net: fix IPSTATS_MIB_OUTPKGS increment in OutForwDatagrams.

Reproduce environment:
network with 3 VM linuxs is connected as below:
VM1<---->VM2(latest kernel 6.5.0-rc7)<---->VM3
VM1: eth0 ip: 192.168.122.207 MTU 1500
VM2: eth0 ip: 192.168.122.208, eth1 ip: 192.168.123.224 MTU 1500
VM3: eth0 ip: 192.168.123.240 MTU 1500

Reproduce:
VM1 send 1400 bytes UDP data to VM3 using tools scapy with flags=0.
scapy command:
send(IP(dst="192.168.123.240",flags=0)/UDP()/str('0'*1400),count=1,
inter=1.000000)

Result:
Before IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
  ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
  OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails
  FragOKs FragFails FragCreates
Ip: 1 64 11 0 3 4 0 0 4 7 0 0 0 0 0 0 0 0 0
......
----------------------------------------------------------------------
After IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
  ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
  OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails
  FragOKs FragFails FragCreates
Ip: 1 64 12 0 3 5 0 0 4 8 0 0 0 0 0 0 0 0 0
......
----------------------------------------------------------------------
"ForwDatagrams" increase from 4 to 5 and "OutRequests" also increase
from 7 to 8.

Issue description and patch:
IPSTATS_MIB_OUTPKTS("OutRequests") is counted with IPSTATS_MIB_OUTOCTETS
("OutOctets") in ip_finish_output2().
According to RFC 4293, it is "OutOctets" counted with "OutTransmits" but
not "OutRequests". "OutRequests" does not include any datagrams counted
in "ForwDatagrams".
ipSystemStatsOutOctets OBJECT-TYPE
    DESCRIPTION
           "The total number of octets in IP datagrams delivered to the
            lower layers for transmission.  Octets from datagrams
            counted in ipIfStatsOutTransmits MUST be counted here.
ipSystemStatsOutRequests OBJECT-TYPE
    DESCRIPTION
           "The total number of IP datagrams that local IP user-
            protocols (including ICMP) supplied to IP in requests for
            transmission.  Note that this counter does not include any
            datagrams counted in ipSystemStatsOutForwDatagrams.
So do patch to define IPSTATS_MIB_OUTPKTS to "OutTransmits" and add
IPSTATS_MIB_OUTREQUESTS for "OutRequests".
Add IPSTATS_MIB_OUTREQUESTS counter in __ip_local_out() for ipv4 and add
IPSTATS_MIB_OUT counter in ip6_finish_output2() for ipv6.

Test result with patch:
Before IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
  ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
  OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails
  FragOKs FragFails FragCreates OutTransmits
Ip: 1 64 9 0 5 1 0 0 3 3 0 0 0 0 0 0 0 0 0 4
......
root@qemux86-64:~# cat /proc/net/netstat
......
IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts InBcastPkts
  OutBcastPkts InOctets OutOctets InMcastOctets OutMcastOctets
  InBcastOctets OutBcastOctets InCsumErrors InNoECTPkts InECT1Pkts
  InECT0Pkts InCEPkts ReasmOverlaps
IpExt: 0 0 0 0 0 0 2976 1896 0 0 0 0 0 9 0 0 0 0
----------------------------------------------------------------------
After IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
  ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
  OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails
  FragOKs FragFails FragCreates OutTransmits
Ip: 1 64 10 0 5 2 0 0 3 3 0 0 0 0 0 0 0 0 0 5
......
root@qemux86-64:~# cat /proc/net/netstat
......
IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts InBcastPkts
  OutBcastPkts InOctets OutOctets InMcastOctets OutMcastOctets
  InBcastOctets OutBcastOctets InCsumErrors InNoECTPkts InECT1Pkts
  InECT0Pkts InCEPkts ReasmOverlaps
IpExt: 0 0 0 0 0 0 4404 3324 0 0 0 0 0 10 0 0 0 0
----------------------------------------------------------------------
"ForwDatagrams" increase from 1 to 2 and "OutRequests" is keeping 3.
"OutTransmits" increase from 4 to 5 and "OutOctets" increase 1428.
Signed-off-by: Heng Guo <heng.guo@windriver.com>
Reviewed-by: Kun Song <Kun.Song@windriver.com>
Reviewed-by: Filip Pudak <filip.pudak@windriver.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/snmp.h

