Merge branch 'af_xdp-stats'

Ciara Loftus says:

====================
This series introduces new statistics for af_xdp:
1. drops due to rx ring being full
2. drops due to fill ring being empty
3. failures pulling an item from the tx ring

These statistics should assist users debugging and troubleshooting
peformance issues and packet drops.

The statistics are made available though the getsockopt and xsk_diag
interfaces, and the ability to dump these extended statistics is made
available in the xdpsock application via the --extra-stats or -x flag.

A separate patch which will add ss/iproute2 support will follow.
====================

Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>