include/qemu/queue.h

   1 /*      $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */
   2
   3 /*
   4  * QEMU version: Copy from netbsd, removed debug code, removed some of
   5  * the implementations.  Left in singly-linked lists, lists, simple
   6  * queues, and tail queues.
   7  */
   8
   9 /*
  10  * Copyright (c) 1991, 1993
  11  *      The Regents of the University of California.  All rights reserved.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  38  */
  39
  40 #ifndef QEMU_SYS_QUEUE_H
  41 #define QEMU_SYS_QUEUE_H
  42
  43 /*
  44  * This file defines four types of data structures: singly-linked lists,
  45  * lists, simple queues, and tail queues.
  46  *
  47  * A singly-linked list is headed by a single forward pointer. The
  48  * elements are singly linked for minimum space and pointer manipulation
  49  * overhead at the expense of O(n) removal for arbitrary elements. New
  50  * elements can be added to the list after an existing element or at the
  51  * head of the list.  Elements being removed from the head of the list
  52  * should use the explicit macro for this purpose for optimum
  53  * efficiency. A singly-linked list may only be traversed in the forward
  54  * direction.  Singly-linked lists are ideal for applications with large
  55  * datasets and few or no removals or for implementing a LIFO queue.
  56  *
  57  * A list is headed by a single forward pointer (or an array of forward
  58  * pointers for a hash table header). The elements are doubly linked
  59  * so that an arbitrary element can be removed without a need to
  60  * traverse the list. New elements can be added to the list before
  61  * or after an existing element or at the head of the list. A list
  62  * may only be traversed in the forward direction.
  63  *
  64  * A simple queue is headed by a pair of pointers, one the head of the
  65  * list and the other to the tail of the list. The elements are singly
  66  * linked to save space, so elements can only be removed from the
  67  * head of the list. New elements can be added to the list after
  68  * an existing element, at the head of the list, or at the end of the
  69  * list. A simple queue may only be traversed in the forward direction.
  70  *
  71  * A tail queue is headed by a pair of pointers, one to the head of the
  72  * list and the other to the tail of the list. The elements are doubly
  73  * linked so that an arbitrary element can be removed without a need to
  74  * traverse the list. New elements can be added to the list before or
  75  * after an existing element, at the head of the list, or at the end of
  76  * the list. A tail queue may be traversed in either direction.
  77  *
  78  * For details on the use of these macros, see the queue(3) manual page.
  79  */
  80
  81 /*
  82  * List definitions.
  83  */
  84 #define QLIST_HEAD(name, type)                                          \
  85 struct name {                                                           \
  86         struct type *lh_first;  /* first element */                     \
  87 }
  88
  89 #define QLIST_HEAD_INITIALIZER(head)                                    \
  90         { NULL }
  91
  92 #define QLIST_ENTRY(type)                                               \
  93 struct {                                                                \
  94         struct type *le_next;   /* next element */                      \
  95         struct type **le_prev;  /* address of previous next element */  \
  96 }
  97
  98 /*
  99  * List functions.
