1 files changed, 29 insertions, 9 deletions

diff --git a/net/dsa/tag_sja1105.c b/net/dsa/tag_sja1105.c
index a5f3b73da417..92a626a05e82 100644
--- a/net/dsa/tag_sja1105.c
+++ b/net/dsa/tag_sja1105.c
@@ -545,10 +545,7 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
 	is_link_local = sja1105_is_link_local(skb);
 	is_meta = sja1105_is_meta_frame(skb);
 
-	if (sja1105_skb_has_tag_8021q(skb)) {
-		/* Normal traffic path. */
-		sja1105_vlan_rcv(skb, &source_port, &switch_id, &vbid, &vid);
-	} else if (is_link_local) {
+	if (is_link_local) {
 		/* Management traffic path. Switch embeds the switch ID and
 		 * port ID into bytes of the destination MAC, courtesy of
 		 * the incl_srcpt options.
@@ -562,16 +559,39 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
 		sja1105_meta_unpack(skb, &meta);
 		source_port = meta.source_port;
 		switch_id = meta.switch_id;
-	} else {
+	}
+
+	/* Normal data plane traffic and link-local frames are tagged with
+	 * a tag_8021q VLAN which we have to strip
+	 */
+	if (sja1105_skb_has_tag_8021q(skb)) {
+		int tmp_source_port = -1, tmp_switch_id = -1;
+
+		sja1105_vlan_rcv(skb, &tmp_source_port, &tmp_switch_id, &vbid,
+				 &vid);
+		/* Preserve the source information from the INCL_SRCPT option,
+		 * if available. This allows us to not overwrite a valid source
+		 * port and switch ID with zeroes when receiving link-local
+		 * frames from a VLAN-unaware bridged port (non-zero vbid) or a
+		 * VLAN-aware bridged port (non-zero vid).
+		 */
+		if (source_port == -1)
+			source_port = tmp_source_port;
+		if (switch_id == -1)
+			switch_id = tmp_switch_id;
+	} else if (source_port == -1 && switch_id == -1) {
+		/* Packets with no source information have no chance of
+		 * getting accepted, drop them straight away.
+		 */
 		return NULL;
 	}
 
-	if (vbid >= 1)
+	if (source_port != -1 && switch_id != -1)
+		skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
+	else if (vbid >= 1)
 		skb->dev = dsa_tag_8021q_find_port_by_vbid(netdev, vbid);
-	else if (source_port == -1 || switch_id == -1)
-		skb->dev = dsa_find_designated_bridge_port_by_vid(netdev, vid);
 	else
-		skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
+		skb->dev = dsa_find_designated_bridge_port_by_vid(netdev, vid);
 	if (!skb->dev) {
 		netdev_warn(netdev, "Couldn't decode source port\n");
 		return NULL;