Message ID | 20201031102916.667619-1-vladimir.oltean@nxp.com |
---|---|
Headers | show |
Series | VLAN improvements for Ocelot switch | expand |
Hello, On 31/10/2020 12:29:10+0200, Vladimir Oltean wrote: > Currently, mscc_ocelot ports configure pvid=0 in standalone mode, and > inherit the pvid from the bridge when one is present. > > When the bridge has vlan_filtering=0, the software semantics are that > packets should be received regardless of whether there's a pvid > configured on the ingress port or not. However, ocelot does not observe > those semantics today. > > Moreover, changing the PVID is also a problem with vlan_filtering=0. > We are privately remapping the VID of FDB, MDB entries to the port's > PVID when those are VLAN-unaware (i.e. when the VID of these entries > comes to us as 0). But we have no logic of adjusting that remapping when > the user changes the pvid and vlan_filtering is 0. So stale entries > would be left behind, and untagged traffic will stop matching on them. > > And even if we were to solve that, there's an even bigger problem. If > swp0 has pvid 1, and swp1 has pvid 2, and both are under a vlan_filtering=0 > bridge, they should be able to forward traffic between one another. > However, with ocelot they wouldn't do that. > > The simplest way of fixing this is to never configure the pvid based on > what the bridge is asking for, when vlan_filtering is 0. Only if there > was a VLAN that the bridge couldn't mangle, that we could use as pvid.... > So, turns out, there's 0 just for that. And for a reason: IEEE > 802.1Q-2018, page 247, Table 9-2-Reserved VID values says: > > The null VID. Indicates that the tag header contains only > priority information; no VID is present in the frame. > This VID value shall not be configured as a PVID or a member > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > of a VID Set, or configured in any FDB entry, or used in any > Management operation. > > So, aren't we doing exactly what 802.1Q says not to? Well, in a way, but > what we're doing here is just driver-level bookkeeping, all for the > better. The fact that we're using a pvid of 0 is not observable behavior > from the outside world: the network stack does not see the classified > VLAN that the switch uses, in vlan_filtering=0 mode. And we're also more > consistent with the standalone mode now. > IIRC, we are using pvid 1 because else bridging breaks when CONFIG_VLAN_8021Q is not enabled. Did you test that configuration? -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
On Mon, Nov 02, 2020 at 09:47:20AM +0100, Alexandre Belloni wrote: > IIRC, we are using pvid 1 because else bridging breaks when > CONFIG_VLAN_8021Q is not enabled. Did you test that configuration? Pertinent question. I hadn't tested that, but I did now. [root@LS1028ARDB ~] # zcat /proc/config.gz | grep 8021Q # CONFIG_VLAN_8021Q is not set [root@LS1028ARDB ~] # ip addr flush swp0 [root@LS1028ARDB ~] # ip addr add 192.168.1.2/24 dev swp0 [root@LS1028ARDB ~] # ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1): 56 data bytes 64 bytes from 192.168.1.1: seq=0 ttl=64 time=0.717 ms 64 bytes from 192.168.1.1: seq=1 ttl=64 time=0.442 ms ^C --- 192.168.1.1 ping statistics --- 2 packets transmitted, 2 packets received, 0% packet loss round-trip min/avg/max = 0.442/0.579/0.717 ms [root@LS1028ARDB ~] # ip addr flush swp0 [root@LS1028ARDB ~] # ip link add br0 type bridge [root@LS1028ARDB ~] # ip link set swp0 master br0 [ 409.576303] br0: port 1(swp0) entered blocking state [ 409.581380] br0: port 1(swp0) entered disabled state [ 409.586738] device swp0 entered promiscuous mode [ 409.591866] br0: port 1(swp0) entered blocking state [ 409.596852] br0: port 1(swp0) entered forwarding state [root@LS1028ARDB ~] # ip addr add 192.168.1.2/24 dev br0 [root@LS1028ARDB ~] # ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1): 56 data bytes 64 bytes from 192.168.1.1: seq=0 ttl=64 time=0.768 ms 64 bytes from 192.168.1.1: seq=1 ttl=64 time=0.657 ms 64 bytes from 192.168.1.1: seq=2 ttl=64 time=0.509 ms 64 bytes from 192.168.1.1: seq=3 ttl=64 time=0.513 ms 64 bytes from 192.168.1.1: seq=4 ttl=64 time=0.496 ms ^C --- 192.168.1.1 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max = 0.496/0.588/0.768 ms [root@LS1028ARDB ~] # ip link del br0 [ 135.526825] device swp0 left promiscuous mode [ 135.531729] br0: port 1(swp0) entered disabled state [root@LS1028ARDB ~] # ip addr add 192.168.1.2/24 dev swp0 [root@LS1028ARDB ~] # ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1): 56 data bytes 64 bytes from 192.168.1.1: seq=0 ttl=64 time=0.783 ms 64 bytes from 192.168.1.1: seq=1 ttl=64 time=0.289 ms 64 bytes from 192.168.1.1: seq=2 ttl=64 time=0.412 ms 64 bytes from 192.168.1.1: seq=3 ttl=64 time=0.399 ms 64 bytes from 192.168.1.1: seq=4 ttl=64 time=0.396 ms 64 bytes from 192.168.1.1: seq=5 ttl=64 time=0.390 ms ^C --- 192.168.1.1 ping statistics --- 6 packets transmitted, 6 packets received, 0% packet loss round-trip min/avg/max = 0.289/0.444/0.783 ms There's no logical reason why it wouldn't work. Thanks to your code which ensures VLAN 0 is in the VLAN table. Nobody is removing VLAN 0 right now. /* Because VLAN filtering is enabled, we need VID 0 to get untagged * traffic. It is added automatically if 8021q module is loaded, but * we can't rely on it since module may be not loaded. */ ocelot->vlan_mask[0] = GENMASK(ocelot->num_phys_ports - 1, 0); ocelot_vlant_set_mask(ocelot, 0, ocelot->vlan_mask[0]); I cannot test the mscc_ocelot driver, I am only testing felix DSA, and for that reason I can't even go very far down the history. Remember that when CONFIG_VLAN_8021Q is disabled, CONFIG_BRIDGE_VLAN_FILTERING also needs to be disabled. So logically speaking, nobody calls any VLAN function when CONFIG_VLAN_8021Q is disabled. The standalone configuration should work in this mode too, shouldn't it? I am not sure if there's any relevant difference for mscc_ocelot.
On Sat, 31 Oct 2020 12:29:09 +0200 Vladimir Oltean wrote: > The main reason why I started this work is that deleting the bridge mdb > entries fails when the bridge is deleted, as described here: > https://lore.kernel.org/netdev/20201015173355.564934-1-vladimir.oltean@nxp.com/ > > In short, that happens because the bridge mdb entries are added with a > vid of 1, but deletion is attempted with a vid of 0. So the deletion > code fails to find the mdb entries. > > The solution is to make ocelot use a pvid of 0 when it is under a bridge > with vlan_filtering 0. When vlan_filtering is 1, the pvid of the bridge > is what is programmed into the hardware. > > The patch series also uncovers more bugs and does some more cleanup, but > the above is the main idea behind it. Applied, thanks!