 100  */
 101 #define QLIST_INIT(head) do {                                           \
 102         (head)->lh_first = NULL;                                        \
 103 } while (/*CONSTCOND*/0)
 104
 105 #define QLIST_SWAP(dstlist, srclist, field) do {                        \
 106         void *tmplist;                                                  \
 107         tmplist = (srclist)->lh_first;                                  \
 108         (srclist)->lh_first = (dstlist)->lh_first;                      \
 109         if ((srclist)->lh_first != NULL) {                              \
 110             (srclist)->lh_first->field.le_prev = &(srclist)->lh_first;  \
 111         }                                                               \
 112         (dstlist)->lh_first = tmplist;                                  \
 113         if ((dstlist)->lh_first != NULL) {                              \
 114             (dstlist)->lh_first->field.le_prev = &(dstlist)->lh_first;  \
 115         }                                                               \
 116 } while (/*CONSTCOND*/0)
 117
 118 #define QLIST_INSERT_AFTER(listelm, elm, field) do {                    \
 119         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 120                 (listelm)->field.le_next->field.le_prev =               \
 121                     &(elm)->field.le_next;                              \
 122         (listelm)->field.le_next = (elm);                               \
 123         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 124 } while (/*CONSTCOND*/0)
 125
 126 #define QLIST_INSERT_BEFORE(listelm, elm, field) do {                   \
 127         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 128         (elm)->field.le_next = (listelm);                               \
 129         *(listelm)->field.le_prev = (elm);                              \
 130         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 131 } while (/*CONSTCOND*/0)
 132
 133 #define QLIST_INSERT_HEAD(head, elm, field) do {                        \
 134         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 135                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 136         (head)->lh_first = (elm);                                       \
 137         (elm)->field.le_prev = &(head)->lh_first;                       \
 138 } while (/*CONSTCOND*/0)
 139
 140 #define QLIST_REMOVE(elm, field) do {                                   \
 141         if ((elm)->field.le_next != NULL)                               \
 142                 (elm)->field.le_next->field.le_prev =                   \
 143                     (elm)->field.le_prev;                               \
 144         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 145 } while (/*CONSTCOND*/0)
 146
 147 #define QLIST_FOREACH(var, head, field)                                 \
 148         for ((var) = ((head)->lh_first);                                \
 149                 (var);                                                  \
 150                 (var) = ((var)->field.le_next))
 151
 152 #define QLIST_FOREACH_SAFE(var, head, field, next_var)                  \
 153         for ((var) = ((head)->lh_first);                                \
 154                 (var) && ((next_var) = ((var)->field.le_next), 1);      \
 155                 (var) = (next_var))
 156
 157 /*
 158  * List access methods.
 159  */
 160 #define QLIST_EMPTY(head)                ((head)->lh_first == NULL)
 161 #define QLIST_FIRST(head)                ((head)->lh_first)
 162 #define QLIST_NEXT(elm, field)           ((elm)->field.le_next)
 163
 164
 165 /*
 166  * Singly-linked List definitions.
 167  */
 168 #define QSLIST_HEAD(name, type)                                          \
 169 struct name {                                                           \
 170         struct type *slh_first; /* first element */                     \
 171 }
 172
 173 #define QSLIST_HEAD_INITIALIZER(head)                                    \
 174         { NULL }
 175
 176 #define QSLIST_ENTRY(type)                                               \
 177 struct {                                                                \
 178         struct type *sle_next;  /* next element */                      \
 179 }
 180
 181 /*
 182  * Singly-linked List functions.
 183  */
 184 #define QSLIST_INIT(head) do {                                           \
 185         (head)->slh_first = NULL;                                       \
 186 } while (/*CONSTCOND*/0)
 187
 188 #define QSLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
 189         (elm)->field.sle_next = (slistelm)->field.sle_next;             \
 190         (slistelm)->field.sle_next = (elm);                             \
 191 } while (/*CONSTCOND*/0)
 192
 193 #define QSLIST_INSERT_HEAD(head, elm, field) do {                        \
 194         (elm)->field.sle_next = (head)->slh_first;                       \
 195         (head)->slh_first = (elm);                                       \
 196 } while (/*CONSTCOND*/0)
 197
 198 #define QSLIST_INSERT_HEAD_ATOMIC(head, elm, field) do {                     \
 199         typeof(elm) save_sle_next;                                           \
 200         do {                                                                 \
 201             save_sle_next = (elm)->field.sle_next = (head)->slh_first;       \
 202         } while (atomic_cmpxchg(&(head)->slh_first, save_sle_next, (elm)) != \
 203                  save_sle_next);                                             \
 204 } while (/*CONSTCOND*/0)
 205
 206 #define QSLIST_MOVE_ATOMIC(dest, src) do {                               \
 207         (dest)->slh_first = atomic_xchg(&(src)->slh_first, NULL);        \
 208 } while (/*CONSTCOND*/0)
 209
 210 #define QSLIST_REMOVE_HEAD(head, field) do {                             \
 211         (head)->slh_first = (head)->slh_first->field.sle_next;          \
 212 } while (/*CONSTCOND*/0)
 213
 214 #define QSLIST_REMOVE_AFTER(slistelm, field) do {                        \
 215         (slistelm)->field.sle_next =                                    \
 216             QSLIST_NEXT(QSLIST_NEXT((slistelm), field), field);           \
 217 } while (/*CONSTCOND*/0)
 218
 219 #define QSLIST_FOREACH(var, head, field)                                 \
 220         for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
 221
 222 #define QSLIST_FOREACH_SAFE(var, head, field, tvar)                      \
 223         for ((var) = QSLIST_FIRST((head));                               \
 224             (var) && ((tvar) = QSLIST_NEXT((var), field), 1);            \
 225             (var) = (tvar))
 226
 227 /*
 228  * Singly-linked List access methods.
