[ovs-dev] [PATCH] ofproto-dpif: Maintain tun_id across action lists.

Ben Pfaff blp at nicira.com
Tue Jan 15 23:32:26 UTC 2013

On Tue, Jan 15, 2013 at 02:05:38PM -0800, Jesse Gross wrote:
> Previously, a tunnel ID received on input would be used by default
> on output if the packet was later sent out a tunnel.  This was not
> actually intentional behavior - tunnel information is not supposed
> to carry over.  However, it is useful in the case where move actions
> are used to load the original tunnel ID into registers for further
> processing since otherwise the information is lost before handling
> actions.

I don't think it's limited just to move actions: part of the bug report
was that the original tun_id wasn't being retained for subsequent lookup
in resubmits.  In other words, tracing a flow with initial tun_id of
0x1234 did a first-level flow lookup with that tun_id but it disappeared
in the resubmit.  The report contained a lot of juggling around with
move and load actions that touch tun_id (both as source and destination)
but those really look like red herrings to me.

I don't actually disagree with your analysis, I just think it's slightly
more general than just move actions.

This makes action_xlate_ctx_init() kind of hard to understand so a
comment might be warranted.



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