Re: [PATCH net-next 0/3] net: vlan: fix bridge binding behavior and add selftests

From: Nikolay Aleksandrov
Date: Sat Jul 30 2022 - 12:24:10 EST


On 7/30/22 19:03, Sevinj Aghayeva wrote:
When bridge binding is enabled for a vlan interface, it is expected
that the link state of the vlan interface will track the subset of the
ports that are also members of the corresponding vlan, rather than
that of all ports.

Currently, this feature works as expected when a vlan interface is
created with bridge binding enabled:

ip link add link br name vlan10 type vlan id 10 protocol 802.1q \
bridge_binding on

However, the feature does not work when a vlan interface is created
with bridge binding disabled, and then enabled later:

ip link add link br name vlan10 type vlan id 10 protocol 802.1q \
bridge_binding off
ip link set vlan10 type vlan bridge_binding on

After these two commands, the link state of the vlan interface
continues to track that of all ports, which is inconsistent and
confusing to users. This series fixes this bug and introduces two
tests for the valid behavior.

Sevinj Aghayeva (3):
net: bridge: export br_vlan_upper_change
net: 8021q: fix bridge binding behavior for vlan interfaces
selftests: net: tests for bridge binding behavior

include/linux/if_bridge.h | 9 ++
net/8021q/vlan.h | 2 +-
net/8021q/vlan_dev.c | 21 ++-
net/bridge/br_vlan.c | 7 +-
tools/testing/selftests/net/Makefile | 1 +
.../selftests/net/bridge_vlan_binding_test.sh | 143 ++++++++++++++++++
6 files changed, 176 insertions(+), 7 deletions(-)
create mode 100755 tools/testing/selftests/net/bridge_vlan_binding_test.sh


Hmm.. I don't like this and don't think this bridge function should be exported at all.

Calling bridge state changing functions from 8021q module is not the proper way to solve this. The problem is that the bridge doesn't know that the state has changed, so you can process NETDEV_CHANGE events and check for the bridge vlan which got its state changed and react based on it. I haven't checked in detail, but I think it should be doable. So all
the logic is kept inside the bridge.

Cheers,
Nik