sys/sys/queue.h

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1991, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  32  * $FreeBSD$
  33  */
  34
  35 #ifndef _SYS_QUEUE_H_
  36 #define _SYS_QUEUE_H_
  37
  38 #include <sys/cdefs.h>
  39
  40 /*
  41  * This file defines four types of data structures: singly-linked lists,
  42  * singly-linked tail queues, lists and tail queues.
  43  *
  44  * A singly-linked list is headed by a single forward pointer. The elements
  45  * are singly linked for minimum space and pointer manipulation overhead at
  46  * the expense of O(n) removal for arbitrary elements. New elements can be
  47  * added to the list after an existing element or at the head of the list.
  48  * Elements being removed from the head of the list should use the explicit
  49  * macro for this purpose for optimum efficiency. A singly-linked list may
  50  * only be traversed in the forward direction.  Singly-linked lists are ideal
  51  * for applications with large datasets and few or no removals or for
  52  * implementing a LIFO queue.
  53  *
  54  * A singly-linked tail queue is headed by a pair of pointers, one to the
  55  * head of the list and the other to the tail of the list. The elements are
  56  * singly linked for minimum space and pointer manipulation overhead at the
  57  * expense of O(n) removal for arbitrary elements. New elements can be added
  58  * to the list after an existing element, at the head of the list, or at the
  59  * end of the list. Elements being removed from the head of the tail queue
  60  * should use the explicit macro for this purpose for optimum efficiency.
  61  * A singly-linked tail queue may only be traversed in the forward direction.
  62  * Singly-linked tail queues are ideal for applications with large datasets
  63  * and few or no removals or for implementing a FIFO queue.
  64  *
  65  * A list is headed by a single forward pointer (or an array of forward
  66  * pointers for a hash table header). The elements are doubly linked
  67  * so that an arbitrary element can be removed without a need to
  68  * traverse the list. New elements can be added to the list before
  69  * or after an existing element or at the head of the list. A list
  70  * may be traversed in either direction.
  71  *
  72  * A tail queue is headed by a pair of pointers, one to the head of the
  73  * list and the other to the tail of the list. The elements are doubly
  74  * linked so that an arbitrary element can be removed without a need to
  75  * traverse the list. New elements can be added to the list before or
  76  * after an existing element, at the head of the list, or at the end of
  77  * the list. A tail queue may be traversed in either direction.
  78  *
  79  * For details on the use of these macros, see the queue(3) manual page.
  80  *
  81  * Below is a summary of implemented functions where:
  82  *  +  means the macro is available
  83  *  -  means the macro is not available
  84  *  s  means the macro is available but is slow (runs in O(n) time)
  85  *
  86  *                              SLIST   LIST    STAILQ  TAILQ
  87  * _HEAD                        +       +       +       +
  88  * _CLASS_HEAD                  +       +       +       +
  89  * _HEAD_INITIALIZER            +       +       +       +
  90  * _ENTRY                       +       +       +       +
  91  * _CLASS_ENTRY                 +       +       +       +
  92  * _INIT                        +       +       +       +
  93  * _EMPTY                       +       +       +       +
  94  * _END                         +       +       +       +
  95  * _FIRST                       +       +       +       +
  96  * _NEXT                        +       +       +       +
  97  * _PREV                        -       +       -       +
  98  * _LAST                        -       -       +       +
  99  * _LAST_FAST                   -       -       -       +
 100  * _FOREACH                     +       +       +       +
 101  * _FOREACH_FROM                +       +       +       +
 102  * _FOREACH_SAFE                +       +       +       +
 103  * _FOREACH_FROM_SAFE           +       +       +       +
 104  * _FOREACH_REVERSE             -       -       -       +
 105  * _FOREACH_REVERSE_FROM        -       -       -       +