 229  */
 230 #define QSLIST_EMPTY(head)       ((head)->slh_first == NULL)
 231 #define QSLIST_FIRST(head)       ((head)->slh_first)
 232 #define QSLIST_NEXT(elm, field)  ((elm)->field.sle_next)
 233
 234
 235 /*
 236  * Simple queue definitions.
 237  */
 238 #define QSIMPLEQ_HEAD(name, type)                                       \
 239 struct name {                                                           \
 240     struct type *sqh_first;    /* first element */                      \
 241     struct type **sqh_last;    /* addr of last next element */          \
 242 }
 243
 244 #define QSIMPLEQ_HEAD_INITIALIZER(head)                                 \
 245     { NULL, &(head).sqh_first }
 246
 247 #define QSIMPLEQ_ENTRY(type)                                            \
 248 struct {                                                                \
 249     struct type *sqe_next;    /* next element */                        \
 250 }
 251
 252 /*
 253  * Simple queue functions.
 254  */
 255 #define QSIMPLEQ_INIT(head) do {                                        \
 256     (head)->sqh_first = NULL;                                           \
 257     (head)->sqh_last = &(head)->sqh_first;                              \
 258 } while (/*CONSTCOND*/0)
 259
 260 #define QSIMPLEQ_INSERT_HEAD(head, elm, field) do {                     \
 261     if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)            \
 262         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 263     (head)->sqh_first = (elm);                                          \
 264 } while (/*CONSTCOND*/0)
 265
 266 #define QSIMPLEQ_INSERT_TAIL(head, elm, field) do {                     \
 267     (elm)->field.sqe_next = NULL;                                       \
 268     *(head)->sqh_last = (elm);                                          \
 269     (head)->sqh_last = &(elm)->field.sqe_next;                          \
 270 } while (/*CONSTCOND*/0)
 271
 272 #define QSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {           \
 273     if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)    \
 274         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 275     (listelm)->field.sqe_next = (elm);                                  \
 276 } while (/*CONSTCOND*/0)
 277
 278 #define QSIMPLEQ_REMOVE_HEAD(head, field) do {                          \
 279     if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL)\
 280         (head)->sqh_last = &(head)->sqh_first;                          \
 281 } while (/*CONSTCOND*/0)
 282
 283 #define QSIMPLEQ_SPLIT_AFTER(head, elm, field, removed) do {            \
 284     QSIMPLEQ_INIT(removed);                                             \
 285     if (((removed)->sqh_first = (head)->sqh_first) != NULL) {           \
 286         if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) {      \
 287             (head)->sqh_last = &(head)->sqh_first;                      \
 288         }                                                               \
 289         (removed)->sqh_last = &(elm)->field.sqe_next;                   \
 290         (elm)->field.sqe_next = NULL;                                   \
 291     }                                                                   \
 292 } while (/*CONSTCOND*/0)
 293
 294 #define QSIMPLEQ_REMOVE(head, elm, type, field) do {                    \
 295     if ((head)->sqh_first == (elm)) {                                   \
 296         QSIMPLEQ_REMOVE_HEAD((head), field);                            \
 297     } else {                                                            \
 298         struct type *curelm = (head)->sqh_first;                        \
 299         while (curelm->field.sqe_next != (elm))                         \
