udp: sk_drops handling

In commits 33c732c36169d7022ad7d6eb474b0c9be43a2dc1 ([IPV4]: Add raw
drops counter) and a92aa318b4b369091fd80433c80e62838db8bc1c ([IPV6]:
Add raw drops counter), Wang Chen added raw drops counter for
/proc/net/raw & /proc/net/raw6

This patch adds this capability to UDP sockets too (/proc/net/udp &
/proc/net/udp6).

This means that 'RcvbufErrors' errors found in /proc/net/snmp can be also
be examined for each udp socket.

# grep Udp: /proc/net/snmp
Udp: InDatagrams NoPorts InErrors OutDatagrams RcvbufErrors SndbufErrors
Udp: 23971006 75 899420 16390693 146348 0

# cat /proc/net/udp
 sl  local_address rem_address   st tx_queue rx_queue tr tm->when retrnsmt  ---
uid  timeout inode ref pointer drops
 75: 00000000:02CB 00000000:0000 07 00000000:00000000 00:00000000 00000000  ---
  0        0 2358 2 ffff81082a538c80 0
111: 00000000:006F 00000000:0000 07 00000000:00000000 00:00000000 00000000  ---
  0        0 2286 2 ffff81042dd35c80 146348

In this example, only port 111 (0x006F) was flooded by messages that
user program could not read fast enough. 146348 messages were lost.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 83f74b11d09a..a7c30412de66 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -166,7 +166,7 @@ struct sock_common {
   *     @sk_err: last error
   *     @sk_err_soft: errors that don't cause failure but are the cause of a
   *                   persistent failure not just 'timed out'
-  *     @sk_drops: raw drops counter
+  *     @sk_drops: raw/udp drops counter
   *     @sk_ack_backlog: current listen backlog
   *     @sk_max_ack_backlog: listen backlog set in listen()
   *     @sk_priority: %SO_PRIORITY setting