 106  * _FOREACH_REVERSE_SAFE        -       -       -       +
 107  * _FOREACH_REVERSE_FROM_SAFE   -       -       -       +
 108  * _INSERT_HEAD                 +       +       +       +
 109  * _INSERT_BEFORE               -       +       -       +
 110  * _INSERT_AFTER                +       +       +       +
 111  * _INSERT_TAIL                 -       -       +       +
 112  * _CONCAT                      s       s       +       +
 113  * _REMOVE_AFTER                +       -       +       -
 114  * _REMOVE_HEAD                 +       -       +       -
 115  * _REMOVE                      s       +       s       +
 116  * _SWAP                        +       +       +       +
 117  *
 118  */
 119 #ifdef QUEUE_MACRO_DEBUG
 120 #warn Use QUEUE_MACRO_DEBUG_TRACE and/or QUEUE_MACRO_DEBUG_TRASH
 121 #define QUEUE_MACRO_DEBUG_TRACE
 122 #define QUEUE_MACRO_DEBUG_TRASH
 123 #endif
 124
 125 #ifdef QUEUE_MACRO_DEBUG_TRACE
 126 /* Store the last 2 places the queue element or head was altered */
 127 struct qm_trace {
 128         unsigned long    lastline;
 129         unsigned long    prevline;
 130         const char      *lastfile;
 131         const char      *prevfile;
 132 };
 133
 134 #define TRACEBUF        struct qm_trace trace;
 135 #define TRACEBUF_INITIALIZER    { __LINE__, 0, __FILE__, NULL } ,
 136
 137 #define QMD_TRACE_HEAD(head) do {                                       \
 138         (head)->trace.prevline = (head)->trace.lastline;                \
 139         (head)->trace.prevfile = (head)->trace.lastfile;                \
 140         (head)->trace.lastline = __LINE__;                              \
 141         (head)->trace.lastfile = __FILE__;                              \
 142 } while (0)
 143
 144 #define QMD_TRACE_ELEM(elem) do {                                       \
 145         (elem)->trace.prevline = (elem)->trace.lastline;                \
 146         (elem)->trace.prevfile = (elem)->trace.lastfile;                \
 147         (elem)->trace.lastline = __LINE__;                              \
 148         (elem)->trace.lastfile = __FILE__;                              \
 149 } while (0)
 150
 151 #else   /* !QUEUE_MACRO_DEBUG_TRACE */
 152 #define QMD_TRACE_ELEM(elem)
 153 #define QMD_TRACE_HEAD(head)
 154 #define TRACEBUF
 155 #define TRACEBUF_INITIALIZER
 156 #endif  /* QUEUE_MACRO_DEBUG_TRACE */
 157
 158 #ifdef QUEUE_MACRO_DEBUG_TRASH
 159 #define QMD_SAVELINK(name, link)        void **name = (void *)&(link)
 160 #define TRASHIT(x)              do {(x) = (void *)-1;} while (0)
 161 #define QMD_IS_TRASHED(x)       ((x) == (void *)(intptr_t)-1)
 162 #else   /* !QUEUE_MACRO_DEBUG_TRASH */
 163 #define QMD_SAVELINK(name, link)
 164 #define TRASHIT(x)
 165 #define QMD_IS_TRASHED(x)       0
 166 #endif  /* 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 #define SLIST_END(head)         NULL
 310
 311 /*
 312  * Singly-linked Tail queue declarations.
 313  */
 314 #define STAILQ_HEAD(name, type)                                         \
 315 struct name {                                                           \
 316         struct type *stqh_first;/* first element */                     \
 317         struct type **stqh_last;/* addr of last next element */         \
 318 }
 319
 320 #define STAILQ_CLASS_HEAD(name, type)                                   \
 321 struct name {                                                           \
 322         class type *stqh_first; /* first element */                     \
 323         class type **stqh_last; /* addr of last next element */         \
 324 }
 325
 326 #define STAILQ_HEAD_INITIALIZER(head)                                   \
 327         { NULL, &(head).stqh_first }
 328
 329 #define STAILQ_ENTRY(type)                                              \
 330 struct {                                                                \
 331         struct type *stqe_next; /* next element */                      \
 332 }
 333
 334 #define STAILQ_CLASS_ENTRY(type)                                        \
 335 struct {                                                                \
 336         class type *stqe_next;  /* next element */                      \
 337 }
 338
 339 /*
 340  * Singly-linked Tail queue functions.
