net: dsa: tag_ocelot: avoid accessing ds->priv in ocelot_rcv

Taggers should be written to do something valid irrespective of the
switch driver that they are attached to. This is even more true now,
because since the introduction of the .change_tag_protocol method, a
certain tagger is not necessarily strictly associated with a driver any
longer, and I would like to be able to test all taggers with dsa_loop in
the future.

In the case of ocelot, it needs to move the classified VLAN from the DSA
tag into the skb if the port is VLAN-aware. We can allow it to do that
by looking at the dp->vlan_filtering property, no need to invoke
structures which are specific to ocelot.

Signed-off-by: Vladimir Oltean <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/dsa/tag_ocelot.c

···
 				  struct net_device *netdev,
 				  struct packet_type *pt)
 {
-	struct dsa_port *cpu_dp = netdev->dsa_ptr;
-	struct dsa_switch *ds = cpu_dp->ds;
-	struct ocelot *ocelot = ds->priv;
 	u64 src_port, qos_class;
 	u64 vlan_tci, tag_type;
 	u8 *start = skb->data;
+	struct dsa_port *dp;
 	u8 *extraction;
 	u16 vlan_tpid;
 
···
 	 * equal to the pvid of the ingress port and should not be used for
 	 * processing.
 	 */
+	dp = dsa_slave_to_port(skb->dev);
 	vlan_tpid = tag_type ? ETH_P_8021AD : ETH_P_8021Q;
 
-	if (ocelot->ports[src_port]->vlan_aware &&
+	if (dsa_port_is_vlan_filtering(dp) &&
 	    eth_hdr(skb)->h_proto == htons(vlan_tpid)) {
 		u16 dummy_vlan_tci;