[dpdk-dev] [PATCH v2 1/3] eal/windows: replace sys/queue.h with a complete one from FreeBSD

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

Limited version imported previously lacks STAILQ macros used by tracing
and SLIST macros used by memory management.  Import a complete file from
FreeBSD, since its license exception is already approved by Technical
Board.

Signed-off-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
---
 lib/librte_eal/windows/include/sys/queue.h | 663 +++++++++++++++++++--
 1 file changed, 601 insertions(+), 62 deletions(-)

diff --git a/lib/librte_eal/windows/include/sys/queue.h b/lib/librte_eal/windows/include/sys/queue.h
index a65949a78..9756bee6f 100644
--- a/lib/librte_eal/windows/include/sys/queue.h
+++ b/lib/librte_eal/windows/include/sys/queue.h
@@ -8,7 +8,36 @@
 #define	_SYS_QUEUE_H_
 
 /*
- * This file defines tail queues.
+ * This file defines four types of data structures: singly-linked lists,
+ * singly-linked tail queues, lists 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 singly-linked 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
+ * 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, at the head of the list, or at the
+ * end of the list. Elements being removed from the head of the tail queue
+ * should use the explicit macro for this purpose for optimum efficiency.
+ * A singly-linked tail queue may only be traversed in the forward direction.
+ * Singly-linked tail queues are ideal for applications with large datasets
+ * and few or no removals or for implementing a FIFO 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 be traversed in either 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
@@ -17,65 +46,93 @@
  * 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.
+ *
  * Below is a summary of implemented functions where:
  *  +  means the macro is available
  *  -  means the macro is not available
  *  s  means the macro is available but is slow (runs in O(n) time)
  *
- *				TAILQ
- * _HEAD			+
- * _CLASS_HEAD			+
- * _HEAD_INITIALIZER		+
- * _ENTRY			+
- * _CLASS_ENTRY			+
- * _INIT			+
- * _EMPTY			+
- * _FIRST			+
- * _NEXT			+
- * _PREV			+
- * _LAST			+
- * _LAST_FAST			+
- * _FOREACH			+
- * _FOREACH_FROM		+
- * _FOREACH_SAFE		+
- * _FOREACH_FROM_SAFE		+
- * _FOREACH_REVERSE		+
- * _FOREACH_REVERSE_FROM	+
- * _FOREACH_REVERSE_SAFE	+
- * _FOREACH_REVERSE_FROM_SAFE	+
- * _INSERT_HEAD			+
- * _INSERT_BEFORE		+
- * _INSERT_AFTER		+
- * _INSERT_TAIL			+
- * _CONCAT			+
- * _REMOVE_AFTER		-
- * _REMOVE_HEAD			-
- * _REMOVE			+
- * _SWAP			+
+ *				SLIST	LIST	STAILQ	TAILQ
+ * _HEAD			+	+	+	+
+ * _CLASS_HEAD			+	+	+	+
+ * _HEAD_INITIALIZER		+	+	+	+
+ * _ENTRY			+	+	+	+
+ * _CLASS_ENTRY			+	+	+	+
+ * _INIT			+	+	+	+
+ * _EMPTY			+	+	+	+
+ * _FIRST			+	+	+	+
+ * _NEXT			+	+	+	+
+ * _PREV			-	+	-	+
+ * _LAST			-	-	+	+
+ * _LAST_FAST			-	-	-	+
+ * _FOREACH			+	+	+	+
+ * _FOREACH_FROM		+	+	+	+
+ * _FOREACH_SAFE		+	+	+	+
+ * _FOREACH_FROM_SAFE		+	+	+	+
+ * _FOREACH_REVERSE		-	-	-	+
+ * _FOREACH_REVERSE_FROM	-	-	-	+
+ * _FOREACH_REVERSE_SAFE	-	-	-	+
+ * _FOREACH_REVERSE_FROM_SAFE	-	-	-	+
+ * _INSERT_HEAD			+	+	+	+
+ * _INSERT_BEFORE		-	+	-	+
+ * _INSERT_AFTER		+	+	+	+
+ * _INSERT_TAIL			-	-	+	+
+ * _CONCAT			s	s	+	+
+ * _REMOVE_AFTER		+	-	+	-
+ * _REMOVE_HEAD			+	-	+	-
+ * _REMOVE			s	+	s	+
+ * _SWAP			+	+	+	+
  *
  */
-
-#ifdef __cplusplus
-extern "C" {
+#ifdef QUEUE_MACRO_DEBUG
+#warn Use QUEUE_MACRO_DEBUG_TRACE and/or QUEUE_MACRO_DEBUG_TRASH
+#define	QUEUE_MACRO_DEBUG_TRACE
+#define	QUEUE_MACRO_DEBUG_TRASH
 #endif
 
