[PATCH] list: introduce list_replace() helper
list_replace() is similar to list_replace_rcu(), but unlike
list_replace_rcu() it
could be used when list_empty(old) == 1
doesn't use barriers
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/list.h b/include/linux/list.h
index 76f0571..a02642e 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -197,12 +197,35 @@
entry->prev = LIST_POISON2;
}
+/**
+ * list_replace - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ * Note: if 'old' was empty, it will be overwritten.
+ */
+static inline void list_replace(struct list_head *old,
+ struct list_head *new)
+{
+ new->next = old->next;
+ new->next->prev = new;
+ new->prev = old->prev;
+ new->prev->next = new;
+}
+
+static inline void list_replace_init(struct list_head *old,
+ struct list_head *new)
+{
+ list_replace(old, new);
+ INIT_LIST_HEAD(old);
+}
+
/*
* list_replace_rcu - replace old entry by new one
* @old : the element to be replaced
* @new : the new element to insert
*
* The old entry will be replaced with the new entry atomically.
+ * Note: 'old' should not be empty.
*/
static inline void list_replace_rcu(struct list_head *old,
struct list_head *new)