qemu-e2k/include/qemu/queue.h
Stefan Hajnoczi a31ca6801c qemu/queue.h: clear linked list pointers on remove
Do not leave stale linked list pointers around after removal.  It's
safer to set them to NULL so that use-after-removal results in an
immediate segfault.

The RCU queue removal macros are unchanged since nodes may still be
traversed after removal.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://lore.kernel.org/r/20200224103406.1894923-2-stefanha@redhat.com
Message-Id: <20200224103406.1894923-2-stefanha@redhat.com>
2020-03-09 16:39:20 +00:00

576 lines
28 KiB
C

/* $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */
/*
* QEMU version: Copy from netbsd, removed debug code, removed some of
* the implementations. Left in singly-linked lists, lists, simple
* queues, and tail queues.
*/
/*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)queue.h 8.5 (Berkeley) 8/20/94
*/
#ifndef QEMU_SYS_QUEUE_H
#define QEMU_SYS_QUEUE_H
/*
* This file defines four types of data structures: singly-linked lists,
* lists, simple queues, and tail queues.
*
* A singly-linked list is headed by a single forward pointer. The
* elements are singly linked for minimum space and pointer manipulation
* overhead at the expense of O(n) removal for arbitrary elements. New
* elements can be added to the list after an existing element or at the
* head of the list. Elements being removed from the head of the list
* should use the explicit macro for this purpose for optimum
* efficiency. A singly-linked list may only be traversed in the forward
* direction. Singly-linked lists are ideal for applications with large
* datasets and few or no removals or for implementing a LIFO queue.
*
* A list is headed by a single forward pointer (or an array of forward
* pointers for a hash table header). The elements are doubly linked
* so that an arbitrary element can be removed without a need to
* traverse the list. New elements can be added to the list before
* or after an existing element or at the head of the list. A list
* may only be traversed in the forward direction.
*
* A simple queue is headed by a pair of pointers, one the head of the
* list and the other to the tail of the list. The elements are singly
* linked to save space, so elements can only be removed from the
* head of the list. New elements can be added to the list after
* an existing element, at the head of the list, or at the end of the
* list. A simple queue may only be traversed in the forward direction.
*
* A tail queue is headed by a pair of pointers, one to the head of the
* list and the other to the tail of the list. The elements are doubly
* linked so that an arbitrary element can be removed without a need to
* traverse the list. New elements can be added to the list before or
* after an existing element, at the head of the list, or at the end of
* the list. A tail queue may be traversed in either direction.
*
* For details on the use of these macros, see the queue(3) manual page.
*/
/*
* List definitions.
*/
#define QLIST_HEAD(name, type) \
struct name { \
struct type *lh_first; /* first element */ \
}
#define QLIST_HEAD_INITIALIZER(head) \
{ NULL }
#define QLIST_ENTRY(type) \
struct { \
struct type *le_next; /* next element */ \
struct type **le_prev; /* address of previous next element */ \
}
/*
* List functions.
*/
#define QLIST_INIT(head) do { \
(head)->lh_first = NULL; \
} while (/*CONSTCOND*/0)
#define QLIST_SWAP(dstlist, srclist, field) do { \
void *tmplist; \
tmplist = (srclist)->lh_first; \
(srclist)->lh_first = (dstlist)->lh_first; \
if ((srclist)->lh_first != NULL) { \
(srclist)->lh_first->field.le_prev = &(srclist)->lh_first; \
} \
(dstlist)->lh_first = tmplist; \
if ((dstlist)->lh_first != NULL) { \
(dstlist)->lh_first->field.le_prev = &(dstlist)->lh_first; \
} \
} while (/*CONSTCOND*/0)
#define QLIST_INSERT_AFTER(listelm, elm, field) do { \
if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
(listelm)->field.le_next->field.le_prev = \
&(elm)->field.le_next; \
(listelm)->field.le_next = (elm); \
