Re: [PATCH net-next] net: dsa: fix preparation of a port STP update

[Vivien Didelot <vivien.didelot@savoirfairelinux.com>]

On Sep. Tuesday 29 (40) 06:42 PM, Andrew Lunn wrote:
> On Tue, Sep 29, 2015 at 12:38:36PM -0400, Vivien Didelot wrote:
> > Because of the default 0 value of ret in dsa_slave_port_attr_set, a
> > driver may return -EOPNOTSUPP from the commit phase of a STP state,
> > which triggers a WARN() from switchdev.
> > 
> > This happened on a 6185 switch which does not support hardware bridging.
> > 
> > Reported-by: Andrew Lunn <andrew@lunn.ch>
> > Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
> 
> Acked-by: Andrew Lunn <andrew@lunn.ch>
> Fixes: 3563606258cf ("switchdev: convert STP update to switchdev attr set")
> 
> David:
>   This should be included in the next -rc.

Nope. A new transaction model has been introduced in the meantime and
this code changed. I send a fix based on v4.3-rc3 right away.

Thanks,
-v

> 
> Thanks
> 	Andrew
> 
> > ---
> >  net/dsa/slave.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/net/dsa/slave.c b/net/dsa/slave.c
> > index 0ae427c..02a3af8 100644
> > --- a/net/dsa/slave.c
> > +++ b/net/dsa/slave.c
> > @@ -453,12 +453,17 @@ static int dsa_slave_port_attr_set(struct net_device *dev,
> >  				   struct switchdev_attr *attr,
> >  				   struct switchdev_trans *trans)
> >  {
> > -	int ret = 0;
> > +	struct dsa_slave_priv *p = netdev_priv(dev);
> > +	struct dsa_switch *ds = p->parent;
> > +	int ret;
> >  
> >  	switch (attr->id) {
> >  	case SWITCHDEV_ATTR_PORT_STP_STATE:
> > -		if (switchdev_trans_ph_commit(trans))
> > -			ret = dsa_slave_stp_update(dev, attr->u.stp_state);
> > +		if (switchdev_trans_ph_prepare(trans))
> > +			ret = ds->drv->port_stp_update ? 0 : -EOPNOTSUPP;
> > +		else
> > +			ret = ds->drv->port_stp_update(ds, p->port,
> > +						       attr->u.stp_state);
> >  		break;
> >  	default:
> >  		ret = -EOPNOTSUPP;
> > -- 
> > 2.6.0
> >