 341  */
 342 #define STAILQ_CONCAT(head1, head2) do {                                \
 343         if (!STAILQ_EMPTY((head2))) {                                   \
 344                 *(head1)->stqh_last = (head2)->stqh_first;              \
 345                 (head1)->stqh_last = (head2)->stqh_last;                \
 346                 STAILQ_INIT((head2));                                   \
 347         }                                                               \
 348 } while (0)
 349
 350 #define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
 351
 352 #define STAILQ_FIRST(head)      ((head)->stqh_first)
 353
 354 #define STAILQ_FOREACH(var, head, field)                                \
 355         for((var) = STAILQ_FIRST((head));                               \
 356            (var);                                                       \
 357            (var) = STAILQ_NEXT((var), field))
 358
 359 #define STAILQ_FOREACH_FROM(var, head, field)                           \
 360         for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));            \
 361            (var);                                                       \
 362            (var) = STAILQ_NEXT((var), field))
 363
 364 #define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
 365         for ((var) = STAILQ_FIRST((head));                              \
 366             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 367             (var) = (tvar))
 368
 369 #define STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)                \
 370         for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));            \
 371             (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
 372             (var) = (tvar))
 373
 374 #define STAILQ_INIT(head) do {                                          \
 375         STAILQ_FIRST((head)) = NULL;                                    \
 376         (head)->stqh_last = &STAILQ_FIRST((head));                      \
 377 } while (0)
 378
 379 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
 380         if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
 381                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 382         STAILQ_NEXT((tqelm), field) = (elm);                            \
 383 } while (0)
 384
 385 #define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
 386         if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
 387                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 388         STAILQ_FIRST((head)) = (elm);                                   \
 389 } while (0)
 390
 391 #define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
 392         STAILQ_NEXT((elm), field) = NULL;                               \
 393         *(head)->stqh_last = (elm);                                     \
 394         (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
 395 } while (0)
 396
 397 #define STAILQ_LAST(head, type, field)                          \
 398         (STAILQ_EMPTY((head)) ? NULL :                          \
 399             __containerof((head)->stqh_last,                    \
 400             QUEUE_TYPEOF(type), field.stqe_next))
 401
 402 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
 403
 404 #define STAILQ_REMOVE(head, elm, type, field) do {                      \
 405         QMD_SAVELINK(oldnext, (elm)->field.stqe_next);                  \
 406         if (STAILQ_FIRST((head)) == (elm)) {                            \
 407                 STAILQ_REMOVE_HEAD((head), field);                      \
 408         }                                                               \
 409         else {                                                          \
 410                 QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head);        \
 411                 while (STAILQ_NEXT(curelm, field) != (elm))             \
 412                         curelm = STAILQ_NEXT(curelm, field);            \
 413                 STAILQ_REMOVE_AFTER(head, curelm, field);               \
 414         }                                                               \
 415         TRASHIT(*oldnext);                                              \
 416 } while (0)
 417
 418 #define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
 419         if ((STAILQ_NEXT(elm, field) =                                  \
 420              STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
 421                 (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
 422 } while (0)
 423
 424 #define STAILQ_REMOVE_HEAD(head, field) do {                            \
 425         if ((STAILQ_FIRST((head)) =                                     \
 426              STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
 427                 (head)->stqh_last = &STAILQ_FIRST((head));              \
 428 } while (0)
 429
 430 #define STAILQ_SWAP(head1, head2, type) do {                            \
 431         QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1);           \
 432         QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last;            \
 433         STAILQ_FIRST(head1) = STAILQ_FIRST(head2);                      \
 434         (head1)->stqh_last = (head2)->stqh_last;                        \
 435         STAILQ_FIRST(head2) = swap_first;                               \
 436         (head2)->stqh_last = swap_last;                                 \
 437         if (STAILQ_EMPTY(head1))                                        \
 438                 (head1)->stqh_last = &STAILQ_FIRST(head1);              \
 439         if (STAILQ_EMPTY(head2))                                        \
 440                 (head2)->stqh_last = &STAILQ_FIRST(head2);              \
 441 } while (0)
 442
 443 #define STAILQ_END(head)        NULL
 444
 445
 446 /*
 447  * List declarations.