-/*
- * List definitions.
- */
-#define	LIST_HEAD(name, type)						\
-struct name {								\
-	struct type *lh_first;	/* first element */			\
-}
+#ifdef QUEUE_MACRO_DEBUG_TRACE
+/* Store the last 2 places the queue element or head was altered */
+struct qm_trace {
+	unsigned long	 lastline;
+	unsigned long	 prevline;
+	const char	*lastfile;
+	const char	*prevfile;
+};
+
+#define	TRACEBUF	struct qm_trace trace;
+#define	TRACEBUF_INITIALIZER	{ __LINE__, 0, __FILE__, NULL } ,
+
+#define	QMD_TRACE_HEAD(head) do {					\
+	(head)->trace.prevline = (head)->trace.lastline;		\
+	(head)->trace.prevfile = (head)->trace.lastfile;		\
+	(head)->trace.lastline = __LINE__;				\
+	(head)->trace.lastfile = __FILE__;				\
+} while (0)
 
+#define	QMD_TRACE_ELEM(elem) do {					\
+	(elem)->trace.prevline = (elem)->trace.lastline;		\
+	(elem)->trace.prevfile = (elem)->trace.lastfile;		\
+	(elem)->trace.lastline = __LINE__;				\
+	(elem)->trace.lastfile = __FILE__;				\
+} while (0)
+
+#else	/* !QUEUE_MACRO_DEBUG_TRACE */
 #define	QMD_TRACE_ELEM(elem)
 #define	QMD_TRACE_HEAD(head)
 #define	TRACEBUF
 #define	TRACEBUF_INITIALIZER
+#endif	/* QUEUE_MACRO_DEBUG_TRACE */
 
+#ifdef QUEUE_MACRO_DEBUG_TRASH
+#define	QMD_SAVELINK(name, link)	void **name = (void *)&(link)
+#define	TRASHIT(x)		do {(x) = (void *)-1;} while (0)
+#define	QMD_IS_TRASHED(x)	((x) == (void *)(intptr_t)-1)
+#else	/* !QUEUE_MACRO_DEBUG_TRASH */
+#define	QMD_SAVELINK(name, link)
 #define	TRASHIT(x)
 #define	QMD_IS_TRASHED(x)	0
-
-#define	QMD_SAVELINK(name, link)
+#endif	/* QUEUE_MACRO_DEBUG_TRASH */
 
 #ifdef __cplusplus
 /*
@@ -86,6 +143,445 @@ struct name {								\
 #define	QUEUE_TYPEOF(type) struct type
 #endif
 
