Subject: [PATCH net-next 0/8] net: Shift responsibility for FDB notifications to drivers

From: Petr Machata <[email-masked]>
Date: Tue, 22 Oct 2024 16:50:11 +0200

Currently when FDB entries are added to or deleted from a VXLAN netdevice,
the VXLAN driver emits one notification, including the VXLAN-specific
attributes. The core however always sends a notification as well, a generic
one. Thus two notifications are unnecessarily sent for these operations. A
similar situation comes up with bridge driver, which also emits
notifications on its own.

 # ip link add name vx type vxlan id 1000 dstport 4789
 # bridge monitor fdb &
 [1] 1981693
 # bridge fdb add de:ad:be:ef:13:37 dev vx self dst 192.0.2.1
 de:ad:be:ef:13:37 dev vx dst 192.0.2.1 self permanent
 de:ad:be:ef:13:37 dev vx self permanent

In order to prevent this duplicity, shift the responsibility to send the
notification always to the drivers. Only where the default FDB add / del
operations are used does the core emit notifications. If fdb_add and
fdb_del are overridden, the driver should do that instead.

To facilitate upholding this new responsibility, export rtnl_fdb_notify()
for drivers to use.

Besides this approach, we considered just passing a boolean back from the
driver, which would indicate whether the notification was done. But the
approach presented here seems cleaner.

Patches #1 to #3 are concerned with the above.

In the remaining patches, #4 to #8, add a selftest. This takes place across
several patches. Many of the helpers we would like to use for the test are
in forwarding/lib.sh, whereas net/ is a more suitable place for the test,
so the libraries need to be massaged a bit first.

Petr Machata (8):
  net: rtnetlink: Publish rtnl_fdb_notify()
  ndo_fdb_add: Shift responsibility for notifying to drivers
  ndo_fdb_del: Shift responsibility for notifying to drivers
  selftests: net: lib: Move logging from forwarding/lib.sh here
  selftests: net: lib: Move tests_run from forwarding/lib.sh here
  selftests: net: lib: Move checks from forwarding/lib.sh here
  selftests: net: lib: Add kill_process
  selftests: net: fdb_notify: Add a test for FDB notifications

 drivers/net/ethernet/intel/i40e/i40e_main.c   |   3 +
 drivers/net/ethernet/intel/ice/ice_main.c     |   6 +
 drivers/net/ethernet/mscc/ocelot_net.c        |  16 +-
 .../net/ethernet/qlogic/qlcnic/qlcnic_main.c  |  10 +-
 drivers/net/macvlan.c                         |   6 +
 include/linux/netdevice.h                     |   5 +
 include/linux/rtnetlink.h                     |   2 +
 net/core/rtnetlink.c                          |  24 +-
 .../drivers/net/mlxsw/devlink_trap.sh         |   2 +-
 .../net/mlxsw/devlink_trap_l3_drops.sh        |   4 +-
 .../net/mlxsw/devlink_trap_l3_exceptions.sh   |  12 +-
 .../net/mlxsw/devlink_trap_tunnel_ipip.sh     |   4 +-
 .../net/mlxsw/devlink_trap_tunnel_ipip6.sh    |   4 +-
 .../net/mlxsw/devlink_trap_tunnel_vxlan.sh    |   4 +-
 .../mlxsw/devlink_trap_tunnel_vxlan_ipv6.sh   |   4 +-
 .../selftests/drivers/net/mlxsw/tc_sample.sh  |   4 +-
 .../net/netdevsim/fib_notifications.sh        |   6 +-
 tools/testing/selftests/net/Makefile          |   2 +-
 .../selftests/net/drop_monitor_tests.sh       |   2 +-
 tools/testing/selftests/net/fdb_notify.sh     |  95 ++++++++
 tools/testing/selftests/net/fib_tests.sh      |   8 +-
 .../selftests/net/forwarding/devlink_lib.sh   |   2 +-
 tools/testing/selftests/net/forwarding/lib.sh | 199 +---------------
 .../selftests/net/forwarding/tc_police.sh     |   8 +-
 tools/testing/selftests/net/lib.sh            | 223 ++++++++++++++++++
 25 files changed, 409 insertions(+), 246 deletions(-)
 create mode 100755 tools/testing/selftests/net/fdb_notify.sh

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2.45.0