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  * _FIRST                       +       +       +       +
  95  * _NEXT                        +       +       +       +
  96  * _PREV                        -       +       -       +
  97  * _LAST                        -       -       +       +
  98  * _FOREACH                     +       +       +       +
  99  * _FOREACH_FROM                +       +       +       +
 100  * _FOREACH_SAFE                +       +       +       +
 101  * _FOREACH_FROM_SAFE           +       +       +       +
 102  * _FOREACH_REVERSE             -       -       -       +
 103  * _FOREACH_REVERSE_FROM        -       -       -       +
 104  * _FOREACH_REVERSE_SAFE        -       -       -       +
 105  * _FOREACH_REVERSE_FROM_SAFE   -       -       -       +
 106  * _INSERT_HEAD                 +       +       +       +
 107  * _INSERT_BEFORE               -       +       -       +
 108  * _INSERT_AFTER                +       +       +       +
 109  * _INSERT_TAIL                 -       -       +       +
 110  * _CONCAT                      s       s       +       +
 111  * _REMOVE_AFTER                +       -       +       -
 112  * _REMOVE_HEAD                 +       -       +       -
 113  * _REMOVE                      s       +       s       +
 114  * _SWAP                        +       +       +       +
 115  *
 116  */
 117 #ifdef QUEUE_MACRO_DEBUG
 118 #warn Use QUEUE_MACRO_DEBUG_TRACE and/or QUEUE_MACRO_DEBUG_TRASH
 119 #define QUEUE_MACRO_DEBUG_TRACE
 120 #define QUEUE_MACRO_DEBUG_TRASH
 121 #endif
 122
 123 #ifdef QUEUE_MACRO_DEBUG_TRACE
 124 /* Store the last 2 places the queue element or head was altered */
 125 struct qm_trace {
 126         unsigned long    lastline;
 127         unsigned long    prevline;
 128         const char      *lastfile;
 129         const char      *prevfile;
 130 };
 131
 132 #define TRACEBUF        struct qm_trace trace;
 133 #define TRACEBUF_INITIALIZER    { __LINE__, 0, __FILE__, NULL } ,
 134
 135 #define QMD_TRACE_HEAD(head) do {                                       \
 136         (head)->trace.prevline = (head)->trace.lastline;                \
 137         (head)->trace.prevfile = (head)->trace.lastfile;                \
 138         (head)->trace.lastline = __LINE__;                              \
 139         (head)->trace.lastfile = __FILE__;                              \
 140 } while (0)
 141
 142 #define QMD_TRACE_ELEM(elem) do {                                       \
 143         (elem)->trace.prevline = (elem)->trace.lastline;                \
 144         (elem)->trace.prevfile = (elem)->trace.lastfile;                \
 145         (elem)->trace.lastline = __LINE__;                              \
 146         (elem)->trace.lastfile = __FILE__;                              \
 147 } while (0)
 148
 149 #else   /* !QUEUE_MACRO_DEBUG_TRACE */
 150 #define QMD_TRACE_ELEM(elem)
 151 #define QMD_TRACE_HEAD(head)
 152 #define TRACEBUF
 153 #define TRACEBUF_INITIALIZER
 154 #endif  /* QUEUE_MACRO_DEBUG_TRACE */
 155
 156 #ifdef QUEUE_MACRO_DEBUG_TRASH
 157 #define TRASHIT(x)              do {(x) = (void *)-1;} while (0)
 158 #define QMD_IS_TRASHED(x)       ((x) == (void *)(intptr_t)-1)
 159 #else   /* !QUEUE_MACRO_DEBUG_TRASH */
 160 #define TRASHIT(x)
 161 #define QMD_IS_TRASHED(x)       0
 162 #endif  /* QUEUE_MACRO_DEBUG_TRASH */
 163
 164 #if defined(QUEUE_MACRO_DEBUG_TRACE) || defined(QUEUE_MACRO_DEBUG_TRASH)
 165 #define QMD_SAVELINK(name, link)        void **name = (void *)&(link)
 166 #else   /* !QUEUE_MACRO_DEBUG_TRACE && !QUEUE_MACRO_DEBUG_TRASH */
 167 #define QMD_SAVELINK(name, link)
 168 #endif  /* QUEUE_MACRO_DEBUG_TRACE || QUEUE_MACRO_DEBUG_TRASH */
 169
 170 #ifdef __cplusplus
 171 /*
 172  * In C++ there can be structure lists and class lists:
 173  */
 174 #define QUEUE_TYPEOF(type) type
 175 #else
 176 #define QUEUE_TYPEOF(type) struct type
 177 #endif
 178
 179 /*
 180  * Singly-linked List declarations.