+/*
+ * Singly-linked List declarations.
+ */
+#define	SLIST_HEAD(name, type)						\
+struct name {								\
+	struct type *slh_first;	/* first element */			\
+}
+
+#define	SLIST_CLASS_HEAD(name, type)					\
+struct name {								\
+	class type *slh_first;	/* first element */			\
+}
+
+#define	SLIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define	SLIST_ENTRY(type)						\
+struct {								\
+	struct type *sle_next;	/* next element */			\
+}
+
+#define	SLIST_CLASS_ENTRY(type)						\
+struct {								\
+	class type *sle_next;		/* next element */		\
+}
+
+/*
+ * Singly-linked List functions.
+ */
+#if (defined(_KERNEL) && defined(INVARIANTS))
+#define	QMD_SLIST_CHECK_PREVPTR(prevp, elm) do {			\
+	if (*(prevp) != (elm))						\
+		panic("Bad prevptr *(%p) == %p != %p",			\
+		    (prevp), *(prevp), (elm));				\
+} while (0)
+#else
+#define	QMD_SLIST_CHECK_PREVPTR(prevp, elm)
+#endif
+
+#define SLIST_CONCAT(head1, head2, type, field) do {			\
+	QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1);		\
+	if (curelm == NULL) {						\
+		if ((SLIST_FIRST(head1) = SLIST_FIRST(head2)) != NULL)	\
+			SLIST_INIT(head2);				\
+	} else if (SLIST_FIRST(head2) != NULL) {			\
+		while (SLIST_NEXT(curelm, field) != NULL)		\
+			curelm = SLIST_NEXT(curelm, field);		\
+		SLIST_NEXT(curelm, field) = SLIST_FIRST(head2);		\
+		SLIST_INIT(head2);					\
+	}								\
+} while (0)
+
+#define	SLIST_EMPTY(head)	((head)->slh_first == NULL)
+
+#define	SLIST_FIRST(head)	((head)->slh_first)
+
+#define	SLIST_FOREACH(var, head, field)					\
+	for ((var) = SLIST_FIRST((head));				\
+	    (var);							\
+	    (var) = SLIST_NEXT((var), field))
+
+#define	SLIST_FOREACH_FROM(var, head, field)				\
+	for ((var) = ((var) ? (var) : SLIST_FIRST((head)));		\
+	    (var);							\
+	    (var) = SLIST_NEXT((var), field))
+
+#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = SLIST_FIRST((head));				\
+	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
+#define	SLIST_FOREACH_FROM_SAFE(var, head, field, tvar)			\
+	for ((var) = ((var) ? (var) : SLIST_FIRST((head)));		\
+	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
+#define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
+	for ((varp) = &SLIST_FIRST((head));				\
+	    ((var) = *(varp)) != NULL;					\
+	    (varp) = &SLIST_NEXT((var), field))
+
+#define	SLIST_INIT(head) do {						\
+	SLIST_FIRST((head)) = NULL;					\
+} while (0)
+
+#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
+	SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);	\
+	SLIST_NEXT((slistelm), field) = (elm);				\
+} while (0)
+
+#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
+	SLIST_NEXT((elm), field) = SLIST_FIRST((head));			\
+	SLIST_FIRST((head)) = (elm);					\
+} while (0)
+
+#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
+
+#define	SLIST_REMOVE(head, elm, type, field) do {			\
+	QMD_SAVELINK(oldnext, (elm)->field.sle_next);			\
+	if (SLIST_FIRST((head)) == (elm)) {				\
+		SLIST_REMOVE_HEAD((head), field);			\
+	}								\
+	else {								\
+		QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head);		\
+		while (SLIST_NEXT(curelm, field) != (elm))		\
+			curelm = SLIST_NEXT(curelm, field);		\
+		SLIST_REMOVE_AFTER(curelm, field);			\
+	}								\
+	TRASHIT(*oldnext);						\
+} while (0)
+
+#define SLIST_REMOVE_AFTER(elm, field) do {				\
+	SLIST_NEXT(elm, field) =					\
+	    SLIST_NEXT(SLIST_NEXT(elm, field), field);			\
+} while (0)
+
+#define	SLIST_REMOVE_HEAD(head, field) do {				\
+	SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);	\
+} while (0)
+
+#define	SLIST_REMOVE_PREVPTR(prevp, elm, field) do {			\
+	QMD_SLIST_CHECK_PREVPTR(prevp, elm);				\
+	*(prevp) = SLIST_NEXT(elm, field);				\
+	TRASHIT((elm)->field.sle_next);					\
+} while (0)
+
+#define SLIST_SWAP(head1, head2, type) do {				\
+	QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1);		\
+	SLIST_FIRST(head1) = SLIST_FIRST(head2);			\
+	SLIST_FIRST(head2) = swap_first;				\
+} while (0)
+
+/*
+ * 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_CLASS_HEAD(name, type)					\
+struct name {								\
+	class type *stqh_first;	/* first element */			\
+	class 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 */			\
+}
+
+#define	STAILQ_CLASS_ENTRY(type)					\
+struct {								\
+	class type *stqe_next;	/* next element */			\
+}
+
+/*
+ * Singly-linked Tail queue functions.
+ */
+#define	STAILQ_CONCAT(head1, head2) do {				\
+	if (!STAILQ_EMPTY((head2))) {					\
+		*(head1)->stqh_last = (head2)->stqh_first;		\
+		(head1)->stqh_last = (head2)->stqh_last;		\
+		STAILQ_INIT((head2));					\
+	}								\
+} while (0)
+
+#define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)
+
+#define	STAILQ_FIRST(head)	((head)->stqh_first)
+
+#define	STAILQ_FOREACH(var, head, field)				\
+	for((var) = STAILQ_FIRST((head));				\
+	   (var);							\
+	   (var) = STAILQ_NEXT((var), field))
+
+#define	STAILQ_FOREACH_FROM(var, head, field)				\
