netdev - Re: [PATCH RFC 1/2] net: dsa: integrate with SWITCHDEV for HW bridging

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Date:	Sun, 22 Feb 2015 18:20:44 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org
CC:	davem@...emloft.net, vivien.didelot@...oirfairelinux.com,
	jerome.oufella@...oirfairelinux.com, andrew@...n.ch,
	cphealy@...il.com
Subject: Re: [PATCH RFC 1/2] net: dsa: integrate with SWITCHDEV for HW bridging

On 02/17/2015 11:26 AM, 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:
>

Hi Florian,

>
> +/* Return a bitmask of all ports being currently bridged. 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)
> +{
> +	unsigned int port;
> +	u32 mask = 0;
> +
> +	for (port = 0; port < DSA_MAX_PORTS; port++) {
> +		if (!((1 << port) & ds->phys_port_mask))
> +			continue;
> +
> +		if (ds->ports[port]->priv_flags & IFF_BRIDGE_PORT)
> +			mask |= 1 << port;

Problem is that the function can be called through dsa_slave_netdevice_event
before the slave devices are fully initialized.

After adding

+               if (!ds->ports[port]) {
+                       netdev_err(bridge,
+                                  "No ports data for port %d, mask=0x%x\n",
+                                  port, ds->phys_port_mask);
+                       continue;
+               }

and with some more debug messages added to dsa_switch_setup(), I see the following.

[   14.187290] e1000e 0000:00:19.0 em1: [0]: Creating slave device for port 1(port1)
[   14.272605] e1000e 0000:00:19.0 em1: [0]: Creating slave device for port 2(port2)
[   14.353118] e1000e 0000:00:19.0 em1: [0]: Creating slave device for port 3(port3)
[   14.472002] br0: No ports data for port 3, mask=0x1e
[   14.472053] br0: No ports data for port 4, mask=0x1e
[   14.472753] e1000e 0000:00:19.0 em1: [0]: Creating slave device for port 4(host2esb)

This happens if I add the bridge configuration to /etc/network/interfaces instead
of creating the bridge manually. Apparently dsa_switch_setup() is not yet complete
when dsa_slave_netdevice_event is executed to handle a state change on one of its
newly created slave interfaces.

The relevant information from /etc/network/interfaces is:

auto br0

iface port1 inet manual
iface port2 inet manual

iface br0 inet dhcp
	bridge_ports port1 port2
	up ifconfig br0 mtu 1492

Any idea how to best address this ?

Thanks,
Guenter

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