net: dsa: stop updating master MTU from master.c

At present there are two paths for changing the MTU of the DSA master.

The first is:

dsa_tree_setup
-> dsa_tree_setup_ports
   -> dsa_port_setup
      -> dsa_slave_create
         -> dsa_slave_change_mtu
            -> dev_set_mtu(master)

The second is:

dsa_tree_setup
-> dsa_tree_setup_master
   -> dsa_master_setup
      -> dev_set_mtu(dev)

So the dev_set_mtu() call from dsa_master_setup() has been effectively
superseded by the dsa_slave_change_mtu(slave_dev, ETH_DATA_LEN) that is
done from dsa_slave_create() for each user port. The later function also
updates the master MTU according to the largest user port MTU from the
tree. Therefore, updating the master MTU through a separate code path
isn't needed.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dsa/master.c b/net/dsa/master.c
index e8e1985..f4efb24 100644 (file)
--- a/net/dsa/master.c
+++ b/net/dsa/master.c
@@ -330,28 +330,13 @@ static const struct attribute_group dsa_group = {
        .attrs  = dsa_slave_attrs,
 };
 
-static void dsa_master_reset_mtu(struct net_device *dev)
-{
-       int err;
-
-       rtnl_lock();
-       err = dev_set_mtu(dev, ETH_DATA_LEN);
-       if (err)
-               netdev_dbg(dev,
-                          "Unable to reset MTU to exclude DSA overheads\n");
-       rtnl_unlock();
-}
-
 static struct lock_class_key dsa_master_addr_list_lock_key;
 
 int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp)
 {
-       const struct dsa_device_ops *tag_ops = cpu_dp->tag_ops;
        struct dsa_switch *ds = cpu_dp->ds;
        struct device_link *consumer_link;
-       int mtu, ret;
-
-       mtu = ETH_DATA_LEN + dsa_tag_protocol_overhead(tag_ops);
+       int ret;
 
        /* The DSA master must use SET_NETDEV_DEV for this to work. */
        consumer_link = device_link_add(ds->dev, dev->dev.parent,
@@ -361,13 +346,6 @@ int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp)
                           "Failed to create a device link to DSA switch %s\n",
                           dev_name(ds->dev));
 
-       rtnl_lock();
-       ret = dev_set_mtu(dev, mtu);
-       rtnl_unlock();
-       if (ret)
-               netdev_warn(dev, "error %d setting MTU to %d to include DSA overhead\n",
-                           ret, mtu);
-
        /* If we use a tagging format that doesn't have an ethertype
         * field, make sure that all packets from this point on get
         * sent to the tag format's receive function.
@@ -405,7 +383,6 @@ void dsa_master_teardown(struct net_device *dev)
        sysfs_remove_group(&dev->dev.kobj, &dsa_group);
        dsa_netdev_ops_set(dev, NULL);
        dsa_master_ethtool_teardown(dev);
-       dsa_master_reset_mtu(dev);
        dsa_master_set_promiscuity(dev, -1);
 
        dev->dsa_ptr = NULL;