 181  */
 182 #define SLIST_HEAD(name, type)                                          \
 183 struct name {                                                           \
 184         struct type *slh_first; /* first element */                     \
 185 }
 186
 187 #define SLIST_CLASS_HEAD(name, type)                                    \
 188 struct name {                                                           \
 189         class type *slh_first;  /* first element */                     \
 190 }
 191
 192 #define SLIST_HEAD_INITIALIZER(head)                                    \
 193         { NULL }
 194
 195 #define SLIST_ENTRY(type)                                               \
 196 struct {                                                                \
 197         struct type *sle_next;  /* next element */                      \
 198 }
 199
 200 #define SLIST_CLASS_ENTRY(type)                                         \
 201 struct {                                                                \
 202         class type *sle_next;           /* next element */              \
 203 }
 204
 205 /*
 206  * Singly-linked List functions.
 207  */
 208 #if (defined(_KERNEL) && defined(INVARIANTS))
 209 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm) do {                        \
 210         if (*(prevp) != (elm))                                          \
 211                 panic("Bad prevptr *(%p) == %p != %p",                  \
 212                     (prevp), *(prevp), (elm));                          \
 213 } while (0)
 214 #else
 215 #define QMD_SLIST_CHECK_PREVPTR(prevp, elm)
 216 #endif
 217
 218 #define SLIST_CONCAT(head1, head2, type, field) do {                    \
 219         QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1);                \
 220         if (curelm == NULL) {                                           \
 221                 if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL)  \
 222                         SLIST_INIT(head2);                              \
 223         } else if (SLIST_FIRST(head2) != NULL) {                        \
 224                 while (SLIST_NEXT(curelm, field) != NULL)               \
 225                         curelm = SLIST_NEXT(curelm, field);             \
 226                 SLIST_NEXT(curelm, field) = SLIST_FIRST(head2);         \
 227                 SLIST_INIT(head2);                                      \
 228         }                                                               \
 229 } while (0)
 230
 231 #define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
 232
 233 #define SLIST_FIRST(head)       ((head)->slh_first)
 234
 235 #define SLIST_FOREACH(var, head, field)                                 \
 236         for ((var) = SLIST_FIRST((head));                               \
 237             (var);                                                      \
 238             (var) = SLIST_NEXT((var), field))
 239
 240 #define SLIST_FOREACH_FROM(var, head, field)                            \
 241         for ((var) = ((var) ? (var) : SLIST_FIRST((head)));             \
 242             (var);                                                      \
 243             (var) = SLIST_NEXT((var), field))
 244
 245 #define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 246         for ((var) = SLIST_FIRST((head));                               \
 247             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 248             (var) = (tvar))
 249
 250 #define SLIST_FOREACH_FROM_SAFE(var, head, field, tvar)                 \
 251         for ((var) = ((var) ? (var) : SLIST_FIRST((head)));             \
 252             (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
 253             (var) = (tvar))
 254
 255 #define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
 256         for ((varp) = &SLIST_FIRST((head));                             \
 257             ((var) = *(varp)) != NULL;                                  \
 258             (varp) = &SLIST_NEXT((var), field))
 259
 260 #define SLIST_INIT(head) do {                                           \
 261         SLIST_FIRST((head)) = NULL;                                     \
 262 } while (0)
 263
 264 #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 265         SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
 266         SLIST_NEXT((slistelm), field) = (elm);                          \
 267 } while (0)
 268
 269 #define SLIST_INSERT_HEAD(head, elm, field) do {                        \
 270         SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
 271         SLIST_FIRST((head)) = (elm);                                    \
 272 } while (0)
 273
 274 #define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 275
 276 #define SLIST_REMOVE(head, elm, type, field) do {                       \
 277         QMD_SAVELINK(oldnext, (elm)->field.sle_next);                   \
 278         if (SLIST_FIRST((head)) == (elm)) {                             \
 279                 SLIST_REMOVE_HEAD((head), field);                       \
 280         }                                                               \
 281         else {                                                          \
 282                 QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head);         \
 283                 while (SLIST_NEXT(curelm, field) != (elm))              \
 284                         curelm = SLIST_NEXT(curelm, field);             \
 285                 SLIST_REMOVE_AFTER(curelm, field);                      \
 286         }                                                               \
 287         TRASHIT(*oldnext);                                              \
 288 } while (0)
 289
 290 #define SLIST_REMOVE_AFTER(elm, field) do {                             \
 291         SLIST_NEXT(elm, field) =                                        \
 292             SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
 293 } while (0)
 294
 295 #define SLIST_REMOVE_HEAD(head, field) do {                             \
 296         SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
 297 } while (0)
 298
 299 #define SLIST_REMOVE_PREVPTR(prevp, elm, field) do {                    \
 300         QMD_SLIST_CHECK_PREVPTR(prevp, elm);                            \
 301         *(prevp) = SLIST_NEXT(elm, field);                              \
 302         TRASHIT((elm)->field.sle_next);                                 \
 303 } while (0)
 304
 305 #define SLIST_SWAP(head1, head2, type) do {                             \
 306         QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1);            \
 307         SLIST_FIRST(head1) = SLIST_FIRST(head2);                        \
 308         SLIST_FIRST(head2) = swap_first;                                \
 309 } while (0)
 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
 444 /*
 445  * List declarations.
