cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
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queue.h (29156B)


      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)                                          \
     85struct name {                                                           \
     86        struct type *lh_first;  /* first element */                     \
     87}
     88
     89#define QLIST_HEAD_INITIALIZER(head)                                    \
     90        { NULL }
     91
     92#define QLIST_ENTRY(type)                                               \
     93struct {                                                                \
     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        (elm)->field.le_next = NULL;                                    \
    146        (elm)->field.le_prev = NULL;                                    \
    147} while (/*CONSTCOND*/0)
    148
    149/*
    150 * Like QLIST_REMOVE() but safe to call when elm is not in a list
    151 */
    152#define QLIST_SAFE_REMOVE(elm, field) do {                              \
    153        if ((elm)->field.le_prev != NULL) {                             \
    154                if ((elm)->field.le_next != NULL)                       \
    155                        (elm)->field.le_next->field.le_prev =           \
    156                            (elm)->field.le_prev;                       \
    157                *(elm)->field.le_prev = (elm)->field.le_next;           \
    158                (elm)->field.le_next = NULL;                            \
    159                (elm)->field.le_prev = NULL;                            \
    160        }                                                               \
    161} while (/*CONSTCOND*/0)
    162
    163/* Is elm in a list? */
    164#define QLIST_IS_INSERTED(elm, field) ((elm)->field.le_prev != NULL)
    165
    166#define QLIST_FOREACH(var, head, field)                                 \
    167        for ((var) = ((head)->lh_first);                                \
    168                (var);                                                  \
    169                (var) = ((var)->field.le_next))
    170
    171#define QLIST_FOREACH_SAFE(var, head, field, next_var)                  \
    172        for ((var) = ((head)->lh_first);                                \
    173                (var) && ((next_var) = ((var)->field.le_next), 1);      \
    174                (var) = (next_var))
    175
    176/*
    177 * List access methods.
    178 */
    179#define QLIST_EMPTY(head)                ((head)->lh_first == NULL)
    180#define QLIST_FIRST(head)                ((head)->lh_first)
    181#define QLIST_NEXT(elm, field)           ((elm)->field.le_next)
    182
    183
    184/*
    185 * Singly-linked List definitions.
    186 */
    187#define QSLIST_HEAD(name, type)                                          \
    188struct name {                                                           \
    189        struct type *slh_first; /* first element */                     \
    190}
    191
    192#define QSLIST_HEAD_INITIALIZER(head)                                    \
    193        { NULL }
    194
    195#define QSLIST_ENTRY(type)                                               \
    196struct {                                                                \
    197        struct type *sle_next;  /* next element */                      \
    198}
    199
    200/*
    201 * Singly-linked List functions.
    202 */
    203#define QSLIST_INIT(head) do {                                           \
    204        (head)->slh_first = NULL;                                       \
    205} while (/*CONSTCOND*/0)
    206
    207#define QSLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
    208        (elm)->field.sle_next = (slistelm)->field.sle_next;             \
    209        (slistelm)->field.sle_next = (elm);                             \
    210} while (/*CONSTCOND*/0)
    211
    212#define QSLIST_INSERT_HEAD(head, elm, field) do {                        \
    213        (elm)->field.sle_next = (head)->slh_first;                       \
    214        (head)->slh_first = (elm);                                       \
    215} while (/*CONSTCOND*/0)
    216
    217#define QSLIST_INSERT_HEAD_ATOMIC(head, elm, field) do {                     \
    218        typeof(elm) save_sle_next;                                           \
    219        do {                                                                 \
    220            save_sle_next = (elm)->field.sle_next = (head)->slh_first;       \
    221        } while (qatomic_cmpxchg(&(head)->slh_first, save_sle_next, (elm)) !=\
    222                 save_sle_next);                                             \
    223} while (/*CONSTCOND*/0)
    224
    225#define QSLIST_MOVE_ATOMIC(dest, src) do {                               \
    226        (dest)->slh_first = qatomic_xchg(&(src)->slh_first, NULL);       \
    227} while (/*CONSTCOND*/0)
    228
    229#define QSLIST_REMOVE_HEAD(head, field) do {                             \
    230        typeof((head)->slh_first) elm = (head)->slh_first;               \
    231        (head)->slh_first = elm->field.sle_next;                         \
    232        elm->field.sle_next = NULL;                                      \
    233} while (/*CONSTCOND*/0)
    234
    235#define QSLIST_REMOVE_AFTER(slistelm, field) do {                       \
    236        typeof(slistelm) next = (slistelm)->field.sle_next;             \
    237        (slistelm)->field.sle_next = next->field.sle_next;              \
    238        next->field.sle_next = NULL;                                    \
    239} while (/*CONSTCOND*/0)
    240
    241#define QSLIST_REMOVE(head, elm, type, field) do {                      \
    242    if ((head)->slh_first == (elm)) {                                   \
    243        QSLIST_REMOVE_HEAD((head), field);                              \
    244    } else {                                                            \
    245        struct type *curelm = (head)->slh_first;                        \
    246        while (curelm->field.sle_next != (elm))                         \
    247            curelm = curelm->field.sle_next;                            \
    248        curelm->field.sle_next = curelm->field.sle_next->field.sle_next; \
    249        (elm)->field.sle_next = NULL;                                   \
    250    }                                                                   \
    251} while (/*CONSTCOND*/0)
    252
    253#define QSLIST_FOREACH(var, head, field)                                 \
    254        for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
    255
    256#define QSLIST_FOREACH_SAFE(var, head, field, tvar)                      \
    257        for ((var) = QSLIST_FIRST((head));                               \
    258            (var) && ((tvar) = QSLIST_NEXT((var), field), 1);            \
    259            (var) = (tvar))
    260
    261/*
    262 * Singly-linked List access methods.
