Re: dpdk16.11 RC2 package ipv4 reassembly example can't work

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

Hi all,

On Wed, Nov 02, 2016 at 08:39:31AM +0000, Lu, Wenzhuo wrote:
> Correct the typo of receiver.
> 
> Hi Adrien,
> The change from struct ip_frag_pkt pkt[0]  to struct ip_frag_pkt pkt[] will make IP reassembly not working. I think this is not the root cause. Maybe Konstantin can give us some idea.
> But I notice one thing, you change some from [0] to [], but others just add '__extension__'. I believe if you add '__extension__' for struct ip_frag_pkt pkt[0], we'll not hit this issue. Just curious why you use 2 ways to resolve the same problem.

I've used the __extension__ method whenever the C99 syntax could not work
due to invalid usage in the code, e.g. a flexible array cannot be the only
member of a struct, you cannot make arrays out of structures that contain
such fields, while there is no such constraint with the GNU syntax.

For example see __extension__ uint8_t action_data[0] in struct
rte_pipeline_table_entry. The C99 could not be used because of
test_table_acl.c:

  struct rte_pipeline_table_entry entries[5];

If replacing ip_frag_pkt[] with __extension__ ip_frag_pkt pkt[0] in
rte_ip_frag.h solves the issue, either some code is breaking some constraint
somewhere or this change broke the ABI (unlikely considering a simple
recompilation should have taken care of the issue). I did not notice any
change in sizeof(struct rte_ip_frag_tbl) nor offsetof(struct
rte_ip_frag_tbl, pkt) on my setup, perhaps the compilation flags used in
your test affect them somehow.

Can you confirm whether only reverting this particular field solves the
issue?

> From: Xu, HuilongX
> Sent: Wednesday, November 2, 2016 4:29 PM
> To: drien.mazarguil@6wind.com
> Cc: Ananyev, Konstantin; Liu, Yu Y; Chen, WeichunX; Lu, Wenzhuo; Xu, HuilongX
> Subject: dpdk16.11 RC2 package ipv4 reassembly example can't work
> 
> Hi mazarguil,
> I find ip reassembly example can't work with dpdk16.11 rc2 package.
> But when I reset dpdk code before 347a1e037fd323e6c2af55d17f7f0dc4bfe1d479, it works ok.
> Could you have time to check this issue, thanks  a lot.
> Unzip password: intel123
> 
> Test detail info:
> 
> os&kernel:4.2.3-300.fc23.x86_64
> gcc version:5.3.1 20160406 (Red Hat 5.3.1-6) (GCC)
> NIC:03:00.0 Ethernet controller [0200]: Intel Corporation Ethernet Connection X552/X557-AT 10GBASE-T [8086:15ad] and
> 84:00.0 Ethernet controller [0200]: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection [8086:10fb] (rev 01)
> package: dpdk16.11.rc2.tar.gz
> test steps:
> 1. build and install dpdk
> 2. build ip_reassembly example
> 3. run ip_reassembly
> ./examples/ip_reassembly/build/ip_reassembly -c 0x2 -n 4 - -p 0x1 --maxflows=1024 --flowttl=10s
> 4. set tester port mtu
> ip link set mtu 9000 dev ens160f1
> 5. setup scapy on tester and send packet
> scapy
> pcap = rdpcap("file.pcap")
> sendp(pcap, iface="ens160f1")
> 6. sniff packet on tester and check packet
> test result:
> dpdk16.04 reassembly packet successful but dpdk16.11 reassembly pack failed.
> 
> comments:
> file.pcap: send packets pcap file
> tcpdump_16.04_reassembly_successful.pcap: sniff packets by tcpdump on 16.04.
> tcpdump_reset_code_reassembly_failed.pcap: sniff packets by tcpdump on 16.11
> reset_code_reassembly_successful_.jpg: reassembly a packets successful detail info
> dpdk16.11_reassembly_failed.jpg: reassembly a packets failed detail info
> 

-- 
Adrien Mazarguil
6WIND