))                                   \
 486                 panic("Bad link elm %p next->prev != elm", (elm));      \
 487 } while (0)
 488
 489 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 490         if (*(elm)->field.le_prev != (elm))                             \
 491                 panic("Bad link elm %p prev->next != elm", (elm));      \
 492 } while (0)
 493 #else
 494 #define QMD_LIST_CHECK_HEAD(head, field)
 495 #define QMD_LIST_CHECK_NEXT(elm, field)
 496 #define QMD_LIST_CHECK_PREV(elm, field)
 497 #endif /* (_KERNEL && INVARIANTS) */
 498
 499 #define LIST_CONCAT(head1, head2, type, field) do {                           \
 500         QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1);                       \
 501         if (curelm == NULL) {                                                 \
 502                 if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) {        \
 503                         LIST_FIRST(head2)->field.le_prev =                    \
 504                             &LIST_FIRST((head1));                             \
 505                         LIST_INIT(head2);                                     \
 506                 }                                                             \
 507         } else if (LIST_FIRST(head2) != NULL) {                               \
 508                 while (LIST_NEXT(curelm, field) != NULL)                      \
 509                         curelm = LIST_NEXT(curelm, field);                    \
 510                 LIST_NEXT(curelm, field) = LIST_FIRST(head2);                 \
 511                 LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
 512                 LIST_INIT(head2);                                             \
 513         }                                                                     \
 514 } while (0)
 515
 516 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 517
 518 #define LIST_FIRST(head)        ((head)->lh_first)
 519
 520 #define LIST_FOREACH(var, head, field)                                  \
 521         for ((var) = LIST_FIRST((head));                                \
 522             (var);                                                      \
 523             (var) = LIST_NEXT((var), field))
 524
 525 #define LIST_FOREACH_FROM(var, head, field)                             \
 526         for ((var) = ((var) ? (var) : LIST_FIRST((head)));              \
 527             (var);                                                      \
 528             (var) = LIST_NEXT((var), field))
 529
 530 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 531         for ((var) = LIST_FIRST((head));                                \
 532             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 533             (var) = (tvar))
 534
 535 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar)                  \
 536         for ((var) = ((var) ? (var) : LIST_FIRST((head)));              \
 537             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 538             (var) = (tvar))
 539
 540 #define LIST_INIT(head) do {                                            \
 541         LIST_FIRST((head)) = NULL;                                      \
 542 } while (0)
 543
 544 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 545         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 546         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 547                 LIST_NEXT((listelm), field)->field.le_prev =            \
 548                     &LIST_NEXT((elm), field);                           \
 549         LIST_NEXT((listelm), field) = (elm);                            \
 550         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 551 } while (0)
 552
 553 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 554         QMD_LIST_CHECK_PREV(listelm, field);                            \
 555         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 556         LIST_NEXT((elm), field) = (listelm);                            \
 557         *(listelm)->field.le_prev = (elm);                              \
 558         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 559 } while (0)
 560
 561 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 562         QMD_LIST_CHECK_HEAD((head), field);                             \
 563         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 564                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 565         LIST_FIRST((head)) = (elm);                                     \
 566         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 567 } while (0)
 568
 569 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 570
 571 #define LIST_PREV(elm, head, type, field)                       \
 572         ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :   \
 573             __containerof((elm)->field.le_prev,                 \
 574             QUEUE_TYPEOF(type), field.le_next))
 575
 576 #define LIST_REMOVE(elm, field) do {                                    \
 577         QMD_SAVELINK(oldnext, (elm)->field.le_next);                    \
 578         QMD_SAVELINK(oldprev, (elm)->field.le_prev);                    \
 579         QMD_LIST_CHECK_NEXT(elm, field);                                \
 580         QMD_LIST_CHECK_PREV(elm, field);                                \
 581         if (LIST_NEXT((elm), field) != NULL)                            \
 582                 LIST_NEXT((elm), field)->field.le_prev =                \
 583                     (elm)->field.le_prev;                               \
 584         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 585         TRASHIT(*oldnext);                                              \
 586         TRASHIT(*oldprev);                                              \
 587 } while (0)
 588
 589 #define LIST_SWAP(head1, head2, type, field) do {                       \
 590         QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1);               \
 591         LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
 592         LIST_FIRST((head2)) = swap_tmp;                                 \
 593         if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
 594                 swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
 595         if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
 596                 swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
 597 } while (0)
 598
 599 /*
 600  * Tail queue declarations.
