net: track success and failure of TCP PMTU probing

Track success and failure of TCP PMTU probing.

Signed-off-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index da5d483..3abd9d7 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -300,6 +300,8 @@
 	SNMP_MIB_ITEM("TCPACKSkippedChallenge", LINUX_MIB_TCPACKSKIPPEDCHALLENGE),
 	SNMP_MIB_ITEM("TCPWinProbe", LINUX_MIB_TCPWINPROBE),
 	SNMP_MIB_ITEM("TCPKeepAlive", LINUX_MIB_TCPKEEPALIVE),
+	SNMP_MIB_ITEM("TCPMTUPFail", LINUX_MIB_TCPMTUPFAIL),
+	SNMP_MIB_ITEM("TCPMTUPSuccess", LINUX_MIB_TCPMTUPSUCCESS),
 	SNMP_MIB_SENTINEL
 };