[PATCH RFC net-next 12/19] net: dsa: tag_lan9303: split out common tag accessors

[Alexander Lobakin]

...as they will be needed in the upcoming GRO callbacks.

Signed-off-by: Alexander Lobakin <alobakin@xxxxxxxx>
---
 net/dsa/tag_lan9303.c | 46 +++++++++++++++++++++++++++++--------------
 1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/net/dsa/tag_lan9303.c b/net/dsa/tag_lan9303.c
index d328a44381a9..ba03502986a4 100644
--- a/net/dsa/tag_lan9303.c
+++ b/net/dsa/tag_lan9303.c
@@ -38,6 +38,32 @@
 # define LAN9303_TAG_RX_TRAPPED_TO_CPU (LAN9303_TAG_RX_IGMP | \
 					LAN9303_TAG_RX_STP)
 
+static inline bool lan9303_sanity_check(const u8 *data)
+{
+	/* '->data' points into the middle of our special VLAN tag information:
+	 *
+	 * ~ MAC src   | 0x81 | 0x00 | 0xyy | 0xzz | ether type
+	 *                           ^
+	 *                        ->data
+	 */
+	return *(__be16 *)(data - 2) == htons(ETH_P_8021Q);
+}
+
+static inline bool lan9303_trapped_to_cpu(const u8 *data)
+{
+	return *(data + 1) & LAN9303_TAG_RX_TRAPPED_TO_CPU;
+}
+
+static inline int lan9303_source_port(const u8 *data)
+{
+	return *(data + 1) & GENMASK(1, 0);
+}
+
+static inline __be16 lan9303_encap_proto(const u8 *data)
+{
+	return *(__be16 *)(data + 2);
+}
+
 /* Decide whether to transmit using ALR lookup, or transmit directly to
  * port using tag. ALR learning is performed only when using ALR lookup.
  * If the two external ports are bridged and the frame is unicast,
@@ -85,8 +111,6 @@ static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
 static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 				   struct packet_type *pt)
 {
-	u16 *lan9303_tag;
-	u16 lan9303_tag1;
 	unsigned int source_port;
 
 	if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
@@ -95,21 +119,12 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 		return NULL;
 	}
 
-	/* '->data' points into the middle of our special VLAN tag information:
-	 *
-	 * ~ MAC src   | 0x81 | 0x00 | 0xyy | 0xzz | ether type
-	 *                           ^
-	 *                        ->data
-	 */
-	lan9303_tag = (u16 *)(skb->data - 2);
-
-	if (lan9303_tag[0] != htons(ETH_P_8021Q)) {
+	if (!lan9303_sanity_check(skb->data)) {
 		dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n");
 		return NULL;
 	}
 
-	lan9303_tag1 = ntohs(lan9303_tag[1]);
-	source_port = lan9303_tag1 & 0x3;
+	source_port = lan9303_source_port(skb->data);
 
 	skb->dev = dsa_master_find_slave(dev, 0, source_port);
 	if (!skb->dev) {
@@ -117,13 +132,14 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 		return NULL;
 	}
 
+	skb->offload_fwd_mark = !lan9303_trapped_to_cpu(skb->data);
+
 	/* remove the special VLAN tag between the MAC addresses
 	 * and the current ethertype field.
 	 */
 	skb_pull_rcsum(skb, 2 + 2);
 	memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN),
 		2 * ETH_ALEN);
-	skb->offload_fwd_mark = !(lan9303_tag1 & LAN9303_TAG_RX_TRAPPED_TO_CPU);
 
 	return skb;
 }
@@ -132,7 +148,7 @@ static void lan9303_flow_dissect(const struct sk_buff *skb, __be16 *proto,
 				 int *offset)
 {
 	*offset = LAN9303_TAG_LEN;
-	*proto = *(__be16 *)(skb->data + 2);
+	*proto = lan9303_encap_proto(skb->data);
 }
 
 static const struct dsa_device_ops lan9303_netdev_ops = {
-- 
2.24.1