Merge branch 'vxlan-FDB-veto'

Petr Machata says:

====================
vxlan: Allow vetoing FDB operations

mlxsw does not implement handling of the more advanced types of VXLAN
FDB entries. In order to provide visibility to users, it is important to
be able to reject such FDB entries, ideally with an explanation passed
in extended ack. This patch set implements this.

In patches #1-#4, vxlan is gradually transformed to support vetoing of
FDB entries added (or modified) through vxlan_fdb_update(), and the
default FDB entry added in __vxlan_dev_create().

Patches #5-#7 deal with vxlan_changelink(). The existing code recognizes
that vxlan_fdb_update() may fail, but doesn't attempt to keep things
intact if it does. These patches change the function in several steps to
gracefully handle vetoes (or other failures).

Then in patches #8-#11, extack arguments are added, respectively, to
ndo_fdb_add(), mlxsw's mlxsw_sp_nve_ops.fdb_replay, the functions that
connect to the VXLAN vetoing code, and call_switchdev_notifiers(). Note
that call_switchdev_blocking_notifiers() already does support extack.

Finally in patch #12, mlxsw is extended to add extack messages to
rejected FDB entries. In patch #13, the functionality is tested.
====================

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