diff options
Diffstat (limited to 'misc/sys')
| -rw-r--r-- | misc/sys/queue.h | 441 |
1 files changed, 389 insertions, 52 deletions
diff --git a/misc/sys/queue.h b/misc/sys/queue.h index 5b6e2a0a23..d709d48be5 100644 --- a/misc/sys/queue.h +++ b/misc/sys/queue.h @@ -10,7 +10,7 @@ * 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. - * 4. Neither the name of the University nor the names of its contributors + * 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. * @@ -26,29 +26,46 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * @(#)queue.h 8.3 (Berkeley) 12/13/93 + * @(#)queue.h 8.5 (Berkeley) 8/20/94 */ -#ifndef _SYS_QUEUE_H -#define _SYS_QUEUE_H 1 +#ifndef _SYS_QUEUE_H_ +#define _SYS_QUEUE_H_ /* - * This file defines three types of data structures: lists, tail queues, - * and circular queues. + * This file defines five types of data structures: singly-linked lists, + * lists, simple queues, tail queues, and circular 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 after - * an existing element or at the head of the list. A list may only be - * traversed in the forward direction. + * 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 after - * an existing element, at the head of the list, or at the end of the - * list. A tail queue may only be traversed in the forward direction. + * 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. * * A circle 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 @@ -64,12 +81,15 @@ /* * List definitions. */ -#define LIST_HEAD(name, type) \ +#define LIST_HEAD(name, type) \ struct name { \ struct type *lh_first; /* first element */ \ } -#define LIST_ENTRY(type) \ +#define LIST_HEAD_INITIALIZER(head) \ + { NULL } + +#define LIST_ENTRY(type) \ struct { \ struct type *le_next; /* next element */ \ struct type **le_prev; /* address of previous next element */ \ @@ -78,73 +98,315 @@ struct { \ /* * List functions. */ -#define LIST_INIT(head) { \ +#define LIST_INIT(head) do { \ (head)->lh_first = NULL; \ -} +} while (/*CONSTCOND*/0) -#define LIST_INSERT_AFTER(listelm, elm, field) { \ +#define LIST_INSERT_AFTER(listelm, elm, field) do { \ + QUEUEDEBUG_LIST_OP((listelm), field) \ 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 LIST_INSERT_HEAD(head, elm, field) { \ +#define LIST_INSERT_BEFORE(listelm, elm, field) do { \ + QUEUEDEBUG_LIST_OP((listelm), field) \ + (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 LIST_INSERT_HEAD(head, elm, field) do { \ + QUEUEDEBUG_LIST_INSERT_HEAD((head), (elm), field) \ 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 LIST_REMOVE(elm, field) { \ +#define LIST_REMOVE(elm, field) do { \ + QUEUEDEBUG_LIST_OP((elm), field) \ 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; \ + QUEUEDEBUG_LIST_POSTREMOVE((elm), field) \ +} while (/*CONSTCOND*/0) + +#define LIST_FOREACH(var, head, field) \ + for ((var) = ((head)->lh_first); \ + (var); \ + (var) = ((var)->field.le_next)) + +/* + * List access methods. + */ +#define LIST_EMPTY(head) ((head)->lh_first == NULL) +#define LIST_FIRST(head) ((head)->lh_first) +#define LIST_NEXT(elm, field) ((elm)->field.le_next) + + +/* + * Singly-linked List definitions. + */ +#define SLIST_HEAD(name, type) \ +struct name { \ + struct type *slh_first; /* first element */ \ +} + +#define SLIST_HEAD_INITIALIZER(head) \ + { NULL } + +#define SLIST_ENTRY(type) \ +struct { \ + struct type *sle_next; /* next element */ \ +} + +/* + * Singly-linked List functions. + */ +#define SLIST_INIT(head) do { \ + (head)->slh_first = NULL; \ +} while (/*CONSTCOND*/0) + +#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ + (elm)->field.sle_next = (slistelm)->field.sle_next; \ + (slistelm)->field.sle_next = (elm); \ +} while (/*CONSTCOND*/0) + +#define SLIST_INSERT_HEAD(head, elm, field) do { \ + (elm)->field.sle_next = (head)->slh_first; \ + (head)->slh_first = (elm); \ +} while (/*CONSTCOND*/0) + +#define SLIST_REMOVE_HEAD(head, field) do { \ + (head)->slh_first = (head)->slh_first->field.sle_next; \ +} while (/*CONSTCOND*/0) + +#define