[PATCH net-next v4 0/5] Support for fdb ECMP nexthop groups

[Roopa Prabhu <roopa@cumulusnetworks.com>]

From: Roopa Prabhu <roopa@cumulusnetworks.com>

This series introduces ecmp nexthops and nexthop groups
for mac fdb entries. In subsequent patches this is used
by the vxlan driver fdb entries. The use case is
E-VPN multihoming [1,2,3] which requires bridged vxlan traffic
to be load balanced to remote switches (vteps) belonging to
the same multi-homed ethernet segment (This is analogous to
a multi-homed LAG but over vxlan).

Changes include new nexthop flag NHA_FDB for nexthops
referenced by fdb entries. These nexthops only have ip.
The patches make sure that routes dont reference such nexthops.

example:
$ip nexthop add id 12 via 172.16.1.2 fdb
$ip nexthop add id 13 via 172.16.1.3 fdb
$ip nexthop add id 102 group 12/13 fdb

$bridge fdb add 02:02:00:00:00:13 dev vxlan1000 nhid 101 self

[1] E-VPN https://tools.ietf.org/html/rfc7432
[2] E-VPN VxLAN: https://tools.ietf.org/html/rfc8365
[3] LPC talk with mention of nexthop groups for L2 ecmp
http://vger.kernel.org/lpc_net2018_talks/scaling_bridge_fdb_database_slidesV3.pdf

v4 -
    - fix error path free_skb in vxlan_xmit_nh
    - fix atomic notifier initialization issue
      (Reported-by: kernel test robot <rong.a.chen@intel.com>)
      The reported error was easy to locate and fix, but i was not
      able to re-test with the robot reproducer script due to some
      other issues with running the script on my test system.

v3 - fix wording in selftest print as pointed out by davidA

v2 -
	- dropped nikolays fixes for nexthop multipath null pointer deref
	  (he will send those separately)
	- added negative tests for route add with fdb nexthop + a few more
	- Fixes for a few  fdb replace conditions found during more testing
	- Moved to rcu_dereference_rtnl in vxlan_fdb_info and consolidate rcu
	  dereferences
	- Fixes to build failures Reported-by: kbuild test robot <lkp@intel.com>
	- DavidA, I am going to send a separate patch for the neighbor code validation
	  for NDA_NH_ID if thats ok.


Roopa Prabhu (5):
  nexthop: support for fdb ecmp nexthops
  vxlan: ecmp support for mac fdb entries
  nexthop: add support for notifiers
  vxlan: support for nexthop notifiers
  selftests: net: add fdb nexthop tests

 drivers/net/vxlan.c                         | 340 ++++++++++++++++++++++------
 include/net/ip6_fib.h                       |   1 +
 include/net/netns/nexthop.h                 |   1 +
 include/net/nexthop.h                       |  44 ++++
 include/net/vxlan.h                         |  25 ++
 include/uapi/linux/neighbour.h              |   1 +
 include/uapi/linux/nexthop.h                |   3 +
 net/core/neighbour.c                        |   2 +
 net/ipv4/nexthop.c                          | 159 +++++++++++--
 net/ipv6/route.c                            |   5 +
 tools/testing/selftests/net/fib_nexthops.sh | 160 ++++++++++++-
 11 files changed, 651 insertions(+), 90 deletions(-)

-- 
2.1.4