(elm)->field.le_prev = &(listelm)->field.le_next; \
} while (/*CONSTCOND*/0)
#define QLIST_INSERT_BEFORE(listelm, elm, field) do { \
(elm)->field.le_prev = (listelm)->field.le_prev; \
(elm)->field.le_next = (listelm); \
*(listelm)->field.le_prev = (elm); \
(listelm)->field.le_prev = &(elm)->field.le_next; \
} while (/*CONSTCOND*/0)
#define QLIST_INSERT_HEAD(head, elm, field) do { \
if (((elm)->field.le_next = (head)->lh_first) != NULL) \
(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
(head)->lh_first = (elm); \
(elm)->field.le_prev = &(head)->lh_first; \
} while (/*CONSTCOND*/0)
#define QLIST_REMOVE(elm, field) do { \
if ((elm)->field.le_next != NULL) \
(elm)->field.le_next->field.le_prev = \
(elm)->field.le_prev; \
*(elm)->field.le_prev = (elm)->field.le_next; \
(elm)->field.le_next = NULL; \
(elm)->field.le_prev = NULL; \
} while (/*CONSTCOND*/0)
/*
* Like QLIST_REMOVE() but safe to call when elm is not in a list
*/
#define QLIST_SAFE_REMOVE(elm, field) do { \
if ((elm)->field.le_prev != NULL) { \
if ((elm)->field.le_next != NULL) \
(elm)->field.le_next->field.le_prev = \
(elm)->field.le_prev; \
*(elm)->field.le_prev = (elm)->field.le_next; \
(elm)->field.le_next = NULL; \
(elm)->field.le_prev = NULL; \
} \
} while (/*CONSTCOND*/0)
/* Is elm in a list? */
#define QLIST_IS_INSERTED(elm, field) ((elm)->field.le_prev != NULL)
#define QLIST_FOREACH(var, head, field) \
for ((var) = ((head)->lh_first); \
(var); \
(var) = ((var)->field.le_next))
#define QLIST_FOREACH_SAFE(var, head, field, next_var) \
for ((var) = ((head)->lh_first); \
(var) && ((next_var) = ((var)->field.le_next), 1); \
(var) = (next_var))
/*
* List access methods.
*/
#define QLIST_EMPTY(head) ((head)->lh_first == NULL)
#define QLIST_FIRST(head) ((head)->lh_first)
#define QLIST_NEXT(elm, field) ((elm)->field.le_next)
/*
* Singly-linked List definitions.
*/
#define QSLIST_HEAD(name, type) \
struct name { \
struct type *slh_first; /* first element */ \
}
#define QSLIST_HEAD_INITIALIZER(head) \
{ NULL }
#define QSLIST_ENTRY(type) \
struct { \
struct type *sle_next; /* next element */ \
}
/*
* Singly-linked List functions.
*/
#define QSLIST_INIT(head) do { \
(head)->slh_first = NULL; \
} while (/*CONSTCOND*/0)
#define QSLIST_INSERT_AFTER(slistelm, elm, field) do { \
(elm)->field.sle_next = (slistelm)->field.sle_next; \
(slistelm)->field.sle_next = (elm); \
} while (/*CONSTCOND*/0)
#define QSLIST_INSERT_HEAD(head, elm, field) do { \
(elm)->field.sle_next = (head)->slh_first; \
(head)->slh_first = (elm); \
} while (/*CONSTCOND*/0)
#define QSLIST_INSERT_HEAD_ATOMIC(head, elm, field) do { \
typeof(elm) save_sle_next; \
do { \
save_sle_next = (elm)->field.sle_next = (head)->slh_first; \
} while (atomic_cmpxchg(&(head)->slh_first, save_sle_next, (elm)) != \
save_sle_next); \
} while (/*CONSTCOND*/0)
#define QSLIST_MOVE_ATOMIC(dest, src) do { \
(dest)->slh_first = atomic_xchg(&(src)->slh_first, NULL); \
} while (/*CONSTCOND*/0)
#define QSLIST_REMOVE_HEAD(head, field) do { \
typeof((head)->slh_first) elm = (head)->slh_first; \
(head)->slh_first = elm->field.sle_next; \
elm->field.sle_next = NULL; \
} while (/*CONSTCOND*/0)
#define QSLIST_REMOVE_AFTER(slistelm, field) do { \
typeof(slistelm) next = (slistelm)->field.sle_next; \
(slistelm)->field.sle_next = next->field.sle_next; \
next->field.sle_next = NULL; \
} while (/*CONSTCOND*/0)
#define QSLIST_REMOVE(head, elm, type, field) do { \
if ((head)->slh_first == (elm)) { \
QSLIST_REMOVE_HEAD((head), field); \
} else { \
struct type *curelm = (head)->slh_first; \
while (curelm->field.sle_next != (elm)) \
curelm = curelm->field.sle_next; \
curelm->field.sle_next = curelm->field.sle_next->field.sle_next; \
(elm)->field.sle_next = NULL; \
} \
} while (/*CONSTCOND*/0)
#define QSLIST_FOREACH(var, head, field) \
for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
#define QSLIST_FOREACH_SAFE(var, head, field, tvar) \
for ((var) = QSLIST_FIRST((head)); \
(var) && ((tvar) = QSLIST_NEXT((var), field), 1); \
(var) = (tvar))
/*
* Singly-linked List access methods.