    263 */
    264#define QSLIST_EMPTY(head)       ((head)->slh_first == NULL)
    265#define QSLIST_FIRST(head)       ((head)->slh_first)
    266#define QSLIST_NEXT(elm, field)  ((elm)->field.sle_next)
    267
    268
    269/*
    270 * Simple queue definitions.
    271 */
    272#define QSIMPLEQ_HEAD(name, type)                                       \
    273struct name {                                                           \
    274    struct type *sqh_first;    /* first element */                      \
    275    struct type **sqh_last;    /* addr of last next element */          \
    276}
    277
    278#define QSIMPLEQ_HEAD_INITIALIZER(head)                                 \
    279    { NULL, &(head).sqh_first }
    280
    281#define QSIMPLEQ_ENTRY(type)                                            \
    282struct {                                                                \
    283    struct type *sqe_next;    /* next element */                        \
    284}
    285
    286/*
    287 * Simple queue functions.
    288 */
    289#define QSIMPLEQ_INIT(head) do {                                        \
    290    (head)->sqh_first = NULL;                                           \
    291    (head)->sqh_last = &(head)->sqh_first;                              \
    292} while (/*CONSTCOND*/0)
    293
    294#define QSIMPLEQ_INSERT_HEAD(head, elm, field) do {                     \
    295    if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)            \
    296        (head)->sqh_last = &(elm)->field.sqe_next;                      \
    297    (head)->sqh_first = (elm);                                          \
    298} while (/*CONSTCOND*/0)
    299
    300#define QSIMPLEQ_INSERT_TAIL(head, elm, field) do {                     \
    301    (elm)->field.sqe_next = NULL;                                       \
    302    *(head)->sqh_last = (elm);                                          \
    303    (head)->sqh_last = &(elm)->field.sqe_next;                          \
    304} while (/*CONSTCOND*/0)
    305
    306#define QSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {           \
    307    if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)    \
    308        (head)->sqh_last = &(elm)->field.sqe_next;                      \
    309    (listelm)->field.sqe_next = (elm);                                  \
    310} while (/*CONSTCOND*/0)
    311
    312#define QSIMPLEQ_REMOVE_HEAD(head, field) do {                          \
    313    typeof((head)->sqh_first) elm = (head)->sqh_first;                  \
    314    if (((head)->sqh_first = elm->field.sqe_next) == NULL)              \
    315        (head)->sqh_last = &(head)->sqh_first;                          \
    316    elm->field.sqe_next = NULL;                                         \
    317} while (/*CONSTCOND*/0)
    318
    319#define QSIMPLEQ_SPLIT_AFTER(head, elm, field, removed) do {            \
    320    QSIMPLEQ_INIT(removed);                                             \
    321    if (((removed)->sqh_first = (head)->sqh_first) != NULL) {           \
    322        if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) {      \
    323            (head)->sqh_last = &(head)->sqh_first;                      \
    324        }                                                               \
    325        (removed)->sqh_last = &(elm)->field.sqe_next;                   \
    326        (elm)->field.sqe_next = NULL;                                   \
    327    }                                                                   \
    328} while (/*CONSTCOND*/0)
    329
    330#define QSIMPLEQ_REMOVE(head, elm, type, field) do {                    \
    331    if ((head)->sqh_first == (elm)) {                                   \
    332        QSIMPLEQ_REMOVE_HEAD((head), field);                            \
    333    } else {                                                            \
    334        struct type *curelm = (head)->sqh_first;                        \
    335        while (curelm->field.sqe_next != (elm))                         \
