[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>

3 files changed, 7 insertions, 6 deletions

diff --git a/Documentation/networking/udplite.txt b/Documentation/networking/udplite.txt
index b6409cab075c..3870f280280b 100644
--- a/Documentation/networking/udplite.txt
+++ b/Documentation/networking/udplite.txt
@@ -236,7 +236,7 @@
 
   This displays UDP-Lite statistics variables, whose meaning is as follows.
 
-   InDatagrams:     Total number of received datagrams.
+   InDatagrams:     The total number of datagrams delivered to users.
 
    NoPorts:         Number of packets received to an unknown port.
                     These cases are counted separately (not as InErrors).
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 03c400ca14c5..3465d4ad301b 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:
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index ee1cc3f8599f..b0474a618bbe 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -164,6 +164,8 @@ try_again:
         if (err)
                 goto out_free;
 
+        UDP6_INC_STATS_USER(UDP_MIB_INDATAGRAMS, is_udplite);
+
         sock_recv_timestamp(msg, sk, skb);
 
         /* Copy the address. */
@@ -292,7 +294,7 @@ int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
                         UDP6_INC_STATS_BH(UDP_MIB_RCVBUFERRORS, up->pcflag);
                 goto drop;
         }
-        UDP6_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
+
         return 0;
 drop:
         UDP6_INC_STATS_BH(UDP_MIB_INERRORS, up->pcflag);