tcp: Add SNMP counter for DEFER_ACCEPT
Its currently hard to diagnose when ACK frames are dropped because an
application set TCP_DEFER_ACCEPT on its listening socket.
See http://bugzilla.kernel.org/show_bug.cgi?id=15507
This patch adds a SNMP value, named TCPDeferAcceptDrop
netstat -s | grep TCPDeferAcceptDrop
TCPDeferAcceptDrop: 0
This counter is incremented every time we drop a pure ACK frame received
by a socket in SYN_RECV state because its SYNACK retrans count is lower
than defer_accept value.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/snmp.h b/include/linux/snmp.h
index 4435d10..d2a9aa3 100644
--- a/include/linux/snmp.h
+++ b/include/linux/snmp.h
@@ -227,6 +227,7 @@
LINUX_MIB_SACKSHIFTFALLBACK,
LINUX_MIB_TCPBACKLOGDROP,
LINUX_MIB_TCPMINTTLDROP, /* RFC 5082 */
+ LINUX_MIB_TCPDEFERACCEPTDROP,
__LINUX_MIB_MAX
};