William Tu says:
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gre: add collect_md mode for ERSPAN tunnel
This patch series provide collect_md mode for ERSPAN tunnel. The fist patch
refactors the existing gre_fb_xmit function by exacting the route cache
portion into a new function called prepare_fb_xmit. The second patch
introduces the collect_md mode for ERSPAN tunnel, by calling the
prepare_fb_xmit function and adding ERSPAN specific logic. The final patch
adds the test case using bpf_skb_{set,get}_tunnel_{key,opt}.
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Signed-off-by: David S. Miller <davem@davemloft.net>