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Message-ID: <20230825075505.3932972-1-heng.guo@windriver.com>
Date: Fri, 25 Aug 2023 15:55:04 +0800
From: Heng Guo <heng.guo@...driver.com>
To: <davem@...emloft.net>, <sahern@...nel.org>, <edumazet@...gle.com>,
<kuba@...nel.org>, <pabeni@...hat.com>
CC: <netdev@...r.kernel.org>, <Richard.Danter@...driver.com>,
<filip.pudak@...driver.com>, <heng.guo@...driver.com>
Subject: [PATCH 0/1] Issue description and debug
Hi maintainers,
The IPSTATS_MIB_OUTOCTETS increment is duplicated in SNMP test.
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
VM2: eth0 ip: 192.168.122.208, eth1 ip: 192.168.123.104
VM3: eth0 ip: 192.168.123.240
Reproduce:
VM1 send 1400 bytes UDP data to VM3 using tools scapy.
scapy command:
send(IP(dst="192.168.123.240",flags=0)/UDP()/str('0'*1400),count=1,
inter=1.000000)
Result:
----------------------------------------------------------------------
root@...ux86-64:~# cat /proc/net/netstat
TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailed ......
TcpExt: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ......
IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts
InBcastPkts OutBcastPkts InOctets OutOctets ......
IpExt: 0 0 0 0 0 0 796 140 0 0 0 0 0 4 0 0 0 0
root@...ux86-64:~#
root@...ux86-64:~# cat /proc/net/netstat
TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailed ......
TcpExt: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ......
IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts
InBcastPkts OutBcastPkts InOctets OutOctets ......
IpExt: 0 0 0 0 0 0 2224 2996 0 0 0 0 0 5 0 0 0 0
----------------------------------------------------------------------
OutOctets increment is duplicated (2996-140=2856)
Issue description and debug:
Add dump_stack() in ip_output(), get below test logs with core stack.
----------------------------------------------------------------------
root@...ux86-64:~# dmesg
[ 0.000000] Linux version 6.5.0-rc7-yocto-standard (oe-user@...host)
(x86_64-poky-linux-gcc (GCC) 13.2.0, GNU ld (GNU Binutils)
2.41.0.20230731) #1 SMP PREEMPT_DY3
[ 0.000000] Command line: root=/dev/vda rw console=ttyS0 mem=256M
ip=dhcp
[ 0.000000] BIOS-provided physical RAM map:
......
[ 64.225063] ip_forward_finish: IPSTATS_MIB_OUTOCTETS len:1428
[ 64.228672] ip_output: increase IPSTATS_MIB_OUT len:1428
[ 64.228695] CPU: 0 PID: 0 Comm: swapper/0 Not tainted
6.5.0-rc7-yocto-standard #1
[ 64.228709] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.13.0-1ubuntu1.1 04/01/2014
[ 64.228715] Call Trace:
[ 64.228721] <IRQ>
[ 64.228728] dump_stack_lvl+0x3b/0x50
[ 64.228744] dump_stack+0x14/0x20
[ 64.228756] ip_output+0x129/0x140
[ 64.228770] ? dump_stack_lvl+0x47/0x50
[ 64.228785] ip_forward_finish+0xc8/0xe0
[ 64.228801] ip_forward+0x540/0x5a0
[ 64.228819] ip_sublist_rcv_finish+0x72/0x80
[ 64.228834] ip_sublist_rcv+0x160/0x1a0
[ 64.228854] ip_list_rcv+0xff/0x130
[ 64.228871] __netif_receive_skb_list_core+0x21b/0x240
[ 64.228891] netif_receive_skb_list_internal+0x1b9/0x2d0
[ 64.228935] ? detach_buf_split+0x76/0x150
[ 64.228966] napi_complete_done+0x78/0x190
[ 64.228979] virtnet_poll+0x48f/0x5e0
[ 64.229001] __napi_poll+0x31/0x1d0
[ 64.229014] net_rx_action+0x295/0x300
[ 64.229030] __do_softirq+0xff/0x315
[ 64.229047] irq_exit_rcu+0x82/0xd0
[ 64.229059] common_interrupt+0xb5/0xd0
[ 64.229072] </IRQ>
[ 64.229077] <TASK>
