net: dsa: fix preparation of a port STP update

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>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 04f01535d2b6afe84df8db88ecda25a97e39dbc4..7b1d9ec74e09289eee75340d1638f595170a42cb 100644 (file)
--- 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;