list: Add list_add_after()

Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

ccan/list/list.h

@@ -183,6 +183,25 @@ static inline void list_add_before(struct list_head *h, struct list_node *n,
 		(void)list_debug(h);
 }
 
+/**
+ * list_add_after - add an entry after another entry.
+ * @h: the list_head to add the node to (we use it for debug purposes, can be NULL)
+ * @n: the list_node to add to the list.
+ * @p: the list_node of the other entry
+ *
+ * The list_node does not need to be initialized; it will be overwritten.
+ */
+static inline void list_add_after(struct list_head *h, struct list_node *n,
+				  struct list_node *p)
+{
+	n->next = p->next;
+	n->prev = p;
+	p->next = n;
+	n->next->prev = n;
+	if (h)
+		(void)list_debug(h);
+}
+
 /**
  * list_add_tail - add an entry at the end of a linked list.
  * @h: the list_head to add the node to