[Bridge question] Issue with removing MDB entry after enabling VLAN filtering

[Hangbin Liu <liuhangbin@gmail.com>]

Hi everyone,

Our QE team reported that after adding an MDB entry, enabling VLAN filtering,
and then removing the MDB entry, the removal fails. e.g.

+ ip link add dev br0 type bridge
+ ip link add dev vethin type veth peer name vethout
+ ip link add dev vethin1 type veth peer name vethout1
+ ip link set vethout up && ip link set vethout1 up && ip link set vethin up  && ip link set vethin1 up && ip link set br0 up
+ ip link set vethout master br0
+ ip link set vethout1 master br0
+ echo 1 > /sys/class/net/br0/bridge/multicast_snooping
+ echo 1 > /sys/class/net/br0/bridge/multicast_querier
+ bridge mdb add dev br0 port vethout1 grp 225.1.1.10 src 192.168.2.1
+ echo 1 > /sys/class/net/br0/bridge/vlan_filtering
+ bridge mdb del dev br0 port vethout1 grp  225.1.1.10  src 192.168.2.1
RTNETLINK answers: Invalid argument

From reviewing the code in br_mdb_del(), I noticed that it sets the VLAN tag
if VLAN filtering is enabled and the VLAN is not specified.

I'm not sure if the QE’s operation is valid under these circumstances.
Do we need to disable VLAN filtering before removing the MDB entry if
it was added without VLAN filtering?

Thanks
Hangbin