netdev - Re: [PATCH net-next 4/6] net: dsa: Don't program the VLAN as pvid on the upstream port

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Date:   Mon, 19 Aug 2019 20:15:55 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>, vivien.didelot@...il.com,
        andrew@...n.ch, idosch@...sch.org, roopa@...ulusnetworks.com,
        nikolay@...ulusnetworks.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next 4/6] net: dsa: Don't program the VLAN as pvid on
 the upstream port



On 8/19/2019 5:00 PM, Vladimir Oltean wrote:
> Commit b2f81d304cee ("net: dsa: add CPU and DSA ports as VLAN members")
> programs the VLAN from the bridge into the specified port as well as the
> upstream port, with the same set of flags.
> 
> Consider the typical case of installing pvid 1 on user port 1, pvid 2 on
> user port 2, etc. The upstream port would end up having a pvid equal to
> the last user port whose pvid was programmed from the bridge. Less than
> useful.
> 
> So just don't change the pvid of the upstream port and let it be
> whatever the driver set it internally to be.

This patch should allow removing the !dsa_is_cpu_port() checks from
b53_common.c:b53_vlan_add, about time :)

It seems to me that the fundamental issue here is that because we do not
have a user visible network device that 1:1 maps with the CPU (or DSA)
ports for that matter (and for valid reasons, they would represent two
ends of the same pipe), we do not have a good way to control the CPU
port VLAN attributes.

There was a prior attempt at allowing using the bridge master device to
program the CPU port's VLAN attributes, see [1], but I did not follow up
with that until [2] and then life caught me. If you can/want, that would
be great (not asking for TPS reports).

[1]:
https://lists.linuxfoundation.org/pipermail/bridge/2016-November/010112.html
[2]:
https://lore.kernel.org/lkml/20180624153339.13572-1-f.fainelli@gmail.com/T/

> 
> Signed-off-by: Vladimir Oltean <olteanv@...il.com>
> ---
>  net/dsa/switch.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/net/dsa/switch.c b/net/dsa/switch.c
> index 84ab2336131e..02ccc53f1926 100644
> --- a/net/dsa/switch.c
> +++ b/net/dsa/switch.c
> @@ -239,17 +239,21 @@ dsa_switch_vlan_prepare_bitmap(struct dsa_switch *ds,
>  			       const struct switchdev_obj_port_vlan *vlan,
>  			       const unsigned long *bitmap)
>  {
> +	struct switchdev_obj_port_vlan v = *vlan;
>  	int port, err;
>  
>  	if (!ds->ops->port_vlan_prepare || !ds->ops->port_vlan_add)
>  		return -EOPNOTSUPP;
>  
>  	for_each_set_bit(port, bitmap, ds->num_ports) {
> -		err = dsa_port_vlan_check(ds, port, vlan);
> +		if (dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port))
> +			v.flags &= ~BRIDGE_VLAN_INFO_PVID;
> +
> +		err = dsa_port_vlan_check(ds, port, &v);
>  		if (err)
>  			return err;
>  
> -		err = ds->ops->port_vlan_prepare(ds, port, vlan);
> +		err = ds->ops->port_vlan_prepare(ds, port, &v);
>  		if (err)
>  			return err;
>  	}
> @@ -262,10 +266,14 @@ dsa_switch_vlan_add_bitmap(struct dsa_switch *ds,
>  			   const struct switchdev_obj_port_vlan *vlan,
>  			   const unsigned long *bitmap)
>  {
> +	struct switchdev_obj_port_vlan v = *vlan;
>  	int port;
>  
> -	for_each_set_bit(port, bitmap, ds->num_ports)
> -		ds->ops->port_vlan_add(ds, port, vlan);
> +	for_each_set_bit(port, bitmap, ds->num_ports) {
> +		if (dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port))
> +			v.flags &= ~BRIDGE_VLAN_INFO_PVID;
> +		ds->ops->port_vlan_add(ds, port, &v);
> +	}
>  }
>  
>  static int dsa_switch_vlan_add(struct dsa_switch *ds,
> 

-- 
Florian