On Fri, 28 Jun 2019 at 15:30, Ido Schimmel [off-list ref] wrote:

On Tue, Jun 25, 2019 at 11:49:29PM +0300, Vladimir Oltean wrote:

quoted

A number of DSA drivers (BCM53XX, Microchip KSZ94XX, Mediatek MT7530
at the very least), as well as Mellanox Spectrum (I didn't look at all
the pure switchdev drivers) try to restore the pvid to a default value
on .port_vlan_del.

I don't know about DSA drivers, but that's not what mlxsw is doing. If
the VLAN that is configured as PVID is deleted from the bridge port, the
driver instructs the port to discard untagged and prio-tagged packets.
This is consistent with the bridge driver's behavior.

We do have a flow the "restores" the PVID, but that's when a port is
unlinked from its bridge master. The PVID we set is 4095 which cannot be
configured by the 8021q / bridge driver. This is due to the way the
underlying hardware works. Even if a port is not bridged and used purely
for routing, packets still do L2 lookup first which sends them directly
to the router block. If PVID is not configured, untagged packets could
not be routed. Obviously, at egress we strip this VLAN.

quoted

Sure, the port stops receiving traffic when its pvid is a VLAN ID that
is not installed in its hw filter, but as far as the bridge core is
concerned, this is to be expected:

# bridge vlan add dev swp2 vid 100 pvid untagged
# bridge vlan
port    vlan ids
swp5     1 PVID Egress Untagged

swp2     1 Egress Untagged
         100 PVID Egress Untagged

swp3     1 PVID Egress Untagged

swp4     1 PVID Egress Untagged

br0      1 PVID Egress Untagged
# ping 10.0.0.1
PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
64 bytes from 10.0.0.1: icmp_seq=1 ttl=64 time=0.682 ms
64 bytes from 10.0.0.1: icmp_seq=2 ttl=64 time=0.299 ms
64 bytes from 10.0.0.1: icmp_seq=3 ttl=64 time=0.251 ms
64 bytes from 10.0.0.1: icmp_seq=4 ttl=64 time=0.324 ms
64 bytes from 10.0.0.1: icmp_seq=5 ttl=64 time=0.257 ms
^C

--- 10.0.0.1 ping statistics ---

5 packets transmitted, 5 received, 0% packet loss, time 4188ms
rtt min/avg/max/mdev = 0.251/0.362/0.682/0.163 ms
# bridge vlan del dev swp2 vid 100
# bridge vlan
port    vlan ids
swp5     1 PVID Egress Untagged

swp2     1 Egress Untagged

swp3     1 PVID Egress Untagged

swp4     1 PVID Egress Untagged

br0      1 PVID Egress Untagged

# ping 10.0.0.1
PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
^C

--- 10.0.0.1 ping statistics ---

8 packets transmitted, 0 received, 100% packet loss, time 7267ms

What is the consensus here? Is there a reason why the bridge driver
doesn't take care of this?

Take care of what? :) Always maintaining a PVID on the bridge port? It's
completely OK not to have a PVID.

Yes, I didn't think it through during the first email. I came to the
same conclusion in the second one.

quoted

Do switchdev drivers have to restore the pvid to always be
operational, even if their state becomes inconsistent with the upper
dev? Is it just 'nice to have'? What if VID 1 isn't in the hw filter
either (perfectly legal)?

Are you saying that DSA drivers always maintain a PVID on the bridge
port and allow untagged traffic to ingress regardless of the bridge
driver's configuration? If so, I think this needs to be fixed.

Well, not at the DSA core level.
But for Microchip:
https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/tree/drivers/net/dsa/microchip/ksz9477.c#n576
For Broadcom:
https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/tree/drivers/net/dsa/b53/b53_common.c#n1376
For Mediatek:
https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/tree/drivers/net/dsa/mt7530.c#n1196

There might be others as well.

Thanks,
-Vladimir