In some settings offload might calculate hash from decapsulated packet. Reserve a bit in packet header rsstype to indicate that.
Add m_adj_decap() that acts similarly to m_adj, but also either clear flowid if it is not marked as inner, or transfer it to the decapsulated header, clearing inner indicator. It depends on the internals of m_adj() that reuses the argument packet header for the result.
Use m_adj_decap() for decapsulating vxlan(4) and gif(4) input packets.
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