Merge branch 'mlxsw-PFC-and-headroom-selftests'

Petr Machata says:

====================
mlxsw: PFC and headroom selftests

Recent changes in the headroom management code made it clear that an
automated way of testing this functionality is needed. This patchset brings
two tests: a synthetic headroom behavior test, which verifies mechanics of
headroom management. And a PFC test, which verifies whether this behavior
actually translates into a working lossless configuration.

Both of these tests rely on mlnx_qos[1], a tool that interfaces with Linux
DCB API. The tool was originally written to work with Mellanox NICs, but
does not actually rely on anything Mellanox-specific, and can be used for
mlxsw as well as for any other NIC-like driver. Unlike Open LLDP it does
support buffer commands and permits a fire-and-forget approach to
configuration, which makes it very handy for writing of selftests.

Patches #1-#3 extend the selftest devlink_lib.sh in various ways. Patch #4
then adds a helper wrapper for mlnx_qos to mlxsw's qos_lib.sh.

Patch #5 adds a test for management of port headroom.

Patch #6 adds a PFC test.

[1] https://github.com/Mellanox/mlnx-tools/
====================

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