[dpdk-users] dpdk with snort 2.9.9 receive from DPDK ring

Padam Jeet Singh padam.singh at inventum.net
Wed Aug 30 07:15:21 CEST 2017

> On 30-Aug-2017, at 2:21 AM, Ming Fu <Ming.Fu at esentire.com> wrote:
> I am making a snort DAQ module to receive packet from DPDK capture through a ring. The snort version is 2.9.9 and DPDK version is 17.08. The code is very similar to the multi_process/client_server_mp example. The DPDK is initialized in daq initialize function and mbuf received from daq acquire function. Snort inspects the mbuf but does not re-inject back to the network, so daq free the mbuf by rte_pktmbuf_free(mbuf) in the same thread as it calls rte_ring_dequeue_burst();
> The snort successfully received the first burst of 32 packets, but it fails on the first rte_pktmbuf_free().
> Seems some internal dpdk function pointer is NULL.
> #0  0x0000000000000000 in ?? ()
> #1  0x00000000004f7a8d in rte_mempool_ops_enqueue_bulk (n=<optimized out>, obj_table=<optimized out>, mp=<optimized out>)
>    at /home/mfu/work/dpdk-17.08/build/include/rte_mempool.h:497
> #2  __mempool_generic_put (cache=<optimized out>, n=1, obj_table=0x7fffffffe6e8, mp=<optimized out>) at /home/mfu/work/dpdk-17.08/build/include/rte_mempool.h:1069
> #3  rte_mempool_generic_put (flags=<optimized out>, cache=<optimized out>, n=1, obj_table=0x7fffffffe6e8, mp=<optimized out>)
>    at /home/mfu/work/dpdk-17.08/build/include/rte_mempool.h:1109
> #4  rte_mempool_put_bulk (n=1, obj_table=0x7fffffffe6e8, mp=<optimized out>) at /home/mfu/work/dpdk-17.08/build/include/rte_mempool.h:1132
> #5  rte_mempool_put (obj=<optimized out>, mp=<optimized out>) at /home/mfu/work/dpdk-17.08/build/include/rte_mempool.h:1150
> #6  rte_mbuf_raw_free (m=<optimized out>) at /home/mfu/work/dpdk-17.08/build/include/rte_mbuf.h:853
> #7  rte_pktmbuf_free_seg (m=<optimized out>) at /home/mfu/work/dpdk-17.08/build/include/rte_mbuf.h:1349
> #8  rte_pktmbuf_free (m=<optimized out>) at /home/mfu/work/dpdk-17.08/build/include/rte_mbuf.h:1369
> #9  dpdk_daq_acquire (handle=0x1af6910, cnt=0, callback=<optimized out>, metaback=<optimized out>, user=<optimized out>) at daq_dpdk.c:234
> #10 0x00000000004551d3 in DAQ_Acquire ()
> #11 0x0000000000437828 in SnortMain ()
> #12 0x00007ffff61af830 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
> #13 0x0000000000406d29 in _start ()
> I notice that snort has three threads,
> (gdb) info thread
>  Id   Target Id         Frame
> * 1    Thread 0x7ffff7fdf8c0 (LWP 42472) "snort" 0x0000000000000000 in ?? ()
>  2    Thread 0x7fffdff5a700 (LWP 42481) "eal-intr-thread" 0x00007ffff62969d3 in epoll_wait () from /lib/x86_64-linux-gnu/libc.so.6
>  3    Thread 0x7fffdf4d5700 (LWP 42482) "snort" 0x00007ffff625b30d in nanosleep () from /lib/x86_64-linux-gnu/libc.so.6
> Would it be a problem if the rte_pktmbuf_free() is not called from the eal thread?

The rte_mbuf_free internally calls rte_mempool put calls - which should only be called from a EAL thread - so yes, only call rte_pktmbuf_free from an EAL thread.

> Thanks
> Ming


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