Merge branch 'selftests: xsk: various simplifications'

Magnus Karlsson says:

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

This patch set mainly contains various simplifications to the xsk
selftests. The only exception is the introduction of packet streams
that describes what the Tx process should send and what the Rx process
should receive. If it receives anything else, the test fails. This
mechanism can be used to produce tests were all packets are not
received by the Rx thread or modified in some way. An example of this
is if an XDP program does XDP_PASS on some of the packets.

This patch set will be followed by another patch set that implements a
new structure that will facilitate adding new tests. A couple of new
tests will also be included in that patch set.

v2 -> v3:

* Reworked patch 12 so that it now has functions for creating and
  destroying ifobjects. Simplifies the code. [Maciej]
* The packet stream now allocates the supplied buffer array length,
  instead of the default one. [Maciej]
* pkt_stream_get_pkt() now returns NULL when indexing a non-existing
  packet. [Maciej]
* pkt_validate() is now is_pkt_valid(). [Maciej]
* Slowed down packet sending speed even more in patch 11 so that slow
  systems do not silenty drop packets in skb mode.

v1 -> v2:

* Dropped the patch with per process limit changes as it is not needed
  [Yonghong]
* Improved the commit message of patch 1 [Yonghong]
* Fixed a spelling error in patch 9

Thanks: Magnus
====================

Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>