netdev - Re: [PATCH net-next] net: ethernet: ti: cpsw: drop vid0 configuration in dual

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Date:   Thu, 29 Nov 2018 17:23:09 -0600
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>
Subject: Re: [PATCH net-next] net: ethernet: ti: cpsw: drop vid0 configuration
 in dual_mac modey



On 11/29/18 9:26 AM, Ivan Khoronzhuk wrote:
> On Wed, Nov 28, 2018 at 03:15:46PM -0600, Grygorii Strashko wrote:
>>
>>
>> On 11/26/18 2:07 PM, Ivan Khoronzhuk wrote:
>>> On Mon, Nov 26, 2018 at 12:57:20PM -0600, Grygorii Strashko wrote:
>>>>
>>>>
>>>> On 11/26/18 10:26 AM, Ivan Khoronzhuk wrote:
>>>>> On Sun, Nov 25, 2018 at 05:46:26PM -0600, Grygorii Strashko wrote:
>>>>>> In dual_mac mode CPSW driver uses vid1 and vid2 by default to implement
>>>>>> dual mac mode wich are used to configure pvids for each external ports.
>>>>>> But, historicaly, it also adds vid0 to ALE table and sets "untag" bits for both
>>>>>> ext. ports. As result, it's imposible to use priority tagged packets in
>>>>>> dual mac mode.
>>>>>>
>>>>>> Hence, drop vid0 configuration in dual mac mode as it's not required for dual
>>>>>> mac mode functionality and, this way, make it possible to use priority
>>>>>> tagged packet in dual mac mode.
>>>>> So, now it's enabled to be added via regular ndo.
>>>>> I have similar change in mind, but was going to send it after
>>>>> mcast/ucast, and - enabling same vlans patch...
>>>>>
>>>>> 2 things stopped me to add this:
>>>>>
>>>>> 1) Moving it to be enabled via regular call is Ok, but in dual mac mode
>>>>> it causes overlaps, at least while vid deletion. So decided to wait till
>>>>> same vlans series is applied.
>>>>
>>>> TI driver documentation mentions this restriction
>>>> "While adding VLAN id to the eth interfaces,
>>>> same VLAN id should not be added in both interfaces which will lead to VLAN
>>>> forwarding and act as switch"
>>> It's not accurate now.
>>> This sw bug "acting like a switch" was fixed indirectly in LKML ).
>>> And at least for upstream version, not TISDK, desc should be updated,
>>> but better do this when it fixed completely and merged with TISDK.
>>>
>>> I know about this "written" restriction
>>> (for tiSDK, and it's not TRM after all ...),
>>> it can be avoided and it's partly avoided now ...
>>
>> I'd like to clarify point about supporting same VLANs in dual_mac mode,
>> to avoid future misunderstanding, overall: it's *not* supported as
>> adding same VLAN to both netdevices will cause unknown unicast packets
>> leaking between interfaces and it can't be avoided - hw limitation.
> 
> Simple test shows no issues with ucast leaking.
> But for current buggy ucast vlan implementation it's not possible to verify,
> not sure but probably leaking in your case cuased by hidden toggling of
> interface to promisc while added ucast to vlans or other reason or so.
> Anyway I just decided to check specifically ucasts
> (macst as you know are not normal now).
> 
> For verification you need to apply ucast fix (including vlans) first:
> https://git.linaro.org/people/ivan.khoronzhuk/tsn_kernel.git/log/?h=vlan_addr_flt_fix
> 
> This is generic fix (not sure it will be approved, need try RFC) but implement
> the same as local fix for vlan ucasts:
> https://git.linaro.org/people/ivan.khoronzhuk/tsn_kernel.git/log/?h=ucast_vlan_fix
> 
> Any of those are correct. I've used generic one.
> Applied the following scheme:
> 
>                      +--------------------------+
>                      | host 74:DA:EA:47:7D:9C   |
>                      +--------------------------+
> 
>                         +---------------------+
>              |       am572 evm     |
>                         |    eth0      eth1   |
>                         +----------+----------+
>                         | eth0.400 | eth1.400 |
>                         +----------+----------+
>                             ^          |
>                             |          |  +-----------+
> +-----------------+        |          |  |     PC    |
> | BBB eth0.400    |--------+          +->| Wireshark |
> +-----------------+                      +-----------+
> 
> 
> 1) Configure vlans on am572x evm
> ip link add link eth0 name eth0.400 type vlan id 400
> ip link add link eth1 name eth1.400 type vlan id 400
> 
> 2) On BBB side:
> # ip link add link eth0 name eth0.400 type vlan id 400
> Send ucast vlan traffic to the am572 evm, vlan ucast address is unreq on am572.
> # ./plget -i eth0.400 -t ptpl2 -m tx-lat -n 160 -s 10 -a 74:DA:EA:47:7D:66
> # ./plget -i eth0.400 -t ptpl2 -m tx-lat -n 160 -s 10 -a 18:03:73:66:87:42
> 
> 3) Observe silence on PC wireshark.
> 
> Thus, no see issues with this.
> 
> PS: I'm sure in plget tool, you can use your own.

I'm using packeth to generate udp packets (vlan) src=PC dst=unknown
if there is record in ALE table which looks like:
type: vlan , vid = 100, untag_force = 0x0, reg_mcast = 0x7, unreg_mcast = 0x0, member_list = 0x7
then above udp packet will be forwarded to BBB.



-- 
regards,
-grygorii