Merge branch 'mlxsw-update-adjacency-index-more-efficiently'

Ido Schimmel says:

====================
mlxsw: Update adjacency index more efficiently

The device supports an operation that allows the driver to issue one
request to update the adjacency index for all the routes in a given
virtual router (VR) from old index and size to new ones. This is useful
in case the configuration of a certain nexthop group is updated and its
adjacency index changes.

Currently, the driver does not use this operation in an efficient
manner. It iterates over all the routes using the nexthop group and
issues an update request for the VR if it is not the same as the
previous VR.

Instead, this patch set tracks the VRs in which the nexthop group is
used and issues one request for each VR.

Example:

8k IPv6 routes were added in an alternating manner to two VRFs. All the
routes are using the same nexthop object ('nhid 1').

Before:

 Performance counter stats for 'ip nexthop replace id 1 via 2001:db8:1::2 dev swp3':

            16,385      devlink:devlink_hwmsg

       4.255933213 seconds time elapsed

       0.000000000 seconds user
       0.666923000 seconds sys

Number of EMAD transactions corresponds to number of routes using the
nexthop group.

After:

 Performance counter stats for 'ip nexthop replace id 1 via 2001:db8:1::2 dev swp3':

                 3      devlink:devlink_hwmsg

       0.077655094 seconds time elapsed

       0.000000000 seconds user
       0.076698000 seconds sys

Number of EMAD transactions corresponds to number of VRFs / VRs.

Patch set overview:

Patch #1 is a fix for a bug introduced in previous submission. Detected
by Coverity.

Patches #2 and #3 are preparations.

Patch #4 tracks the VRs a nexthop group is member of.

Patch #5 uses the membership tracking from the previous patch to issue
one update request per each VR.
====================

Link: https://lore.kernel.org/r/20201125193505.1052466-1-idosch@idosch.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>