@@ -24,7 +24,7 @@ enum
 	IPSTATS_MIB_INOCTETS,			/* InOctets */
 	IPSTATS_MIB_INDELIVERS,			/* InDelivers */
 	IPSTATS_MIB_OUTFORWDATAGRAMS,		/* OutForwDatagrams */
-	IPSTATS_MIB_OUTPKTS,			/* OutRequests */
+	IPSTATS_MIB_OUTREQUESTS,		/* OutRequests */
 	IPSTATS_MIB_OUTOCTETS,			/* OutOctets */
 /* other fields */
 	IPSTATS_MIB_INHDRERRORS,		/* InHdrErrors */
@@ -57,6 +57,7 @@ enum
 	IPSTATS_MIB_ECT0PKTS,			/* InECT0Pkts */
 	IPSTATS_MIB_CEPKTS,			/* InCEPkts */
 	IPSTATS_MIB_REASM_OVERLAPS,		/* ReasmOverlaps */
+	IPSTATS_MIB_OUTPKTS,			/* OutTransmits */
 	__IPSTATS_MIB_MAX
 };
 

net/ipv4/ip_output.c

@@ -101,6 +101,8 @@ int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	struct iphdr *iph = ip_hdr(skb);
 
+	IP_INC_STATS(net, IPSTATS_MIB_OUTREQUESTS);
+
 	iph_set_totlen(iph, skb->len);
 	ip_send_check(iph);
 

net/ipv4/proc.c

@@ -83,7 +83,7 @@ static const struct snmp_mib snmp4_ipstats_list[] = {
 	SNMP_MIB_ITEM("InUnknownProtos", IPSTATS_MIB_INUNKNOWNPROTOS),
 	SNMP_MIB_ITEM("InDiscards", IPSTATS_MIB_INDISCARDS),
 	SNMP_MIB_ITEM("InDelivers", IPSTATS_MIB_INDELIVERS),
-	SNMP_MIB_ITEM("OutRequests", IPSTATS_MIB_OUTPKTS),
+	SNMP_MIB_ITEM("OutRequests", IPSTATS_MIB_OUTREQUESTS),
 	SNMP_MIB_ITEM("OutDiscards", IPSTATS_MIB_OUTDISCARDS),
 	SNMP_MIB_ITEM("OutNoRoutes", IPSTATS_MIB_OUTNOROUTES),
 	SNMP_MIB_ITEM("ReasmTimeout", IPSTATS_MIB_REASMTIMEOUT),
@@ -93,6 +93,7 @@ static const struct snmp_mib snmp4_ipstats_list[] = {
 	SNMP_MIB_ITEM("FragOKs", IPSTATS_MIB_FRAGOKS),
 	SNMP_MIB_ITEM("FragFails", IPSTATS_MIB_FRAGFAILS),
 	SNMP_MIB_ITEM("FragCreates", IPSTATS_MIB_FRAGCREATES),
+	SNMP_MIB_ITEM("OutTransmits", IPSTATS_MIB_OUTPKTS),
 	SNMP_MIB_SENTINEL
 };
 

net/ipv6/ip6_output.c

@@ -117,6 +117,8 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
 			return res;
 	}
 
+	IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
+
 	rcu_read_lock();
 	nexthop = rt6_nexthop((struct rt6_info *)dst, daddr);
 	neigh = __ipv6_neigh_lookup_noref(dev, nexthop);
@@ -328,7 +330,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
 
 	mtu = dst_mtu(dst);
 	if ((skb->len <= mtu) || skb->ignore_df || skb_is_gso(skb)) {
-		IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
+		IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS);
 
