[PATCH v1 net-next 6/6] net: dsa: tag_ocelot: use VLAN information from tagging header when available

From: Xiaoliang Yang
Date: Wed May 06 2020 - 03:54:14 EST


From: Vladimir Oltean <vladimir.oltean@xxxxxxx>

When the Extraction Frame Header contains a valid classified VLAN, use
that instead of the VLAN header present in the packet.

Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
---
net/dsa/tag_ocelot.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)

diff --git a/net/dsa/tag_ocelot.c b/net/dsa/tag_ocelot.c
index 59de1315100f..8c93a78bda5b 100644
--- a/net/dsa/tag_ocelot.c
+++ b/net/dsa/tag_ocelot.c
@@ -181,9 +181,16 @@ static struct sk_buff *ocelot_rcv(struct sk_buff *skb,
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;
+ struct ocelot_port *ocelot_port;
u64 src_port, qos_class;
u8 *start = skb->data;
+ struct ethhdr *hdr;
u8 *extraction;
+ u64 vlan_tci;
+ u16 vid;

/* Revert skb->data by the amount consumed by the DSA master,
* so it points to the beginning of the frame.
@@ -211,6 +218,7 @@ static struct sk_buff *ocelot_rcv(struct sk_buff *skb,

packing(extraction, &src_port, 46, 43, OCELOT_TAG_LEN, UNPACK, 0);
packing(extraction, &qos_class, 19, 17, OCELOT_TAG_LEN, UNPACK, 0);
+ packing(extraction, &vlan_tci, 15, 0, OCELOT_TAG_LEN, UNPACK, 0);

skb->dev = dsa_master_find_slave(netdev, 0, src_port);
if (!skb->dev)
@@ -225,6 +233,27 @@ static struct sk_buff *ocelot_rcv(struct sk_buff *skb,
skb->offload_fwd_mark = 1;
skb->priority = qos_class;

+ /* The VID from the extraction header contains the classified VLAN. But
+ * if VLAN awareness is off and no retagging is done via VCAP IS1, that
+ * classified VID will always be the pvid of the src_port.
+ * port. We want Linux to see the classified VID, but only if the switch
+ * intended to send the packet as untagged, i.e. if the VID is different
+ * than the CPU port's untagged (native) VID.
+ */
+ vid = vlan_tci & VLAN_VID_MASK;
+ hdr = eth_hdr(skb);
+ ocelot_port = ocelot->ports[src_port];
+ if (hdr->h_proto == htons(ETH_P_8021Q) && vid != ocelot_port->pvid) {
+ u16 dummy_vlan_tci;
+
+ skb_push_rcsum(skb, ETH_HLEN);
+ __skb_vlan_pop(skb, &dummy_vlan_tci);
+ skb_pull_rcsum(skb, ETH_HLEN);
+ skb_reset_network_header(skb);
+ skb_reset_transport_header(skb);
+ __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlan_tci);
+ }
+
return skb;
}

--
2.17.1