 601  */
 602 #define TAILQ_HEAD(name, type)                                          \
 603 struct name {                                                           \
 604         struct type *tqh_first; /* first element */                     \
 605         struct type **tqh_last; /* addr of last next element */         \
 606         TRACEBUF                                                        \
 607 }
 608
 609 #define TAILQ_CLASS_HEAD(name, type)                                    \
 610 struct name {                                                           \
 611         class type *tqh_first;  /* first element */                     \
 612         class type **tqh_last;  /* addr of last next element */         \
 613         TRACEBUF                                                        \
 614 }
 615
 616 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 617         { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
 618
 619 #define TAILQ_ENTRY(type)                                               \
 620 struct {                                                                \
 621         struct type *tqe_next;  /* next element */                      \
 622         struct type **tqe_prev; /* address of previous next element */  \
 623         TRACEBUF                                                        \
 624 }
 625
 626 #define TAILQ_CLASS_ENTRY(type)                                         \
 627 struct {                                                                \
 628         class type *tqe_next;   /* next element */                      \
 629         class type **tqe_prev;  /* address of previous next element */  \
 630         TRACEBUF                                                        \
 631 }
 632
 633 /*
 634  * Tail queue functions.
 635  */
 636 #if (defined(_KERNEL) && defined(INVARIANTS))
 637 #define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
 638         if (!TAILQ_EMPTY(head) &&                                       \
 639             TAILQ_FIRST((head))->field.tqe_prev !=                      \
 640              &TAILQ_FIRST((head)))                                      \
 641                 panic("Bad tailq head %p first->prev != head", (head)); \
 642 } while (0)
 643
 644 #define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
 645         if (*(head)->tqh_last != NULL)                                  \
 646                 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
 647 } while (0)
 648
 649 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
 650         if (TAILQ_NEXT((elm), field) != NULL &&                         \
 651             TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
 652              &((elm)->field.tqe_next))                                  \
 653                 panic("Bad link elm %p next->prev != elm", (elm));      \
 654 } while (0)
 655
 656 #define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
 657         if (*(elm)->field.tqe_prev != (elm))                            \
 658                 panic("Bad link elm %p prev->next != elm", (elm));      \
 659 } while (0)
 660 #else
 661 #define QMD_TAILQ_CHECK_HEAD(head, field)
 662 #define QMD_TAILQ_CHECK_TAIL(head, headname)
 663 #define QMD_TAILQ_CHECK_NEXT(elm, field)
 664 #define QMD_TAILQ_CHECK_PREV(elm, field)
 665 #endif /* (_KERNEL && INVARIANTS) */
 666
 667 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 668         if (!TAILQ_EMPTY(head2)) {                                      \
 669                 *(head1)->tqh_last = (head2)->tqh_first;                \
 670                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 671                 (head1)->tqh_last = (head2)->tqh_last;                  \
 672                 TAILQ_INIT((head2));                                    \
 673                 QMD_TRACE_HEAD(head1);                                  \
 674                 QMD_TRACE_HEAD(head2);                                  \
 675         }                                                               \
 676 } while (0)
 677
 678 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 679
 680 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 681
 682 #define TAILQ_FOREACH(var, head, field)                                 \
 683         for ((var) = TAILQ_FIRST((head));                               \
 684             (var);                                                      \
 685             (var) = TAILQ_NEXT((var), field))
 686
 687 #define TAILQ_FOREACH_FROM(var, head, field)                            \
 688         for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));             \
 689             (var);                                                      \
 690             (var) = TAILQ_NEXT((var), field))
 691
 692 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 693         for ((var) = TAILQ_FIRST((head));                               \
 694             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 695             (var) = (tvar))
 696
 697 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)                 \
 698         for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));             \
 699             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 700             (var) = (tvar))
 701
 702 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 703         for ((var) = TAILQ_LAST((head), headname);                      \
 704             (var);                                                      \
 705             (var) = TAILQ_PREV((var), headname, field))
 706
 707 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field)          \
 708         for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
 709             (var);                                                      \
 710             (var) = TAILQ_PREV((var), headname, field))
 711
 712 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 713         for ((var) = TAILQ_LAST((head), headname);                      \
 714             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 715             (var) = (tvar))
 716
 717 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
 718         for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
