Sync queue(3) from FreeBSD

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=85147

include/bsd/sys/queue.h

@@ -65,7 +65,7 @@
  * 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.
+ * 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
@@ -85,12 +85,16 @@
  * _EMPTY			+	+	+	+
  * _FIRST			+	+	+	+
  * _NEXT			+	+	+	+
- * _PREV			-	-	-	+
+ * _PREV			-	+	-	+
  * _LAST			-	-	+	+
  * _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		+	+	+	+
@@ -99,19 +103,22 @@
  * _REMOVE_AFTER		+	-	+	-
  * _REMOVE_HEAD			+	-	+	-
  * _REMOVE			+	+	+	+
+ * _SWAP			+	+	+	+
  *
  */
 #ifdef QUEUE_MACRO_DEBUG
 /* Store the last 2 places the queue element or head was altered */
 struct qm_trace {
-	char * lastfile;
+	unsigned long	 lastline;
-	int lastline;
+	unsigned long	 prevline;
-	char * prevfile;
+	const char	*lastfile;
-	int prevline;
+	const char	*prevfile;
 };
 
 #define	TRACEBUF	struct qm_trace trace;
+#define	TRACEBUF_INITIALIZER	{ __FILE__, __LINE__, NULL, 0 } ,
 #define	TRASHIT(x)	do {(x) = (void *)-1;} while (0)
+#define	QMD_SAVELINK(name, link)	void **name = (void *)&(link)
 
 #define	QMD_TRACE_HEAD(head) do {					\
 	(head)->trace.prevline = (head)->trace.lastline;		\
@@ -130,7 +137,9 @@ struct qm_trace {
 #else
 #define	QMD_TRACE_ELEM(elem)
 #define	QMD_TRACE_HEAD(head)
+#define	QMD_SAVELINK(name, link)
 #define	TRACEBUF
+#define	TRACEBUF_INITIALIZER
 #define	TRASHIT(x)
 #endif	/* QUEUE_MACRO_DEBUG */
 
@@ -162,11 +171,21 @@ struct {								\
 	    (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;					\
@@ -189,6 +208,7 @@ struct {								\
 #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);			\
 	}								\
@@ -198,7 +218,7 @@ struct {								\
 			curelm = SLIST_NEXT(curelm, field);		\
 		SLIST_REMOVE_AFTER(curelm, field);			\
 	}								\
-	TRASHIT((elm)->field.sle_next);					\
+	TRASHIT(*oldnext);						\
 } while (0)
 
 #define SLIST_REMOVE_AFTER(elm, field) do {				\
@@ -210,6 +230,12 @@ struct {								\
 	SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);	\
 } while (0)
 
+#define SLIST_SWAP(head1, head2, type) do {				\
+	struct type *swap_first = SLIST_FIRST(head1);			\
+	SLIST_FIRST(head1) = SLIST_FIRST(head2);			\
+	SLIST_FIRST(head2) = swap_first;				\
+} while (0)
+
 /*
  * Singly-linked Tail queue declarations.
  */
@@ -247,12 +273,21 @@ struct {								\
 	   (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));			\
@@ -277,14 +312,13 @@ struct {								\
 } while (0)
 
 #define	STAILQ_LAST(head, type, field)					\
-	(STAILQ_EMPTY((head)) ?						\
+	(STAILQ_EMPTY((head)) ? NULL :					\
-		NULL :							\
+	    __containerof((head)->stqh_last, struct type, field.stqe_next))
-	        ((struct type *)(void *)				\
-		((char *)((head)->stqh_last) - __offsetof(struct type, field))))
 
 #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);			\
 	}								\
@@ -294,13 +328,7 @@ struct {								\
 			curelm = STAILQ_NEXT(curelm, field);		\
 		STAILQ_REMOVE_AFTER(head, curelm, field);		\
 	}								\
-	TRASHIT((elm)->field.stqe_next);				\
+	TRASHIT(*oldnext);						\
-} 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_REMOVE_AFTER(head, elm, field) do {			\
@@ -309,6 +337,12 @@ struct {								\
 		(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 {				\
 	struct type *swap_first = STAILQ_FIRST(head1);			\
 	struct type **swap_last = (head1)->stqh_last;			\
@@ -378,11 +412,21 @@ struct {								\
 	    (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)
@@ -414,15 +458,21 @@ struct {								\
 
