UDP-GRO not working

[Kumara Parameshwaran]

Hi ,

I tried using the UDP GRO feature in DPDK recently and it did not see working. I understand the GRO for UDP is applicable only for fragmented packets, there is the following check in gro_udp4.c
/*
* Don't process non-fragment packet.
*/
if (!is_ipv4_fragment(ipv4_hdr))
return -1;


There looks to be some conflict in the definition of RTE_PTYPE in rte_mbuf_ptype.h and the usage of this in GRO layer, rte_gro.c

The below are the definitions,

#define RTE_PTYPE_L4_TCP                    0x00000100
#define RTE_PTYPE_L4_UDP                    0x00000200
#define RTE_PTYPE_L4_FRAG                   0x00000300

Below is the check in GRO layer,

#define IS_IPV4_TCP_PKT(ptype) (RTE_ETH_IS_IPV4_HDR(ptype) && \
        ((ptype & RTE_PTYPE_L4_TCP) == RTE_PTYPE_L4_TCP) && \
        (RTE_ETH_IS_TUNNEL_PKT(ptype) == 0))

#define IS_IPV4_UDP_PKT(ptype) (RTE_ETH_IS_IPV4_HDR(ptype) && \
        ((ptype & RTE_PTYPE_L4_UDP) == RTE_PTYPE_L4_UDP) && \
        (RTE_ETH_IS_TUNNEL_PKT(ptype) == 0))

So, for a fragmented UDP packet both RTE_PTYPE_L4_TCP & RTE_PTYPE_L4_UDP would be set and the GRO layer would be not able to interpret the packet type right.

I am using rte_net_get_ptype API before the packet is being sent to the GRO subsystem as the DPDK PMD for the NIC I am using would not set the packet types as required by the GRO subsystem.

I would like to contribute a patch for this bug if this indeed is an issue, I was thinking if the GRO subsystem is L4 fragmented then in the GRO layer invoked the appropriate handler, either gro_tcp4_reassemble or gro_ud4_reassemble.

Please let me know if I am missing something here.

Thanks,
Param.
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