netdev - Re: bpf filter : support for vlan tag

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Date:	Tue, 16 Oct 2012 13:34:56 +0200
From:	Daniel Borkmann <danborkmann@...earbox.net>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Ani Sinha <ani@...stanetworks.com>, netdev@...r.kernel.org
Subject: Re: bpf filter : support for vlan tag

On Tue, Oct 16, 2012 at 1:28 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Tue, 2012-10-16 at 13:00 +0200, Daniel Borkmann wrote:
>> On Tue, Oct 16, 2012 at 8:46 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>> > On Mon, 2012-10-15 at 19:10 -0700, Ani Sinha wrote:
>> >> 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.
>
> There is plenty of room in ancillary space
>
> Note that if speed is needed, we also want to update various JIT
> implementations.

Thanks for the patch. My kernel was still compiling and mutt was
already open for a submission on the vlan_tx_tag_present() operation.
:-)
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