 719             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 720             (var) = (tvar))
 721
 722 #define TAILQ_INIT(head) do {                                           \
 723         TAILQ_FIRST((head)) = NULL;                                     \
 724         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 725         QMD_TRACE_HEAD(head);                                           \
 726 } while (0)
 727
 728 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 729         QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
 730         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 731                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 732                     &TAILQ_NEXT((elm), field);                          \
 733         else {                                                          \
 734                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 735                 QMD_TRACE_HEAD(head);                                   \
 736         }                                                               \
 737         TAILQ_NEXT((listelm), field) = (elm);                           \
 738         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 739         QMD_TRACE_ELEM(&(elm)->field);                                  \
 740         QMD_TRACE_ELEM(&(listelm)->field);                              \
 741 } while (0)
 742
 743 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 744         QMD_TAILQ_CHECK_PREV(listelm, field);                           \
 745         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 746         TAILQ_NEXT((elm), field) = (listelm);                           \
 747         *(listelm)->field.tqe_prev = (elm);                             \
 748         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 749         QMD_TRACE_ELEM(&(elm)->field);                                  \
 750         QMD_TRACE_ELEM(&(listelm)->field);                              \
 751 } while (0)
 752
 753 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 754         QMD_TAILQ_CHECK_HEAD(head, field);                              \
 755         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 756                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 757                     &TAILQ_NEXT((elm), field);                          \
 758         else                                                            \
 759                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 760         TAILQ_FIRST((head)) = (elm);                                    \
 761         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 762         QMD_TRACE_HEAD(head);                                           \
 763         QMD_TRACE_ELEM(&(elm)->field);                                  \
 764 } while (0)
 765
 766 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 767         QMD_TAILQ_CHECK_TAIL(head, field);                              \
 768         TAILQ_NEXT((elm), field) = NULL;                                \
 769         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 770         *(head)->tqh_last = (elm);                                      \
 771         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 772         QMD_TRACE_HEAD(head);                                           \
 773         QMD_TRACE_ELEM(&(elm)->field);                                  \
 774 } while (0)
 775
 776 #define TAILQ_LAST(head, headname)                                      \
 777         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 778
 779 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 780
 781 #define TAILQ_PREV(elm, headname, field)                                \
 782         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 783
 784 #define TAILQ_REMOVE(head, elm, field) do {                             \
 785         QMD_SAVELINK(oldnext, (elm)->field.tqe_next);                   \
 786         QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);                   \
 787         QMD_TAILQ_CHECK_NEXT(elm, field);                               \
 788         QMD_TAILQ_CHECK_PREV(elm, field);                               \
 789         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 790                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 791                     (elm)->field.tqe_prev;                              \
 792         else {                                                          \
 793                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 794                 QMD_TRACE_HEAD(head);                                   \
 795         }                                                               \
 796         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 797         TRASHIT(*oldnext);                                              \
 798         TRASHIT(*oldprev);                                              \
 799         QMD_TRACE_ELEM(&(elm)->field);                                  \
 800 } while (0)
 801
 802 #define TAILQ_SWAP(head1, head2, type, field) do {                      \
 803         QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first;            \
 804         QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last;             \
 805         (head1)->tqh_first = (head2)->tqh_first;                        \
 806         (head1)->tqh_last = (head2)->tqh_last;                          \
 807         (head2)->tqh_first = swap_first;                                \
 808         (head2)->tqh_last = swap_last;                                  \
 809         if ((swap_first = (head1)->tqh_first) != NULL)                  \
 810                 swap_first->field.tqe_prev = &(head1)->tqh_first;       \
 811         else                                                            \
 812                 (head1)->tqh_last = &(head1)->tqh_first;                \
 813         if ((swap_first = (head2)->tqh_first) != NULL)                  \
 814                 swap_first->field.tqe_prev = &(head2)->tqh_first;       \
 815         else                                                            \
 816                 (head2)->tqh_last = &(head2)->tqh_first;                \
 817 } while (0)
 818
 819 #endif /* !_SYS_QUEUE_H_ */