Index: sys/sys/tree.h
===================================================================
RCS file: /cvs/src/sys/sys/tree.h,v
retrieving revision 1.25
diff -u -p -r1.25 tree.h
--- sys/sys/tree.h	26 Sep 2016 08:08:51 -0000	1.25
+++ sys/sys/tree.h	5 Jun 2017 03:59:59 -0000
@@ -814,6 +814,9 @@ void	*_rb_prev(const struct rb_type *, v
 void	*_rb_left(const struct rb_type *, void *);
 void	*_rb_right(const struct rb_type *, void *);
 void	*_rb_parent(const struct rb_type *, void *);
+void	 _rb_set_left(const struct rb_type *, void *, void *);
+void	 _rb_set_right(const struct rb_type *, void *, void *);
+void	 _rb_set_parent(const struct rb_type *, void *, void *);
 void	*_rb_color(const struct rb_type *, void *);
 void	 _rb_poison(const struct rb_type *, void *, unsigned long);
 int	 _rb_check(const struct rb_type *, void *, unsigned long);
@@ -908,6 +911,24 @@ _name##_RBT_PARENT(struct _type *elm)			
 }									\
 									\
 __unused static inline void						\
+_name##_RBT_SET_LEFT(struct _type *elm, struct _type *left)		\
+{									\
+	return _rb_set_left(_name##_RBT_TYPE, elm, left);		\
+}									\
+									\
+__unused static inline void						\
+_name##_RBT_SET_RIGHT(struct _type *elm, struct _type *right)		\
+{									\
+	return _rb_set_right(_name##_RBT_TYPE, elm, right);		\
+}									\
+									\
+__unused static inline void						\
+_name##_RBT_SET_PARENT(struct _type *elm, struct _type *parent)		\
+{									\
+	return _rb_set_parent(_name##_RBT_TYPE, elm, parent);		\
+}									\
+									\
+__unused static inline void						\
 _name##_RBT_POISON(struct _type *elm, unsigned long poison)		\
 {									\
 	return _rb_poison(_name##_RBT_TYPE, elm, poison);		\
@@ -959,6 +980,9 @@ RBT_GENERATE_INTERNAL(_name, _type, _fie
 #define RBT_LEFT(_name, _elm)		_name##_RBT_LEFT(_elm)
 #define RBT_RIGHT(_name, _elm)		_name##_RBT_RIGHT(_elm)
 #define RBT_PARENT(_name, _elm)		_name##_RBT_PARENT(_elm)
+#define RBT_SET_LEFT(_name, _elm, _l)	_name##_RBT_SET_LEFT(_elm, _l)
+#define RBT_SET_RIGHT(_name, _elm, _r)	_name##_RBT_SET_RIGHT(_elm, _r)
+#define RBT_SET_PARENT(_name, _elm, _p)	_name##_RBT_SET_PARENT(_elm, _p)
 #define RBT_POISON(_name, _elm, _p)	_name##_RBT_POISON(_elm, _p)
 #define RBT_CHECK(_name, _elm, _p)	_name##_RBT_CHECK(_elm, _p)
 
Index: sys/kern/subr_tree.c
===================================================================
RCS file: /cvs/src/sys/kern/subr_tree.c,v
retrieving revision 1.6
diff -u -p -r1.6 subr_tree.c
--- sys/kern/subr_tree.c	20 Sep 2016 01:11:27 -0000	1.6
+++ sys/kern/subr_tree.c	5 Jun 2017 03:59:59 -0000
@@ -593,6 +593,33 @@ _rb_parent(const struct rb_type *t, void
 }
 
 void
+_rb_set_left(const struct rb_type *t, void *node, void *left)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	struct rb_entry *rbl = (left == NULL) ? NULL : rb_n2e(t, left);
+
+	RBE_LEFT(rbe) = rbl;
+}
+
+void
+_rb_set_right(const struct rb_type *t, void *node, void *right)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	struct rb_entry *rbr = (right == NULL) ? NULL : rb_n2e(t, right);
+
+	RBE_RIGHT(rbe) = rbr;
+}
+
+void
+_rb_set_parent(const struct rb_type *t, void *node, void *parent)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	struct rb_entry *rbp = (parent == NULL) ? NULL : rb_n2e(t, parent);
+
+	RBE_PARENT(rbe) = rbp;
+}
+
+void
 _rb_poison(const struct rb_type *t, void *node, unsigned long poison)
 {
 	struct rb_entry *rbe = rb_n2e(t, node);
Index: share/man/man9/RBT_INIT.9
===================================================================
RCS file: /cvs/src/share/man/man9/RBT_INIT.9,v
retrieving revision 1.5
diff -u -p -r1.5 RBT_INIT.9
--- share/man/man9/RBT_INIT.9	15 Sep 2016 06:07:22 -0000	1.5
+++ share/man/man9/RBT_INIT.9	5 Jun 2017 03:59:59 -0000
@@ -61,6 +61,9 @@
 .Nm RBT_LEFT ,
 .Nm RBT_RIGHT ,
 .Nm RBT_PARENT ,
+.Nm RBT_SET_LEFT ,
+.Nm RBT_SET_RIGHT ,
+.Nm RBT_SET_PARENT ,
 .Nm RBT_FOREACH ,
 .Nm RBT_FOREACH_SAFE ,
 .Nm RBT_FOREACH_REVERSE ,
@@ -114,6 +117,12 @@
 .Fn RBT_RIGHT "NAME" "struct TYPE *elm"
 .Ft struct TYPE *
 .Fn RBT_PARENT "NAME" "struct TYPE *elm"
+.Ft void
+.Fn RBT_SET_LEFT "NAME" "struct TYPE *elm" "struct TYPE *left"
+.Ft void
+.Fn RBT_SET_RIGHT "NAME" "struct TYPE *elm" "struct TYPE *right"
+.Ft void
+.Fn RBT_SET_PARENT "NAME" "struct TYPE *elm" "struct TYPE *parent"
 .Fo RBT_FOREACH
 .Fa "VARNAME"
 .Fa "NAME"
@@ -335,6 +344,30 @@ returns a pointer to the parent element 
 .Fa elm
 in a red-black tree of type
 .Fa NAME .
+.Pp
+.Fn RBT_SET_LEFT
+sets the left child pointer of element
+.Fa elm
+to
+.Fa left
+in a red-black tree of type
+.Fa NAME .
+.Pp
+.Fn RBT_SET_RIGHT
+sets the right child pointer of element
+.Fa elm
+to
+.Fa right
+in a red-black tree of type
+.Fa NAME .
+.Pp
+.Fn RBT_SET_PARENT
+sets the parent pointer of element
+.Fa elm
+to
+.Fa parent
+in a red-black tree of type
+.Fa NAME .
 .Ss Red-Black Tree Iterators
 The
 .Fn RBT_FOREACH
@@ -418,6 +451,9 @@ value.
 .Fn RBT_LEFT ,
 .Fn RBT_RIGHT ,
 .Fn RBT_PARENT ,
+.Fn RBT_SET_LEFT ,
+.Fn RBT_SET_RIGHT ,
+.Fn RBT_SET_PARENT ,
 .Fn RBT_FOREACH ,
 .Fn RBT_FOREACH_REVERSE ,
 .Fn RBT_FOREACH_SAFE ,