On Mon, Jan 8, 2018 at 10:48 PM, <liuq...@huawei.com> wrote:
> From: Keefe Liu <liuq...@huawei.com>
>
> The MTU of ipvlan interface should not bigger than the phy device, When we
> run following scripts, we will find there are some problems.
> Step1:
> ip link add link eth0 name ipv1 type ipvlan mode l2
> ip netns add net1
> ip link set dev ipv1 netns net1
> Step2:
> ip netns exec net1 ip link set dev ipv1 mtu 1501
> RTNETLINK answers: Invalid argument
> dmesg info: "ipv1: Invalid MTU 1501 requested, hw max 1500"
> Step3:
> ip link set dev eth0 mtu 1600
> ip netns exec net1 ip link set dev ipv1 mtu 1501
> RTNETLINK answers: Invalid argument
> dmesg info: "ipv1: Invalid MTU 1501 requested, hw max 1500"
> Step4:
> ip link set dev eth0 mtu 1400
> ip netns exec net1 ip link set dev ipv1 mtu 1500
> The result of Step2 is we expected, but the result of Step3 and Step4
> are not.
>
> This patch set ipvlan's maximum MTU to ETH_MAX_MTU, and when we change
> the ipvlan device's MTU, ipvlan_change_mtu() will make sure the new MTU
> no larger than the phy device's MTU.
>
> Signed-off-by: Keefe Liu <liuq...@huawei.com>
> ---
> drivers/net/ipvlan/ipvlan_main.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/net/ipvlan/ipvlan_main.c
> b/drivers/net/ipvlan/ipvlan_main.c
> index 30cb803..84c007d 100644
> --- a/drivers/net/ipvlan/ipvlan_main.c
> +++ b/drivers/net/ipvlan/ipvlan_main.c
> @@ -380,12 +380,24 @@ static int ipvlan_get_iflink(const struct net_device
> *dev)
> return ipvlan->phy_dev->ifindex;
> }
>
> +static int ipvlan_change_mtu(struct net_device *dev, int new_mtu)
> +{
> + struct ipvl_dev *ipvlan = netdev_priv(dev);
> +
> + if (ipvlan->phy_dev->mtu < new_mtu)
> + return -EINVAL;
> +
> + dev->mtu = new_mtu;
> + return 0;
> +}
> +
> static const struct net_device_ops ipvlan_netdev_ops = {
> .ndo_init = ipvlan_init,
> .ndo_uninit = ipvlan_uninit,
> .ndo_open = ipvlan_open,
> .ndo_stop = ipvlan_stop,
> .ndo_start_xmit = ipvlan_start_xmit,
> + .ndo_change_mtu = ipvlan_change_mtu,
> .ndo_fix_features = ipvlan_fix_features,
> .ndo_change_rx_flags = ipvlan_change_rx_flags,
> .ndo_set_rx_mode = ipvlan_set_multicast_mac_filter,
> @@ -680,6 +692,8 @@ void ipvlan_link_setup(struct net_device *dev)
> {
> ether_setup(dev);
>
> + dev->min_mtu = 0;
should be ETH_MIN_MTU since we expect the underlying device to be
ETH_ARPHDR and IPvlan deals with IPv4/IPv6.
> + dev->max_mtu = ETH_MAX_MTU;
> dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
> dev->priv_flags |= IFF_UNICAST_FLT | IFF_NO_QUEUE;
> dev->netdev_ops = &ipvlan_netdev_ops;
> --
> 1.8.3.1
>
>
These changes are not sufficient if you want to have different
per-slave mtu settings. One can always change the MTU of the master
device and all per-slave settings will get wiped. I don't think
that's a desired outcome.
