[PATCH net-next 1/1] vlan: restore offload use on vlan transmit

[Andrew Gallatin <gallatin@myri.com>]

This patch copies the vlan device's dev->features to its
dev->vlan_features, which allows packets to arrive at
vlan_dev_hard_start_xmit() with their offloads intact.

When a packet destined for a vlan interface is transmitted, it passes
through dev_hard_start_xmit() (and netif_skb_features()) twice.  First
on its way to vlan_dev_hard_start_xmit(), and then again on its way to
the backing device's xmit handler. If the vlan device does not setup
its dev->vlan_features, then netif_skb_features() will strip the
features on the first trip through it (on the way to
vlan_dev_hard_start_xmit()).

Signed-off-by: Andrew Gallatin <gallatin@myri.com>
---
 net/8021q/vlan_dev.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 4a6d31a..9d4b3c9 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -559,6 +559,7 @@ static int vlan_dev_init(struct net_device *dev)
 
 	dev->features |= real_dev->vlan_features | NETIF_F_LLTX;
 	dev->gso_max_size = real_dev->gso_max_size;
+	dev->vlan_features = dev->features;
 
 	/* ipv6 shared card related stuff */
 	dev->dev_id = real_dev->dev_id;
-- 
1.7.9.5