[UDP]: Defer InDataGrams increment until recvmsg() does checksum

Thanks dave, herbert, gerrit, andi and other people for your
discussion about this problem.

UdpInDatagrams can be confusing because it counts packets that
might be dropped later.
Move UdpInDatagrams into recvmsg() as allowed by the RFC.

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 4 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 03c400ca14c..3465d4ad301 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -873,6 +873,8 @@ try_again:
         if (err)
                 goto out_free;
 
+        UDP_INC_STATS_USER(UDP_MIB_INDATAGRAMS, is_udplite);
+
         sock_recv_timestamp(msg, sk, skb);
 
         /* Copy the address. */
@@ -966,10 +968,8 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
                         int ret;
 
                         ret = (*up->encap_rcv)(sk, skb);
-                        if (ret <= 0) {
-                                UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
+                        if (ret <= 0)
                                 return -ret;
-                        }
                 }
 
                 /* FALLTHROUGH -- it's a UDP Packet */
@@ -1023,7 +1023,6 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
                 goto drop;
         }
 
-        UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
         return 0;
 
 drop: