This patch series supports having VLAN devices on top of DSA/switch
ports while the switch has VLAN filtering globally turned on (as is the
case with Broadcom switches). Whether the switch does global or per-port
VLAN filtering, having VLAN entries for these VLAN devices is
beneficial.
We take care of a few possibly problematic cases:
- adding a VLAN device while there is an existing VLAN entry created by
a VLAN aware bridge. The entire bridge's VLAN database and not just
the specific bridge port is being checked to be safe and conserative
- adding a bridge VLAN entry when there is an existing VLAN device
created is also not possible because that would lead to the bridge
being able to manipulate the VLAN device's VID/attributes under its feet
- enslaving a VLAN device into a VLAN aware bridge since that duplicates
functionality already offered by the VLAN aware bridge
Here are the different test cases that were run to exercise this:
ip addr flush dev gphy
ip link add dev br0 type bridge
echo 1 > /sys/class/net/br0/bridge/vlan_filtering
ip link set dev gphy master br0
udhcpc -i br0