 300             curelm = curelm->field.sqe_next;                            \
 301         if ((curelm->field.sqe_next =                                   \
 302             curelm->field.sqe_next->field.sqe_next) == NULL)            \
 303                 (head)->sqh_last = &(curelm)->field.sqe_next;           \
 304     }                                                                   \
 305 } while (/*CONSTCOND*/0)
 306
 307 #define QSIMPLEQ_FOREACH(var, head, field)                              \
 308     for ((var) = ((head)->sqh_first);                                   \
 309         (var);                                                          \
 310         (var) = ((var)->field.sqe_next))
 311
 312 #define QSIMPLEQ_FOREACH_SAFE(var, head, field, next)                   \
 313     for ((var) = ((head)->sqh_first);                                   \
 314         (var) && ((next = ((var)->field.sqe_next)), 1);                 \
 315         (var) = (next))
 316
 317 #define QSIMPLEQ_CONCAT(head1, head2) do {                              \
 318     if (!QSIMPLEQ_EMPTY((head2))) {                                     \
 319         *(head1)->sqh_last = (head2)->sqh_first;                        \
 320         (head1)->sqh_last = (head2)->sqh_last;                          \
 321         QSIMPLEQ_INIT((head2));                                         \
 322     }                                                                   \
 323 } while (/*CONSTCOND*/0)
 324
 325 #define QSIMPLEQ_PREPEND(head1, head2) do {                             \
 326     if (!QSIMPLEQ_EMPTY((head2))) {                                     \
 327         *(head2)->sqh_last = (head1)->sqh_first;                        \
 328         (head1)->sqh_first = (head2)->sqh_first;                          \
 329         QSIMPLEQ_INIT((head2));                                         \
 330     }                                                                   \
 331 } while (/*CONSTCOND*/0)
 332
 333 #define QSIMPLEQ_LAST(head, type, field)                                \
 334     (QSIMPLEQ_EMPTY((head)) ?                                           \
 335         NULL :                                                          \
 336             ((struct type *)(void *)                                    \
 337         ((char *)((head)->sqh_last) - offsetof(struct type, field))))
 338
 339 /*
 340  * Simple queue access methods.
 341  */
 342 #define QSIMPLEQ_EMPTY_ATOMIC(head) (atomic_read(&((head)->sqh_first)) == NULL)
 343 #define QSIMPLEQ_EMPTY(head)        ((head)->sqh_first == NULL)
 344 #define QSIMPLEQ_FIRST(head)        ((head)->sqh_first)
 345 #define QSIMPLEQ_NEXT(elm, field)   ((elm)->field.sqe_next)
 346
 347 typedef struct QTailQLink {
 348     void *tql_next;
 349     struct QTailQLink *tql_prev;
 350 } QTailQLink;
 351
 352 /*
 353  * Tail queue definitions.  The union acts as a poor man template, as if
 354  * it were QTailQLink<type>.
 355  */
 356 #define QTAILQ_HEAD(name, type)                                         \
 357 union name {                                                            \
 358         struct type *tqh_first;       /* first element */               \
 359         QTailQLink tqh_circ;          /* link for circular backwards list */ \
 360 }
 361
 362 #define QTAILQ_HEAD_INITIALIZER(head)                                   \
 363         { .tqh_circ = { NULL, &(head).tqh_circ } }
 364
 365 #define QTAILQ_ENTRY(type)                                              \
 366 union {                                                                 \
 367         struct type *tqe_next;        /* next element */                \
 368         QTailQLink tqe_circ;          /* link for circular backwards list */ \
 369 }
 370
 371 /*
 372  * Tail queue functions.
