list: introduce list_for_each_entry_from_reverse helper

Similar to list_for_each_entry_continue and its reverse variant
list_for_each_entry_continue_reverse, introduce reverse helper for
list_for_each_entry_from.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/list.h b/include/linux/list.h
index d1039ec..ae537fa 100644 (file)
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -527,6 +527,19 @@ static inline void list_splice_tail_init(struct list_head *list,
             pos = list_next_entry(pos, member))
 
 /**
+ * list_for_each_entry_from_reverse - iterate backwards over list of given type
+ *                                    from the current point
+ * @pos:       the type * to use as a loop cursor.
+ * @head:      the head for your list.
+ * @member:    the name of the list_head within the struct.
+ *
+ * Iterate backwards over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from_reverse(pos, head, member)            \
+       for (; &pos->member != (head);                                  \
+            pos = list_prev_entry(pos, member))
+
+/**
  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
  * @pos:       the type * to use as a loop cursor.
  * @n:         another type * to use as temporary storage