Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752747AbcJUChg (ORCPT ); Thu, 20 Oct 2016 22:37:36 -0400 Received: from mail-pf0-f171.google.com ([209.85.192.171]:34225 "EHLO mail-pf0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750997AbcJUChd (ORCPT ); Thu, 20 Oct 2016 22:37:33 -0400 Date: Thu, 20 Oct 2016 22:37:20 -0400 From: Jarod Wilson To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, "K. Y. Srinivasan" , Haiyang Zhang , Shrikrishna Khare , "VMware, Inc." , Wei Liu , Paul Durrant , David Kershner , Aaron Conole Subject: Re: [PATCH net-next v2 6/9] net: use core MTU range checking in virt drivers Message-ID: <20161021023720.GA11396@redhat.com> References: <20161019023333.15760-1-jarod@redhat.com> <20161020175524.6184-1-jarod@redhat.com> <20161020175524.6184-7-jarod@redhat.com> <20161020231559-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161020231559-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2828 Lines: 78 On Thu, Oct 20, 2016 at 11:23:54PM +0300, Michael S. Tsirkin wrote: > On Thu, Oct 20, 2016 at 01:55:21PM -0400, Jarod Wilson wrote: ... > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index fad84f3..720809f 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -1419,17 +1419,6 @@ static const struct ethtool_ops virtnet_ethtool_ops = { > > .set_settings = virtnet_set_settings, > > }; > > > > -#define MIN_MTU 68 > > -#define MAX_MTU 65535 > > - > > -static int virtnet_change_mtu(struct net_device *dev, int new_mtu) > > -{ > > - if (new_mtu < MIN_MTU || new_mtu > MAX_MTU) > > - return -EINVAL; > > - dev->mtu = new_mtu; > > - return 0; > > -} > > - > > static const struct net_device_ops virtnet_netdev = { > > .ndo_open = virtnet_open, > > .ndo_stop = virtnet_close, > > @@ -1437,7 +1426,6 @@ static const struct net_device_ops virtnet_netdev = { > > .ndo_validate_addr = eth_validate_addr, > > .ndo_set_mac_address = virtnet_set_mac_address, > > .ndo_set_rx_mode = virtnet_set_rx_mode, > > - .ndo_change_mtu = virtnet_change_mtu, > > .ndo_get_stats64 = virtnet_stats, > > .ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid, > > .ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid, > > @@ -1748,6 +1736,9 @@ static bool virtnet_validate_features(struct virtio_device *vdev) > > return true; > > } > > > > +#define MIN_MTU ETH_MIN_MTU > > +#define MAX_MTU ETH_MAX_MTU > > + > > Can we drop these btw? Bah. Yeah. Should have just used them directly. I didn't add ETH_MAX_MTU until after doing the virtio_net changes, so I missed that. > > static int virtnet_probe(struct virtio_device *vdev) > > { > > int i, err; > > @@ -1821,6 +1812,10 @@ static int virtnet_probe(struct virtio_device *vdev) > > > > dev->vlan_features = dev->features; > > > > + /* MTU range: 68 - 65535 */ > > + dev->min_mtu = MIN_MTU; > > + dev->max_mtu = MAX_MTU; > > + > > /* Configuration may specify what MAC to use. Otherwise random. */ > > if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) > > virtio_cread_bytes(vdev, > > @@ -1875,8 +1870,10 @@ static int virtnet_probe(struct virtio_device *vdev) > > mtu = virtio_cread16(vdev, > > offsetof(struct virtio_net_config, > > mtu)); > > - if (virtnet_change_mtu(dev, mtu)) > > + if (mtu < dev->min_mtu || mtu > dev->max_mtu) > > In fact the > max_mtu branch does not make sense since a 16 bit > value can't exceed MAX_MTU. Hm. mtu is declared as an int, not sure if there's any sort of type promotion to be worried about (not an area I know much/anything about). Certainly something that could be looked into as a minor optimization, though it's only in a probe path and shouldn't hurt anything, so ... meh? -- Jarod Wilson jarod@redhat.com