+#if (defined(_KERNEL) && defined(INVARIANTS)) || defined(QUEUE_MACRO_DEBUG)
+#define QMD_LIST_CHECK_HEAD(head, field) do { \
+ if (LIST_FIRST((head)) != NULL && \
+ LIST_FIRST((head))->field.le_prev != \
+ &LIST_FIRST((head))) \
+ panic("Bad list head %p first->prev != head", (head)); \
+} while (0)
+
+#define QMD_LIST_CHECK_NEXT(elm, field) do { \
+ if (LIST_NEXT((elm), field) != NULL && \
+ LIST_NEXT((elm), field)->field.le_prev != \
+ &((elm)->field.le_next)) \
+ panic("Bad link elm %p next->prev != elm", (elm)); \
+} while (0)
+
+#define QMD_LIST_CHECK_PREV(elm, field) do { \
+ if (*(elm)->field.le_prev != (elm)) \
+ panic("Bad link elm %p prev->next != elm", (elm)); \
+} while (0)
+#else
+#define QMD_LIST_CHECK_HEAD(head, field)
+#define QMD_LIST_CHECK_NEXT(elm, field)
+#define QMD_LIST_CHECK_PREV(elm, field)
+#endif /* (_KERNEL && INVARIANTS) || QUEUE_MACRO_DEBUG */
+
+#define LIST_EMPTY(head) ((head)->lh_first == NULL)
+
+#define LIST_FIRST(head) ((head)->lh_first)