Merge branch 'mlxsw-Preparation-for-RTNL-removal'

Ido Schimmel says:

====================
mlxsw: Preparation for RTNL removal

The driver currently acquires RTNL in its route insertion path, which
contributes to very large control plane latencies. This patch set
prepares mlxsw for RTNL removal from its route insertion path in a
follow-up patch set.

Patches #1-#2 protect shared resources - KVDL and counter pool - with
their own locks. All allocations of these resources are currently
performed under RTNL, so no locks were required.

Patches #3-#7 ensure that updates to mirroring sessions only take place
in case there are active mirroring sessions. This allows us to avoid
taking RTNL when it is unnecessary, as updating of the mirroring
sessions must be performed under RTNL for the time being.

Patches #8-#10 replace the use of APIs that assume that RTNL is taken
with their RCU counterparts. Specifically, patches #8 and #9 replace
__in_dev_get_rtnl() with __in_dev_get_rcu() under RCU read-side critical
section. Patch #10 replaces __dev_get_by_index() with
dev_get_by_index_rcu().

Patches #11-#15 perform small adjustments in the code to make it easier
to later introduce a router lock instead of relying on RTNL.
====================

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