+	for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));		\
+	   (var);							\
+	   (var) = STAILQ_NEXT((var), field))
+
+#define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = STAILQ_FIRST((head));				\
+	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
+#define	STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)		\
+	for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));		\
+	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
+#define	STAILQ_INIT(head) do {						\
+	STAILQ_FIRST((head)) = NULL;					\
+	(head)->stqh_last = &STAILQ_FIRST((head));			\
+} while (0)
+
+#define	STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {		\
+	if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
+		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
+	STAILQ_NEXT((tqelm), field) = (elm);				\
+} while (0)
+
+#define	STAILQ_INSERT_HEAD(head, elm, field) do {			\
+	if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL)	\
+		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
+	STAILQ_FIRST((head)) = (elm);					\
+} while (0)
+
+#define	STAILQ_INSERT_TAIL(head, elm, field) do {			\
+	STAILQ_NEXT((elm), field) = NULL;				\
+	*(head)->stqh_last = (elm);					\
+	(head)->stqh_last = &STAILQ_NEXT((elm), field);			\
+} while (0)
+
+#define	STAILQ_LAST(head, type, field)				\
+	(STAILQ_EMPTY((head)) ? NULL :				\
+	    __containerof((head)->stqh_last,			\
+	    QUEUE_TYPEOF(type), field.stqe_next))
+
+#define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)
+
+#define	STAILQ_REMOVE(head, elm, type, field) do {			\
+	QMD_SAVELINK(oldnext, (elm)->field.stqe_next);			\
+	if (STAILQ_FIRST((head)) == (elm)) {				\
+		STAILQ_REMOVE_HEAD((head), field);			\
+	}								\
+	else {								\
+		QUEUE_TYPEOF(type) *curelm = STAILQ_FIRST(head);	\
+		while (STAILQ_NEXT(curelm, field) != (elm))		\
+			curelm = STAILQ_NEXT(curelm, field);		\
+		STAILQ_REMOVE_AFTER(head, curelm, field);		\
+	}								\
+	TRASHIT(*oldnext);						\
+} while (0)
+
+#define STAILQ_REMOVE_AFTER(head, elm, field) do {			\
+	if ((STAILQ_NEXT(elm, field) =					\
+	     STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)	\
+		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
+} while (0)
+
+#define	STAILQ_REMOVE_HEAD(head, field) do {				\
+	if ((STAILQ_FIRST((head)) =					\
+	     STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)		\
+		(head)->stqh_last = &STAILQ_FIRST((head));		\
+} while (0)
+
+#define STAILQ_SWAP(head1, head2, type) do {				\
+	QUEUE_TYPEOF(type) *swap_first = STAILQ_FIRST(head1);		\
+	QUEUE_TYPEOF(type) **swap_last = (head1)->stqh_last;		\
+	STAILQ_FIRST(head1) = STAILQ_FIRST(head2);			\
+	(head1)->stqh_last = (head2)->stqh_last;			\
+	STAILQ_FIRST(head2) = swap_first;				\
+	(head2)->stqh_last = swap_last;					\
+	if (STAILQ_EMPTY(head1))					\
+		(head1)->stqh_last = &STAILQ_FIRST(head1);		\
+	if (STAILQ_EMPTY(head2))					\
+		(head2)->stqh_last = &STAILQ_FIRST(head2);		\
+} while (0)
+
+
+/*
+ * List declarations.
+ */
+#define	LIST_HEAD(name, type)						\
+struct name {								\
+	struct type *lh_first;	/* first element */			\
+}
+
+#define	LIST_CLASS_HEAD(name, type)					\
+struct name {								\
+	class type *lh_first;	/* first element */			\
+}
+
+#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 */	\
+}
+
+#define	LIST_CLASS_ENTRY(type)						\
+struct {								\
+	class type *le_next;	/* next element */			\
+	class type **le_prev;	/* address of previous next element */	\
+}
+
+/*
+ * List functions.
+ */
+
+#if (defined(_KERNEL) && defined(INVARIANTS))
+/*
+ * QMD_LIST_CHECK_HEAD(LIST_HEAD *head, LIST_ENTRY NAME)
+ *
+ * If the list is non-empty, validates that the first element of the list
+ * points back at 'head.'
+ */
+#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)
+
+/*
+ * QMD_LIST_CHECK_NEXT(TYPE *elm, LIST_ENTRY NAME)
+ *
+ * If an element follows 'elm' in the list, validates that the next element
+ * points back at 'elm.'
+ */
+#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)
+
+/*
+ * QMD_LIST_CHECK_PREV(TYPE *elm, LIST_ENTRY NAME)
+ *
+ * Validates that the previous element (or head of the list) points to 'elm.'
+ */
+#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) */
+
+#define LIST_CONCAT(head1, head2, type, field) do {			      \
+	QUEUE_TYPEOF(type) *curelm = LIST_FIRST(head1);			      \
+	if (curelm == NULL) {						      \
+		if ((LIST_FIRST(head1) = LIST_FIRST(head2)) != NULL) {	      \
+			LIST_FIRST(head2)->field.le_prev =		      \
+			    &LIST_FIRST((head1));			      \
+			LIST_INIT(head2);				      \
+		}							      \
+	} else if (LIST_FIRST(head2) != NULL) {				      \
+		while (LIST_NEXT(curelm, field) != NULL)		      \
+			curelm = LIST_NEXT(curelm, field);		      \
+		LIST_NEXT(curelm, field) = LIST_FIRST(head2);		      \
+		LIST_FIRST(head2)->field.le_prev = &LIST_NEXT(curelm, field); \
+		LIST_INIT(head2);					      \
+	}								      \
