net: dsa: Be aware of switches where VLAN filtering is a global setting

On some switches, the action of whether to parse VLAN frame headers and use
that information for ingress admission is configurable, but not per
port. Such is the case for the Broadcom BCM53xx and the NXP SJA1105
families, for example. In that case, DSA can prevent the bridge core
from trying to apply different VLAN filtering settings on net devices
that belong to the same switch.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Suggested-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -228,6 +228,11 @@ struct dsa_switch {
 	/* Number of switch port queues */
 	unsigned int		num_tx_queues;
 
+	/* Disallow bridge core from requesting different VLAN awareness
+	 * settings on ports if not hardware-supported
+	 */
+	bool			vlan_filtering_is_global;
+
 	unsigned long		*bitmap;
 	unsigned long		_bitmap;
 

net/dsa/port.c

@@ -154,6 +154,39 @@ void dsa_port_bridge_leave(struct dsa_port *dp, struct net_device *br)
 	dsa_port_set_state_now(dp, BR_STATE_FORWARDING);
 }
 
+static bool dsa_port_can_apply_vlan_filtering(struct dsa_port *dp,
+					      bool vlan_filtering)
+{
+	struct dsa_switch *ds = dp->ds;
+	int i;
+
+	if (!ds->vlan_filtering_is_global)
+		return true;
+
+	/* For cases where enabling/disabling VLAN awareness is global to the
+	 * switch, we need to handle the case where multiple bridges span
+	 * different ports of the same switch device and one of them has a
+	 * different setting than what is being requested.
+	 */
+	for (i = 0; i < ds->num_ports; i++) {
+		struct net_device *other_bridge;
+
+		other_bridge = dsa_to_port(ds, i)->bridge_dev;
+		if (!other_bridge)
+			continue;
+		/* If it's the same bridge, it also has same
+		 * vlan_filtering setting => no need to check
+		 */
+		if (other_bridge == dp->bridge_dev)
+			continue;
+		if (br_vlan_enabled(other_bridge) != vlan_filtering) {
+			dev_err(ds->dev, "VLAN filtering is a global setting\n");
+			return false;
+		}
+	}
+	return true;
+}
+
 int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
 			    struct switchdev_trans *trans)
 {
@@ -164,13 +197,18 @@ int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
 	if (switchdev_trans_ph_prepare(trans))
 		return 0;
 
-	if (ds->ops->port_vlan_filtering) {
-		err = ds->ops->port_vlan_filtering(ds, dp->index,
-						   vlan_filtering);
-		if (err)
-			return err;
-		dp->vlan_filtering = vlan_filtering;
-	}
+	if (!ds->ops->port_vlan_filtering)
+		return 0;
+
+	if (!dsa_port_can_apply_vlan_filtering(dp, vlan_filtering))
+		return -EINVAL;
+
+	err = ds->ops->port_vlan_filtering(ds, dp->index,
+					   vlan_filtering);
+	if (err)
+		return err;
+
+	dp->vlan_filtering = vlan_filtering;
 	return 0;
 }