From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752784AbcCJS5G (ORCPT ); Thu, 10 Mar 2016 13:57:06 -0500 Received: from mail-lb0-f174.google.com ([209.85.217.174]:33329 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751996AbcCJS4z (ORCPT ); Thu, 10 Mar 2016 13:56:55 -0500 Subject: Re: [RFC -next 2/2] virtio_net: Read and use the advised MTU To: Aaron Conole , netdev@vger.kernel.org, "Michael S. Tsirkin" , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <1457620092-24170-1-git-send-email-aconole@redhat.com> <1457620092-24170-3-git-send-email-aconole@redhat.com> From: Sergei Shtylyov Organization: Cogent Embedded Message-ID: <56E1C372.60204@cogentembedded.com> Date: Thu, 10 Mar 2016 21:56:50 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 MIME-Version: 1.0 In-Reply-To: <1457620092-24170-3-git-send-email-aconole@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello. On 03/10/2016 05:28 PM, Aaron Conole wrote: > This patch checks the feature bit for the VIRTIO_NET_F_MTU feature. If it > exists, read the advised MTU and use it. > > No proper error handling is provided for the case where a user changes the > negotiated MTU. A future commit will add proper error handling. Instead, a > warning is emitted if the guest changes the device MTU after previously being > given advice. > > Signed-off-by: Aaron Conole > --- > drivers/net/virtio_net.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 767ab11..7175563 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c [...] > @@ -1390,8 +1391,12 @@ static const struct ethtool_ops virtnet_ethtool_ops = { > > static int virtnet_change_mtu(struct net_device *dev, int new_mtu) > { > + struct virtnet_info *vi = netdev_priv(dev); > if (new_mtu < MIN_MTU || new_mtu > MAX_MTU) > return -EINVAL; > + if (vi->negotiated_mtu == true) { > + pr_warn("changing mtu from negotiated mtu."); > + } {} not needed, see Documentation/CodingStyle. [...] MBR, Sergei