net: dsa: slave: fix of-node leak and phy priority

BugLink: https://bugs.launchpad.net/bugs/1878232

commit 0d8f3c67 upstream.

Make sure to drop the reference taken by of_parse_phandle() before
returning from dsa_slave_phy_setup().

Note that this also modifies the PHY priority so that any fixed-link
node is only parsed when no phy-handle is given, which is in accordance
with the common scheme for this.

Fixes: 0d8bcdd3 ("net: dsa: allow for more complex PHY setups")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/dsa/slave.c

@@ -1031,7 +1031,7 @@ static int dsa_slave_phy_setup(struct dsa_slave_priv *p,
 	p->phy_interface = mode;
 
 	phy_dn = of_parse_phandle(port_dn, "phy-handle", 0);
-	if (of_phy_is_fixed_link(port_dn)) {
+	if (!phy_dn && of_phy_is_fixed_link(port_dn)) {
 		/* In the case of a fixed PHY, the DT node associated
 		 * to the fixed PHY is the Port DT node
 		 */
@@ -1041,7 +1041,7 @@ static int dsa_slave_phy_setup(struct dsa_slave_priv *p,
 			return ret;
 		}
 		phy_is_fixed = true;
-		phy_dn = port_dn;
+		phy_dn = of_node_get(port_dn);
 	}
 
 	if (ds->drv->get_phy_flags)
@@ -1060,6 +1060,7 @@ static int dsa_slave_phy_setup(struct dsa_slave_priv *p,
 			ret = dsa_slave_phy_connect(p, slave_dev, phy_id);
 			if (ret) {
 				netdev_err(slave_dev, "failed to connect to phy%d: %d\n", phy_id, ret);
+				of_node_put(phy_dn);
 				return ret;
 			}
 		} else {
@@ -1068,6 +1069,8 @@ static int dsa_slave_phy_setup(struct dsa_slave_priv *p,
 						phy_flags,
 						p->phy_interface);
 		}
+
+		of_node_put(phy_dn);
 	}
 
 	if (p->phy && phy_is_fixed)