 #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, struct 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((elm)->field.le_next);					\
+	TRASHIT(*oldnext);						\
-	TRASHIT((elm)->field.le_prev);					\
+	TRASHIT(*oldprev);						\
 } while (0)
 
 #define LIST_SWAP(head1, head2, type, field) do {			\
@@ -446,7 +496,7 @@ struct name {								\
 }
 
 #define	TAILQ_HEAD_INITIALIZER(head)					\
-	{ NULL, &(head).tqh_first }
+	{ NULL, &(head).tqh_first, TRACEBUF_INITIALIZER }
 
 #define	TAILQ_ENTRY(type)						\
 struct {								\
@@ -509,21 +559,41 @@ struct {								\
 	    (var);							\
 	    (var) = TAILQ_NEXT((var), field))
 
+#define	TAILQ_FOREACH_FROM(var, head, field)				\
+	for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));		\
+	    (var);							\
+	    (var) = TAILQ_NEXT((var), field))
+
 #define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
 	for ((var) = TAILQ_FIRST((head));				\
 	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
 	    (var) = (tvar))
 
+#define	TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)			\
+	for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));		\
+	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
+	    (var) = (tvar))
+
 #define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
 	for ((var) = TAILQ_LAST((head), headname);			\
 	    (var);							\
 	    (var) = TAILQ_PREV((var), headname, field))
 
+#define	TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field)		\
+	for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));	\
+	    (var);							\
+	    (var) = TAILQ_PREV((var), headname, field))
+
 #define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
 	for ((var) = TAILQ_LAST((head), headname);			\
 	    (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
 	    (var) = (tvar))
 
+#define	TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
+	for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));	\
+	    (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
+	    (var) = (tvar))
+
 #define	TAILQ_INIT(head) do {						\
 	TAILQ_FIRST((head)) = NULL;					\
 	(head)->tqh_last = &TAILQ_FIRST((head));			\
@@ -587,6 +657,8 @@ struct {								\
 	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
 
 #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)				\
@@ -597,8 +669,8 @@ struct {								\
 		QMD_TRACE_HEAD(head);					\
 	}								\
 	*(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);		\
-	TRASHIT((elm)->field.tqe_next);					\
+	TRASHIT(*oldnext);						\
-	TRASHIT((elm)->field.tqe_prev);					\
+	TRASHIT(*oldprev);						\
 	QMD_TRACE_ELEM(&(elm)->field);					\
 } while (0)
 

