Re: bpf filter : support for vlan tag

On Tue, Oct 16, 2012 at 8:46 AM, Eric Dumazet [off-list ref] wrote:

On Mon, 2012-10-15 at 19:10 -0700, Ani Sinha wrote:

quoted

Hi :

I was looking at the kernel side implementation of the BPF filter. I
do not see any code that supports filtering of packets based on
provided vlan tag information from the skbuff. This will make it
impossible to provide any filter to tcpdump that will filter packets
based on the tag information if libpcap uses the kernel filter.

Any help will be much appreciated.

Right, we need a basic support, using a new ancillary definition.

Is the following patch enough to address your need, or do you also need
access to vlan_tx_tag_present() ?

I like this patch, it's especially useful to speed up processing for
packet analyzers. vlan_tx_tag_present() might also be good to have if
this doesn't waste to much room for future ancillary operations.