[ovs-dev] [PATCH] datapath: Add packet metadata support.

[Jesse Gross]

On Fri, Dec 13, 2013 at 10:25 AM, Pravin B Shelar <pshelar at nicira.com> wrote:
> In case of flow-miss kernel sends skb to userspace and then
> userspace sends execute netlink msg to switch the packet.  But
> in this process skb rxhash is not restored. skb rxhash is used
> for calculating tunnel source port for vxlan. If rxhash is not
> restored packet which is sent to miss call handler can get
> different source port compared to rest of packet of the flow.
>
> Following patch adds support for packet metadata which is part
> of packet-attributes.  Kernel can send packet metadata and
> userspace echoes it back to kernel.
> Currently packet metadata consist of skb rxhash.
>
> Signed-off-by: Pravin B Shelar <pshelar at nicira.com>

I've been thinking about this and I keep wondering whether it is
really the right solution. It solves one level of the problem but if
you have a controller that is receiving packet ins and spitting them
back out (the classic OpenFlow model) then you have exactly the same
issue again. From a reordering perspective, it probably doesn't matter
because the time difference between packets would be very large but it
still doesn't seem right.