Merge branch 'XDP-redirect-tracepoints'

Merge branch 'XDP-redirect-tracepoints'

Jesper Dangaard Brouer says:

====================
XDP redirect tracepoints

I feel this is as far as I can take the tracepoint infrastructure to
assist XDP monitoring.

Tracepoints comes with a base overhead of 25 nanosec for an attached
bpf_prog, and 48 nanosec for using a full perf record. This is
problematic for the XDP use-case, but it is very convenient to use the
existing perf infrastructure.

From a performance perspective, the real solution would be to attach
another bpf_prog (that understand xdp_buff), but I'm not sure we want
to introduce yet another bpf attach API for this.

One thing left is to standardize the possible err return codes, to a
limited set, to allow easier (and faster) mapping into a bpf map.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>