[ 64.229083] asm_common_interrupt+0x2b/0x40
[ 64.229095] RIP: 0010:default_idle+0x17/0x20
[ 64.229107] Code: ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90
90 90 f3 0f 1e fa 8b 05 0e f9 e7 00 85 c0 7e 07 0f 00 2d 5b 7c 2c 00 fb
f4 <fa> c3 cc cc cc c0
[ 64.229118] RSP: 0018:ffffffff8d203e38 EFLAGS: 00000246
[ 64.229130] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
0000000000000000
[ 64.229135] RDX: 0000000000000001 RSI: ffffffff8cf9b570 RDI:
0000000000006554
[ 64.229141] RBP: ffffffff8d203e40 R08: ffff9ea94f81f420 R09:
0000000000000001
[ 64.229147] R10: ffff9ea941226e80 R11: 00000000000000b2 R12:
ffffffff8d20a940
[ 64.229153] R13: 0000000000000000 R14: 0000000000000000 R15:
ffffffff8d20a940
[ 64.229169] ? arch_cpu_idle+0xd/0x20
[ 64.229182] default_idle_call+0x36/0xf0
[ 64.229194] do_idle+0x1f1/0x230
[ 64.229208] cpu_startup_entry+0x21/0x30
[ 64.229220] rest_init+0xc5/0xd0
[ 64.229233] arch_call_rest_init+0x12/0x50
[ 64.229246] start_kernel+0x426/0x680
[ 64.229262] x86_64_start_reservations+0x1c/0x30
[ 64.229276] x86_64_start_kernel+0xce/0xe0
[ 64.229290] secondary_startup_64_no_verify+0x179/0x17b
[ 64.229338] </TASK>
[ 64.232465] net_dev_queue: { len:1428, name:eth1,
network_header_type: IPV4, protocol: icmp,
saddr:[192.168.122.1], daddr:[192.168.123.240] }
--------------------------------------------------------------------
Refer to source codes, IPSTATS_MIB_OUTOCTETS is counted in both
ip_forward_finish() and ip_output().
commit edf391ff1723 ("snmp: add missing counters for RFC 4293") had
already added OutOctets for RFC 4293. In commit 2d8dbb04c63e ("snmp: fix
OutOctets counter to include forwarded datagrams"), OutOctets was
counted again, but not removed from ip_output().
And according to RFC 4293 "3.2.3. IP Statistics Tables",
ipIfStatsOutTransmits is not same to ipIfStatsOutForwDatagrams. So
"IPSTATS_MIB_OUTOCTETS must be incremented when incrementing
IPSTATS_MIB_OUTFORWDATAGRAMS" is not accurate. And IPSTATS_MIB_OUTOCTETS
should aslo be counted after fragment by RFC 4293.
Patch:
So do patch to revert this comment and to move IPSTATS_MIB_OUTOCTETS to
ip_finish_output2 for ipv4. Test result is:
----------------------------------------------------------------------
root@...ux86-64:~# cat /proc/net/netstat
TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailed ......
TcpExt: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ......
IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts InBcastPkts
OutBcastPkts InOctets OutOctets ......
IpExt: 0 0 0 0 1 0 1500 516 0 0 328 0 0 7 0 0 0 0
root@...ux86-64:~#
root@...ux86-64:~#
root@...ux86-64:~# cat /proc/net/netstat
TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailed ......
TcpExt: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ......
IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts InBcastPkts
OutBcastPkts InOctets OutOctets ......
IpExt: 0 0 0 0 1 0 2928 1944 0 0 328 0 0 8 0 0 0 0
root@...ux86-64:~# dmesg
----------------------------------------------------------------------
OutOctets increment is only 1428(1944-516).
Thanks,
Heng
Heng Guo (1):
net: ipv4, ipv6: fix IPSTATS_MIB_OUTOCTETS increment duplicated
net/ipv4/ip_forward.c | 1 -
net/ipv4/ip_output.c | 7 +++----
net/ipv4/ipmr.c | 1 -
net/ipv6/ip6_output.c | 1 -
net/ipv6/ip6mr.c | 2 --
5 files changed, 3 insertions(+), 9 deletions(-)
--
2.35.5
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