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Subject[PATCH net-next] net: dsa: Implement flow dissection for tag_brcm.c
Date
Provide a flow_dissect callback which returns the network offset and
where to find the skb protocol, given the tags structure a common
function works for both tagging formats that are supported.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
net/dsa/tag_brcm.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
index 9c3114179690..0d3f796d14a3 100644
--- a/net/dsa/tag_brcm.c
+++ b/net/dsa/tag_brcm.c
@@ -142,6 +142,27 @@ static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,

return skb;
}
+
+static int brcm_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
+ int *offset)
+{
+ /* We have been called on the DSA master network device after
+ * eth_type_trans() which pulled the Ethernet header already.
+ * Frames have one of these two layouts:
+ * -----------------------------------
+ * | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM
+ * -----------------------------------
+ * -----------------------------------
+ * | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND
+ * -----------------------------------
+ * skb->data points 2 bytes before the actual Ethernet type field and
+ * we have an offset of 4bytes between where skb->data and where the
+ * payload starts.
+ */
+ *offset = BRCM_TAG_LEN;
+ *proto = ((__be16 *)skb->data)[1];
+ return 0;
+}
#endif

#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
@@ -177,6 +198,7 @@ static const struct dsa_device_ops brcm_netdev_ops = {
.xmit = brcm_tag_xmit,
.rcv = brcm_tag_rcv,
.overhead = BRCM_TAG_LEN,
+ .flow_dissect = brcm_tag_flow_dissect,
};

DSA_TAG_DRIVER(brcm_netdev_ops);
@@ -205,6 +227,7 @@ static const struct dsa_device_ops brcm_prepend_netdev_ops = {
.xmit = brcm_tag_xmit_prepend,
.rcv = brcm_tag_rcv_prepend,
.overhead = BRCM_TAG_LEN,
+ .flow_dissect = brcm_tag_flow_dissect,
};

DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
--
2.19.1
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