From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eduardo Otubo Subject: Re: [PATCH] xen-netfront, xen-netback: Use correct minimum MTU values Date: Mon, 16 Oct 2017 16:43:34 +0200 Message-ID: <20171016144334.GA2996@vader> References: <1508160032-21689-1-git-send-email-mgamal@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: netdev@vger.kernel.org, xen-devel@lists.xenproject.org, paul.durrant@citrix.com, wei.liu2@citrix.com, linux-kernel@vger.kernel.org, vkuznets@redhat.com, cavery@redhat.com, cheshi@redhat.com To: Mohammed Gamal Return-path: Content-Disposition: inline In-Reply-To: <1508160032-21689-1-git-send-email-mgamal@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, Oct 16, 2017 at 03:20:32PM +0200, Mohammed Gamal wrote: > RFC791 specifies the minimum MTU to be 68, while xen-net{front|back} > drivers use a minimum value of 0. > > When set MTU to 0~67 with xen_net{front|back} driver, the network > will become unreachable immediately, the guest can no longer be pinged. > > xen_net{front|back} should not allow the user to set this value which causes > network problems. > > Reported-by: Chen Shi > Signed-off-by: Mohammed Gamal > --- > drivers/net/xen-netback/interface.c | 2 +- > drivers/net/xen-netfront.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c > index ee8ed9da..4491ca5 100644 > --- a/drivers/net/xen-netback/interface.c > +++ b/drivers/net/xen-netback/interface.c > @@ -486,7 +486,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, > > dev->tx_queue_len = XENVIF_QUEUE_LENGTH; > > - dev->min_mtu = 0; > + dev->min_mtu = ETH_MIN_MTU; > dev->max_mtu = ETH_MAX_MTU - VLAN_ETH_HLEN; > > /* > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index 523387e..8b8689c 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -1316,7 +1316,7 @@ static struct net_device *xennet_create_dev(struct xenbus_device *dev) > netdev->features |= netdev->hw_features; > > netdev->ethtool_ops = &xennet_ethtool_ops; > - netdev->min_mtu = 0; > + netdev->min_mtu = ETH_MIN_MTU; > netdev->max_mtu = XEN_NETIF_MAX_TX_SIZE; > SET_NETDEV_DEV(netdev, &dev->dev); > > -- > 1.8.3.1 > Acked-by: Eduardo Otubo -- Eduardo Otubo Senior Software Engineer @ RedHat