+
+ /* Returns a sequence number which indicates changes in one of 'netdev''s
+ * properties. The returned sequence number must be nonzero so that
+ * callers have a value which they may use as a reset when tracking
+ * 'netdev'.
+ *
+ * Minimally, the returned sequence number is required to change whenever
+ * 'netdev''s flags, features, ethernet address, or carrier changes. The
+ * returned sequence number is allowed to change even when 'netdev' doesn't
+ * change, although implementations should try to avoid this. */
+ unsigned int (*change_seq)(const struct netdev *netdev);