SLIST_REMOVE(head, elm, type, field) do { \ + if ((head)->slh_first == (elm)) { \ + SLIST_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; \ + } \ +} while (/*CONSTCOND*/0) + +#define SLIST_FOREACH(var, head, field) \ + for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next) + +/* + * Singly-linked List access methods. + */ +#define SLIST_EMPTY(head) ((head)->slh_first == NULL) +#define SLIST_FIRST(head) ((head)->slh_first) +#define SLIST_NEXT(elm, field) ((elm)->field.sle_next) + + +/* + * Singly-linked Tail queue declarations. + */ +#define STAILQ_HEAD(name, type) \ +struct name { \ + struct type *stqh_first; /* first element */ \ + struct type **stqh_last; /* addr of last next element */ \ +} + +#define STAILQ_HEAD_INITIALIZER(head) \ + { NULL, &(head).stqh_first } + +#define STAILQ_ENTRY(type) \ +struct { \ + struct type *stqe_next; /* next element */ \ +} + +/* + * Singly-linked Tail queue functions. + */ +#define STAILQ_INIT(head) do { \ + (head)->stqh_first = NULL; \ + (head)->stqh_last = &(head)->stqh_first; \ +} while (/*CONSTCOND*/0) + +#define STAILQ_INSERT_HEAD(head, elm, field) do { \ + if (((elm)->field.stqe_next = (head)->stqh_first) == NULL) \ + (head)->stqh_last = &(elm)->field.stqe_next; \ + (head)->stqh_first = (elm); \ +} while (/*CONSTCOND*/0) + +#define STAILQ_INSERT_TAIL(head, elm, field) do { \ + (elm)->field.stqe_next = NULL; \ + *(head)->stqh_last = (elm); \ + (head)->stqh_last = &(elm)->field.stqe_next; \ +} while (/*CONSTCOND*/0) + +#define STAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ + if (((elm)->field.stqe_next = (listelm)->field.stqe_next) == NULL)\ + (head)->stqh_last = &(elm)->field.stqe_next; \ + (listelm)->field.stqe_next = (elm); \ +} while (/*CONSTCOND*/0) + +#define STAILQ_REMOVE_HEAD(head, field) do { \ + if (((head)->stqh_first = (head)->stqh_first->field.stqe_next) == NULL) \ + (head)->stqh_last = &(head)->stqh_first; \ +} while (/*CONSTCOND*/0) + +#define STAILQ_REMOVE(head, elm, type, field) do { \ + if ((head)->stqh_first == (elm)) { \ + STAILQ_REMOVE_HEAD((head), field); \ + } else { \ + struct type *curelm = (head)->stqh_first; \ + while (curelm->field.stqe_next != (elm)) \ + curelm = curelm->field.stqe_next; \ + if ((curelm->field.stqe_next = \ + curelm->field.stqe_next->field.stqe_next) == NULL) \ + (head)->stqh_last = &(curelm)->field.stqe_next; \ + } \ +} while (/*CONSTCOND*/0) + +#define STAILQ_FOREACH(var, head, field) \ + for ((var) = ((head)->stqh_first); \ + (var); \ + (var) = ((var)->field.stqe_next)) + +/* + * Singly-linked Tail queue access methods. + */ +#define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) +#define STAILQ_FIRST(head) ((head)->stqh_first) +#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) + + +/* + * Simple queue definitions. + */ +#define SIMPLEQ_HEAD(name, type) \ +struct name { \ + struct type *sqh_first; /* first element */ \ + struct type **sqh_last; /* addr of last next element */ \ +} + +#define SIMPLEQ_HEAD_INITIALIZER(head) \ + { NULL, &(head).sqh_first } + +#define SIMPLEQ_ENTRY(type) \ +struct { \ + struct type *sqe_next; /* next element */ \ } /* + * Simple queue functions. + */ +#define SIMPLEQ_INIT(head) do { \ + (head)->sqh_first = NULL; \ + (head)->sqh_last = &(head)->sqh_first; \ +} while (/*CONSTCOND*/0) + +#define SIMPLEQ_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 SIMPLEQ_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 SIMPLEQ_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 SIMPLEQ_REMOVE_HEAD(head, field) do { \ + if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \ + (head)->sqh_last = &(head)->sqh_first; \ +} while (/*CONSTCOND*/0) + +#define SIMPLEQ_REMOVE(head, elm, type, field) do { \ + if ((head)->sqh_first == (elm)) { \ + SIMPLEQ_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; \ + } \ +} while (/*CONSTCOND*/0) + +#define SIMPLEQ_FOREACH(var, head, field) \ + for ((var) = ((head)->sqh_first); \ + (var); \ + (var) = ((var)->field.sqe_next)) + +/* + * Simple queue access