net: dsa: provide an option for drivers to always receive bridge VLANs

DSA assumes that a bridge which has vlan filtering disabled is not
vlan aware, and ignores all vlan configuration. However, the kernel
software bridge code allows configuration in this state.

This causes the kernel's idea of the bridge vlan state and the
hardware state to disagree, so "bridge vlan show" indicates a correct
configuration but the hardware lacks all configuration. Even worse,
enabling vlan filtering on a DSA bridge immediately blocks all traffic
which, given the output of "bridge vlan show", is very confusing.

Provide an option that drivers can set to indicate they want to receive
vlan configuration even when vlan filtering is disabled. At the very
least, this is safe for Marvell DSA bridges, which do not look up
ingress traffic in the VTU if the port is in 8021Q disabled state. It is
also safe for the Ocelot switch family. Whether this change is suitable
for all DSA bridges is not known.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 19 insertions, 4 deletions

diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index a1a0ae242012..adecf73bd608 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -138,6 +138,7 @@ int dsa_port_bridge_join(struct dsa_port *dp, struct net_device *br);
 void dsa_port_bridge_leave(struct dsa_port *dp, struct net_device *br);
 int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
 			    struct switchdev_trans *trans);
+bool dsa_port_skip_vlan_configuration(struct dsa_port *dp);
 int dsa_port_ageing_time(struct dsa_port *dp, clock_t ageing_clock,
 			 struct switchdev_trans *trans);
 int dsa_port_mtu_change(struct dsa_port *dp, int new_mtu,
diff --git a/net/dsa/port.c b/net/dsa/port.c
index ebc8d6cbd1d4..e23ece229c7e 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -257,6 +257,20 @@ int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
 	return 0;
 }
 
+/* This enforces legacy behavior for switch drivers which assume they can't
+ * receive VLAN configuration when enslaved to a bridge with vlan_filtering=0
+ */
+bool dsa_port_skip_vlan_configuration(struct dsa_port *dp)
+{
+	struct dsa_switch *ds = dp->ds;
+
+	if (!dp->bridge_dev)
+		return false;
+
+	return (!ds->configure_vlan_while_not_filtering &&
+		!br_vlan_enabled(dp->bridge_dev));
+}
+
 int dsa_port_ageing_time(struct dsa_port *dp, clock_t ageing_clock,
 			 struct switchdev_trans *trans)
 {
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 61b0de52040a..886490fb203d 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -314,7 +314,7 @@ static int dsa_slave_vlan_add(struct net_device *dev,
 	if (obj->orig_dev != dev)
 		return -EOPNOTSUPP;
 
-	if (dp->bridge_dev && !br_vlan_enabled(dp->bridge_dev))
+	if (dsa_port_skip_vlan_configuration(dp))
 		return 0;
 
 	vlan = *SWITCHDEV_OBJ_PORT_VLAN(obj);
@@ -381,7 +381,7 @@ static int dsa_slave_vlan_del(struct net_device *dev,
 	if (obj->orig_dev != dev)
 		return -EOPNOTSUPP;
 
-	if (dp->bridge_dev && !br_vlan_enabled(dp->bridge_dev))
+	if (dsa_port_skip_vlan_configuration(dp))
 		return 0;
 
 	/* Do not deprogram the CPU port as it may be shared with other user
@@ -1240,7 +1240,7 @@ static int dsa_slave_vlan_rx_add_vid(struct net_device *dev, __be16 proto,
 	 * need to emulate the switchdev prepare + commit phase.
 	 */
 	if (dp->bridge_dev) {
-		if (!br_vlan_enabled(dp->bridge_dev))
+		if (dsa_port_skip_vlan_configuration(dp))
 			return 0;
 
 		/* br_vlan_get_info() returns -EINVAL or -ENOENT if the
@@ -1274,7 +1274,7 @@ static int dsa_slave_vlan_rx_kill_vid(struct net_device *dev, __be16 proto,
 	 * need to emulate the switchdev prepare + commit phase.
 	 */
 	if (dp->bridge_dev) {
-		if (!br_vlan_enabled(dp->bridge_dev))
+		if (dsa_port_skip_vlan_configuration(dp))
 			return 0;
 
 		/* br_vlan_get_info() returns -EINVAL or -ENOENT if the