On Fri, 27 Jul 2018 10:06:41 +0900, Toshiaki Makita wrote:

On 2018/07/27 9:51, Jakub Kicinski wrote:

quoted

On Thu, 26 Jul 2018 23:40:26 +0900, Toshiaki Makita wrote:  

quoted

+		max_mtu = PAGE_SIZE - VETH_XDP_HEADROOM -
+			  peer->hard_header_len -
+			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+		if (peer->mtu > max_mtu) {
+			NL_SET_ERR_MSG_MOD(extack, "Peer MTU is too large to set XDP");
+			err = -ERANGE;
+			goto err;
+		}  

You need to add .ndo_change_mtu and check this condition there too.  

I'm setting peer->max_mtu so no need to add .ndo_change_mtu.
Inappropriate MTU will be refused in dev_set_mtu().

missed that, sorry