net: dsa: tag_ocelot: use VLAN information from tagging header when available

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@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/dsa/tag_ocelot.c b/net/dsa/tag_ocelot.c
index ec16bad..3b468ac 100644 (file)
--- a/net/dsa/tag_ocelot.c
+++ b/net/dsa/tag_ocelot.c
@@ -184,9 +184,14 @@ 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;
        u64 src_port, qos_class;
+       u64 vlan_tci, tag_type;
        u8 *start = skb->data;
        u8 *extraction;
+       u16 vlan_tpid;
 
        /* Revert skb->data by the amount consumed by the DSA master,
         * so it points to the beginning of the frame.
@@ -214,6 +219,8 @@ 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, &tag_type,  16, 16, 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)
@@ -228,6 +235,33 @@ static struct sk_buff *ocelot_rcv(struct sk_buff *skb,
        skb->offload_fwd_mark = 1;
        skb->priority = qos_class;
 
+       /* Ocelot switches copy frames unmodified to the CPU. However, it is
+        * possible for the user to request a VLAN modification through
+        * VCAP_IS1_ACT_VID_REPLACE_ENA. In this case, what will happen is that
+        * the VLAN ID field from the Extraction Header gets updated, but the
+        * 802.1Q header does not (the classified VLAN only becomes visible on
+        * egress through the "port tag" of front-panel ports).
+        * So, for traffic extracted by the CPU, we want to pick up the
+        * classified VLAN and manually replace the existing 802.1Q header from
+        * the packet with it, so that the operating system is always up to
+        * date with the result of tc-vlan actions.
+        * NOTE: In VLAN-unaware mode, we don't want to do that, we want the
+        * frame to remain unmodified, because the classified VLAN is always
+        * equal to the pvid of the ingress port and should not be used for
+        * processing.
+        */
+       vlan_tpid = tag_type ? ETH_P_8021AD : ETH_P_8021Q;
+
+       if (ocelot->ports[src_port]->vlan_aware &&
+           eth_hdr(skb)->h_proto == htons(vlan_tpid)) {
+               u16 dummy_vlan_tci;
+
+               skb_push_rcsum(skb, ETH_HLEN);
+               __skb_vlan_pop(skb, &dummy_vlan_tci);
+               skb_pull_rcsum(skb, ETH_HLEN);
+               __vlan_hwaccel_put_tag(skb, htons(vlan_tpid), vlan_tci);
+       }
+
        return skb;
 }