quoted

+static int ethnl_cable_test_started(struct phy_device *phydev)
+{
+	struct sk_buff *skb;
+	int err = -ENOMEM;
+	void *ehdr;
+
+	skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!skb)
+		goto out;
+
+	ehdr = ethnl_bcastmsg_put(skb, ETHTOOL_MSG_CABLE_TEST_NTF);
+	if (!ehdr) {
+		err = -EINVAL;

This should rather be -EMSGSIZE. But as we are not going to use the
return value anyway, it's only cosmetic problem.

Yes, cut/paste from the alloc function. I might put a phydev_err() in
out: so we get to know about errors.

     Andrew