    336            curelm = curelm->field.sqe_next;                            \
    337        if ((curelm->field.sqe_next =                                   \
    338            curelm->field.sqe_next->field.sqe_next) == NULL)            \
    339                (head)->sqh_last = &(curelm)->field.sqe_next;           \
    340        (elm)->field.sqe_next = NULL;                                   \
    341    }                                                                   \
    342} while (/*CONSTCOND*/0)
    343
    344#define QSIMPLEQ_FOREACH(var, head, field)                              \
    345    for ((var) = ((head)->sqh_first);                                   \
    346        (var);                                                          \
    347        (var) = ((var)->field.sqe_next))
    348
    349#define QSIMPLEQ_FOREACH_SAFE(var, head, field, next)                   \
    350    for ((var) = ((head)->sqh_first);                                   \
    351        (var) && ((next = ((var)->field.sqe_next)), 1);                 \
    352        (var) = (next))
    353
    354#define QSIMPLEQ_CONCAT(head1, head2) do {                              \
    355    if (!QSIMPLEQ_EMPTY((head2))) {                                     \
    356        *(head1)->sqh_last = (head2)->sqh_first;                        \
    357        (head1)->sqh_last = (head2)->sqh_last;                          \
    358        QSIMPLEQ_INIT((head2));                                         \
    359    }                                                                   \
    360} while (/*CONSTCOND*/0)
    361
    362#define QSIMPLEQ_PREPEND(head1, head2) do {                             \
    363    if (!QSIMPLEQ_EMPTY((head2))) {                                     \
    364        *(head2)->sqh_last = (head1)->sqh_first;                        \
    365        (head1)->sqh_first = (head2)->sqh_first;                          \
    366        QSIMPLEQ_INIT((head2));                                         \
    367    }                                                                   \
    368} while (/*CONSTCOND*/0)
    369
    370#define QSIMPLEQ_LAST(head, type, field)                                \
    371    (QSIMPLEQ_EMPTY((head)) ?                                           \
    372        NULL :                                                          \
    373            ((struct type *)(void *)                                    \
    374        ((char *)((head)->sqh_last) - offsetof(struct type, field))))
    375
    376/*
    377 * Simple queue access methods.
    378 */
    379#define QSIMPLEQ_EMPTY_ATOMIC(head) \
    380    (qatomic_read(&((head)->sqh_first)) == NULL)
    381#define QSIMPLEQ_EMPTY(head)        ((head)->sqh_first == NULL)
    382#define QSIMPLEQ_FIRST(head)        ((head)->sqh_first)
    383#define QSIMPLEQ_NEXT(elm, field)   ((elm)->field.sqe_next)
    384
    385typedef struct QTailQLink {
    386    void *tql_next;
    387    struct QTailQLink *tql_prev;
    388} QTailQLink;
    389
    390/*
    391 * Tail queue definitions.  The union acts as a poor man template, as if
    392 * it were QTailQLink<type>.
    393 */
    394#define QTAILQ_HEAD(name, type)                                         \
    395union name {                                                            \
    396        struct type *tqh_first;       /* first element */               \
    397        QTailQLink tqh_circ;          /* link for circular backwards list */ \
    398}
    399
    400#define QTAILQ_HEAD_INITIALIZER(head)                                   \
    401        { .tqh_circ = { NULL, &(head).tqh_circ } }
    402
    403#define QTAILQ_ENTRY(type)                                              \
    404union {                                                                 \
    405        struct type *tqe_next;        /* next element */                \
    406        QTailQLink tqe_circ;          /* link for circular backwards list */ \
    407}
    408
    409/*
    410 * Tail queue functions.
