Re: [PATCH net-next v2 2/3] net: dsa: integrate with SWITCHDEV for HW bridging

[Guenter Roeck <linux@roeck-us.net>]

Hi Florian,

On Tue, Feb 24, 2015 at 12:08:30PM -0800, Florian Fainelli wrote:
> In order to support bridging offloads in DSA switch drivers, select
> NET_SWITCHDEV to get access to the port_stp_update and parent_get_id
> NDOs that we are required to implement.
> 
> To facilitate the integratation at the DSA driver level, we implement 3
> types of operations:
> 
> - port_join_bridge
> - port_leave_bridge
> - port_stp_update
> 
> DSA will resolve which switch ports that are currently bridge port
> members as some Switch hardware/drivers need to know about that to limit
> the register programming to just the relevant registers (especially for
> slow MDIO buses).
> 
> We also take care of setting the correct STP state when slave network
> devices are brought up/down while being bridge members.
> 
> Finally, when a port is leaving the bridge, we make sure we set in
> BR_STATE_FORWARDING state, otherwise the bridge layer would leave it
> disabled as a result of having left the bridge.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
[ ... ]

>  
> +/* Return a bitmask of all ports being currently bridged within a given bridge
> + * device. Note that on leave, the mask will still return the bitmask of ports
> + * currently bridged, prior to port removal, and this is exactly what we want.
> + */
> +static u32 dsa_slave_br_port_mask(struct dsa_switch *ds,
> +				  struct net_device *bridge)
> +{
> +	struct dsa_slave_priv *p;
> +	unsigned int port;
> +	u32 mask = 0;
> +
> +	for (port = 0; port < DSA_MAX_PORTS; port++) {
> +		if (!((1 << port) & ds->phys_port_mask))
> +			continue;
> +
> +		p = netdev_priv(ds->ports[port]);
> +

ds->ports[port] can still be NULL here since the function can be called
before all ports are initialized (which is what I had actually seen).

Thanks,
Guenter