 		/* if egress device is enslaved to an L3 master device pass the
 		 * skb to its handler for processing
@@ -1987,7 +1989,7 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
 	skb->tstamp = cork->base.transmit_time;
 
 	ip6_cork_steal_dst(skb, cork);
-	IP6_UPD_PO_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUT, skb->len);
+	IP6_INC_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUTREQUESTS);
 	if (proto == IPPROTO_ICMPV6) {
 		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
 		u8 icmp6_type;

net/ipv6/mcast.c

@@ -1789,7 +1789,7 @@ static void mld_sendpack(struct sk_buff *skb)
 
 	rcu_read_lock();
 	idev = __in6_dev_get(skb->dev);
-	IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
+	IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS);
 
 	payload_len = (skb_tail_pointer(skb) - skb_network_header(skb)) -
 		sizeof(*pip6);
@@ -2147,8 +2147,7 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
 	full_len = sizeof(struct ipv6hdr) + payload_len;
 
 	rcu_read_lock();
-	IP6_UPD_PO_STATS(net, __in6_dev_get(dev),
-		      IPSTATS_MIB_OUT, full_len);
+	IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_OUTREQUESTS);
 	rcu_read_unlock();
 
 	skb = sock_alloc_send_skb(sk, hlen + tlen + full_len, 1, &err);

net/ipv6/ndisc.c

@@ -504,7 +504,7 @@ void ndisc_send_skb(struct sk_buff *skb, const struct in6_addr *daddr,
 
 	rcu_read_lock();
 	idev = __in6_dev_get(dst->dev);
-	IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
+	IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS);
 
 	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
 		      net, sk, skb, NULL, dst->dev,

net/ipv6/proc.c

@@ -61,7 +61,7 @@ static const struct snmp_mib snmp6_ipstats_list[] = {
 	SNMP_MIB_ITEM("Ip6InDiscards", IPSTATS_MIB_INDISCARDS),
 	SNMP_MIB_ITEM("Ip6InDelivers", IPSTATS_MIB_INDELIVERS),
 	SNMP_MIB_ITEM("Ip6OutForwDatagrams", IPSTATS_MIB_OUTFORWDATAGRAMS),
-	SNMP_MIB_ITEM("Ip6OutRequests", IPSTATS_MIB_OUTPKTS),
+	SNMP_MIB_ITEM("Ip6OutRequests", IPSTATS_MIB_OUTREQUESTS),
 	SNMP_MIB_ITEM("Ip6OutDiscards", IPSTATS_MIB_OUTDISCARDS),
 	SNMP_MIB_ITEM("Ip6OutNoRoutes", IPSTATS_MIB_OUTNOROUTES),
 	SNMP_MIB_ITEM("Ip6ReasmTimeout", IPSTATS_MIB_REASMTIMEOUT),
@@ -84,6 +84,7 @@ static const struct snmp_mib snmp6_ipstats_list[] = {
 	SNMP_MIB_ITEM("Ip6InECT1Pkts", IPSTATS_MIB_ECT1PKTS),
 	SNMP_MIB_ITEM("Ip6InECT0Pkts", IPSTATS_MIB_ECT0PKTS),
 	SNMP_MIB_ITEM("Ip6InCEPkts", IPSTATS_MIB_CEPKTS),
+	SNMP_MIB_ITEM("Ip6OutTransmits", IPSTATS_MIB_OUTPKTS),
 	SNMP_MIB_SENTINEL
 };
 

net/ipv6/raw.c

@@ -651,7 +651,7 @@ static int rawv6_send_hdrinc(struct sock *sk, struct msghdr *msg, int length,
 	 * have been queued for deletion.
 	 */
 	rcu_read_lock();
-	IP6_UPD_PO_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUT, skb->len);
+	IP6_INC_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUTREQUESTS);
 	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, net, sk, skb,
 		      NULL, rt->dst.dev, dst_output);
 	if (err > 0)