net: Introduce skb_tunnel_rx() helper

skb rxhash should be cleared when a skb is handled by a tunnel before
being delivered again, so that correct packet steering can take place.

There are other cleanups and accounting that we can factorize in a new
helper, skb_tunnel_rx()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dst.h

@@ -226,6 +226,26 @@ static inline void skb_dst_force(struct sk_buff *skb)
 	}
 }
 
+
+/**
+ *	skb_tunnel_rx - prepare skb for rx reinsert
+ *	@skb: buffer
+ *	@dev: tunnel device
+ *
+ *	After decapsulation, packet is going to re-enter (netif_rx()) our stack,
+ *	so make some cleanups, and perform accounting.
+ */
+static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
+{
+	skb->dev = dev;
+	/* TODO : stats should be SMP safe */
+	dev->stats.rx_packets++;
+	dev->stats.rx_bytes += skb->len;
+	skb->rxhash = 0;
+	skb_dst_drop(skb);
+	nf_reset(skb);
+}
+
 /* Children define the path of the packet through the
  * Linux networking.  Thus, destinations are stackable.
  */

net/ipv4/ip_gre.c

@@ -538,7 +538,6 @@ static int ipgre_rcv(struct sk_buff *skb)
 	struct ip_tunnel *tunnel;
 	int    offset = 4;
 	__be16 gre_proto;
-	unsigned int len;
 
 	if (!pskb_may_pull(skb, 16))
 		goto drop_nolock;
@@ -629,8 +628,6 @@ static int ipgre_rcv(struct sk_buff *skb)
 			tunnel->i_seqno = seqno + 1;
 		}
 
-		len = skb->len;
-
 		/* Warning: All skb pointers will be invalidated! */
 		if (tunnel->dev->type == ARPHRD_ETHER) {
 			if (!pskb_may_pull(skb, ETH_HLEN)) {
@@ -644,11 +641,7 @@ static int ipgre_rcv(struct sk_buff *skb)
 			skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
 		}
 
-		stats->rx_packets++;
-		stats->rx_bytes += len;
-		skb->dev = tunnel->dev;
-		skb_dst_drop(skb);
-		nf_reset(skb);
+		skb_tunnel_rx(skb, tunnel->dev);
 
 		skb_reset_network_header(skb);
 		ipgre_ecn_decapsulate(iph, skb);

net/ipv4/ipip.c

@@ -374,11 +374,8 @@ static int ipip_rcv(struct sk_buff *skb)
 		skb->protocol = htons(ETH_P_IP);
 		skb->pkt_type = PACKET_HOST;
 
-		tunnel->dev->stats.rx_packets++;
-		tunnel->dev->stats.rx_bytes += skb->len;
-		skb->dev = tunnel->dev;
-		skb_dst_drop(skb);
-		nf_reset(skb);
+		skb_tunnel_rx(skb, tunnel->dev);
+
 		ipip_ecn_decapsulate(iph, skb);
 		netif_rx(skb);
 		rcu_read_unlock();

net/ipv4/ipmr.c

@@ -1831,14 +1831,12 @@ static int __pim_rcv(struct mr_table *mrt, struct sk_buff *skb,
 	skb->mac_header = skb->network_header;
 	skb_pull(skb, (u8*)encap - skb->data);
 	skb_reset_network_header(skb);
-	skb->dev = reg_dev;
 	skb->protocol = htons(ETH_P_IP);
 	skb->ip_summed = 0;
 	skb->pkt_type = PACKET_HOST;
-	skb_dst_drop(skb);
-	reg_dev->stats.rx_bytes += skb->len;
-	reg_dev->stats.rx_packets++;
-	nf_reset(skb);
+
+	skb_tunnel_rx(skb, reg_dev);
+
 	netif_rx(skb);
 	dev_put(reg_dev);
 

net/ipv6/ip6_tunnel.c

@@ -723,14 +723,10 @@ static int ip6_tnl_rcv(struct sk_buff *skb, __u16 protocol,
 		skb->protocol = htons(protocol);
 		skb->pkt_type = PACKET_HOST;
 		memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
-		skb->dev = t->dev;
-		skb_dst_drop(skb);
-		nf_reset(skb);
 
-		dscp_ecn_decapsulate(t, ipv6h, skb);
+		skb_tunnel_rx(skb, t->dev);
 
-		t->dev->stats.rx_packets++;
-		t->dev->stats.rx_bytes += skb->len;
+		dscp_ecn_decapsulate(t, ipv6h, skb);
 		netif_rx(skb);
 		rcu_read_unlock();
 		return 0;

net/ipv6/ip6mr.c

@@ -658,14 +658,12 @@ static int pim6_rcv(struct sk_buff *skb)
 	skb->mac_header = skb->network_header;
 	skb_pull(skb, (u8 *)encap - skb->data);
 	skb_reset_network_header(skb);
-	skb->dev = reg_dev;
 	skb->protocol = htons(ETH_P_IPV6);
 	skb->ip_summed = 0;
 	skb->pkt_type = PACKET_HOST;
-	skb_dst_drop(skb);
-	reg_dev->stats.rx_bytes += skb->len;
-	reg_dev->stats.rx_packets++;
-	nf_reset(skb);
+
+	skb_tunnel_rx(skb, reg_dev);
+
 	netif_rx(skb);
 	dev_put(reg_dev);
 	return 0;

net/ipv6/sit.c

@@ -566,11 +566,9 @@ static int ipip6_rcv(struct sk_buff *skb)
 			kfree_skb(skb);
 			return 0;
 		}
-		tunnel->dev->stats.rx_packets++;
-		tunnel->dev->stats.rx_bytes += skb->len;
-		skb->dev = tunnel->dev;
-		skb_dst_drop(skb);
-		nf_reset(skb);
+
+		skb_tunnel_rx(skb, tunnel->dev);
+
 		ipip6_ecn_decapsulate(iph, skb);
 		netif_rx(skb);
 		rcu_read_unlock();