Add list insert routines

Add new list insertion routines list_insert_before(), list_insert_after(),
and list_add_tail().  Also, change list_add() to use list_insert_after().

Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

2 files changed, 23 insertions, 9 deletions

diff --git a/lib/list/list.c b/lib/list/list.c
index d9bc532..b781bc6 100644
--- a/lib/list/list.c
+++ b/lib/list/list.c
@@ -7,13 +7,20 @@ void list_init(struct list *list)
 	list->head.prev = &list->head;
 }
 
-void list_add(struct list *list, struct list_item *new)
+void list_insert_before(struct list_item *next, struct list_item *new)
 {
-	new->next = list->head.next;
-	new->prev = &list->head;
+	new->next = next;
+	new->prev = next->prev;
+	next->prev->next = new;
+	next->prev = new;
+}
 
-	list->head.next->prev = new;
-	list->head.next = new;
+void list_insert_after(struct list_item *prev, struct list_item *new)
+{
+	new->next = prev->next;
+	new->prev = prev;
+	prev->next->prev = new;
+	prev->next = new;
 }
 
 void list_remove(struct list_item *item)
@@ -21,4 +28,3 @@ void list_remove(struct list_item *item)
 	item->next->prev = item->prev;
 	item->prev->next = item->next;
 }
-
diff --git a/lib/list/list.h b/lib/list/list.h
index 3858cf6..fe2c1d3 100644
--- a/lib/list/list.h
+++ b/lib/list/list.h
@@ -31,9 +31,17 @@ struct list {
 	     pos = list_entry(pos->member.next, typeof(*pos), member))
 
 void list_init(struct list *list);
-
-void list_add(struct list *list, struct list_item *item);
-
+void list_insert_before(struct list_item *next, struct list_item *new);
+void list_insert_after(struct list_item *prev, struct list_item *new);
 void list_remove(struct list_item *item);
 
+static inline void list_add(struct list *list, struct list_item *new)
+{
+	list_insert_after(&list->head, new);
+}
+static inline void list_add_tail(struct list *list, struct list_item *new)
+{
+	list_insert_before(&list->head, new);
+}
+
 #endif /* _LIST_H */