UDP: Account for TX drops

UDP layer is currently not incrementing error counters when packets are
dropped. Use the SNDBUFERRORS to indicate packet drops on send.

Signed-off-by: Christoph Lameter <cl@linux-foundation.org>

---
 net/ipv4/udp.c |    7 +++++++
 1 file changed, 7 insertions(+)

Index: linux-2.6/net/ipv4/udp.c
===================================================================
--- linux-2.6.orig/net/ipv4/udp.c	2009-08-26 13:21:30.000000000 +0000
+++ linux-2.6/net/ipv4/udp.c	2009-08-26 13:46:35.000000000 +0000
@@ -559,6 +559,13 @@ static int udp_push_pending_frames(struc
 
 send:
 	err = ip_push_pending_frames(sk);
+
+	if (err)
+		/*
+		 * Packet was dropped.
+		 */
+		UDP_INC_STATS_USER(sock_net(sk),
+			UDP_MIB_SNDBUFERRORS, is_udplite);
 out:
 	up->len = 0;
 	up->pending = 0;