Subject: Re: [PATCH net-next v4] switchdev: fix stp update API to work with layered netdevices

From: roopa <[email-masked]>
Date: Tue, 17 Mar 2015 05:42:23 -0700

On 3/16/15, 11:10 PM, Scott Feldman wrote:
> On Mon, Mar 16, 2015 at 10:32 AM,  <[email-masked]> wrote:
>> From: Roopa Prabhu <[email-masked]>
>>
>> make it same as the netdev_switch_port_bridge_setlink/dellink
>> api (ie traverse lowerdevs to get to the switch port).
>>
>> removes "WARN_ON(!ops->ndo_switch_parent_id_get)" because
>> direct bridge ports can be stacked netdevices (like bonds
>> and team of switch ports) which may not imeplement this ndo.
>>
>> v2 to v3:
>>          - remove changes to bond and team. Bring back the
>>          transparently following lowerdevs like i initially
>>          had for setlink/getlink
>>          (http://www.spinics.net/lists/netdev/msg313436.html)
>>          dave and scott feldman also seem to prefer it be that
>>          way and move to non-transparent way of doing things
>>          if we see a problem down the lane.
>>
>> v3 to v4:
>>          - fix ret initialization
>>
>> Signed-off-by: Roopa Prabhu <[email-masked]>
>> ---
>>   net/switchdev/switchdev.c |   20 ++++++++++++++++----
>>   1 file changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
>> index c9bfa00..e593b59 100644
>> --- a/net/switchdev/switchdev.c
>> +++ b/net/switchdev/switchdev.c
>> @@ -47,11 +47,23 @@ EXPORT_SYMBOL_GPL(netdev_switch_parent_id_get);
>>   int netdev_switch_port_stp_update(struct net_device *dev, u8 state)
>>   {
>>          const struct swdev_ops *ops = dev->swdev_ops;
>> +       struct net_device *lower_dev;
>> +       struct list_head *iter;
>> +       int ret = -EOPNOTSUPP, err;
>>
>> -       if (!ops || !ops->swdev_port_stp_update)
>> -               return -EOPNOTSUPP;
>> -       WARN_ON(!ops->swdev_parent_id_get);
>> -       return ops->swdev_port_stp_update(dev, state);
>> +       if (!(dev->features & NETIF_F_HW_SWITCH_OFFLOAD))
>> +               return ret;
> I would drop the NETIF_F_HW_SWITCH_OFFLOAD check.  It's not telling
> you anything more than the next test for ops->swdev_port_stp_update.

This was mainly to avoid lowerdev walk where you know that the dev does 
not have the feature.
example: the bond carries this feature flag  if any of its slaves have it.
The lowerdev walk can be stopped at the bond.

I don't mind removing the check, if you prefer that.

thanks,
Roopa