net: dsa: Fix tagging attribute location

While introducing the DSA tagging protocol attribute, it was added to the DSA
slave network devices, but those actually see untagged traffic (that is their
whole purpose). Correct this mistake by putting the tagging sysfs attribute
under the DSA master network device where this is the information that we need.

While at it, also correct the sysfs documentation mistake that missed the
"dsa/" directory component of the attribute.

Fixes: 98cdb480 ("net: dsa: Expose tagging protocol to user-space")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/ABI/testing/sysfs-class-net-dsa

-What:		/sys/class/net/<iface>/tagging
+What:		/sys/class/net/<iface>/dsa/tagging
 Date:		August 2018
 KernelVersion:	4.20
 Contact:	netdev@vger.kernel.org

net/dsa/master.c

@@ -158,8 +158,31 @@ static void dsa_master_ethtool_teardown(struct net_device *dev)
 	cpu_dp->orig_ethtool_ops = NULL;
 }
 
+static ssize_t tagging_show(struct device *d, struct device_attribute *attr,
+			    char *buf)
+{
+	struct net_device *dev = to_net_dev(d);
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
+
+	return sprintf(buf, "%s\n",
+		       dsa_tag_protocol_to_str(cpu_dp->tag_ops));
+}
+static DEVICE_ATTR_RO(tagging);
+
+static struct attribute *dsa_slave_attrs[] = {
+	&dev_attr_tagging.attr,
+	NULL
+};
+
+static const struct attribute_group dsa_group = {
+	.name	= "dsa",
+	.attrs	= dsa_slave_attrs,
+};
+
 int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp)
 {
+	int ret;
+
 	/* 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.
@@ -168,11 +191,20 @@ int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp)
 
 	dev->dsa_ptr = cpu_dp;
 
-	return dsa_master_ethtool_setup(dev);
+	ret = dsa_master_ethtool_setup(dev);
+	if (ret)
+		return ret;
+
+	ret = sysfs_create_group(&dev->dev.kobj, &dsa_group);
+	if (ret)
+		dsa_master_ethtool_teardown(dev);
+
+	return ret;
 }
 
 void dsa_master_teardown(struct net_device *dev)
 {
+	sysfs_remove_group(&dev->dev.kobj, &dsa_group);
 	dsa_master_ethtool_teardown(dev);
 
 	dev->dsa_ptr = NULL;

net/dsa/slave.c

@@ -1058,27 +1058,6 @@ static struct device_type dsa_type = {
 	.name	= "dsa",
 };
 
-static ssize_t tagging_show(struct device *d, struct device_attribute *attr,
-			    char *buf)
-{
-	struct net_device *dev = to_net_dev(d);
-	struct dsa_port *dp = dsa_slave_to_port(dev);
-
-	return sprintf(buf, "%s\n",
-		       dsa_tag_protocol_to_str(dp->cpu_dp->tag_ops));
-}
-static DEVICE_ATTR_RO(tagging);
-
-static struct attribute *dsa_slave_attrs[] = {
-	&dev_attr_tagging.attr,
-	NULL
-};
-
-static const struct attribute_group dsa_group = {
-	.name	= "dsa",
-	.attrs	= dsa_slave_attrs,
-};
-
 static void dsa_slave_phylink_validate(struct net_device *dev,
 				       unsigned long *supported,
 				       struct phylink_link_state *state)
@@ -1374,14 +1353,8 @@ int dsa_slave_create(struct dsa_port *port)
 		goto out_phy;
 	}
 
-	ret = sysfs_create_group(&slave_dev->dev.kobj, &dsa_group);
-	if (ret)
-		goto out_unreg;
-
 	return 0;
 
-out_unreg:
-	unregister_netdev(slave_dev);
 out_phy:
 	rtnl_lock();
 	phylink_disconnect_phy(p->dp->pl);
@@ -1405,7 +1378,6 @@ void dsa_slave_destroy(struct net_device *slave_dev)
 	rtnl_unlock();
 
 	dsa_slave_notify(slave_dev, DSA_PORT_UNREGISTER);
-	sysfs_remove_group(&slave_dev->dev.kobj, &dsa_group);
 	unregister_netdev(slave_dev);
 	phylink_destroy(dp->pl);
 	free_percpu(p->stats64);