Another thing to note:

Given the union of validation_data pointer and min/max, we'll always get
into this:

+	/* validate range */
+	if (pt->min || pt->max) {

if validation_data is set, but of course end up taking the default case,
where nothing further happens:

+		default:
+			/* no further validation */
+			validate = false;
+			break;
+		}
+
+		if (validate && (value < pt->min || value > pt->max)) {
+			NL_SET_ERR_MSG_ATTR(extack, nla,
+					    "integer out of range");
+			return -ERANGE;
+		}
+	}
+
 	return 0;

I'm not *entirely* happy with this, but I haven't been able to come up
with a way that doesn't do this, doesn't duplicate the nla types list
(NLA_{U,S}{8,16,32,64}) in the code, and also loads the attribute value
only if validation is needed.

johannes