net: dsa: don't emit targeted cross-chip notifiers for MTU change

A cross-chip notifier with "targeted_match=true" is one that matches
only the local port of the switch that emitted it. In other words,
passing through the cross-chip notifier layer serves no purpose.

Eliminate this concept by calling directly ds->ops->port_change_mtu
instead of emitting a targeted cross-chip notifier. This leaves the
DSA_NOTIFIER_MTU event being emitted only for MTU updates on the CPU
port, which need to be reflected also across all DSA links.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/dsa_priv.h

@@ -100,7 +100,6 @@ struct dsa_notifier_vlan_info {
 /* DSA_NOTIFIER_MTU */
 struct dsa_notifier_mtu_info {
 	const struct dsa_port *dp;
-	bool targeted_match;
 	int mtu;
 };
 
@@ -231,8 +230,7 @@ int dsa_port_mst_enable(struct dsa_port *dp, bool on,
 			struct netlink_ext_ack *extack);
 int dsa_port_vlan_msti(struct dsa_port *dp,
 		       const struct switchdev_vlan_msti *msti);
-int dsa_port_mtu_change(struct dsa_port *dp, int new_mtu,
-			bool targeted_match);
+int dsa_port_mtu_change(struct dsa_port *dp, int new_mtu);
 int dsa_port_fdb_add(struct dsa_port *dp, const unsigned char *addr,
 		     u16 vid);
 int dsa_port_fdb_del(struct dsa_port *dp, const unsigned char *addr,

net/dsa/port.c

@@ -930,12 +930,10 @@ int dsa_port_vlan_msti(struct dsa_port *dp,
 	return ds->ops->vlan_msti_set(ds, *dp->bridge, msti);
 }
 
-int dsa_port_mtu_change(struct dsa_port *dp, int new_mtu,
-			bool targeted_match)
+int dsa_port_mtu_change(struct dsa_port *dp, int new_mtu)
 {
 	struct dsa_notifier_mtu_info info = {
 		.dp = dp,
-		.targeted_match = targeted_match,
 		.mtu = new_mtu,
 	};
 

net/dsa/slave.c

@@ -1859,15 +1859,14 @@ int dsa_slave_change_mtu(struct net_device *dev, int new_mtu)
 			goto out_master_failed;
 
 		/* We only need to propagate the MTU of the CPU port to
-		 * upstream switches, so create a non-targeted notifier which
-		 * updates all switches.
+		 * upstream switches, so emit a notifier which updates them.
 		 */
-		err = dsa_port_mtu_change(cpu_dp, cpu_mtu, false);
+		err = dsa_port_mtu_change(cpu_dp, cpu_mtu);
 		if (err)
 			goto out_cpu_failed;
 	}
 
-	err = dsa_port_mtu_change(dp, new_mtu, true);
+	err = ds->ops->port_change_mtu(ds, dp->index, new_mtu);
 	if (err)
 		goto out_port_failed;
 
@@ -1880,8 +1879,7 @@ int dsa_slave_change_mtu(struct net_device *dev, int new_mtu)
 out_port_failed:
 	if (new_master_mtu != old_master_mtu)
 		dsa_port_mtu_change(cpu_dp, old_master_mtu -
-				    dsa_tag_protocol_overhead(cpu_dp->tag_ops),
-				    false);
+				    dsa_tag_protocol_overhead(cpu_dp->tag_ops));
 out_cpu_failed:
 	if (new_master_mtu != old_master_mtu)
 		dev_set_mtu(master, old_master_mtu);

net/dsa/switch.c

@@ -49,19 +49,7 @@ static int dsa_switch_ageing_time(struct dsa_switch *ds,
 static bool dsa_port_mtu_match(struct dsa_port *dp,
 			       struct dsa_notifier_mtu_info *info)
 {
-	if (dp == info->dp)
-		return true;
-
-	/* Do not propagate to other switches in the tree if the notifier was
-	 * targeted for a single switch.
-	 */
-	if (info->targeted_match)
-		return false;
-
-	if (dsa_port_is_dsa(dp) || dsa_port_is_cpu(dp))
-		return true;
-
-	return false;
+	return dp == info->dp || dsa_port_is_dsa(dp) || dsa_port_is_cpu(dp);
 }
 
 static int dsa_switch_mtu(struct dsa_switch *ds,