Re: [PATCH v4 net-next 3/6] drivers: net: dsa: add locked fdb entry flag to drivers

netdev
2022-07-17T13:09:20Z

On 2022-07-17 14:57, Vladimir Oltean wrote:
> On Sun, Jul 17, 2022 at 02:21:47PM +0200, netdev@kapio-technology.com
> wrote:
>> On 2022-07-13 14:39, Ido Schimmel wrote:
>> > On Wed, Jul 13, 2022 at 09:09:58AM +0200, netdev@kapio-technology.com
>> > wrote:
>>
>> >
>> > What are "Storm Prevention" and "zero-DPV" FDB entries?
>>
>> They are both FDB entries that at the HW level drops all packets
>> having a
>> specific SA, thus using minimum resources.
>> (thus the name "Storm Prevention" aka, protection against DOS attacks.
>> We
>> must remember that we operate with CPU based learning.)
>
> DPV means Destination Port Vector, and an ATU entry with a DPV of 0
> essentially means a FDB entry pointing nowhere, so it will drop the
> packet. That's a slight problem with Hans' implementation, the bridge
> thinks that the locked FDB entry belongs to port X, but in reality it
> matches on all bridged ports (since it matches by FID). FID allocation
> in mv88e6xxx is slightly strange, all VLAN-unaware bridge ports,
> belonging to any bridge, share the same FID, so the FDB databases are
> not exactly isolated from each other.

But if the locked port is vlan aware and has a pvid, it should not block
other ports. Besides the fid will be zero with vlan unaware afaik, and
all with zero fid do not create locked entries.