Merge branch 'double-fix bpf_test_run + XDP_PASS recycling'

Merge branch 'double-fix bpf_test_run + XDP_PASS recycling'

Alexander Lobakin says:

====================

Enabling skb PP recycling revealed a couple issues in the bpf_test_run
code. Recycling broke the assumption that the headroom won't ever be
touched during the test_run execution: xdp_scrub_frame() invalidates the
XDP frame at the headroom start, while neigh xmit code overwrites 2 bytes
to the left of the Ethernet header. The first makes the kernel panic in
certain cases, while the second breaks xdp_do_redirect selftest on BE.
test_run is a limited-scope entity, so let's hope no more corner cases
will happen here or at least they will be as easy and pleasant to fix
as those two.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>