 448  */
 449 #define LIST_HEAD(name, type)                                           \
 450 struct name {                                                           \
 451         struct type *lh_first;  /* first element */                     \
 452 }
 453
 454 #define LIST_CLASS_HEAD(name, type)                                     \
 455 struct name {                                                           \
 456         class type *lh_first;   /* first element */                     \
 457 }
 458
 459 #define LIST_HEAD_INITIALIZER(head)                                     \
 460         { NULL }
 461
 462 #define LIST_ENTRY(type)                                                \
 463 struct {                                                                \
 464         struct type *le_next;   /* next element */                      \
 465         struct type **le_prev;  /* address of previous next element */  \
 466 }
 467
 468 #define LIST_CLASS_ENTRY(type)                                          \
 469 struct {                                                                \
 470         class type *le_next;    /* next element */                      \
 471         class type **le_prev;   /* address of previous next element */  \
 472 }
 473
 474 /*
 475  * List functions.
 476  */
 477
 478 #if (defined(_KERNEL) && defined(INVARIANTS))
 479 /*
 480  * QMD_LIST_CHECK_HEAD(LIST_HEAD *head, LIST_ENTRY NAME)
 481  *
 482  * If the list is non-empty, validates that the first element of the list
 483  * points back at 'head.'
 484  */
 485 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 486         if (LIST_FIRST((head)) != NULL &&                               \
 487             LIST_FIRST((head))->field.le_prev !=                        \
 488              &LIST_FIRST((head)))                                       \
 489                 panic("Bad list head %p first->prev != head", (head));  \
 490 } while (0)
 491
 492 /*
 493  * QMD_LIST_CHECK_NEXT(TYPE *elm, LIST_ENTRY NAME)
 494  *
 495  * If an element follows 'elm' in the list, validates that the next element
 496  * points back at 'elm.'
 497  */
 498 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 499         if (LIST_NEXT((elm), field) != NULL &&                          \
 500             LIST_NEXT((elm), field)->field.le_prev !=                   \
 501              &((elm)->field.le_next))                                   \
 502                 panic("Bad link elm %p next->prev != elm", (elm));      \
 503 } while (0)
 504
 505 /*
 506  * QMD_LIST_CHECK_PREV(TYPE *elm, LIST_ENTRY NAME)
 507  *
 508  * Validates that the previous element (or head of the list) points to 'elm.'
 509  */
 510 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 511         if (*(elm)->field.le_prev != (elm))                             \
 512                 panic("Bad link elm %p prev->next != elm", (elm));      \
 513 } while (0)
 514 #else
 515 #define QMD_LIST_CHECK_HEAD(head, field)
 516 #define QMD_LIST_CHECK_NEXT(elm, field)
 517 #define QMD_LIST_CHECK_PREV(elm, field)
 518 #endif /* (_KERNEL && INVARIANTS) */
 519
 520 #define LIST_CONCAT(head1, head2, type, field) do {                           \
 521         QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1);                       \
 522         if (curelm == NULL) {                                                 \
 523                 if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) {        \
 524                         LIST_FIRST(head2)->field.le_prev =                    \
 525                             &LIST_FIRST((head1));                             \
 526                         LIST_INIT(head2);                                     \
 527                 }                                                             \
 528         } else if (LIST_FIRST(head2) != NULL) {                               \
 529                 while (LIST_NEXT(curelm, field) != NULL)                      \
 530                         curelm = LIST_NEXT(curelm, field);                    \
 531                 LIST_NEXT(curelm, field) = LIST_FIRST(head2);                 \
 532                 LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
 533                 LIST_INIT(head2);                                             \
 534         }                                                                     \
 535 } while (0)
 536
 537 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 538
 539 #define LIST_FIRST(head)        ((head)->lh_first)
 540
 541 #define LIST_FOREACH(var, head, field)                                  \
 542         for ((var) = LIST_FIRST((head));                                \
 543             (var);                                                      \
 544             (var) = LIST_NEXT((var), field))
 545
 546 #define LIST_FOREACH_FROM(var, head, field)                             \
 547         for ((var) = ((var) ? (var) : LIST_FIRST((head)));              \
 548             (var);                                                      \
 549             (var) = LIST_NEXT((var), field))
 550
 551 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 552         for ((var) = LIST_FIRST((head));                                \
 553             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 554             (var) = (tvar))
 555
 556 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar)                  \
 557         for ((var) = ((var) ? (var) : LIST_FIRST((head)));              \
 558             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 559             (var) = (tvar))
