[TCP] MIB: Count FRTO's successfully detected spurious RTOs

Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/snmp.h

@@ -213,6 +213,7 @@ enum
 	LINUX_MIB_TCPSACKDISCARD,		/* TCPSACKDiscard */
 	LINUX_MIB_TCPDSACKIGNOREDOLD,		/* TCPSACKIgnoredOld */
 	LINUX_MIB_TCPDSACKIGNOREDNOUNDO,	/* TCPSACKIgnoredNoUndo */
+	LINUX_MIB_TCPSPURIOUSRTOS,		/* TCPSpuriousRTOs */
 	__LINUX_MIB_MAX
 };
 

net/ipv4/proc.c

@@ -245,6 +245,7 @@ static const struct snmp_mib snmp4_net_list[] = {
 	SNMP_MIB_ITEM("TCPSACKDiscard", LINUX_MIB_TCPSACKDISCARD),
 	SNMP_MIB_ITEM("TCPDSACKIgnoredOld", LINUX_MIB_TCPDSACKIGNOREDOLD),
 	SNMP_MIB_ITEM("TCPDSACKIgnoredNoUndo", LINUX_MIB_TCPDSACKIGNOREDNOUNDO),
+	SNMP_MIB_ITEM("TCPSpuriousRTOs", LINUX_MIB_TCPSPURIOUSRTOS),
 	SNMP_MIB_SENTINEL
 };
 

net/ipv4/tcp_input.c

@@ -2935,6 +2935,7 @@ static int tcp_process_frto(struct sock *sk, int flag)
 		}
 		tp->frto_counter = 0;
 		tp->undo_marker = 0;
+		NET_INC_STATS_BH(LINUX_MIB_TCPSPURIOUSRTOS);
 	}
 	return 0;
 }