methods. + */ +#define SIMPLEQ_EMPTY(head) ((head)->sqh_first == NULL) +#define SIMPLEQ_FIRST(head) ((head)->sqh_first) +#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next) + + +/* * Tail queue definitions. */ -#define TAILQ_HEAD(name, type) \ +#define _TAILQ_HEAD(name, type, qual) \ struct name { \ - struct type *tqh_first; /* first element */ \ - struct type **tqh_last; /* addr of last next element */ \ + qual type *tqh_first; /* first element */ \ + qual type *qual *tqh_last; /* addr of last next element */ \ } +#define TAILQ_HEAD(name, type) _TAILQ_HEAD(name, struct type,) + +#define TAILQ_HEAD_INITIALIZER(head) \ + { NULL, &(head).tqh_first } -#define TAILQ_ENTRY(type) \ +#define _TAILQ_ENTRY(type, qual) \ struct { \ - struct type *tqe_next; /* next element */ \ - struct type **tqe_prev; /* address of previous next element */ \ + qual type *tqe_next; /* next element */ \ + qual type *qual *tqe_prev; /* address of previous next element */\ } +#define TAILQ_ENTRY(type) _TAILQ_ENTRY(struct type,) /* * Tail queue functions. */ -#define TAILQ_INIT(head) { \ +#define TAILQ_INIT(head) do { \ (head)->tqh_first = NULL; \ (head)->tqh_last = &(head)->tqh_first; \ -} +} while (/*CONSTCOND*/0) -#define TAILQ_INSERT_HEAD(head, elm, field) { \ +#define TAILQ_INSERT_HEAD(head, elm, field) do { \ + QUEUEDEBUG_TAILQ_INSERT_HEAD((head), (elm), field) \ if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \ - (elm)->field.tqe_next->field.tqe_prev = \ + (head)->tqh_first->field.tqe_prev = \ &(elm)->field.tqe_next; \ else \ (head)->tqh_last = &(elm)->field.tqe_next; \ (head)->tqh_first = (elm); \ (elm)->field.tqe_prev = &(head)->tqh_first; \ -} +} while (/*CONSTCOND*/0) -#define TAILQ_INSERT_TAIL(head, elm, field) { \ +#define TAILQ_INSERT_TAIL(head, elm, field) do { \ + QUEUEDEBUG_TAILQ_INSERT_TAIL((head), (elm), field) \ (elm)->field.tqe_next = NULL; \ (elm)->field.tqe_prev = (head)->tqh_last; \ *(head)->tqh_last = (elm); \ (head)->tqh_last = &(elm)->field.tqe_next; \ -} +} while (/*CONSTCOND*/0) -#define TAILQ_INSERT_AFTER(head, listelm, elm, field) { \ +#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ + QUEUEDEBUG_TAILQ_OP((listelm), field) \ if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\ (elm)->field.tqe_next->field.tqe_prev = \ &(elm)->field.tqe_next; \ @@ -152,27 +414,64 @@ struct { \ (head)->tqh_last = &(elm)->field.tqe_next; \ (listelm)->field.tqe_next = (elm); \ (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \ -} +} while (/*CONSTCOND*/0) + +#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ + QUEUEDEBUG_TAILQ_OP((listelm), field) \ + (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ + (elm)->field.tqe_next = (listelm); \ + *(listelm)->field.tqe_prev = (elm); \ + (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \ +} while (/*CONSTCOND*/0) -#define TAILQ_REMOVE(head, elm, field) { \ +#define TAILQ_REMOVE(head, elm, field) do { \ + QUEUEDEBUG_TAILQ_PREREMOVE((head), (elm), field) \ + QUEUEDEBUG_TAILQ_OP((elm), field) \ if (((elm)->field.tqe_next) != NULL) \ (elm)->field.tqe_next->field.tqe_prev = \ (elm)->field.tqe_prev; \ else \ (head)->tqh_last = (elm)->field.tqe_prev; \ *(elm)->field.tqe_prev = (elm)->field.tqe_next; \ -} + QUEUEDEBUG_TAILQ_POSTREMOVE((elm), field); \ +} while (/*CONSTCOND*/0) + +#define TAILQ_FOREACH(var, head, field) \ + for ((var) = ((head)->tqh_first); \ + (var); \ + (var) = ((var)->field.tqe_next)) + +#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ + for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last)); \ + (var); \ + (var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last))) + +/* + * Tail queue access methods. + */ +#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) +#define TAILQ_FIRST(head) ((head)->tqh_first) +#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) + +#define TAILQ_LAST(head, headname) \ + (*(((struct headname *)((head)->tqh_last))->tqh_last)) +#define TAILQ_PREV(elm, headname, field) \ + (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) + /* * Circular