net: dsa: Don't set skb->protocol on outgoing tagged packets

Setting skb->protocol to a private protocol type may result in warning
messages such as
	e1000e 0000:00:19.0 em1: checksum_partial proto=dada!

This happens if the L3 protocol is IP or IPv6 and skb->ip_summed is set
to CHECKSUM_PARTIAL. Looking through the code, it appears that changing
skb->protocol for transmitted packets is not necessary and may actually
be harmful. For example, it prevents purposely unmodified (from a DSA
perspective) network drivers from properly setting up their transmit
checksum offload pointers since they inspect skb->protocol to set up the
IPv4 header or IPv6 header pointers. So don't unnecessarily change the
protocol field.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/tag_dsa.c

@@ -63,8 +63,6 @@ static netdev_tx_t dsa_xmit(struct sk_buff *skb, struct net_device *dev)
 		dsa_header[3] = 0x00;
 	}
 
-	skb->protocol = htons(ETH_P_DSA);
-
 	skb->dev = p->parent->dst->master_netdev;
 	dev_queue_xmit(skb);
 

net/dsa/tag_edsa.c

@@ -76,8 +76,6 @@ static netdev_tx_t edsa_xmit(struct sk_buff *skb, struct net_device *dev)
 		edsa_header[7] = 0x00;
 	}
 
-	skb->protocol = htons(ETH_P_EDSA);
-
 	skb->dev = p->parent->dst->master_netdev;
 	dev_queue_xmit(skb);
 

net/dsa/tag_trailer.c

@@ -57,8 +57,6 @@ static netdev_tx_t trailer_xmit(struct sk_buff *skb, struct net_device *dev)
 	trailer[2] = 0x10;
 	trailer[3] = 0x00;
 
-	nskb->protocol = htons(ETH_P_TRAILER);
-
 	nskb->dev = p->parent->dst->master_netdev;
 	dev_queue_xmit(nskb);