linux-kernel - Re: [PATCH net-next 2/2] net: dsa: mt7530: add support for bridge port isolation

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Date: Sun, 16 Jun 2024 10:39:37 +0200
From: Matthias Schiffer <mschiffer@...verse-factory.net>
To: Arınç ÜNAL <arinc.unal@...nc9.com>
Cc: Andrew Lunn <andrew@...n.ch>, Florian Fainelli <f.fainelli@...il.com>,
 Vladimir Oltean <olteanv@...il.com>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 Daniel Golle <daniel@...rotopia.org>, DENG Qingfang <dqfext@...il.com>,
 Sean Wang <sean.wang@...iatek.com>
Subject: Re: [PATCH net-next 2/2] net: dsa: mt7530: add support for bridge
 port isolation

On 16/06/2024 08:52, Arınç ÜNAL wrote:
> On 15/06/2024 01:21, Matthias Schiffer wrote:
>> Remove a pair of ports from the port matrix when both ports have the
>> isolated flag set.
>>
>> Signed-off-by: Matthias Schiffer <mschiffer@...verse-factory.net>
>> ---
>>   drivers/net/dsa/mt7530.c | 21 ++++++++++++++++++---
>>   drivers/net/dsa/mt7530.h |  1 +
>>   2 files changed, 19 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
>> index ecacaefdd694..44939379aba8 100644
>> --- a/drivers/net/dsa/mt7530.c
>> +++ b/drivers/net/dsa/mt7530.c
>> @@ -1303,7 +1303,8 @@ mt7530_stp_state_set(struct dsa_switch *ds, int 
>> port, u8 state)
>>   }
>>   static void mt7530_update_port_member(struct mt7530_priv *priv, int port,
>> -                      const struct net_device *bridge_dev, bool join)
>> +                      const struct net_device *bridge_dev,
>> +                      bool join)
> 
> Run git clang-format on this patch as well please.

Oops, will do.


> 
>>       __must_hold(&priv->reg_mutex)
>>   {
>>       struct dsa_port *dp = dsa_to_port(priv->ds, port), *other_dp;
>> @@ -1311,6 +1312,7 @@ static void mt7530_update_port_member(struct 
>> mt7530_priv *priv, int port,
>>       struct dsa_port *cpu_dp = dp->cpu_dp;
>>       u32 port_bitmap = BIT(cpu_dp->index);
>>       int other_port;
>> +    bool isolated;
>>       dsa_switch_for_each_user_port(other_dp, priv->ds) {
>>           other_port = other_dp->index;
>> @@ -1327,7 +1329,9 @@ static void mt7530_update_port_member(struct 
>> mt7530_priv *priv, int port,
>>           if (!dsa_port_offloads_bridge_dev(other_dp, bridge_dev))
>>               continue;
>> -        if (join) {
>> +        isolated = p->isolated && other_p->isolated;
>> +
>> +        if (join && !isolated) {
>>               other_p->pm |= PCR_MATRIX(BIT(port));
>>               port_bitmap |= BIT(other_port);
>>           } else {
> 
> Why must other_p->isolated be true as well? If I understand correctly, when
> a user port is isolated, non isolated ports can't communicate with it
> whilst the CPU port can. If I were to isolate a port which is the only
> isolated one at the moment, the isolated flag would not be true. Therefore,
> the isolated port would not be removed from the port matrix of other user
> ports. Why not only check for p->isolated?

As far as I can tell, the rules are:

- non-isolated ports can communicate with every port
- isolated ports can't communicate with other isolated ports
- communication is symmetric

You'll find that the logic works the same for non-offloaded bridge 
forwarding (see should_deliver() in net/bridge/br_forward.c and 
br_skb_isolated() in net/bridge/br_private.h).

Matthias

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