Hi Jiri,
On Tue, Oct 04, 2016 at 02:30:01PM +0200, Jiri Benc wrote:
> It can never happen that there's a vlan tag in the packet but not in
> skb->vlan_tci. This is ensured in __netif_receive_skb_core and honored by
> skb_vlan_push and skb_vlan_pop. The code dealing with such case is a dead
> code.
>
This code is also called for packets passed back down from userspace
(after the flow key miss and upcall). So it does happen that we have a
skb without skb->vlan_tci set.
See the chain:
ovs_packet_cmd_execute()
ovs_flow_key_extract_userspace()
key_extract()
parse_vlan()
> Moreover, the likely() statement around skb_vlan_tag_present is bogus. This
> code is called whenever flow key is being extracted from the packet. The
> packet may be as likely vlan tagged as not.
>
I guess the unlikely scenario is the one I mention above.