+} while (0)
+
+#define	LIST_EMPTY(head)	((head)->lh_first == NULL)
+
+#define	LIST_FIRST(head)	((head)->lh_first)
+
+#define	LIST_FOREACH(var, head, field)					\
+	for ((var) = LIST_FIRST((head));				\
+	    (var);							\
+	    (var) = LIST_NEXT((var), field))
+
+#define	LIST_FOREACH_FROM(var, head, field)				\
+	for ((var) = ((var) ? (var) : LIST_FIRST((head)));		\
+	    (var);							\
+	    (var) = LIST_NEXT((var), field))
+
+#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = LIST_FIRST((head));				\
+	    (var) && ((tvar) = LIST_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
+#define	LIST_FOREACH_FROM_SAFE(var, head, field, tvar)			\
+	for ((var) = ((var) ? (var) : LIST_FIRST((head)));		\
+	    (var) && ((tvar) = LIST_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
+#define	LIST_INIT(head) do {						\
+	LIST_FIRST((head)) = NULL;					\
+} while (0)
+
+#define	LIST_INSERT_AFTER(listelm, elm, field) do {			\
+	QMD_LIST_CHECK_NEXT(listelm, field);				\
+	if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
+		LIST_NEXT((listelm), field)->field.le_prev =		\
+		    &LIST_NEXT((elm), field);				\
+	LIST_NEXT((listelm), field) = (elm);				\
+	(elm)->field.le_prev = &LIST_NEXT((listelm), field);		\
+} while (0)
+
+#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
+	QMD_LIST_CHECK_PREV(listelm, field);				\
+	(elm)->field.le_prev = (listelm)->field.le_prev;		\
+	LIST_NEXT((elm), field) = (listelm);				\
+	*(listelm)->field.le_prev = (elm);				\
+	(listelm)->field.le_prev = &LIST_NEXT((elm), field);		\
+} while (0)
+
+#define	LIST_INSERT_HEAD(head, elm, field) do {				\
+	QMD_LIST_CHECK_HEAD((head), field);				\
+	if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)	\
+		LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
+	LIST_FIRST((head)) = (elm);					\
+	(elm)->field.le_prev = &LIST_FIRST((head));			\
+} while (0)
+
+#define	LIST_NEXT(elm, field)	((elm)->field.le_next)
+
+#define	LIST_PREV(elm, head, type, field)			\
+	((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :	\
+	    __containerof((elm)->field.le_prev,			\
+	    QUEUE_TYPEOF(type), field.le_next))
+
+#define	LIST_REMOVE(elm, field) do {					\
+	QMD_SAVELINK(oldnext, (elm)->field.le_next);			\
+	QMD_SAVELINK(oldprev, (elm)->field.le_prev);			\
+	QMD_LIST_CHECK_NEXT(elm, field);				\
+	QMD_LIST_CHECK_PREV(elm, field);				\
+	if (LIST_NEXT((elm), field) != NULL)				\
+		LIST_NEXT((elm), field)->field.le_prev = 		\
+		    (elm)->field.le_prev;				\
+	*(elm)->field.le_prev = LIST_NEXT((elm), field);		\
+	TRASHIT(*oldnext);						\
+	TRASHIT(*oldprev);						\
+} while (0)
+
+#define LIST_SWAP(head1, head2, type, field) do {			\
+	QUEUE_TYPEOF(type) *swap_tmp = LIST_FIRST(head1);		\
+	LIST_FIRST((head1)) = LIST_FIRST((head2));			\
+	LIST_FIRST((head2)) = swap_tmp;					\
+	if ((swap_tmp = LIST_FIRST((head1))) != NULL)			\
+		swap_tmp->field.le_prev = &LIST_FIRST((head1));		\
+	if ((swap_tmp = LIST_FIRST((head2))) != NULL)			\
+		swap_tmp->field.le_prev = &LIST_FIRST((head2));		\
+} while (0)
+
 /*
  * Tail queue declarations.
  */
@@ -123,10 +619,58 @@ struct {								\
 /*
  * Tail queue functions.
  */
+#if (defined(_KERNEL) && defined(INVARIANTS))
+/*
+ * QMD_TAILQ_CHECK_HEAD(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
+ *
+ * If the tailq is non-empty, validates that the first element of the tailq
+ * points back at 'head.'
+ */
+#define	QMD_TAILQ_CHECK_HEAD(head, field) do {				\
+	if (!TAILQ_EMPTY(head) &&					\
+	    TAILQ_FIRST((head))->field.tqe_prev !=			\
+	     &TAILQ_FIRST((head)))					\
+		panic("Bad tailq head %p first->prev != head", (head));	\
+} while (0)
+
+/*
+ * QMD_TAILQ_CHECK_TAIL(TAILQ_HEAD *head, TAILQ_ENTRY NAME)
+ *
+ * Validates that the tail of the tailq is a pointer to pointer to NULL.
+ */
+#define	QMD_TAILQ_CHECK_TAIL(head, field) do {				\
+	if (*(head)->tqh_last != NULL)					\
+	    	panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); 	\
+} while (0)
+
+/*
+ * QMD_TAILQ_CHECK_NEXT(TYPE *elm, TAILQ_ENTRY NAME)
+ *
+ * If an element follows 'elm' in the tailq, validates that the next element
+ * points back at 'elm.'
+ */
+#define	QMD_TAILQ_CHECK_NEXT(elm, field) do {				\
+	if (TAILQ_NEXT((elm), field) != NULL &&				\
+	    TAILQ_NEXT((elm), field)->field.tqe_prev !=			\
+	     &((elm)->field.tqe_next))					\
+		panic("Bad link elm %p next->prev != elm", (elm));	\
+} while (0)
+
+/*
+ * QMD_TAILQ_CHECK_PREV(TYPE *elm, TAILQ_ENTRY NAME)
+ *
+ * Validates that the previous element (or head of the tailq) points to 'elm.'
+ */
+#define	QMD_TAILQ_CHECK_PREV(elm, field) do {				\
+	if (*(elm)->field.tqe_prev != (elm))				\
+		panic("Bad link elm %p prev->next != elm", (elm));	\
+} while (0)
+#else
 #define	QMD_TAILQ_CHECK_HEAD(head, field)
 #define	QMD_TAILQ_CHECK_TAIL(head, headname)
 #define	QMD_TAILQ_CHECK_NEXT(elm, field)
 #define	QMD_TAILQ_CHECK_PREV(elm, field)
+#endif /* (_KERNEL && INVARIANTS) */
 
