net: ipv4, ipv6: fix IPSTATS_MIB_OUTOCTETS increment duplicated

commit edf391ff ("snmp: add missing counters for RFC 4293") had
already added OutOctets for RFC 4293. In commit 2d8dbb04 ("snmp: fix
OutOctets counter to include forwarded datagrams"), OutOctets was
counted again, but not removed from ip_output().

According to RFC 4293 "3.2.3. IP Statistics Tables",
ipipIfStatsOutTransmits is not equal to ipIfStatsOutForwDatagrams. So
"IPSTATS_MIB_OUTOCTETS must be incremented when incrementing" is not
accurate. And IPSTATS_MIB_OUTOCTETS should be counted after fragment.

This patch reverts commit 2d8dbb04 ("snmp: fix OutOctets counter to
include forwarded datagrams") and move IPSTATS_MIB_OUTOCTETS to
ip_finish_output2 for ipv4.
Reviewed-by: Filip Pudak <filip.pudak@windriver.com>
Signed-off-by: Heng Guo <heng.guo@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_forward.c

@@ -67,7 +67,6 @@ static int ip_forward_finish(struct net *net, struct sock *sk, struct sk_buff *s
 	struct ip_options *opt	= &(IPCB(skb)->opt);
 
 	__IP_INC_STATS(net, IPSTATS_MIB_OUTFORWDATAGRAMS);
-	__IP_ADD_STATS(net, IPSTATS_MIB_OUTOCTETS, skb->len);
 
 #ifdef CONFIG_NET_SWITCHDEV
 	if (skb->offload_l3_fwd_mark) {

net/ipv4/ip_output.c

@@ -207,6 +207,9 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
 	} else if (rt->rt_type == RTN_BROADCAST)
 		IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
 
+	/* OUTOCTETS should be counted after fragment */
+	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
+
 	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
 		skb = skb_expand_head(skb, hh_len);
 		if (!skb)
@@ -366,8 +369,6 @@ int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 	/*
 	 *	If the indicated interface is up and running, send the packet.
 	 */
-	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
-
 	skb->dev = dev;
 	skb->protocol = htons(ETH_P_IP);
 
@@ -424,8 +425,6 @@ int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
 
-	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
-
 	skb->dev = dev;
 	skb->protocol = htons(ETH_P_IP);
 

net/ipv4/ipmr.c

@@ -1804,7 +1804,6 @@ static inline int ipmr_forward_finish(struct net *net, struct sock *sk,
 	struct ip_options *opt = &(IPCB(skb)->opt);
 
 	IP_INC_STATS(net, IPSTATS_MIB_OUTFORWDATAGRAMS);
-	IP_ADD_STATS(net, IPSTATS_MIB_OUTOCTETS, skb->len);
 
 	if (unlikely(opt->optlen))
 		ip_forward_options(skb);

net/ipv6/ip6_output.c

@@ -451,7 +451,6 @@ static inline int ip6_forward_finish(struct net *net, struct sock *sk,
 	struct dst_entry *dst = skb_dst(skb);
 
 	__IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
-	__IP6_ADD_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTOCTETS, skb->len);
 
 #ifdef CONFIG_NET_SWITCHDEV
 	if (skb->offload_l3_fwd_mark) {

net/ipv6/ip6mr.c

@@ -2010,8 +2010,6 @@ static inline int ip6mr_forward2_finish(struct net *net, struct sock *sk, struct
 {
 	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 		      IPSTATS_MIB_OUTFORWDATAGRAMS);
-	IP6_ADD_STATS(net, ip6_dst_idev(skb_dst(skb)),
-		      IPSTATS_MIB_OUTOCTETS, skb->len);
 	return dst_output(net, sk, skb);
 }