man/queue.3bsd

@@ -9,7 +9,7 @@
 .\" 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.
 .\"
@@ -28,15 +28,17 @@
 .\"	@(#)queue.3	8.2 (Berkeley) 1/24/94
 .\" $FreeBSD$
 .\"
-.Dd May 13, 2011
+.Dd June 17, 2013
-.Dt QUEUE 3bsd
+.Dt QUEUE 3
 .Os
 .Sh NAME
 .Nm SLIST_EMPTY ,
 .Nm SLIST_ENTRY ,
 .Nm SLIST_FIRST ,
 .Nm SLIST_FOREACH ,
+.Nm SLIST_FOREACH_FROM ,
 .Nm SLIST_FOREACH_SAFE ,
+.Nm SLIST_FOREACH_FROM_SAFE ,
 .Nm SLIST_HEAD ,
 .Nm SLIST_HEAD_INITIALIZER ,
 .Nm SLIST_INIT ,
@@ -52,7 +54,9 @@
 .Nm STAILQ_ENTRY ,
 .Nm STAILQ_FIRST ,
 .Nm STAILQ_FOREACH ,
+.Nm STAILQ_FOREACH_FROM ,
 .Nm STAILQ_FOREACH_SAFE ,
+.Nm STAILQ_FOREACH_FROM_SAFE ,
 .Nm STAILQ_HEAD ,
 .Nm STAILQ_HEAD_INITIALIZER ,
 .Nm STAILQ_INIT ,
@@ -69,7 +73,9 @@
 .Nm LIST_ENTRY ,
 .Nm LIST_FIRST ,
 .Nm LIST_FOREACH ,
+.Nm LIST_FOREACH_FROM ,
 .Nm LIST_FOREACH_SAFE ,
+.Nm LIST_FOREACH_FROM_SAFE ,
 .Nm LIST_HEAD ,
 .Nm LIST_HEAD_INITIALIZER ,
 .Nm LIST_INIT ,
@@ -77,6 +83,7 @@
 .Nm LIST_INSERT_BEFORE ,
 .Nm LIST_INSERT_HEAD ,
 .Nm LIST_NEXT ,
+.Nm LIST_PREV ,
 .Nm LIST_REMOVE ,
 .Nm LIST_SWAP ,
 .Nm TAILQ_CONCAT ,
@@ -84,9 +91,13 @@
 .Nm TAILQ_ENTRY ,
 .Nm TAILQ_FIRST ,
 .Nm TAILQ_FOREACH ,
+.Nm TAILQ_FOREACH_FROM ,
 .Nm TAILQ_FOREACH_SAFE ,
+.Nm TAILQ_FOREACH_FROM_SAFE ,
 .Nm TAILQ_FOREACH_REVERSE ,
+.Nm TAILQ_FOREACH_REVERSE_FROM ,
 .Nm TAILQ_FOREACH_REVERSE_SAFE ,
+.Nm TAILQ_FOREACH_REVERSE_FROM_SAFE ,
 .Nm TAILQ_HEAD ,
 .Nm TAILQ_HEAD_INITIALIZER ,
 .Nm TAILQ_INIT ,
@@ -108,7 +119,9 @@ lists and tail queues
 .Fn SLIST_ENTRY "TYPE"
 .Fn SLIST_FIRST "SLIST_HEAD *head"
 .Fn SLIST_FOREACH "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME"
+.Fn SLIST_FOREACH_FROM "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME"
 .Fn SLIST_FOREACH_SAFE "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME" "TYPE *temp_var"
+.Fn SLIST_FOREACH_FROM_SAFE "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME" "TYPE *temp_var"
 .Fn SLIST_HEAD "HEADNAME" "TYPE"
 .Fn SLIST_HEAD_INITIALIZER "SLIST_HEAD head"
 .Fn SLIST_INIT "SLIST_HEAD *head"
@@ -125,7 +138,9 @@ lists and tail queues
 .Fn STAILQ_ENTRY "TYPE"
 .Fn STAILQ_FIRST "STAILQ_HEAD *head"
 .Fn STAILQ_FOREACH "TYPE *var" "STAILQ_HEAD *head" "STAILQ_ENTRY NAME"
+.Fn STAILQ_FOREACH_FROM "TYPE *var" "STAILQ_HEAD *head" "STAILQ_ENTRY NAME"
 .Fn STAILQ_FOREACH_SAFE "TYPE *var" "STAILQ_HEAD *head" "STAILQ_ENTRY NAME" "TYPE *temp_var"
+.Fn STAILQ_FOREACH_FROM_SAFE "TYPE *var" "STAILQ_HEAD *head" "STAILQ_ENTRY NAME" "TYPE *temp_var"
 .Fn STAILQ_HEAD "HEADNAME" "TYPE"
 .Fn STAILQ_HEAD_INITIALIZER "STAILQ_HEAD head"
 .Fn STAILQ_INIT "STAILQ_HEAD *head"
@@ -143,7 +158,9 @@ lists and tail queues
 .Fn LIST_ENTRY "TYPE"
 .Fn LIST_FIRST "LIST_HEAD *head"
 .Fn LIST_FOREACH "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME"
+.Fn LIST_FOREACH_FROM "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME"
 .Fn LIST_FOREACH_SAFE "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME" "TYPE *temp_var"
+.Fn LIST_FOREACH_FROM_SAFE "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME" "TYPE *temp_var"
 .Fn LIST_HEAD "HEADNAME" "TYPE"
 .Fn LIST_HEAD_INITIALIZER "LIST_HEAD head"
 .Fn LIST_INIT "LIST_HEAD *head"
@@ -151,6 +168,7 @@ lists and tail queues
 .Fn LIST_INSERT_BEFORE "TYPE *listelm" "TYPE *elm" "LIST_ENTRY NAME"
 .Fn LIST_INSERT_HEAD "LIST_HEAD *head" "TYPE *elm" "LIST_ENTRY NAME"
 .Fn LIST_NEXT "TYPE *elm" "LIST_ENTRY NAME"