    411 */
    412#define QTAILQ_INIT(head) do {                                          \
    413        (head)->tqh_first = NULL;                                       \
    414        (head)->tqh_circ.tql_prev = &(head)->tqh_circ;                  \
    415} while (/*CONSTCOND*/0)
    416
    417#define QTAILQ_INSERT_HEAD(head, elm, field) do {                       \
    418        if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
    419            (head)->tqh_first->field.tqe_circ.tql_prev =                \
    420                &(elm)->field.tqe_circ;                                 \
    421        else                                                            \
    422            (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;         \
    423        (head)->tqh_first = (elm);                                      \
    424        (elm)->field.tqe_circ.tql_prev = &(head)->tqh_circ;             \
    425} while (/*CONSTCOND*/0)
    426
    427#define QTAILQ_INSERT_TAIL(head, elm, field) do {                       \
    428        (elm)->field.tqe_next = NULL;                                   \
    429        (elm)->field.tqe_circ.tql_prev = (head)->tqh_circ.tql_prev;     \
    430        (head)->tqh_circ.tql_prev->tql_next = (elm);                    \
    431        (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;             \
    432} while (/*CONSTCOND*/0)
    433
    434#define QTAILQ_INSERT_AFTER(head, listelm, elm, field) do {             \
    435        if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
    436            (elm)->field.tqe_next->field.tqe_circ.tql_prev =            \
    437                &(elm)->field.tqe_circ;                                 \
    438        else                                                            \
    439            (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;         \
    440        (listelm)->field.tqe_next = (elm);                              \
    441        (elm)->field.tqe_circ.tql_prev = &(listelm)->field.tqe_circ;    \
    442} while (/*CONSTCOND*/0)
    443
    444#define QTAILQ_INSERT_BEFORE(listelm, elm, field) do {                       \
    445        (elm)->field.tqe_circ.tql_prev = (listelm)->field.tqe_circ.tql_prev; \
    446        (elm)->field.tqe_next = (listelm);                                   \
    447        (listelm)->field.tqe_circ.tql_prev->tql_next = (elm);                \
    448        (listelm)->field.tqe_circ.tql_prev = &(elm)->field.tqe_circ;         \
    449} while (/*CONSTCOND*/0)
    450
    451#define QTAILQ_REMOVE(head, elm, field) do {                            \
    452        if (((elm)->field.tqe_next) != NULL)                            \
    453            (elm)->field.tqe_next->field.tqe_circ.tql_prev =            \
    454                (elm)->field.tqe_circ.tql_prev;                         \
    455        else                                                            \
    456            (head)->tqh_circ.tql_prev = (elm)->field.tqe_circ.tql_prev; \
    457        (elm)->field.tqe_circ.tql_prev->tql_next = (elm)->field.tqe_next; \
    458        (elm)->field.tqe_circ.tql_prev = NULL;                          \
    459        (elm)->field.tqe_circ.tql_next = NULL;                          \
    460        (elm)->field.tqe_next = NULL;                                   \
    461} while (/*CONSTCOND*/0)
    462
    463/* remove @left, @right and all elements in between from @head */
    464#define QTAILQ_REMOVE_SEVERAL(head, left, right, field) do {            \
    465        if (((right)->field.tqe_next) != NULL)                          \
    466            (right)->field.tqe_next->field.tqe_circ.tql_prev =          \
    467                (left)->field.tqe_circ.tql_prev;                        \
    468        else                                                            \
    469            (head)->tqh_circ.tql_prev = (left)->field.tqe_circ.tql_prev; \
    470        (left)->field.tqe_circ.tql_prev->tql_next = (right)->field.tqe_next; \
    471    } while (/*CONSTCOND*/0)
    472
    473#define QTAILQ_FOREACH(var, head, field)                                \
    474        for ((var) = ((head)->tqh_first);                               \
    475                (var);                                                  \
    476                (var) = ((var)->field.tqe_next))
    477
    478#define QTAILQ_FOREACH_SAFE(var, head, field, next_var)                 \
    479        for ((var) = ((head)->tqh_first);                               \
    480                (var) && ((next_var) = ((var)->field.tqe_next), 1);     \
    481                (var) = (next_var))
    482
    483#define QTAILQ_FOREACH_REVERSE(var, head, field)                        \
    484        for ((var) = QTAILQ_LAST(head);                                 \
    485                (var);                                                  \
    486                (var) = QTAILQ_PREV(var, field))
    487
    488#define QTAILQ_FOREACH_REVERSE_SAFE(var, head, field, prev_var)         \
    489        for ((var) = QTAILQ_LAST(head);                                 \
    490             (var) && ((prev_var) = QTAILQ_PREV(var, field), 1);        \
    491             (var) = (prev_var))
    492
    493/*
    494 * Tail queue access methods.
