Re: [PATCH net-next v7 2/8] net: dsa: Give drivers the chance to veto certain upper devices

[Florian Fainelli <f.fainelli@gmail.com>]

On 10/28/2020 12:42 AM, Kurt Kanzenbach wrote:
> From: Vladimir Oltean <vladimir.oltean@nxp.com>
> 
> Some switches rely on unique pvids to ensure port separation in
> standalone mode, because they don't have a port forwarding matrix
> configurable in hardware. So, setups like a group of 2 uppers with the
> same VLAN, swp0.100 and swp1.100, will cause traffic tagged with VLAN
> 100 to be autonomously forwarded between these switch ports, in spite
> of there being no bridge between swp0 and swp1.
> 
> These drivers need to prevent this from happening. They need to have
> VLAN filtering enabled in standalone mode (so they'll drop frames tagged
> with unknown VLANs) and they can only accept an 8021q upper on a port as
> long as it isn't installed on any other port too. So give them the
> chance to veto bad user requests.
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
> ---
>  include/net/dsa.h |  6 ++++++
>  net/dsa/slave.c   | 12 ++++++++++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/include/net/dsa.h b/include/net/dsa.h
> index 04e93bafb7bd..4e60d2610f20 100644
> --- a/include/net/dsa.h
> +++ b/include/net/dsa.h
> @@ -536,6 +536,12 @@ struct dsa_switch_ops {
>  	void	(*get_regs)(struct dsa_switch *ds, int port,
>  			    struct ethtool_regs *regs, void *p);
>  
> +	/*
> +	 * Upper device tracking.
> +	 */
> +	int	(*port_prechangeupper)(struct dsa_switch *ds, int port,
> +				       struct netdev_notifier_changeupper_info *info);
> +
>  	/*
>  	 * Bridge integration
>  	 */
> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
> index 3bc5ca40c9fb..1919a025c06f 100644
> --- a/net/dsa/slave.c
> +++ b/net/dsa/slave.c
> @@ -1987,10 +1987,22 @@ static int dsa_slave_netdevice_event(struct notifier_block *nb,
>  	switch (event) {
>  	case NETDEV_PRECHANGEUPPER: {
>  		struct netdev_notifier_changeupper_info *info = ptr;
> +		struct dsa_switch *ds;
> +		struct dsa_port *dp;
> +		int err;
>  
>  		if (!dsa_slave_dev_check(dev))
>  			return dsa_prevent_bridging_8021q_upper(dev, ptr);
>  
> +		dp = dsa_slave_to_port(dev);
> +		ds = dp->ds;
> +
> +		if (ds->ops->port_prechangeupper) {
> +			err = ds->ops->port_prechangeupper(ds, dp->index, ptr);

I would pass 'info' instead of 'ptr' here even if there is no functional
difference, this would be clearer. Not a reason to resubmit if
everything else is fine in this series:

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
-- 
Florian