 373  */
 374 #define QTAILQ_INIT(head) do {                                          \
 375         (head)->tqh_first = NULL;                                       \
 376         (head)->tqh_circ.tql_prev = &(head)->tqh_circ;                  \
 377 } while (/*CONSTCOND*/0)
 378
 379 #define QTAILQ_INSERT_HEAD(head, elm, field) do {                       \
 380         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 381             (head)->tqh_first->field.tqe_circ.tql_prev =                \
 382                 &(elm)->field.tqe_circ;                                 \
 383         else                                                            \
 384             (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;         \
 385         (head)->tqh_first = (elm);                                      \
 386         (elm)->field.tqe_circ.tql_prev = &(head)->tqh_circ;             \
 387 } while (/*CONSTCOND*/0)
 388
 389 #define QTAILQ_INSERT_TAIL(head, elm, field) do {                       \
 390         (elm)->field.tqe_next = NULL;                                   \
 391         (elm)->field.tqe_circ.tql_prev = (head)->tqh_circ.tql_prev;     \
 392         (head)->tqh_circ.tql_prev->tql_next = (elm);                    \
 393         (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;             \
 394 } while (/*CONSTCOND*/0)
 395
 396 #define QTAILQ_INSERT_AFTER(head, listelm, elm, field) do {             \
 397         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 398             (elm)->field.tqe_next->field.tqe_circ.tql_prev =            \
 399                 &(elm)->field.tqe_circ;                                 \
 400         else                                                            \
 401             (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;         \
 402         (listelm)->field.tqe_next = (elm);                              \
 403         (elm)->field.tqe_circ.tql_prev = &(listelm)->field.tqe_circ;    \
 404 } while (/*CONSTCOND*/0)
 405
 406 #define QTAILQ_INSERT_BEFORE(listelm, elm, field) do {                       \
 407         (elm)->field.tqe_circ.tql_prev = (listelm)->field.tqe_circ.tql_prev; \
 408         (elm)->field.tqe_next = (listelm);                                   \
 409         (listelm)->field.tqe_circ.tql_prev->tql_next = (elm);                \
 410         (listelm)->field.tqe_circ.tql_prev = &(elm)->field.tqe_circ;         \
 411 } while (/*CONSTCOND*/0)
 412
 413 #define QTAILQ_REMOVE(head, elm, field) do {                            \
 414         if (((elm)->field.tqe_next) != NULL)                            \
 415             (elm)->field.tqe_next->field.tqe_circ.tql_prev =            \
 416                 (elm)->field.tqe_circ.tql_prev;                         \
 417         else                                                            \
 418             (head)->tqh_circ.tql_prev = (elm)->field.tqe_circ.tql_prev; \
 419         (elm)->field.tqe_circ.tql_prev->tql_next = (elm)->field.tqe_next; \
 420         (elm)->field.tqe_circ.tql_prev = NULL;                          \
 421 } while (/*CONSTCOND*/0)
 422
 423 /* remove @left, @right and all elements in between from @head */
 424 #define QTAILQ_REMOVE_SEVERAL(head, left, right, field) do {            \
 425         if (((right)->field.tqe_next) != NULL)                          \
 426             (right)->field.tqe_next->field.tqe_circ.tql_prev =          \
 427                 (left)->field.tqe_circ.tql_prev;                        \
 428         else                                                            \
 429             (head)->tqh_circ.tql_prev = (left)->field.tqe_circ.tql_prev; \
 430         (left)->field.tqe_circ.tql_prev->tql_next = (right)->field.tqe_next; \
 431     } while (/*CONSTCOND*/0)
 432
 433 #define QTAILQ_FOREACH(var, head, field)                                \
 434         for ((var) = ((head)->tqh_first);                               \
 435                 (var);                                                  \
 436                 (var) = ((var)->field.tqe_next))
 437
 438 #define QTAILQ_FOREACH_SAFE(var, head, field, next_var)                 \
 439         for ((var) = ((head)->tqh_first);                               \
 440                 (var) && ((next_var) = ((var)->field.tqe_next), 1);     \
 441                 (var) = (next_var))
 442
 443 #define QTAILQ_FOREACH_REVERSE(var, head, field)                        \
 444         for ((var) = QTAILQ_LAST(head);                                 \
 445                 (var);                                                  \
 446                 (var) = QTAILQ_PREV(var, field))
 447
 448 #define QTAILQ_FOREACH_REVERSE_SAFE(var, head, field, prev_var)         \
 449         for ((var) = QTAILQ_LAST(head);                                 \
 450              (var) && ((prev_var) = QTAILQ_PREV(var, field), 1);        \
 451              (var) = (prev_var))
 452
 453 /*
 454  * Tail queue access methods.