 #define	TAILQ_CONCAT(head1, head2, field) do {				\
 	if (!TAILQ_EMPTY(head2)) {					\
@@ -191,9 +735,8 @@ struct {								\
 
 #define	TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
 	QMD_TAILQ_CHECK_NEXT(listelm, field);				\
-	TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field);	\
-	if (TAILQ_NEXT((listelm), field) != NULL)			\
-		TAILQ_NEXT((elm), field)->field.tqe_prev =		\
+	if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
+		TAILQ_NEXT((elm), field)->field.tqe_prev = 		\
 		    &TAILQ_NEXT((elm), field);				\
 	else {								\
 		(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
@@ -217,8 +760,7 @@ struct {								\
 
 #define	TAILQ_INSERT_HEAD(head, elm, field) do {			\
 	QMD_TAILQ_CHECK_HEAD(head, field);				\
-	TAILQ_NEXT((elm), field) = TAILQ_FIRST((head));			\
-	if (TAILQ_FIRST((head)) != NULL)				\
+	if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)	\
 		TAILQ_FIRST((head))->field.tqe_prev =			\
 		    &TAILQ_NEXT((elm), field);				\
 	else								\
@@ -250,21 +792,24 @@ struct {								\
  * you may want to prefetch the last data element.
  */
 #define	TAILQ_LAST_FAST(head, type, field)			\
-	(TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last,	\
-	QUEUE_TYPEOF(type), field.tqe_next))
+    (TAILQ_EMPTY(head) ? NULL : __containerof((head)->tqh_last, QUEUE_TYPEOF(type), field.tqe_next))
 