queue definitions. */ -#define CIRCLEQ_HEAD(name, type) \ +#define CIRCLEQ_HEAD(name, type) \ struct name { \ struct type *cqh_first; /* first element */ \ struct type *cqh_last; /* last element */ \ } -#define CIRCLEQ_ENTRY(type) \ +#define CIRCLEQ_HEAD_INITIALIZER(head) \ + { (void *)&head, (void *)&head } + +#define CIRCLEQ_ENTRY(type) \ struct { \ struct type *cqe_next; /* next element */ \ struct type *cqe_prev; /* previous element */ \ @@ -181,12 +480,14 @@ struct { \ /* * Circular queue functions. */ -#define CIRCLEQ_INIT(head) { \ +#define CIRCLEQ_INIT(head) do { \ (head)->cqh_first = (void *)(head); \ (head)->cqh_last = (void *)(head); \ -} +} while (/*CONSTCOND*/0) -#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) { \ +#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \ + QUEUEDEBUG_CIRCLEQ_HEAD((head), field) \ + QUEUEDEBUG_CIRCLEQ_ELM((head), (listelm), field) \ (elm)->field.cqe_next = (listelm)->field.cqe_next; \ (elm)->field.cqe_prev = (listelm); \ if ((listelm)->field.cqe_next == (void *)(head)) \ @@ -194,9 +495,11 @@ struct { \ else \ (listelm)->field.cqe_next->field.cqe_prev = (elm); \ (listelm)->field.cqe_next = (elm); \ -} +} while (/*CONSTCOND*/0) -#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) { \ +#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \ + QUEUEDEBUG_CIRCLEQ_HEAD((head), field) \ + QUEUEDEBUG_CIRCLEQ_ELM((head), (listelm), field) \ (elm)->field.cqe_next = (listelm); \ (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \ if ((listelm)->field.cqe_prev == (void *)(head)) \ @@ -204,9 +507,10 @@ struct { \ else \ (listelm)->field.cqe_prev->field.cqe_next = (elm); \ (listelm)->field.cqe_prev = (elm); \ -} +} while (/*CONSTCOND*/0) -#define CIRCLEQ_INSERT_HEAD(head, elm, field) { \ +#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \ + QUEUEDEBUG_CIRCLEQ_HEAD((head), field) \ (elm)->field.cqe_next = (head)->cqh_first; \ (elm)->field.cqe_prev = (void *)(head); \ if ((head)->cqh_last == (void *)(head)) \ @@ -214,9 +518,10 @@ struct { \ else \ (head)->cqh_first->field.cqe_prev = (elm); \ (head)->cqh_first = (elm); \ -} +} while (/*CONSTCOND*/0) -#define CIRCLEQ_INSERT_TAIL(head, elm, field) { \ +#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \ + QUEUEDEBUG_CIRCLEQ_HEAD((head), field) \ (elm)->field.cqe_next = (void *)(head); \ (elm)->field.cqe_prev = (head)->cqh_last; \ if ((head)->cqh_first == (void *)(head)) \ @@ -224,9 +529,11 @@ struct { \ else \ (head)->cqh_last->field.cqe_next = (elm); \ (head)->cqh_last = (elm); \ -} +} while (/*CONSTCOND*/0) -#define CIRCLEQ_REMOVE(head, elm, field) { \ +#define CIRCLEQ_REMOVE(head, elm, field) do { \ + QUEUEDEBUG_CIRCLEQ_HEAD((head), field) \ + QUEUEDEBUG_CIRCLEQ_ELM((head), (elm), field) \ if ((elm)->field.cqe_next == (void *)(head)) \ (head)->cqh_last = (elm)->field.cqe_prev; \ else \ @@ -237,5 +544,35 @@ struct { \ else \ (elm)->field.cqe_prev->field.cqe_next = \ (elm)->field.cqe_next; \ -} + QUEUEDEBUG_CIRCLEQ_POSTREMOVE((elm), field) \ +} while (/*CONSTCOND*/0) + +#define CIRCLEQ_FOREACH(var, head, field) \ + for ((var) = ((head)->cqh_first); \ + (var) != (const void *)(head); \ + (var) = ((var)->field.cqe_next)) + +#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \ + for ((var) = ((head)->cqh_last); \ + (var) != (const void *)(head); \ + (var) = ((var)->field.cqe_prev)) + +/* + * Circular queue access methods. + */ +#define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head)) +#define CIRCLEQ_FIRST(head) ((head)->cqh_first) +#define CIRCLEQ_LAST(head) ((head)->cqh_last) +#define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next) +#define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev) + +#define CIRCLEQ_LOOP_NEXT(head, elm, field) \ + (((elm)->field.cqe_next == (void *)(head)) \ + ? ((head)->cqh_first) \ + : (elm->field.cqe_next)) +#define CIRCLEQ_LOOP_PREV(head, elm, field) \ + (((elm)->field.cqe_prev == (void *)(head)) \ + ? ((head)->cqh_last) \ + : (elm->field.cqe_prev)) + #endif /* sys/queue.h */ |