Re: [dpdk-dev] dpdk16.11 RC2 package ipv4 reassembly example can't work

["Lu, Wenzhuo" <wenzhuo.lu@intel.com>]

Hi Adrien,

> -----Original Message-----
> From: Adrien Mazarguil [mailto:adrien.mazarguil@6wind.com]
> Sent: Wednesday, November 2, 2016 11:21 PM
> To: Lu, Wenzhuo
> Cc: Ananyev, Konstantin; Liu, Yu Y; Chen, WeichunX; Xu, HuilongX;
> dev@dpdk.org
> Subject: Re: dpdk16.11 RC2 package ipv4 reassembly example can't work
> 
> 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.
Thanks for your explanation. I also checked sizeof(struct rte_ip_frag_tbl). I don't see any change either.

> 
> Can you confirm whether only reverting this particular field solves the issue?
Yes. ip_frag_pkt pkt[0] or even ip_frag_pkt pkt[1] can work but ip_frag_pkt pkt[] cannot :(
Do you like the idea of changing the ip_frag_pkt[] to __extension__ ip_frag_pkt pkt[0]?

> 
> > 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