Merge branch 'fix-ptp-received-on-wrong-port-with-bridged-sja1105-dsa'

Vladimir Oltean says:

====================
Fix PTP received on wrong port with bridged SJA1105 DSA

Since the changes were made to tag_8021q to support imprecise RX for
bridged ports, the tag_sja1105 driver still prefers the source port
information deduced from the VLAN headers for link-local traffic, even
though the switch can theoretically do better and report the precise
source port.

The problem is that the tagger doesn't know when to trust one source of
information over another, because the INCL_SRCPT option (to "tag" link
local frames) is sometimes enabled and sometimes it isn't.

The first patch makes the switch provide the hardware tag for link local
traffic under all circumstances, and the second patch makes the tagger
always use that hardware tag as primary source of information for link
local packets.
====================

Link: https://lore.kernel.org/r/20230627094207.3385231-1-vladimir.oltean@nxp.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/dsa/sja1105/sja1105_main.c

@@ -866,11 +866,11 @@ static int sja1105_init_general_params(struct sja1105_private *priv)
 		.hostprio = 7,
 		.mac_fltres1 = SJA1105_LINKLOCAL_FILTER_A,
 		.mac_flt1    = SJA1105_LINKLOCAL_FILTER_A_MASK,
-		.incl_srcpt1 = false,
+		.incl_srcpt1 = true,
 		.send_meta1  = false,
 		.mac_fltres0 = SJA1105_LINKLOCAL_FILTER_B,
 		.mac_flt0    = SJA1105_LINKLOCAL_FILTER_B_MASK,
-		.incl_srcpt0 = false,
+		.incl_srcpt0 = true,
 		.send_meta0  = false,
 		/* Default to an invalid value */
 		.mirr_port = priv->ds->num_ports,
@@ -2405,11 +2405,6 @@ int sja1105_vlan_filtering(struct dsa_switch *ds, int port, bool enabled,
 	general_params->tpid = tpid;
 	/* EtherType used to identify outer tagged (S-tag) VLAN traffic */
 	general_params->tpid2 = tpid2;
-	/* When VLAN filtering is on, we need to at least be able to
-	 * decode management traffic through the "backup plan".
-	 */
-	general_params->incl_srcpt1 = enabled;
-	general_params->incl_srcpt0 = enabled;
 
 	for (port = 0; port < ds->num_ports; port++) {
 		if (dsa_is_unused_port(ds, port))

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;