*/
#define QSLIST_EMPTY(head) ((head)->slh_first == NULL)
#define QSLIST_FIRST(head) ((head)->slh_first)
#define QSLIST_NEXT(elm, field) ((elm)->field.sle_next)
/*
* Simple queue definitions.
*/
#define QSIMPLEQ_HEAD(name, type) \
struct name { \
struct type *sqh_first; /* first element */ \
struct type **sqh_last; /* addr of last next element */ \
}
#define QSIMPLEQ_HEAD_INITIALIZER(head) \
{ NULL, &(head).sqh_first }
#define QSIMPLEQ_ENTRY(type) \
struct { \
struct type *sqe_next; /* next element */ \
}
/*
* Simple queue functions.
*/
#define QSIMPLEQ_INIT(head) do { \
(head)->sqh_first = NULL; \
(head)->sqh_last = &(head)->sqh_first; \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_INSERT_HEAD(head, elm, field) do { \
if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
(head)->sqh_last = &(elm)->field.sqe_next; \
(head)->sqh_first = (elm); \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_INSERT_TAIL(head, elm, field) do { \
(elm)->field.sqe_next = NULL; \
*(head)->sqh_last = (elm); \
(head)->sqh_last = &(elm)->field.sqe_next; \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL) \
(head)->sqh_last = &(elm)->field.sqe_next; \
(listelm)->field.sqe_next = (elm); \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_REMOVE_HEAD(head, field) do { \
typeof((head)->sqh_first) elm = (head)->sqh_first; \
if (((head)->sqh_first = elm->field.sqe_next) == NULL) \
(head)->sqh_last = &(head)->sqh_first; \
elm->field.sqe_next = NULL; \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_SPLIT_AFTER(head, elm, field, removed) do { \
QSIMPLEQ_INIT(removed); \
if (((removed)->sqh_first = (head)->sqh_first) != NULL) { \
if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) { \
(head)->sqh_last = &(head)->sqh_first; \
} \
(removed)->sqh_last = &(elm)->field.sqe_next; \
(elm)->field.sqe_next = NULL; \
} \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_REMOVE(head, elm, type, field) do { \
if ((head)->sqh_first == (elm)) { \
QSIMPLEQ_REMOVE_HEAD((head), field); \
} else { \
struct type *curelm = (head)->sqh_first; \
while (curelm->field.sqe_next != (elm)) \
curelm = curelm->field.sqe_next; \
if ((curelm->field.sqe_next = \
curelm->field.sqe_next->field.sqe_next) == NULL) \
(head)->sqh_last = &(curelm)->field.sqe_next; \
(elm)->field.sqe_next = NULL; \
} \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_FOREACH(var, head, field) \
for ((var) = ((head)->sqh_first); \
(var); \
(var) = ((var)->field.sqe_next))
#define QSIMPLEQ_FOREACH_SAFE(var, head, field, next) \
for ((var) = ((head)->sqh_first); \
(var) && ((next = ((var)->field.sqe_next)), 1); \
(var) = (next))
#define QSIMPLEQ_CONCAT(head1, head2) do { \
if (!QSIMPLEQ_EMPTY((head2))) { \
*(head1)->sqh_last = (head2)->sqh_first; \
(head1)->sqh_last = (head2)->sqh_last; \
QSIMPLEQ_INIT((head2)); \
} \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_PREPEND(head1, head2) do { \
if (!QSIMPLEQ_EMPTY((head2))) { \
*(head2)->sqh_last = (head1)->sqh_first; \
(head1)->sqh_first = (head2)->sqh_first; \
QSIMPLEQ_INIT((head2)); \
} \
} while (/*CONSTCOND*/0)
#define QSIMPLEQ_LAST(head, type, field) \
(QSIMPLEQ_EMPTY((head)) ? \
NULL : \
((struct type *)(void *) \
((char *)((head)->sqh_last) - offsetof(struct type, field))))
/*
* Simple queue access methods.
