net: dsa: move port lists initialization to dsa_port_touch

&cpu_db->fdbs and &cpu_db->mdbs may be uninitialized lists during some
call paths of felix_set_tag_protocol().

There was an attempt to avoid calling dsa_port_walk_fdbs() during setup
by using a "bool change" in the felix driver, but this doesn't work when
the tagging protocol is defined in the device tree, and a change is
triggered by DSA at pseudo-runtime:

dsa_tree_setup_switches
-> dsa_switch_setup
   -> dsa_switch_setup_tag_protocol
      -> ds->ops->change_tag_protocol
dsa_tree_setup_ports
-> dsa_port_setup
   -> &dp->fdbs and &db->mdbs only get initialized here

So it seems like the only way to fix this is to move the initialization
of these lists earlier.

dsa_port_touch() is called from dsa_switch_touch_ports() which is called
from dsa_switch_parse_of(), and this runs completely before
dsa_tree_setup(). Similarly, dsa_switch_release_ports() runs after
dsa_tree_teardown().

Fixes: f9cef64f ("net: dsa: felix: migrate host FDB and MDB entries when changing tag proto")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/dsa2.c

@@ -457,12 +457,6 @@ static int dsa_port_setup(struct dsa_port *dp)
 	if (dp->setup)
 		return 0;
 
-	mutex_init(&dp->addr_lists_lock);
-	mutex_init(&dp->vlans_lock);
-	INIT_LIST_HEAD(&dp->fdbs);
-	INIT_LIST_HEAD(&dp->mdbs);
-	INIT_LIST_HEAD(&dp->vlans);
-
 	if (ds->ops->port_setup) {
 		err = ds->ops->port_setup(ds, dp->index);
 		if (err)
@@ -599,10 +593,6 @@ static void dsa_port_teardown(struct dsa_port *dp)
 		break;
 	}
 
-	WARN_ON(!list_empty(&dp->fdbs));
-	WARN_ON(!list_empty(&dp->mdbs));
-	WARN_ON(!list_empty(&dp->vlans));
-
 	dp->setup = false;
 }
 
@@ -1361,6 +1351,11 @@ static struct dsa_port *dsa_port_touch(struct dsa_switch *ds, int index)
 	dp->ds = ds;
 	dp->index = index;
 
+	mutex_init(&dp->addr_lists_lock);
+	mutex_init(&dp->vlans_lock);
+	INIT_LIST_HEAD(&dp->fdbs);
+	INIT_LIST_HEAD(&dp->mdbs);
+	INIT_LIST_HEAD(&dp->vlans);
 	INIT_LIST_HEAD(&dp->list);
 	list_add_tail(&dp->list, &dst->ports);
 
@@ -1699,6 +1694,9 @@ static void dsa_switch_release_ports(struct dsa_switch *ds)
 	struct dsa_port *dp, *next;
 
 	dsa_switch_for_each_port_safe(dp, next, ds) {
+		WARN_ON(!list_empty(&dp->fdbs));
+		WARN_ON(!list_empty(&dp->mdbs));
+		WARN_ON(!list_empty(&dp->vlans));
 		list_del(&dp->list);
 		kfree(dp);
 	}