 446  */
 447 #define LIST_HEAD(name, type)                                           \
 448 struct name {                                                           \
 449         struct type *lh_first;  /* first element */                     \
 450 }
 451
 452 #define LIST_CLASS_HEAD(name, type)                                     \
 453 struct name {                                                           \
 454         class type *lh_first;   /* first element */                     \
 455 }
 456
 457 #define LIST_HEAD_INITIALIZER(head)                                     \
 458         { NULL }
 459
 460 #define LIST_ENTRY(type)                                                \
 461 struct {                                                                \
 462         struct type *le_next;   /* next element */                      \
 463         struct type **le_prev;  /* address of previous next element */  \
 464 }
 465
 466 #define LIST_CLASS_ENTRY(type)                                          \
 467 struct {                                                                \
 468         class type *le_next;    /* next element */                      \
 469         class type **le_prev;   /* address of previous next element */  \
 470 }
 471
 472 /*
 473  * List functions.
 474  */
 475
 476 #if (defined(_KERNEL) && defined(INVARIANTS))
 477 /*
 478  * QMD_LIST_CHECK_HEAD(LIST_HEAD *head, LIST_ENTRY NAME)
 479  *
 480  * If the list is non-empty, validates that the first element of the list
 481  * points back at 'head.'
 482  */
 483 #define QMD_LIST_CHECK_HEAD(head, field) do {                           \
 484         if (LIST_FIRST((head)) != NULL &&                               \
 485             LIST_FIRST((head))->field.le_prev !=                        \
 486              &LIST_FIRST((head)))                                       \
 487                 panic("Bad list head %p first->prev != head", (head));  \
 488 } while (0)
 489
 490 /*
 491  * QMD_LIST_CHECK_NEXT(TYPE *elm, LIST_ENTRY NAME)
 492  *
 493  * If an element follows 'elm' in the list, validates that the next element
 494  * points back at 'elm.'
 495  */
 496 #define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
 497         if (LIST_NEXT((elm), field) != NULL &&                          \
 498             LIST_NEXT((elm), field)->field.le_prev !=                   \
 499              &((elm)->field.le_next))                                   \
 500                 panic("Bad link elm %p next->prev != elm", (elm));      \
 501 } while (0)
 502
 503 /*
 504  * QMD_LIST_CHECK_PREV(TYPE *elm, LIST_ENTRY NAME)
 505  *
 506  * Validates that the previous element (or head of the list) points to 'elm.'