*/
#define QSIMPLEQ_EMPTY_ATOMIC(head) (atomic_read(&((head)->sqh_first)) == NULL)
#define QSIMPLEQ_EMPTY(head) ((head)->sqh_first == NULL)
#define QSIMPLEQ_FIRST(head) ((head)->sqh_first)
#define QSIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
typedef struct QTailQLink {
void *tql_next;
struct QTailQLink *tql_prev;
} QTailQLink;
/*
* Tail queue definitions. The union acts as a poor man template, as if
* it were QTailQLink<type>.
*/
#define QTAILQ_HEAD(name, type) \
union name { \
struct type *tqh_first; /* first element */ \
QTailQLink tqh_circ; /* link for circular backwards list */ \
}
#define QTAILQ_HEAD_INITIALIZER(head) \
{ .tqh_circ = { NULL, &(head).tqh_circ } }
#define QTAILQ_ENTRY(type) \
union { \
struct type *tqe_next; /* next element */ \
QTailQLink tqe_circ; /* link for circular backwards list */ \
}
/*
* Tail queue functions.
*/
#define QTAILQ_INIT(head) do { \
(head)->tqh_first = NULL; \
(head)->tqh_circ.tql_prev = &(head)->tqh_circ; \
} while (/*CONSTCOND*/0)
#define QTAILQ_INSERT_HEAD(head, elm, field) do { \
if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
(head)->tqh_first->field.tqe_circ.tql_prev = \
&(elm)->field.tqe_circ; \
else \
(head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ; \
(head)->tqh_first = (elm); \
(elm)->field.tqe_circ.tql_prev = &(head)->tqh_circ; \
} while (/*CONSTCOND*/0)
#define QTAILQ_INSERT_TAIL(head, elm, field) do { \
(elm)->field.tqe_next = NULL; \
(elm)->field.tqe_circ.tql_prev = (head)->tqh_circ.tql_prev; \
(head)->tqh_circ.tql_prev->tql_next = (elm); \
(head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ; \
} while (/*CONSTCOND*/0)
#define QTAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
(elm)->field.tqe_next->field.tqe_circ.tql_prev = \
&(elm)->field.tqe_circ; \
else \
(head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ; \
(listelm)->field.tqe_next = (elm); \
(elm)->field.tqe_circ.tql_prev = &(listelm)->field.tqe_circ; \
} while (/*CONSTCOND*/0)
#define QTAILQ_INSERT_BEFORE(listelm, elm, field) do { \
(elm)->field.tqe_circ.tql_prev = (listelm)->field.tqe_circ.tql_prev; \
(elm)->field.tqe_next = (listelm); \
(listelm)->field.tqe_circ.tql_prev->tql_next = (elm); \
(listelm)->field.tqe_circ.tql_prev = &(elm)->field.tqe_circ; \
} while (/*CONSTCOND*/0)
#define QTAILQ_REMOVE(head, elm, field) do { \
if (((elm)->field.tqe_next) != NULL) \
(elm)->field.tqe_next->field.tqe_circ.tql_prev = \
(elm)->field.tqe_circ.tql_prev; \
else \
(head)->tqh_circ.tql_prev = (elm)->field.tqe_circ.tql_prev; \
(elm)->field.tqe_circ.tql_prev->tql_next = (elm)->field.tqe_next; \
(elm)->field.tqe_circ.tql_prev = NULL; \
(elm)->field.tqe_circ.tql_next = NULL; \
(elm)->field.tqe_next = NULL; \
} while (/*CONSTCOND*/0)
/* remove @left, @right and all elements in between from @head */
#define QTAILQ_REMOVE_SEVERAL(head, left, right, field) do { \
if (((right)->field.tqe_next) != NULL) \
(right)->field.tqe_next->field.tqe_circ.tql_prev = \
(left)->field.tqe_circ.tql_prev; \
else \
(head)->tqh_circ.tql_prev = (left)->field.tqe_circ.tql_prev; \
(left)->field.tqe_circ.tql_prev->tql_next = (right)->field.tqe_next; \
} while (/*CONSTCOND*/0)
#define QTAILQ_FOREACH(var, head, field) \
for ((var) = ((head)->tqh_first); \
(var); \
(var) = ((var)->field.tqe_next))
#define QTAILQ_FOREACH_SAFE(var, head, field, next_var) \
for ((var) = ((head)->tqh_first); \
(var) && ((next_var) = ((var)->field.tqe_next), 1); \
(var) = (next_var))
#define QTAILQ_FOREACH_REVERSE(var, head, field) \
for ((var) = QTAILQ_LAST(head); \
(var); \
(var) = QTAILQ_PREV(var, field))
#define QTAILQ_FOREACH_REVERSE_SAFE(var, head, field, prev_var) \
for ((var) = QTAILQ_LAST(head); \
(var) && ((prev_var) = QTAILQ_PREV(var, field), 1); \
(var) = (prev_var))
/*
* Tail queue access methods.
