[PATCH v2 net-next 10/10] net: dsa: tag_ocelot: use VLAN information from tagging header when available

[Xiaoliang Yang]

From: Vladimir Oltean <vladimir.olt...@nxp.com>

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.olt...@nxp.com>
---
 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 b0c98ee4e13b..253188b0e56b 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