net: sk_drops consolidation part 2

- skb_kill_datagram() can increment sk->sk_drops itself, not callers.

- UDP on IPV4 & IPV6 dropped frames (because of bad checksum or policy checks) increment sk_drops

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

net/ipv6/raw.c

@@ -517,7 +517,6 @@ csum_copy_err:
 	   as some normal condition.
 	 */
 	err = (flags&MSG_DONTWAIT) ? -EAGAIN : -EHOSTUNREACH;
-	atomic_inc(&sk->sk_drops);
 	goto out;
 }
 

net/ipv6/udp.c

@@ -390,11 +390,13 @@ int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
 		if (rc == -ENOMEM)
 			UDP6_INC_STATS_BH(sock_net(sk),
 					UDP_MIB_RCVBUFERRORS, is_udplite);
-		goto drop;
+		goto drop_no_sk_drops_inc;
 	}
 
 	return 0;
 drop:
+	atomic_inc(&sk->sk_drops);
+drop_no_sk_drops_inc:
 	UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
 	kfree_skb(skb);
 	return -1;