Messages in this thread | | | Date | Sun, 05 Jan 2014 23:35:54 -0800 | From | John Fastabend <> | Subject | Re: [PATCH net 1/2] macvlan: forbid L2 fowarding offload for macvtap |
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On 01/05/2014 07:21 PM, Jason Wang wrote: > L2 fowarding offload will bypass the rx handler of real device. This will make > the packet could not be forwarded to macvtap device. Another problem is the > dev_hard_start_xmit() called for macvtap does not have any synchronization. > > Fix this by forbidding L2 forwarding for macvtap. > > Cc: John Fastabend <john.r.fastabend@intel.com> > Cc: Neil Horman <nhorman@tuxdriver.com> > Signed-off-by: Jason Wang <jasowang@redhat.com> > --- > drivers/net/macvlan.c | 5 ++++- > 1 files changed, 4 insertions(+), 1 deletions(-) >
I must be missing something.
The lower layer device should set skb->dev to the correct macvtap device on receive so that in netif_receive_skb_core() the macvtap handler is hit. Skipping the macvlan receive handler should be OK because the switching was done by the hardware. If I read macvtap.c correctly macvlan_common_newlink() is called with 'dev' where 'dev' is the macvtap device. Any idea what I'm missing? I guess I'll need to setup a macvtap test case.
And what synchronization are you worried about on dev_hard_start_xmit()? In the L2 forwarding offload case macvlan_open() clears the NETIF_F_LLTX flag so HARD_TX_LOCK protects the driver txq. We might hit this warning in dev_queue_xmit() though,
net_crit_ratelimited("Virtual device %s asks to queue packet!\n",
Perhaps we can remove it.
> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c > index 60406b0..5360f73 100644 > --- a/drivers/net/macvlan.c > +++ b/drivers/net/macvlan.c > @@ -338,6 +338,8 @@ static const struct header_ops macvlan_hard_header_ops = { > .cache_update = eth_header_cache_update, > }; > > +static struct rtnl_link_ops macvlan_link_ops; > + > static int macvlan_open(struct net_device *dev) > { > struct macvlan_dev *vlan = netdev_priv(dev); > @@ -353,7 +355,8 @@ static int macvlan_open(struct net_device *dev) > goto hash_add; > } > > - if (lowerdev->features & NETIF_F_HW_L2FW_DOFFLOAD) { > + if (lowerdev->features & NETIF_F_HW_L2FW_DOFFLOAD && > + dev->rtnl_link_ops == &macvlan_link_ops) { > vlan->fwd_priv = > lowerdev->netdev_ops->ndo_dfwd_add_station(lowerdev, dev); > >
-- John Fastabend Intel Corporation
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