net: dsa: tag_sja1105: add compatibility with hwaccel VLAN tags

Check whether there is any hwaccel VLAN tag on RX, and if there is,
treat it as the tag_8021q header.
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>

net/dsa/tag_sja1105.c

@@ -72,14 +72,21 @@ static inline bool sja1105_is_meta_frame(const struct sk_buff *skb)
 static bool sja1105_can_use_vlan_as_tags(const struct sk_buff *skb)
 {
 	struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
+	u16 vlan_tci;
 
 	if (hdr->h_vlan_proto == htons(ETH_P_SJA1105))
 		return true;
 
-	if (hdr->h_vlan_proto != htons(ETH_P_8021Q))
+	if (hdr->h_vlan_proto != htons(ETH_P_8021Q) &&
+	    !skb_vlan_tag_present(skb))
 		return false;
 
-	return vid_is_dsa_8021q(ntohs(hdr->h_vlan_TCI) & VLAN_VID_MASK);
+	if (skb_vlan_tag_present(skb))
+		vlan_tci = skb_vlan_tag_get(skb);
+	else
+		vlan_tci = ntohs(hdr->h_vlan_TCI);
+
+	return vid_is_dsa_8021q(vlan_tci & VLAN_VID_MASK);
 }
 
 /* This is the first time the tagger sees the frame on RX.
@@ -283,7 +290,8 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
 
 	hdr = eth_hdr(skb);
 	tpid = ntohs(hdr->h_proto);
-	is_tagged = (tpid == ETH_P_SJA1105 || tpid == ETH_P_8021Q);
+	is_tagged = (tpid == ETH_P_SJA1105 || tpid == ETH_P_8021Q ||
+		     skb_vlan_tag_present(skb));
 	is_link_local = sja1105_is_link_local(skb);
 	is_meta = sja1105_is_meta_frame(skb);
 
@@ -292,7 +300,12 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
 	if (is_tagged) {
 		/* Normal traffic path. */
 		skb_push_rcsum(skb, ETH_HLEN);
-		__skb_vlan_pop(skb, &tci);
+		if (skb_vlan_tag_present(skb)) {
+			tci = skb_vlan_tag_get(skb);
+			__vlan_hwaccel_clear_tag(skb);
+		} else {
+			__skb_vlan_pop(skb, &tci);
+		}
 		skb_pull_rcsum(skb, ETH_HLEN);
 		skb_reset_network_header(skb);
 		skb_reset_transport_header(skb);