net: dsa: Ensure that port array elements are initialized before being used

A network device notifier can be called for one or more of the created
slave devices before all slave devices have been registered. This can
result in a mismatch between ds->phys_port_mask and the registered devices
by the time the call is made, and it can result in a slave device being
added to a bridge before its entry in ds->ports[] has been initialized.

Rework the initialization code to initialize entries in ds->ports[] in
dsa_slave_create. With this change, dsa_slave_create no longer needs
to return slave_dev but can return an error code instead.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 7 deletions

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index f23deadf42a0..5be4c928c9c9 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -605,9 +605,8 @@ int dsa_slave_resume(struct net_device *slave_dev)
 	return 0;
 }
 
-struct net_device *
-dsa_slave_create(struct dsa_switch *ds, struct device *parent,
-		 int port, char *name)
+int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
+		     int port, char *name)
 {
 	struct net_device *master = ds->dst->master_netdev;
 	struct net_device *slave_dev;
@@ -617,7 +616,7 @@ dsa_slave_create(struct dsa_switch *ds, struct device *parent,
 	slave_dev = alloc_netdev(sizeof(struct dsa_slave_priv), name,
 				 NET_NAME_UNKNOWN, ether_setup);
 	if (slave_dev == NULL)
-		return slave_dev;
+		return -ENOMEM;
 
 	slave_dev->features = master->vlan_features;
 	slave_dev->ethtool_ops = &dsa_slave_ethtool_ops;
@@ -667,19 +666,21 @@ dsa_slave_create(struct dsa_switch *ds, struct device *parent,
 	ret = dsa_slave_phy_setup(p, slave_dev);
 	if (ret) {
 		free_netdev(slave_dev);
-		return NULL;
+		return ret;
 	}
 
+	ds->ports[port] = slave_dev;
 	ret = register_netdev(slave_dev);
 	if (ret) {
 		netdev_err(master, "error %d registering interface %s\n",
 			   ret, slave_dev->name);
 		phy_disconnect(p->phy);
+		ds->ports[port] = NULL;
 		free_netdev(slave_dev);
-		return NULL;
+		return ret;
 	}
 
 	netif_carrier_off(slave_dev);
 
-	return slave_dev;
+	return 0;
 }