linux-kernel - Re: [PATCH net] net: dsa: b53: Ensure the default VID is untagged

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Message-ID: <ab4e0ce1-dd48-8c1b-8753-a400dfcb38ec@gmail.com>
Date:   Fri, 14 Feb 2020 09:08:30 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     netdev <netdev@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] net: dsa: b53: Ensure the default VID is untagged



On 2/14/2020 2:36 AM, Vladimir Oltean wrote:
> Hi Florian,
> 
> On Thu, 13 Feb 2020 at 21:10, Florian Fainelli <f.fainelli@...il.com> wrote:
>>
>> We need to ensure that the default VID is untagged otherwise the switch
>> will be sending frames tagged frames and the results can be problematic.
>> This is especially true with b53 switches that use VID 0 as their
>> default VLAN since VID 0 has a special meaning.
>>
>> Fixes: fea83353177a ("net: dsa: b53: Fix default VLAN ID")
>> Fixes: 061f6a505ac3 ("net: dsa: Add ndo_vlan_rx_{add, kill}_vid implementation")
>> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
>> ---
>>  drivers/net/dsa/b53/b53_common.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
>> index 449a22172e07..f25c43b300d4 100644
>> --- a/drivers/net/dsa/b53/b53_common.c
>> +++ b/drivers/net/dsa/b53/b53_common.c
>> @@ -1366,6 +1366,9 @@ void b53_vlan_add(struct dsa_switch *ds, int port,
>>
>>                 b53_get_vlan_entry(dev, vid, vl);
>>
>> +               if (vid == b53_default_pvid(dev))
>> +                       untagged = true;
>> +
>>                 vl->members |= BIT(port);
>>                 if (untagged && !dsa_is_cpu_port(ds, port))
>>                         vl->untag |= BIT(port);
>> --
>> 2.17.1
>>
> 
> Don't you mean to force untagged egress only for the pvid value of 0?

The default VID (0 for most switches, 1 for 5325/65) is configured as
pvid during b53_configure_vlan() so when we get a call to port_vlan_add
with VID == 0 this is coming exclusively from
dsa_slave_vlan_rx_add_vid() since the bridge will never program a VID <
1. When dsa_slave_vlan_rx_add_vid() calls us, we do not have any VLAN
flags set in the object.
-- 
Florian