+.Fn LIST_PREV "TYPE *elm" "LIST_HEAD *head" "TYPE" "LIST_ENTRY NAME"
 .Fn LIST_REMOVE "TYPE *elm" "LIST_ENTRY NAME"
 .Fn LIST_SWAP "LIST_HEAD *head1" "LIST_HEAD *head2" "TYPE" "LIST_ENTRY NAME"
 .\"
@@ -159,9 +177,13 @@ lists and tail queues
 .Fn TAILQ_ENTRY "TYPE"
 .Fn TAILQ_FIRST "TAILQ_HEAD *head"
 .Fn TAILQ_FOREACH "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME"
+.Fn TAILQ_FOREACH_FROM "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME"
 .Fn TAILQ_FOREACH_SAFE "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME" "TYPE *temp_var"
+.Fn TAILQ_FOREACH_FROM_SAFE "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME" "TYPE *temp_var"
 .Fn TAILQ_FOREACH_REVERSE "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME"
+.Fn TAILQ_FOREACH_REVERSE_FROM "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME"
 .Fn TAILQ_FOREACH_REVERSE_SAFE "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME" "TYPE *temp_var"
+.Fn TAILQ_FOREACH_REVERSE_FROM_SAFE "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME" "TYPE *temp_var"
 .Fn TAILQ_HEAD "HEADNAME" "TYPE"
 .Fn TAILQ_HEAD_INITIALIZER "TAILQ_HEAD head"
 .Fn TAILQ_INIT "TAILQ_HEAD *head"
@@ -244,8 +266,18 @@ Code size and execution time of operations (except for removal) is about
 twice that of the singly-linked data-structures.
 .El
 .Pp
-Linked lists are the simplest of the doubly linked data structures and support
+Linked lists are the simplest of the doubly linked data structures.
-only the above functionality over singly-linked lists.
+They add the following functionality over the above:
+.Bl -enum -compact -offset indent
+.It
+They may be traversed backwards.
+.El
+However:
+.Bl -enum -compact -offset indent
+.It
+To traverse backwards, an entry to begin the traversal and the list in
+which it is contained must be specified.
+.El
 .Pp
 Tail queues add the following functionality:
 .Bl -enum -compact -offset indent
@@ -349,6 +381,19 @@ turn to
 .Fa var .
 .Pp
 The macro
+.Nm SLIST_FOREACH_FROM
+behaves identically to
+.Nm SLIST_FOREACH
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found SLIST element and begins the loop at
+.Fa var
+instead of the first element in the SLIST referenced by
+.Fa head .
+.Pp
+The macro
 .Nm SLIST_FOREACH_SAFE
 traverses the list referenced by
 .Fa head
@@ -363,6 +408,19 @@ as well as free it from within the loop safely without interfering with the
 traversal.
 .Pp
 The macro
+.Nm SLIST_FOREACH_FROM_SAFE
+behaves identically to
+.Nm SLIST_FOREACH_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found SLIST element and begins the loop at
+.Fa var
+instead of the first element in the SLIST referenced by
+.Fa head .
+.Pp
+The macro
 .Nm SLIST_INIT
 initializes the list referenced by
 .Fa head .
@@ -388,7 +446,8 @@ The macro
 .Nm SLIST_REMOVE_AFTER
 removes the element after
 .Fa elm
-from the list. Unlike
+from the list.
+Unlike
 .Fa SLIST_REMOVE ,
 this macro does not traverse the entire list.
 .Pp
@@ -528,6 +587,19 @@ in turn to
 .Fa var .
 .Pp
 The macro
+.Nm STAILQ_FOREACH_FROM
+behaves identically to
+.Nm STAILQ_FOREACH
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found STAILQ element and begins the loop at
+.Fa var
+instead of the first element in the STAILQ referenced by
+.Fa head .
+.Pp
+The macro
 .Nm STAILQ_FOREACH_SAFE
 traverses the tail queue referenced by
 .Fa head
@@ -542,6 +614,19 @@ as well as free it from within the loop safely without interfering with the