 560
 561 #define LIST_INIT(head) do {                                            \
 562         LIST_FIRST((head)) = NULL;                                      \
 563 } while (0)
 564
 565 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 566         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 567         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 568                 LIST_NEXT((listelm), field)->field.le_prev =            \
 569                     &LIST_NEXT((elm), field);                           \
 570         LIST_NEXT((listelm), field) = (elm);                            \
 571         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 572 } while (0)
 573
 574 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 575         QMD_LIST_CHECK_PREV(listelm, field);                            \
 576         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 577         LIST_NEXT((elm), field) = (listelm);                            \
 578         *(listelm)->field.le_prev = (elm);                              \
 579         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 580 } while (0)
 581
 582 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 583         QMD_LIST_CHECK_HEAD((head), field);                             \
 584         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 585                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 586         LIST_FIRST((head)) = (elm);                                     \
 587         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 588 } while (0)
 589
 590 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 591
 592 #define LIST_PREV(elm, head, type, field)                       \
 593         ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :   \
 594             __containerof((elm)->field.le_prev,                 \
 595             QUEUE_TYPEOF(type), field.le_next))
 596
 597 #define LIST_REMOVE(elm, field) do {                                    \
 598         QMD_SAVELINK(oldnext, (elm)->field.le_next);                    \
 599         QMD_SAVELINK(oldprev, (elm)->field.le_prev);                    \
 600         QMD_LIST_CHECK_NEXT(elm, field);                                \
 601         QMD_LIST_CHECK_PREV(elm, field);                                \
 602         if (LIST_NEXT((elm), field) != NULL)                            \
 603                 LIST_NEXT((elm), field)->field.le_prev =                \
 604                     (elm)->field.le_prev;                               \
 605         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 606         TRASHIT(*oldnext);                                              \
 607         TRASHIT(*oldprev);                                              \
 608 } while (0)
 609
 610 #define LIST_SWAP(head1, head2, type, field) do {                       \
 611         QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1);               \
 612         LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
 613         LIST_FIRST((head2)) = swap_tmp;                                 \
 614         if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
 615                 swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
 616         if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
 617                 swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
 618 } while (0)
 619
 620 #define LIST_END(head)  NULL
 621
 622 /*
 623  * Tail queue declarations.
 624  */
 625 #define TAILQ_HEAD(name, type)                                          \
 626 struct name {                                                           \
 627         struct type *tqh_first; /* first element */                     \
 628         struct type **tqh_last; /* addr of last next element */         \
 629         TRACEBUF                                                        \
 630 }
 631
 632 #define TAILQ_CLASS_HEAD(name, type)                                    \
 633 struct name {                                                           \
 634         class type *tqh_first;  /* first element */                     \
 635         class type **tqh_last;  /* addr of last next element */         \
 636         TRACEBUF                                                        \
 637 }
 638
 639 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 640         { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
 641
 642 #define TAILQ_ENTRY(type)                                               \
 643 struct {                                                                \
 644         struct type *tqe_next;  /* next element */                      \
 645         struct type **tqe_prev; /* address of previous next element */  \
 646         TRACEBUF                                                        \
 647 }
 648
 649 #define TAILQ_CLASS_ENTRY(type)                                         \
 650 struct {                                                                \
 651         class type *tqe_next;   /* next element */                      \
 652         class type **tqe_prev;  /* address of previous next element */  \
 653         TRACEBUF                                                        \
 654 }
 655
 656 /*
 657  * Tail queue functions.
 658  */
 659 #if (defined(_KERNEL) && defined(INVARIANTS))
 660 /*
 661  * QMD_TAILQ_CHECK_HEAD(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
 662  *
 663  * If the tailq is non-empty, validates that the first element of the tailq
 664  * points back at 'head.'
