net: dsa: don't keep track of admin/oper state on LAG DSA masters

We store information about the DSA master's state in
cpu_dp->master_admin_up and cpu_dp->master_oper_up, and this assumes a
bijective association between a CPU port and a DSA master.

However, when we have CPU ports in a LAG (and DSA masters in a LAG too),
the way in which we set up things is that the physical DSA masters still
have dev->dsa_ptr pointing to our cpu_dp, but the bonding/team device
itself also has its dev->dsa_ptr pointing towards one of the CPU port
structures (the first one).

So logically speaking, that first cpu_dp can't keep track of both the
physical master's admin/oper state, and of the bonding master's state.

This isn't even needed; the reason why we keep track of the DSA master's
state is to know when it is available for Ethernet-based register access.
For that use case, we don't even need LAG; we just need to decide upon
one of the physical DSA masters (if there is more than 1 available) and
use that.

This change suppresses dsa_tree_master_{admin,oper}_state_change() calls
on LAG DSA masters (which will be supported in a future change), to
allow the tracking of just physical DSA masters.

Link: https://lore.kernel.org/netdev/628cc94d.1c69fb81.15b0d.422d@mx.google.com/
Suggested-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/dsa/dsa2.c

@@ -1326,6 +1326,12 @@ void dsa_tree_master_admin_state_change(struct dsa_switch_tree *dst,
 	struct dsa_port *cpu_dp = master->dsa_ptr;
 	bool notify = false;
 
+	/* Don't keep track of admin state on LAG DSA masters,
+	 * but rather just of physical DSA masters
+	 */
+	if (netif_is_lag_master(master))
+		return;
+
 	if ((dsa_port_master_is_operational(cpu_dp)) !=
 	    (up && cpu_dp->master_oper_up))
 		notify = true;
@@ -1343,6 +1349,12 @@ void dsa_tree_master_oper_state_change(struct dsa_switch_tree *dst,
 	struct dsa_port *cpu_dp = master->dsa_ptr;
 	bool notify = false;
 
+	/* Don't keep track of oper state on LAG DSA masters,
+	 * but rather just of physical DSA masters
+	 */
+	if (netif_is_lag_master(master))
+		return;
+
 	if ((dsa_port_master_is_operational(cpu_dp)) !=
 	    (cpu_dp->master_admin_up && up))
 		notify = true;