    495 */
    496#define QTAILQ_EMPTY(head)               ((head)->tqh_first == NULL)
    497#define QTAILQ_FIRST(head)               ((head)->tqh_first)
    498#define QTAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
    499#define QTAILQ_IN_USE(elm, field)        ((elm)->field.tqe_circ.tql_prev != NULL)
    500
    501#define QTAILQ_LINK_PREV(link)                                          \
    502        ((link).tql_prev->tql_prev->tql_next)
    503#define QTAILQ_LAST(head)                                               \
    504        ((typeof((head)->tqh_first)) QTAILQ_LINK_PREV((head)->tqh_circ))
    505#define QTAILQ_PREV(elm, field)                                         \
    506        ((typeof((elm)->field.tqe_next)) QTAILQ_LINK_PREV((elm)->field.tqe_circ))
    507
    508#define field_at_offset(base, offset, type)                                    \
    509        ((type *) (((char *) (base)) + (offset)))
    510
    511/*
    512 * Raw access of elements of a tail queue head.  Offsets are all zero
    513 * because it's a union.
    514 */
    515#define QTAILQ_RAW_FIRST(head)                                                 \
    516        field_at_offset(head, 0, void *)
    517#define QTAILQ_RAW_TQH_CIRC(head)                                              \
    518        field_at_offset(head, 0, QTailQLink)
    519
    520/*
    521 * Raw access of elements of a tail entry
    522 */
    523#define QTAILQ_RAW_NEXT(elm, entry)                                            \
    524        field_at_offset(elm, entry, void *)
    525#define QTAILQ_RAW_TQE_CIRC(elm, entry)                                        \
    526        field_at_offset(elm, entry, QTailQLink)
    527/*
    528 * Tail queue traversal using pointer arithmetic.
    529 */
    530#define QTAILQ_RAW_FOREACH(elm, head, entry)                                   \
    531        for ((elm) = *QTAILQ_RAW_FIRST(head);                                  \
    532             (elm);                                                            \
    533             (elm) = *QTAILQ_RAW_NEXT(elm, entry))
    534/*
    535 * Tail queue insertion using pointer arithmetic.
    536 */
    537#define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do {                           \
    538        *QTAILQ_RAW_NEXT(elm, entry) = NULL;                                    \
    539        QTAILQ_RAW_TQE_CIRC(elm, entry)->tql_prev = QTAILQ_RAW_TQH_CIRC(head)->tql_prev; \
    540        QTAILQ_RAW_TQH_CIRC(head)->tql_prev->tql_next = (elm);                  \
    541        QTAILQ_RAW_TQH_CIRC(head)->tql_prev = QTAILQ_RAW_TQE_CIRC(elm, entry);  \
    542} while (/*CONSTCOND*/0)
    543
    544#define QLIST_RAW_FIRST(head)                                                  \
    545        field_at_offset(head, 0, void *)
    546
    547#define QLIST_RAW_NEXT(elm, entry)                                             \
    548        field_at_offset(elm, entry, void *)
    549
    550#define QLIST_RAW_PREVIOUS(elm, entry)                                         \
    551        field_at_offset(elm, entry + sizeof(void *), void *)
    552
    553#define QLIST_RAW_FOREACH(elm, head, entry)                                    \
    554        for ((elm) = *QLIST_RAW_FIRST(head);                                   \
    555             (elm);                                                            \
    556             (elm) = *QLIST_RAW_NEXT(elm, entry))
    557
    558#define QLIST_RAW_INSERT_AFTER(head, prev, elem, entry) do {                   \
    559        *QLIST_RAW_NEXT(prev, entry) = elem;                                   \
    560        *QLIST_RAW_PREVIOUS(elem, entry) = QLIST_RAW_NEXT(prev, entry);        \
    561        *QLIST_RAW_NEXT(elem, entry) = NULL;                                   \
    562} while (0)
    563
    564#define QLIST_RAW_INSERT_HEAD(head, elm, entry) do {                           \
    565        void *first = *QLIST_RAW_FIRST(head);                                  \
    566        *QLIST_RAW_FIRST(head) = elm;                                          \
    567        *QLIST_RAW_PREVIOUS(elm, entry) = QLIST_RAW_FIRST(head);               \
    568        if (first) {                                                           \
    569            *QLIST_RAW_NEXT(elm, entry) = first;                               \
    570            *QLIST_RAW_PREVIOUS(first, entry) = QLIST_RAW_NEXT(elm, entry);    \
    571        } else {                                                               \
    572            *QLIST_RAW_NEXT(elm, entry) = NULL;                                \
    573        }                                                                      \
    574} while (0)
    575
    576#endif /* QEMU_SYS_QUEUE_H */