 665  */
 666 #define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
 667         if (!TAILQ_EMPTY(head) &&                                       \
 668             TAILQ_FIRST((head))->field.tqe_prev !=                      \
 669              &TAILQ_FIRST((head)))                                      \
 670                 panic("Bad tailq head %p first->prev != head", (head)); \
 671 } while (0)
 672
 673 /*
 674  * QMD_TAILQ_CHECK_TAIL(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
 675  *
 676  * Validates that the tail of the tailq is a pointer to pointer to NULL.
 677  */
 678 #define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
 679         if (*(head)->tqh_last != NULL)                                  \
 680                 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
 681 } while (0)
 682
 683 /*
 684  * QMD_TAILQ_CHECK_NEXT(TYPE *elm, TAILQ_ENTRY NAME)
 685  *
 686  * If an element follows 'elm' in the tailq, validates that the next element
 687  * points back at 'elm.'
 688  */
 689 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
 690         if (TAILQ_NEXT((elm), field) != NULL &&                         \
 691             TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
 692              &((elm)->field.tqe_next))                                  \
 693                 panic("Bad link elm %p next->prev != elm", (elm));      \
 694 } while (0)
 695
 696 /*
 697  * QMD_TAILQ_CHECK_PREV(TYPE *elm, TAILQ_ENTRY NAME)
 698  *
 699  * Validates that the previous element (or head of the tailq) points to 'elm.'
 700  */
 701 #define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
 702         if (*(elm)->field.tqe_prev != (elm))                            \
 703                 panic("Bad link elm %p prev->next != elm", (elm));      \
 704 } while (0)
 705 #else
 706 #define QMD_TAILQ_CHECK_HEAD(head, field)
 707 #define QMD_TAILQ_CHECK_TAIL(head, headname)
 708 #define QMD_TAILQ_CHECK_NEXT(elm, field)
 709 #define QMD_TAILQ_CHECK_PREV(elm, field)
 710 #endif /* (_KERNEL && INVARIANTS) */
 711
 712 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 713         if (!TAILQ_EMPTY(head2)) {                                      \
 714                 *(head1)->tqh_last = (head2)->tqh_first;                \
 715                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 716                 (head1)->tqh_last = (head2)->tqh_last;                  \
 717                 TAILQ_INIT((head2));                                    \
 718                 QMD_TRACE_HEAD(head1);                                  \
 719                 QMD_TRACE_HEAD(head2);                                  \
 720         }                                                               \
 721 } while (0)
 722
 723 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 724
 725 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 726
 727 #define TAILQ_FOREACH(var, head, field)                                 \
 728         for ((var) = TAILQ_FIRST((head));                               \
 729             (var);                                                      \
 730             (var) = TAILQ_NEXT((var), field))
 731
 732 #define TAILQ_FOREACH_FROM(var, head, field)                            \
 733         for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));             \
 734             (var);                                                      \
 735             (var) = TAILQ_NEXT((var), field))
 736
 737 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 738         for ((var) = TAILQ_FIRST((head));                               \
 739             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 740             (var) = (tvar))
 741
 742 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)                 \
 743         for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));             \
 744             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 745             (var) = (tvar))
 746
 747 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 748         for ((var) = TAILQ_LAST((head), headname);                      \
 749             (var);                                                      \
 750             (var) = TAILQ_PREV((var), headname, field))
 751
 752 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field)          \
 753         for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
 754             (var);                                                      \
 755             (var) = TAILQ_PREV((var), headname, field))
 756
 757 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 758         for ((var) = TAILQ_LAST((head), headname);                      \
 759             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 760             (var) = (tvar))
 761
 762 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
 763         for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
 764             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 765             (var) = (tvar))
 766
 767 #define TAILQ_INIT(head) do {                                           \
 768         TAILQ_FIRST((head)) = NULL;                                     \
 769         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 770         QMD_TRACE_HEAD(head);                                           \
 771 } while (0)
 772
 773 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 774         QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
 775         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 776                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 777                     &TAILQ_NEXT((elm), field);                          \
 778         else {                                                          \
 779                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 780                 QMD_TRACE_HEAD(head);                                   \
 781         }                                                               \