 507  */
 508 #define QMD_LIST_CHECK_PREV(elm, field) do {                            \
 509         if (*(elm)->field.le_prev != (elm))                             \
 510                 panic("Bad link elm %p prev->next != elm", (elm));      \
 511 } while (0)
 512 #else
 513 #define QMD_LIST_CHECK_HEAD(head, field)
 514 #define QMD_LIST_CHECK_NEXT(elm, field)
 515 #define QMD_LIST_CHECK_PREV(elm, field)
 516 #endif /* (_KERNEL && INVARIANTS) */
 517
 518 #define LIST_CONCAT(head1, head2, type, field) do {                           \
 519         QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1);                       \
 520         if (curelm == NULL) {                                                 \
 521                 if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) {        \
 522                         LIST_FIRST(head2)->field.le_prev =                    \
 523                             &LIST_FIRST((head1));                             \
 524                         LIST_INIT(head2);                                     \
 525                 }                                                             \
 526         } else if (LIST_FIRST(head2) != NULL) {                               \
 527                 while (LIST_NEXT(curelm, field) != NULL)                      \
 528                         curelm = LIST_NEXT(curelm, field);                    \
 529                 LIST_NEXT(curelm, field) = LIST_FIRST(head2);                 \
 530                 LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
 531                 LIST_INIT(head2);                                             \
 532         }                                                                     \
 533 } while (0)
 534
 535 #define LIST_EMPTY(head)        ((head)->lh_first == NULL)
 536
 537 #define LIST_FIRST(head)        ((head)->lh_first)
 538
 539 #define LIST_FOREACH(var, head, field)                                  \
 540         for ((var) = LIST_FIRST((head));                                \
 541             (var);                                                      \
 542             (var) = LIST_NEXT((var), field))
 543
 544 #define LIST_FOREACH_FROM(var, head, field)                             \
 545         for ((var) = ((var) ? (var) : LIST_FIRST((head)));              \
 546             (var);                                                      \
 547             (var) = LIST_NEXT((var), field))
 548
 549 #define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
 550         for ((var) = LIST_FIRST((head));                                \
 551             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 552             (var) = (tvar))
 553
 554 #define LIST_FOREACH_FROM_SAFE(var, head, field, tvar)                  \
 555         for ((var) = ((var) ? (var) : LIST_FIRST((head)));              \
 556             (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
 557             (var) = (tvar))
 558
 559 #define LIST_INIT(head) do {                                            \
 560         LIST_FIRST((head)) = NULL;                                      \
 561 } while (0)
 562
 563 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 564         QMD_LIST_CHECK_NEXT(listelm, field);                            \
 565         if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
 566                 LIST_NEXT((listelm), field)->field.le_prev =            \
 567                     &LIST_NEXT((elm), field);                           \
 568         LIST_NEXT((listelm), field) = (elm);                            \
 569         (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
 570 } while (0)
 571
 572 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 573         QMD_LIST_CHECK_PREV(listelm, field);                            \
 574         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 575         LIST_NEXT((elm), field) = (listelm);                            \
 576         *(listelm)->field.le_prev = (elm);                              \
 577         (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
 578 } while (0)
 579
 580 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 581         QMD_LIST_CHECK_HEAD((head), field);                             \
 582         if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
 583                 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
 584         LIST_FIRST((head)) = (elm);                                     \
 585         (elm)->field.le_prev = &LIST_FIRST((head));                     \
 586 } while (0)
 587
 588 #define LIST_NEXT(elm, field)   ((elm)->field.le_next)
 589
 590 #define LIST_PREV(elm, head, type, field)                       \
 591         ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :   \
 592             __containerof((elm)->field.le_prev,                 \
 593             QUEUE_TYPEOF(type), field.le_next))
 594
 595 #define LIST_REMOVE(elm, field) do {                                    \
 596         QMD_SAVELINK(oldnext, (elm)->field.le_next);                    \
 597         QMD_SAVELINK(oldprev, (elm)->field.le_prev);                    \
 598         QMD_LIST_CHECK_NEXT(elm, field);                                \
 599         QMD_LIST_CHECK_PREV(elm, field);                                \
 600         if (LIST_NEXT((elm), field) != NULL)                            \
 601                 LIST_NEXT((elm), field)->field.le_prev =                \
 602                     (elm)->field.le_prev;                               \
 603         *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
 604         TRASHIT(*oldnext);                                              \
 605         TRASHIT(*oldprev);                                              \
 606 } while (0)
 607
 608 #define LIST_SWAP(head1, head2, type, field) do {                       \
 609         QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1);               \
 610         LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
 611         LIST_FIRST((head2)) = swap_tmp;                                 \
 612         if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
 613                 swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
 614         if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
 615                 swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
 616 } while (0)
 617
 618 /*
 619  * Tail queue declarations.
 620  */
 621 #define TAILQ_HEAD(name, type)                                          \
 622 struct name {                                                           \
 623         struct type *tqh_first; /* first element */                     \
 624         struct type **tqh_last; /* addr of last next element */         \
 625         TRACEBUF                                                        \
 626 }
 627
 628 #define TAILQ_CLASS_HEAD(name, type)                                    \
 629 struct name {                                                           \
 630         class type *tqh_first;  /* first element */                     \
 631         class type **tqh_last;  /* addr of last next element */         \
 632         TRACEBUF                                                        \
 633 }
 634
 635 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 636         { NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
 637
 638 #define TAILQ_ENTRY(type)                                               \
 639 struct {                                                                \
 640         struct type *tqe_next;  /* next element */                      \
 641         struct type **tqe_prev; /* address of previous next element */  \
 642         TRACEBUF                                                        \
 643 }
 644
 645 #define TAILQ_CLASS_ENTRY(type)                                         \
 646 struct {                                                                \
 647         class type *tqe_next;   /* next element */                      \
 648         class type **tqe_prev;  /* address of previous next element */  \
 649         TRACEBUF                                                        \
 650 }
 651
 652 /*
 653  * Tail queue functions.
