[PATCH] Add list_for_each_entry_safe_reverse()

Add list_for_each_entry_safe_reverse() to linux/list.h

This is needed by unmerged cachefs and be an as-yet-unreviewed
device_shutdown() fix.
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Patrick Mochel <mochel@digitalimplant.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/list.h

@@ -435,6 +435,20 @@ static inline void list_splice_init(struct list_head *list,
 	     &pos->member != (head);						\
 	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
 
+/**
+ * list_for_each_entry_safe_reverse - iterate backwards over list of given type safe against
+ *				      removal of list entry
+ * @pos:	the type * to use as a loop counter.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
+	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
+		n = list_entry(pos->member.prev, typeof(*pos), member);	\
+	     &pos->member != (head); 					\
+	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))
+
 /**
  * list_for_each_rcu	-	iterate over an rcu-protected list
  * @pos:	the &struct list_head to use as a loop counter.