Commit 066dfc42 authored by Vladimir Oltean's avatar Vladimir Oltean Committed by David S. Miller
Browse files

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



This reverts commit a1ff94c2.

Switch drivers that don't implement ->port_change_mtu() will cause the
DSA master to remain with an MTU of 1500, since we've deleted the other
code path. In turn, this causes a regression for those systems, where
MTU-sized traffic can no longer be terminated.

Revert the change taking into account the fact that rtnl_lock() is now
taken top-level from the callers of dsa_master_setup() and
dsa_master_teardown(). Also add a comment in order for it to be
absolutely clear why it is still needed.

Fixes: a1ff94c2 ("net: dsa: stop updating master MTU from master.c")
Reported-by: default avatarLuiz Angelo Daros de Luca <luizluca@gmail.com>
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: default avatarLuiz Angelo Daros de Luca <luizluca@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1effe8ca

net/dsa/master.c

+24 −1
Original line number Diff line number Diff line
@@ -335,11 +335,24 @@ static const struct attribute_group dsa_group = { 
	.attrs	= dsa_slave_attrs,

};



static void dsa_master_reset_mtu(struct net_device *dev)

{

	int err;



	err = dev_set_mtu(dev, ETH_DATA_LEN);

	if (err)

		netdev_dbg(dev,

			   "Unable to reset MTU to exclude DSA overheads\n");

}



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 ret;

	int mtu, ret;



	mtu = ETH_DATA_LEN + dsa_tag_protocol_overhead(tag_ops);



	/* The DSA master must use SET_NETDEV_DEV for this to work. */

	consumer_link = device_link_add(ds->dev, dev->dev.parent,
@@ -349,6 +362,15 @@ 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));



	/* The switch driver may not implement ->port_change_mtu(), case in

	 * which dsa_slave_change_mtu() will not update the master MTU either,

	 * so we need to do that here.

	 */

	ret = dev_set_mtu(dev, mtu);

	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.
@@ -384,6 +406,7 @@ 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;