 782         TAILQ_NEXT((listelm), field) = (elm);                           \
 783         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 784         QMD_TRACE_ELEM(&(elm)->field);                                  \
 785         QMD_TRACE_ELEM(&(listelm)->field);                              \
 786 } while (0)
 787
 788 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 789         QMD_TAILQ_CHECK_PREV(listelm, field);                           \
 790         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 791         TAILQ_NEXT((elm), field) = (listelm);                           \
 792         *(listelm)->field.tqe_prev = (elm);                             \
 793         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 794         QMD_TRACE_ELEM(&(elm)->field);                                  \
 795         QMD_TRACE_ELEM(&(listelm)->field);                              \
 796 } while (0)
 797
 798 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 799         QMD_TAILQ_CHECK_HEAD(head, field);                              \
 800         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 801                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 802                     &TAILQ_NEXT((elm), field);                          \
 803         else                                                            \
 804                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 805         TAILQ_FIRST((head)) = (elm);                                    \
 806         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 807         QMD_TRACE_HEAD(head);                                           \
 808         QMD_TRACE_ELEM(&(elm)->field);                                  \
 809 } while (0)
 810
 811 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 812         QMD_TAILQ_CHECK_TAIL(head, field);                              \
 813         TAILQ_NEXT((elm), field) = NULL;                                \
 814         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 815         *(head)->tqh_last = (elm);                                      \
 816         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 817         QMD_TRACE_HEAD(head);                                           \
 818         QMD_TRACE_ELEM(&(elm)->field);                                  \
 819 } while (0)
 820
 821 #define TAILQ_LAST(head, headname)                                      \
 822         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 823
 824 /*
 825  * The FAST function is fast in that it causes no data access other
 826  * then the access to the head. The standard LAST function above
 827  * will cause a data access of both the element you want and
 828  * the previous element. FAST is very useful for instances when
 829  * you may want to prefetch the last data element.
 830  */
 831 #define TAILQ_LAST_FAST(head, type, field)                      \
 832     (TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last, QUEUE_TYPEOF(type), field.tqe_next))
 833
 834 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 835
 836 #define TAILQ_PREV(elm, headname, field)                                \
 837         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 838
 839 #define TAILQ_PREV_FAST(elm, head, type, field)                         \
 840     ((elm)->field.tqe_prev == &(head)->tqh_first ? NULL :               \
 841      __containerof((elm)->field.tqe_prev, QUEUE_TYPEOF(type), field.tqe_next))
 842
 843 #define TAILQ_REMOVE(head, elm, field) do {                             \
 844         QMD_SAVELINK(oldnext, (elm)->field.tqe_next);                   \
 845         QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);                   \
 846         QMD_TAILQ_CHECK_NEXT(elm, field);                               \
 847         QMD_TAILQ_CHECK_PREV(elm, field);                               \
 848         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 849                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 850                     (elm)->field.tqe_prev;                              \
 851         else {                                                          \
 852                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 853                 QMD_TRACE_HEAD(head);                                   \
 854         }                                                               \
 855         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 856         TRASHIT(*oldnext);                                              \
 857         TRASHIT(*oldprev);                                              \
 858         QMD_TRACE_ELEM(&(elm)->field);                                  \
 859 } while (0)
 860
 861 #define TAILQ_SWAP(head1, head2, type, field) do {                      \
 862         QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first;            \
 863         QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last;             \
 864         (head1)->tqh_first = (head2)->tqh_first;                        \
 865         (head1)->tqh_last = (head2)->tqh_last;                          \
 866         (head2)->tqh_first = swap_first;                                \
 867         (head2)->tqh_last = swap_last;                                  \
 868         if ((swap_first = (head1)->tqh_first) != NULL)                  \
 869                 swap_first->field.tqe_prev = &(head1)->tqh_first;       \
 870         else                                                            \
 871                 (head1)->tqh_last = &(head1)->tqh_first;                \
 872         if ((swap_first = (head2)->tqh_first) != NULL)                  \
 873                 swap_first->field.tqe_prev = &(head2)->tqh_first;       \
 874         else                                                            \
 875                 (head2)->tqh_last = &(head2)->tqh_first;                \
 876 } while (0)
 877
 878 #define TAILQ_END(head)         NULL
 879
 880 #endif /* !_SYS_QUEUE_H_ */