From a1ff94c2973c43bc1e2677ac63ebb15b1d1ff846 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Thu, 6 Jan 2022 01:11:14 +0200 Subject: [PATCH 3/6] 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 dev_set_mtu(dev) So the dev_set_mtu() call from dsa_master_setup() has been effectively superseded by the dsa_slave_change_mtu(slave_dev, ETH_DATA_LEN) that is done from dsa_slave_create() for each user port.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 Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- net/dsa/master.c | 25 +------------------------ 1 file changed, 1 insertion(+), 24 deletions(-) diff --git a/net/dsa/master.c b/net/dsa/master.c index e8e19857621b..f4efb244f91d 100644 --- 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; -- 2.34.1