On 2018/07/24 9:27, Jakub Kicinski wrote:
> On Mon, 23 Jul 2018 00:13:03 +0900, Toshiaki Makita wrote:
>> From: Toshiaki Makita <makita.toshi...@lab.ntt.co.jp>
>>
>> All oversized packets including GSO packets are dropped if XDP is
>> enabled on receiver side, so don't send such packets from peer.
>>
>> Drop TSO and SCTP fragmentation features so that veth devices themselves
>> segment packets with XDP enabled. Also cap MTU accordingly.
>>
>> Signed-off-by: Toshiaki Makita <makita.toshi...@lab.ntt.co.jp>
>
> Is there any precedence for fixing up features and MTU like this? Most
> drivers just refuse to install the program if settings are incompatible.
I don't know any precedence. I can refuse the program on installing it
when features and MTU are not appropriate. Is it preferred?
Note that with current implementation wanted_features are not touched so
features will be restored when the XDP program is removed. MTU will not
be restored though, as I do not remember the original MTU.
>> diff --git a/drivers/net/veth.c b/drivers/net/veth.c
>> index 78fa08cb6e24..f5b72e937d9d 100644
>> --- a/drivers/net/veth.c
>> +++ b/drivers/net/veth.c
>> @@ -542,6 +542,23 @@ static int veth_get_iflink(const struct net_device *dev)
>> return iflink;
>> }
>>
>> +static netdev_features_t veth_fix_features(struct net_device *dev,
>> + netdev_features_t features)
>> +{
>> + struct veth_priv *priv = netdev_priv(dev);
>> + struct net_device *peer;
>> +
>> + peer = rtnl_dereference(priv->peer);
>> + if (peer) {
>> + struct veth_priv *peer_priv = netdev_priv(peer);
>> +
>> + if (peer_priv->_xdp_prog)
>> + features &= ~NETIF_F_GSO_SOFTWARE;
>> + }
>> +
>> + return features;
>> +}
>> +
>> static void veth_set_rx_headroom(struct net_device *dev, int new_hr)
>> {
>> struct veth_priv *peer_priv, *priv = netdev_priv(dev);
>> @@ -591,14 +608,33 @@ static int veth_xdp_set(struct net_device *dev, struct
>> bpf_prog *prog,
>> goto err;
>> }
>> }
>> +
>> + if (!old_prog) {
>> + peer->hw_features &= ~NETIF_F_GSO_SOFTWARE;
>> + peer->max_mtu = PAGE_SIZE - VETH_XDP_HEADROOM -
>> + peer->hard_header_len -
>> + SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
>> + if (peer->mtu > peer->max_mtu)
>> + dev_set_mtu(peer, peer->max_mtu);
>> + }
>> }
>>
>> if (old_prog) {
>> - if (!prog && dev->flags & IFF_UP)
>> - veth_disable_xdp(dev);
>> + if (!prog) {
>> + if (dev->flags & IFF_UP)
>> + veth_disable_xdp(dev);
>> +
>> + if (peer) {
>> + peer->hw_features |= NETIF_F_GSO_SOFTWARE;
>> + peer->max_mtu = ETH_MAX_MTU;
>> + }
>> + }
>> bpf_prog_put(old_prog);
>> }
>>
>> + if ((!!old_prog ^ !!prog) && peer)
>> + netdev_update_features(peer);
>> +
>> return 0;
>> err:
>> priv->_xdp_prog = old_prog;
>> @@ -643,6 +679,7 @@ static const struct net_device_ops veth_netdev_ops = {
>> .ndo_poll_controller = veth_poll_controller,
>> #endif
>> .ndo_get_iflink = veth_get_iflink,
>> + .ndo_fix_features = veth_fix_features,
>> .ndo_features_check = passthru_features_check,
>> .ndo_set_rx_headroom = veth_set_rx_headroom,
>> .ndo_bpf = veth_xdp,
--
Toshiaki Makita