 654  */
 655 #if (defined(_KERNEL) && defined(INVARIANTS))
 656 /*
 657  * QMD_TAILQ_CHECK_HEAD(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
 658  *
 659  * If the tailq is non-empty, validates that the first element of the tailq
 660  * points back at 'head.'
 661  */
 662 #define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
 663         if (!TAILQ_EMPTY(head) &&                                       \
 664             TAILQ_FIRST((head))->field.tqe_prev !=                      \
 665              &TAILQ_FIRST((head)))                                      \
 666                 panic("Bad tailq head %p first->prev != head", (head)); \
 667 } while (0)
 668
 669 /*
 670  * QMD_TAILQ_CHECK_TAIL(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
 671  *
 672  * Validates that the tail of the tailq is a pointer to pointer to NULL.
 673  */
 674 #define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
 675         if (*(head)->tqh_last != NULL)                                  \
 676                 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
 677 } while (0)
 678
 679 /*
 680  * QMD_TAILQ_CHECK_NEXT(TYPE *elm, TAILQ_ENTRY NAME)
 681  *
 682  * If an element follows 'elm' in the tailq, validates that the next element
 683  * points back at 'elm.'
 684  */
 685 #define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
 686         if (TAILQ_NEXT((elm), field) != NULL &&                         \
 687             TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
 688              &((elm)->field.tqe_next))                                  \
 689                 panic("Bad link elm %p next->prev != elm", (elm));      \
 690 } while (0)
 691
 692 /*
 693  * QMD_TAILQ_CHECK_PREV(TYPE *elm, TAILQ_ENTRY NAME)
 694  *
 695  * Validates that the previous element (or head of the tailq) points to 'elm.'
 696  */
 697 #define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
 698         if (*(elm)->field.tqe_prev != (elm))                            \
 699                 panic("Bad link elm %p prev->next != elm", (elm));      \
 700 } while (0)
 701 #else
 702 #define QMD_TAILQ_CHECK_HEAD(head, field)
 703 #define QMD_TAILQ_CHECK_TAIL(head, headname)
 704 #define QMD_TAILQ_CHECK_NEXT(elm, field)
 705 #define QMD_TAILQ_CHECK_PREV(elm, field)
 706 #endif /* (_KERNEL && INVARIANTS) */
 707
 708 #define TAILQ_CONCAT(head1, head2, field) do {                          \
 709         if (!TAILQ_EMPTY(head2)) {                                      \
 710                 *(head1)->tqh_last = (head2)->tqh_first;                \
 711                 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
 712                 (head1)->tqh_last = (head2)->tqh_last;                  \
 713                 TAILQ_INIT((head2));                                    \
 714                 QMD_TRACE_HEAD(head1);                                  \
 715                 QMD_TRACE_HEAD(head2);                                  \
 716         }                                                               \
 717 } while (0)
 718
 719 #define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
 720
 721 #define TAILQ_FIRST(head)       ((head)->tqh_first)
 722
 723 #define TAILQ_FOREACH(var, head, field)                                 \
 724         for ((var) = TAILQ_FIRST((head));                               \
 725             (var);                                                      \
 726             (var) = TAILQ_NEXT((var), field))
 727
 728 #define TAILQ_FOREACH_FROM(var, head, field)                            \
 729         for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));             \
 730             (var);                                                      \
 731             (var) = TAILQ_NEXT((var), field))
 732
 733 #define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
 734         for ((var) = TAILQ_FIRST((head));                               \
 735             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 736             (var) = (tvar))
 737
 738 #define TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)                 \
 739         for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));             \
 740             (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
 741             (var) = (tvar))
 742
 743 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
 744         for ((var) = TAILQ_LAST((head), headname);                      \
 745             (var);                                                      \
 746             (var) = TAILQ_PREV((var), headname, field))
 747
 748 #define TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field)          \
 749         for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
 750             (var);                                                      \
 751             (var) = TAILQ_PREV((var), headname, field))
 752
 753 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
 754         for ((var) = TAILQ_LAST((head), headname);                      \
 755             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 756             (var) = (tvar))
 757
 758 #define TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
 759         for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));    \
 760             (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
 761             (var) = (tvar))
 762
 763 #define TAILQ_INIT(head) do {                                           \
 764         TAILQ_FIRST((head)) = NULL;                                     \
 765         (head)->tqh_last = &TAILQ_FIRST((head));                        \
 766         QMD_TRACE_HEAD(head);                                           \
 767 } while (0)
 768
 769 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 770         QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