 #define	TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
 
 #define	TAILQ_PREV(elm, headname, field)				\
 	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 
+#define	TAILQ_PREV_FAST(elm, head, type, field)				\
+    ((elm)->field.tqe_prev == &(head)->tqh_first ? NULL :		\
+     __containerof((elm)->field.tqe_prev, QUEUE_TYPEOF(type), field.tqe_next))
+
 #define	TAILQ_REMOVE(head, elm, field) do {				\
 	QMD_SAVELINK(oldnext, (elm)->field.tqe_next);			\
 	QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);			\
 	QMD_TAILQ_CHECK_NEXT(elm, field);				\
 	QMD_TAILQ_CHECK_PREV(elm, field);				\
 	if ((TAILQ_NEXT((elm), field)) != NULL)				\
-		TAILQ_NEXT((elm), field)->field.tqe_prev =		\
+		TAILQ_NEXT((elm), field)->field.tqe_prev = 		\
 		    (elm)->field.tqe_prev;				\
 	else {								\
 		(head)->tqh_last = (elm)->field.tqe_prev;		\
@@ -277,26 +822,20 @@ struct {								\
 } while (0)
 
 #define TAILQ_SWAP(head1, head2, type, field) do {			\
-	QUEUE_TYPEOF(type) * swap_first = (head1)->tqh_first;		\
-	QUEUE_TYPEOF(type) * *swap_last = (head1)->tqh_last;		\
+	QUEUE_TYPEOF(type) *swap_first = (head1)->tqh_first;		\
+	QUEUE_TYPEOF(type) **swap_last = (head1)->tqh_last;		\
 	(head1)->tqh_first = (head2)->tqh_first;			\
 	(head1)->tqh_last = (head2)->tqh_last;				\
 	(head2)->tqh_first = swap_first;				\
 	(head2)->tqh_last = swap_last;					\
-	swap_first = (head1)->tqh_first;				\
-	if (swap_first != NULL)						\
+	if ((swap_first = (head1)->tqh_first) != NULL)			\
 		swap_first->field.tqe_prev = &(head1)->tqh_first;	\
 	else								\
 		(head1)->tqh_last = &(head1)->tqh_first;		\
-	swap_first = (head2)->tqh_first;				\
-	if (swap_first != NULL)			\
+	if ((swap_first = (head2)->tqh_first) != NULL)			\
 		swap_first->field.tqe_prev = &(head2)->tqh_first;	\
 	else								\
 		(head2)->tqh_last = &(head2)->tqh_first;		\
 } while (0)
 
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* _SYS_QUEUE_H_ */
+#endif /* !_SYS_QUEUE_H_ */
-- 
2.25.1