 455  */
 456 #define QTAILQ_EMPTY(head)               ((head)->tqh_first == NULL)
 457 #define QTAILQ_FIRST(head)               ((head)->tqh_first)
 458 #define QTAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 459 #define QTAILQ_IN_USE(elm, field)        ((elm)->field.tqe_circ.tql_prev != NULL)
 460
 461 #define QTAILQ_LINK_PREV(link)                                          \
 462         ((link).tql_prev->tql_prev->tql_next)
 463 #define QTAILQ_LAST(head)                                               \
 464         ((typeof((head)->tqh_first)) QTAILQ_LINK_PREV((head)->tqh_circ))
 465 #define QTAILQ_PREV(elm, field)                                         \
 466         ((typeof((elm)->field.tqe_next)) QTAILQ_LINK_PREV((elm)->field.tqe_circ))
 467
 468 #define field_at_offset(base, offset, type)                                    \
 469         ((type *) (((char *) (base)) + (offset)))
 470
 471 /*
 472  * Raw access of elements of a tail queue head.  Offsets are all zero
 473  * because it's a union.
 474  */
 475 #define QTAILQ_RAW_FIRST(head)                                                 \
 476         field_at_offset(head, 0, void *)
 477 #define QTAILQ_RAW_TQH_CIRC(head)                                              \
 478         field_at_offset(head, 0, QTailQLink)
 479
 480 /*
 481  * Raw access of elements of a tail entry
 482  */
 483 #define QTAILQ_RAW_NEXT(elm, entry)                                            \
 484         field_at_offset(elm, entry, void *)
 485 #define QTAILQ_RAW_TQE_CIRC(elm, entry)                                        \
 486         field_at_offset(elm, entry, QTailQLink)
 487 /*
 488  * Tail queue traversal using pointer arithmetic.
 489  */
 490 #define QTAILQ_RAW_FOREACH(elm, head, entry)                                   \
 491         for ((elm) = *QTAILQ_RAW_FIRST(head);                                  \
 492              (elm);                                                            \
 493              (elm) = *QTAILQ_RAW_NEXT(elm, entry))
 494 /*
 495  * Tail queue insertion using pointer arithmetic.
 496  */
 497 #define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do {                           \
 498         *QTAILQ_RAW_NEXT(elm, entry) = NULL;                                    \
 499         QTAILQ_RAW_TQE_CIRC(elm, entry)->tql_prev = QTAILQ_RAW_TQH_CIRC(head)->tql_prev; \
 500         QTAILQ_RAW_TQH_CIRC(head)->tql_prev->tql_next = (elm);                  \
 501         QTAILQ_RAW_TQH_CIRC(head)->tql_prev = QTAILQ_RAW_TQE_CIRC(elm, entry);  \
 502 } while (/*CONSTCOND*/0)
 503
 504 #endif /* QEMU_SYS_QUEUE_H */