 771         if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
 772                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 773                     &TAILQ_NEXT((elm), field);                          \
 774         else {                                                          \
 775                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 776                 QMD_TRACE_HEAD(head);                                   \
 777         }                                                               \
 778         TAILQ_NEXT((listelm), field) = (elm);                           \
 779         (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
 780         QMD_TRACE_ELEM(&(elm)->field);                                  \
 781         QMD_TRACE_ELEM(&(listelm)->field);                              \
 782 } while (0)
 783
 784 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 785         QMD_TAILQ_CHECK_PREV(listelm, field);                           \
 786         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 787         TAILQ_NEXT((elm), field) = (listelm);                           \
 788         *(listelm)->field.tqe_prev = (elm);                             \
 789         (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
 790         QMD_TRACE_ELEM(&(elm)->field);                                  \
 791         QMD_TRACE_ELEM(&(listelm)->field);                              \
 792 } while (0)
 793
 794 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 795         QMD_TAILQ_CHECK_HEAD(head, field);                              \
 796         if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
 797                 TAILQ_FIRST((head))->field.tqe_prev =                   \
 798                     &TAILQ_NEXT((elm), field);                          \
 799         else                                                            \
 800                 (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
 801         TAILQ_FIRST((head)) = (elm);                                    \
 802         (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
 803         QMD_TRACE_HEAD(head);                                           \
 804         QMD_TRACE_ELEM(&(elm)->field);                                  \
 805 } while (0)
 806
 807 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 808         QMD_TAILQ_CHECK_TAIL(head, field);                              \
 809         TAILQ_NEXT((elm), field) = NULL;                                \
 810         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 811         *(head)->tqh_last = (elm);                                      \
 812         (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
 813         QMD_TRACE_HEAD(head);                                           \
 814         QMD_TRACE_ELEM(&(elm)->field);                                  \
 815 } while (0)
 816
 817 #define TAILQ_LAST(head, headname)                                      \
 818         (*(((struct headname *)((head)->tqh_last))->tqh_last))
 819
 820 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 821
 822 #define TAILQ_PREV(elm, headname, field)                                \
 823         (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 824
 825 #define TAILQ_REMOVE(head, elm, field) do {                             \
 826         QMD_SAVELINK(oldnext, (elm)->field.tqe_next);                   \
 827         QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);                   \
 828         QMD_TAILQ_CHECK_NEXT(elm, field);                               \
 829         QMD_TAILQ_CHECK_PREV(elm, field);                               \
 830         if ((TAILQ_NEXT((elm), field)) != NULL)                         \
 831                 TAILQ_NEXT((elm), field)->field.tqe_prev =              \
 832                     (elm)->field.tqe_prev;                              \
 833         else {                                                          \
 834                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 835                 QMD_TRACE_HEAD(head);                                   \
 836         }                                                               \
 837         *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
 838         TRASHIT(*oldnext);                                              \
 839         TRASHIT(*oldprev);                                              \
 840         QMD_TRACE_ELEM(&(elm)->field);                                  \
 841 } while (0)
 842
 843 #define TAILQ_SWAP(head1, head2, type, field) do {                      \
 844         QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first;            \
 845         QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last;             \
 846         (head1)->tqh_first = (head2)->tqh_first;                        \
 847         (head1)->tqh_last = (head2)->tqh_last;                          \
 848         (head2)->tqh_first = swap_first;                                \
 849         (head2)->tqh_last = swap_last;                                  \
 850         if ((swap_first = (head1)->tqh_first) != NULL)                  \
 851                 swap_first->field.tqe_prev = &(head1)->tqh_first;       \
 852         else                                                            \
 853                 (head1)->tqh_last = &(head1)->tqh_first;                \
 854         if ((swap_first = (head2)->tqh_first) != NULL)                  \
 855                 swap_first->field.tqe_prev = &(head2)->tqh_first;       \
 856         else                                                            \
 857                 (head2)->tqh_last = &(head2)->tqh_first;                \
 858 } while (0)
 859
 860 #endif /* !_SYS_QUEUE_H_ */