[PATCH net] add support of IFF_XMIT_DST_RELEASE bit in vlan

[Vadim Fedorenko]

Some time ago Eric Dumazet suggested a "hack the IFF_XMIT_DST_RELEASE
flag on the vlan netdev". But the last comment was "does not support
properly bonding/team.(If the real_dev->privflags IFF_XMIT_DST_RELEASE
bit changes, we want to update all the vlans at the same time )"

I've extended that patch to support changes of IFF_XMIT_DST_RELEASE in
bonding/team.
Both bonding and team call netdev_change_features() after recalculation
of features including priv_flags IFF_XMIT_DST_RELEASE bit. So the only
thing needed to support is to recheck this bit in
vlan_transfer_features().

Suggested-by: Eric Dumazet <eric.duma...@gmail.com>
Signed-off-by: Vadim Fedorenko <vfedore...@yandex-team.ru>
---
 net/8021q/vlan.c         | 3 +++
 net/8021q/vlan_netlink.c | 1 +
 2 files changed, 4 insertions(+)

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 9649579..510986c 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -328,6 +328,9 @@ static void vlan_transfer_features(struct net_device *dev,
        vlandev->fcoe_ddp_xid = dev->fcoe_ddp_xid;
 #endif
 
+       vlandev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
+       vlandev->priv_flags |= (vlan->real_dev->priv_flags & 
IFF_XMIT_DST_RELEASE);
+
        netdev_update_features(vlandev);
 }
 
diff --git a/net/8021q/vlan_netlink.c b/net/8021q/vlan_netlink.c
index 5e831de..9472de8 100644
--- a/net/8021q/vlan_netlink.c
+++ b/net/8021q/vlan_netlink.c
@@ -143,6 +143,7 @@ static int vlan_newlink(struct net *src_net, struct 
net_device *dev,
        vlan->vlan_proto = proto;
        vlan->vlan_id    = nla_get_u16(data[IFLA_VLAN_ID]);
        vlan->real_dev   = real_dev;
+       dev->priv_flags |= (real_dev->priv_flags & IFF_XMIT_DST_RELEASE);
        vlan->flags      = VLAN_FLAG_REORDER_HDR;
 
        err = vlan_check_real_dev(real_dev, vlan->vlan_proto, vlan->vlan_id);
-- 
1.9.1