Message ID | 1458075853-14789-3-git-send-email-aconole@redhat.com |
---|---|
State | RFC, archived |
Delegated to: | David Miller |
Headers | show |
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 <aconole@bytheb.org> > --- > 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
On Tue, Mar 15, 2016 at 05:04:13PM -0400, 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. I don't see this as an error. Device might at best give a hint, user/network admin always knows best. > > Signed-off-by: Aaron Conole <aconole@bytheb.org> > --- > 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 > @@ -146,6 +146,7 @@ struct virtnet_info { > virtio_net_ctrl_ack ctrl_status; > u8 ctrl_promisc; > u8 ctrl_allmulti; > + bool negotiated_mtu; > }; > > struct padded_vnet_hdr { > @@ -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)) > + pr_warn("changing mtu while the advised mtu bit exists."); I don't really see why are we warning here. Just drop this chunk, as well as the flag in struct virtnet_info. > dev->mtu = new_mtu; > return 0; > } > @@ -1836,6 +1840,13 @@ static int virtnet_probe(struct virtio_device *vdev) > if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) > vi->has_cvq = true; > > + if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) { > + vi->negotiated_mtu = true; > + dev->mtu = virtio_cread16(vdev, > + offsetof(struct virtio_net_config, > + mtu)); > + } > + > if (vi->any_header_sg) > dev->needed_headroom = vi->hdr_len; > > @@ -2019,6 +2030,7 @@ static unsigned int features[] = { > VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, > VIRTIO_NET_F_CTRL_MAC_ADDR, > VIRTIO_F_ANY_LAYOUT, > + VIRTIO_NET_F_MTU, > }; > > static struct virtio_driver virtio_net_driver = { > -- > 2.5.0
Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> writes: > 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 <aconole@bytheb.org> >> --- >> 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. Okay, I will do that. Thanks so much for the review (again), Sergei! -Aaron > [...] > > MBR, Sergei
"Michael S. Tsirkin" <mst@redhat.com> writes: > On Tue, Mar 15, 2016 at 05:04:13PM -0400, 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. > > I don't see this as an error. Device might at best give a hint, > user/network admin always knows best. > >> >> Signed-off-by: Aaron Conole <aconole@bytheb.org> >> --- >> 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 >> @@ -146,6 +146,7 @@ struct virtnet_info { >> virtio_net_ctrl_ack ctrl_status; >> u8 ctrl_promisc; >> u8 ctrl_allmulti; >> + bool negotiated_mtu; >> }; >> >> struct padded_vnet_hdr { >> @@ -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)) >> + pr_warn("changing mtu while the advised mtu bit exists."); > > I don't really see why are we warning here. Just drop this chunk, > as well as the flag in struct virtnet_info. Okay. I was warning because the user is changing this after telling to use something different - but if you don't think it's an error, I will drop it. Thanks so much for the review, Michael! -Aaron >> dev->mtu = new_mtu; >> return 0; >> } >> @@ -1836,6 +1840,13 @@ static int virtnet_probe(struct virtio_device *vdev) >> if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) >> vi->has_cvq = true; >> >> + if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) { >> + vi->negotiated_mtu = true; >> + dev->mtu = virtio_cread16(vdev, >> + offsetof(struct virtio_net_config, >> + mtu)); >> + } >> + >> if (vi->any_header_sg) >> dev->needed_headroom = vi->hdr_len; >> >> @@ -2019,6 +2030,7 @@ static unsigned int features[] = { >> VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, >> VIRTIO_NET_F_CTRL_MAC_ADDR, >> VIRTIO_F_ANY_LAYOUT, >> + VIRTIO_NET_F_MTU, >> }; >> >> static struct virtio_driver virtio_net_driver = { >> -- >> 2.5.0
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 @@ -146,6 +146,7 @@ struct virtnet_info { virtio_net_ctrl_ack ctrl_status; u8 ctrl_promisc; u8 ctrl_allmulti; + bool negotiated_mtu; }; struct padded_vnet_hdr { @@ -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)) + pr_warn("changing mtu while the advised mtu bit exists."); dev->mtu = new_mtu; return 0; } @@ -1836,6 +1840,13 @@ static int virtnet_probe(struct virtio_device *vdev) if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) vi->has_cvq = true; + if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) { + vi->negotiated_mtu = true; + dev->mtu = virtio_cread16(vdev, + offsetof(struct virtio_net_config, + mtu)); + } + if (vi->any_header_sg) dev->needed_headroom = vi->hdr_len; @@ -2019,6 +2030,7 @@ static unsigned int features[] = { VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, VIRTIO_NET_F_CTRL_MAC_ADDR, VIRTIO_F_ANY_LAYOUT, + VIRTIO_NET_F_MTU, }; static struct virtio_driver virtio_net_driver = {
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 <aconole@bytheb.org> --- 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(+)