From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966835AbcCPOLn (ORCPT ); Wed, 16 Mar 2016 10:11:43 -0400 Received: from mail-lf0-f52.google.com ([209.85.215.52]:35722 "EHLO mail-lf0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932868AbcCPOLl (ORCPT ); Wed, 16 Mar 2016 10:11:41 -0400 Subject: Re: [RFC v2 -next 2/2] virtio_net: Read the advised MTU To: Aaron Conole , netdev@vger.kernel.org, "Michael S. Tsirkin" , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <1458075853-14789-1-git-send-email-aconole@redhat.com> <1458075853-14789-3-git-send-email-aconole@redhat.com> From: Sergei Shtylyov Message-ID: <56E9699A.9030908@cogentembedded.com> Date: Wed, 16 Mar 2016 17:11:38 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <1458075853-14789-3-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 3/16/2016 12:04 AM, 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 > --- > v2: > * Whitespace cleanup in the last hunk > * Code style change around the pr_warn > * Additional test for mtu change before printing warning > > drivers/net/virtio_net.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 767ab11..429fe01 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c [...] > @@ -1390,8 +1391,11 @@ 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) && (dev->mtu != new_mtu)) Inner parens not needed, please be consistent with the code above. [...] MBR, Sergei