ethernet: Add helper for assigning packet type when dest address does not match device address

Enable reuse of logic in eth_type_trans for determining packet type.
Suggested-by: Sabrina Dubroca <sd@queasysnail.net>
Cc: stable@vger.kernel.org
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/r/20240423181319.115860-3-rrameshbabu@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/linux/etherdevice.h

@@ -607,6 +607,31 @@ static inline void eth_hw_addr_gen(struct net_device *dev, const u8 *base_addr,
 	eth_hw_addr_set(dev, addr);
 }
 
+/**
+ * eth_skb_pkt_type - Assign packet type if destination address does not match
+ * @skb: Assigned a packet type if address does not match @dev address
+ * @dev: Network device used to compare packet address against
+ *
+ * If the destination MAC address of the packet does not match the network
+ * device address, assign an appropriate packet type.
+ */
+static inline void eth_skb_pkt_type(struct sk_buff *skb,
+				    const struct net_device *dev)
+{
+	const struct ethhdr *eth = eth_hdr(skb);
+
+	if (unlikely(!ether_addr_equal_64bits(eth->h_dest, dev->dev_addr))) {
+		if (unlikely(is_multicast_ether_addr_64bits(eth->h_dest))) {
+			if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
+				skb->pkt_type = PACKET_BROADCAST;
+			else
+				skb->pkt_type = PACKET_MULTICAST;
+		} else {
+			skb->pkt_type = PACKET_OTHERHOST;
+		}
+	}
+}
+
 /**
  * eth_skb_pad - Pad buffer to mininum number of octets for Ethernet frame
  * @skb: Buffer to pad

net/ethernet/eth.c

@@ -164,17 +164,7 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 	eth = (struct ethhdr *)skb->data;
 	skb_pull_inline(skb, ETH_HLEN);
 
-	if (unlikely(!ether_addr_equal_64bits(eth->h_dest,
-					      dev->dev_addr))) {
-		if (unlikely(is_multicast_ether_addr_64bits(eth->h_dest))) {
-			if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
-				skb->pkt_type = PACKET_BROADCAST;
-			else
-				skb->pkt_type = PACKET_MULTICAST;
-		} else {
-			skb->pkt_type = PACKET_OTHERHOST;
-		}
-	}
+	eth_skb_pkt_type(skb, dev);
 
 	/*
 	 * Some variants of DSA tagging don't have an ethertype field