*/
#define QTAILQ_EMPTY(head) ((head)->tqh_first == NULL)
#define QTAILQ_FIRST(head) ((head)->tqh_first)
#define QTAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
#define QTAILQ_IN_USE(elm, field) ((elm)->field.tqe_circ.tql_prev != NULL)
#define QTAILQ_LINK_PREV(link) \
((link).tql_prev->tql_prev->tql_next)
#define QTAILQ_LAST(head) \
((typeof((head)->tqh_first)) QTAILQ_LINK_PREV((head)->tqh_circ))
#define QTAILQ_PREV(elm, field) \
((typeof((elm)->field.tqe_next)) QTAILQ_LINK_PREV((elm)->field.tqe_circ))
#define field_at_offset(base, offset, type) \
((type *) (((char *) (base)) + (offset)))
/*
* Raw access of elements of a tail queue head. Offsets are all zero
* because it's a union.
*/
#define QTAILQ_RAW_FIRST(head) \
field_at_offset(head, 0, void *)
#define QTAILQ_RAW_TQH_CIRC(head) \
field_at_offset(head, 0, QTailQLink)
/*
* Raw access of elements of a tail entry
*/
#define QTAILQ_RAW_NEXT(elm, entry) \
field_at_offset(elm, entry, void *)
#define QTAILQ_RAW_TQE_CIRC(elm, entry) \
field_at_offset(elm, entry, QTailQLink)
/*
* Tail queue traversal using pointer arithmetic.
*/
#define QTAILQ_RAW_FOREACH(elm, head, entry) \
for ((elm) = *QTAILQ_RAW_FIRST(head); \
(elm); \
(elm) = *QTAILQ_RAW_NEXT(elm, entry))
/*
* Tail queue insertion using pointer arithmetic.
*/
#define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do { \
*QTAILQ_RAW_NEXT(elm, entry) = NULL; \
QTAILQ_RAW_TQE_CIRC(elm, entry)->tql_prev = QTAILQ_RAW_TQH_CIRC(head)->tql_prev; \
QTAILQ_RAW_TQH_CIRC(head)->tql_prev->tql_next = (elm); \
QTAILQ_RAW_TQH_CIRC(head)->tql_prev = QTAILQ_RAW_TQE_CIRC(elm, entry); \
} while (/*CONSTCOND*/0)
#define QLIST_RAW_FIRST(head) \
field_at_offset(head, 0, void *)
#define QLIST_RAW_NEXT(elm, entry) \
field_at_offset(elm, entry, void *)
#define QLIST_RAW_PREVIOUS(elm, entry) \
field_at_offset(elm, entry + sizeof(void *), void *)
#define QLIST_RAW_FOREACH(elm, head, entry) \
for ((elm) = *QLIST_RAW_FIRST(head); \
(elm); \
(elm) = *QLIST_RAW_NEXT(elm, entry))
#define QLIST_RAW_INSERT_AFTER(head, prev, elem, entry) do { \
*QLIST_RAW_NEXT(prev, entry) = elem; \
*QLIST_RAW_PREVIOUS(elem, entry) = QLIST_RAW_NEXT(prev, entry); \
*QLIST_RAW_NEXT(elem, entry) = NULL; \
} while (0)
#define QLIST_RAW_INSERT_HEAD(head, elm, entry) do { \
void *first = *QLIST_RAW_FIRST(head); \
*QLIST_RAW_FIRST(head) = elm; \
*QLIST_RAW_PREVIOUS(elm, entry) = QLIST_RAW_FIRST(head); \
if (first) { \
*QLIST_RAW_NEXT(elm, entry) = first; \
*QLIST_RAW_PREVIOUS(first, entry) = QLIST_RAW_NEXT(elm, entry); \
} else { \
*QLIST_RAW_NEXT(elm, entry) = NULL; \
} \
} while (0)
#endif /* QEMU_SYS_QUEUE_H */