Subject: Re: [patch net-next v3 08/17] bridge: call netdev_sw_port_stp_update when bridge port STP status changes

From: Florian Fainelli <[email-masked]>
Date: Tue, 25 Nov 2014 14:20:14 -0800

On 25/11/14 07:58, Andy Gospodarek wrote:
> On Tue, Nov 25, 2014 at 11:28:39AM +0100, Jiri Pirko wrote:
>> From: Scott Feldman <[email-masked]>
>>
>> To notify switch driver of change in STP state of bridge port, add new
>> .ndo op and provide switchdev wrapper func to call ndo op. Use it in bridge
>> code then.
>>
>> Signed-off-by: Scott Feldman <[email-masked]>
>> Signed-off-by: Jiri Pirko <[email-masked]>

[snip]

>>  #include "br_private.h"
>>  #include "br_private_stp.h"
>> @@ -39,6 +40,7 @@ void br_log_state(const struct net_bridge_port *p)
>>  void br_set_state(struct net_bridge_port *p, unsigned int state)
>>  {
>>  	p->state = state;
>> +	netdev_switch_port_stp_update(p->dev, state);
> 
> The only thing that concerns me about this patch is the fact that there
> is nothing paying attention to the return code.
> 
> This means if *something* in the driver fails to set the STP state we
> have no way to feed this information back to the user to let them know
> that their hardware isn't exactly functioning as we expect.

This typically translates into an actual HW register write in general
(writing the STP algorithm result per-port), so although they typically
don't fail in most HW transports, I so no harm in returning something
useful just in case.

Once you do this, feel free to add a:

Acked-by: Florian Fainelli <[email-masked]>

Thanks!

> 
> I do not expect that this first set would provide full feedback to
> br_make_forwarding, br_make_blocking, etc, to allow spanning tree to
> properly deal with the failure (that change is fine to add later), but a
> short one-liner indicating that the call to the hardware  failed would e
> good.  What about something simple like this:
> 
> void br_set_state(struct net_bridge_port *p, unsigned int state)
> {
> 	int ret;
> 	p->state = state;
> 	ret = netdev_switch_port_stp_update(p->dev, state);
> 	if (ret && ret != -EOPNOTSUPP)
> 		br_warn(br, "error setting offload STP state for interface %s\n",
> 			p->dev->name);
> }
> 
>>  
>>  /* called under bridge lock */
>> diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
>> index 66973de..d162b21 100644
>> --- a/net/switchdev/switchdev.c
>> +++ b/net/switchdev/switchdev.c
>> @@ -31,3 +31,22 @@ int netdev_switch_parent_id_get(struct net_device *dev,
>>  	return ops->ndo_switch_parent_id_get(dev, psid);
>>  }
>>  EXPORT_SYMBOL(netdev_switch_parent_id_get);
>> +
>> +/**
>> + *	netdev_switch_port_stp_update - Notify switch device port of STP
>> + *					state change
>> + *	@dev: port device
>> + *	@state: port STP state
>> + *
>> + *	Notify switch device port of bridge port STP state change.
>> + */
>> +int netdev_switch_port_stp_update(struct net_device *dev, u8 state)
>> +{
>> +	const struct net_device_ops *ops = dev->netdev_ops;
>> +
>> +	if (!ops->ndo_switch_port_stp_update)
>> +		return -EOPNOTSUPP;
>> +	WARN_ON(!ops->ndo_switch_parent_id_get);
>> +	return ops->ndo_switch_port_stp_update(dev, state);
>> +}
>> +EXPORT_SYMBOL(netdev_switch_port_stp_update);
>> -- 
>> 1.9.3
>>