- /* Checks the status of CFM configured on 'ofport'. Returns true if the
- * port's CFM status was successfully stored into '*status'. Returns false
- * if the port did not have CFM configured, in which case '*status' is
- * indeterminate.
+ /* Checks the status of CFM configured on 'ofport'. Returns 0 if the
+ * port's CFM status was successfully stored into '*status'. Returns
+ * negative number if there is no status change since last update.
+ * Returns positive errno otherwise.
+ *
+ * EOPNOTSUPP as a return value indicates that this ofproto_class does not
+ * support CFM, as does a null pointer.