 traversal.
 .Pp
 The macro
+.Nm STAILQ_FOREACH_FROM_SAFE
+behaves identically to
+.Nm STAILQ_FOREACH_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found STAILQ element and begins the loop at
+.Fa var
+instead of the first element in the STAILQ referenced by
+.Fa head .
+.Pp
+The macro
 .Nm STAILQ_INIT
 initializes the tail queue referenced by
 .Fa head .
@@ -579,7 +664,8 @@ The macro
 .Nm STAILQ_REMOVE_AFTER
 removes the element after
 .Fa elm
-from the tail queue. Unlike
+from the tail queue.
+Unlike
 .Fa STAILQ_REMOVE ,
 this macro does not traverse the entire tail queue.
 .Pp
@@ -717,6 +803,19 @@ in the forward direction, assigning each element in turn to
 .Fa var .
 .Pp
 The macro
+.Nm LIST_FOREACH_FROM
+behaves identically to
+.Nm LIST_FOREACH
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found LIST element and begins the loop at
+.Fa var
+instead of the first element in the LIST referenced by
+.Fa head .
+.Pp
+The macro
 .Nm LIST_FOREACH_SAFE
 traverses the list referenced by
 .Fa head
@@ -730,6 +829,19 @@ as well as free it from within the loop safely without interfering with the
 traversal.
 .Pp
 The macro
+.Nm LIST_FOREACH_FROM_SAFE
+behaves identically to
+.Nm LIST_FOREACH_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found LIST element and begins the loop at
+.Fa var
+instead of the first element in the LIST referenced by
+.Fa head .
+.Pp
+The macro
 .Nm LIST_INIT
 initializes the list referenced by
 .Fa head .
@@ -759,6 +871,14 @@ The macro
 returns the next element in the list, or NULL if this is the last.
 .Pp
 The macro
+.Nm LIST_PREV
+returns the previous element in the list, or NULL if this is the first.
+List
+.Fa head
+must contain element
+.Fa elm .
+.Pp
+The macro
 .Nm LIST_REMOVE
 removes the element
 .Fa elm
@@ -894,12 +1014,38 @@ is set to
 if the loop completes normally, or if there were no elements.
 .Pp
 The macro
+.Nm TAILQ_FOREACH_FROM
+behaves identically to
+.Nm TAILQ_FOREACH
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found TAILQ element and begins the loop at
+.Fa var
+instead of the first element in the TAILQ referenced by
+.Fa head .
+.Pp
+The macro
 .Nm TAILQ_FOREACH_REVERSE
 traverses the tail queue referenced by
 .Fa head
 in the reverse direction, assigning each element in turn to
 .Fa var .
 .Pp
+The macro
+.Nm TAILQ_FOREACH_REVERSE_FROM
+behaves identically to
+.Nm TAILQ_FOREACH_REVERSE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found TAILQ element and begins the reverse loop at
+.Fa var
+instead of the last element in the TAILQ referenced by
+.Fa head .
+.Pp
 The macros
 .Nm TAILQ_FOREACH_SAFE
 and
@@ -919,6 +1065,32 @@ as well as free it from within the loop safely without interfering with the
 traversal.
 .Pp
 The macro
+.Nm TAILQ_FOREACH_FROM_SAFE
+behaves identically to
+.Nm TAILQ_FOREACH_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found TAILQ element and begins the loop at
+.Fa var
+instead of the first element in the TAILQ referenced by
+.Fa head .
+.Pp
+The macro
+.Nm TAILQ_FOREACH_REVERSE_FROM_SAFE
+behaves identically to
+.Nm TAILQ_FOREACH_REVERSE_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found TAILQ element and begins the reverse loop at
+.Fa var
+instead of the last element in the TAILQ referenced by
+.Fa head .
+.Pp
+The macro
 .Nm TAILQ_INIT
 initializes the tail queue referenced by
 .Fa head .