From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jakub Kicinski <jakub.kicinski@netronome.com>
Subject: Re: [PATCH v5 bpf-next 3/9] veth: Avoid drops by oversized packets
 when XDP is enabled
Date: Thu, 26 Jul 2018 18:08:47 -0700
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        <aa000680-a097-cd1a-e4ab-aacf9d172b04@lab.ntt.co.jp>
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Cc: Toshiaki Makita <toshiaki.makita1@gmail.com>,
        netdev@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Jesper Dangaard Brouer <brouer@redhat.com>
To: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
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On Fri, 27 Jul 2018 10:06:41 +0900, Toshiaki Makita wrote:
> On 2018/07/27 9:51, Jakub Kicinski wrote:
> > On Thu, 26 Jul 2018 23:40:26 +0900, Toshiaki Makita wrote:  
> >> +		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