Re: [PATCH v13] gro: fix reordering of packets in GRO layer

[胡嘉瑜 <hujiayu.hu@foxmail.com>]

在 2024/1/9 上午12:04, Kumara Parameshwaran 写道:
> In the current implementation when a packet is received with
> special TCP flag(s) set, only that packet is delivered out of order.
> There could be already coalesced packets in the GRO table
> belonging to the same flow but not delivered.
> This fix makes sure that the entire segment is delivered with the
> special flag(s) set which is how the Linux GRO is also implemented
>
> Signed-off-by: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
> ---
> 	If the received packet is not a pure ACK packet, we check if
> 	there are any previous packets in the flow, if present we indulge
> 	the received packet also in the coalescing logic and update the flags
> 	of the last recived packet to the entire segment which would avoid
> 	re-ordering.
>
> 	Lets say a case where P1(PSH), P2(ACK), P3(ACK)  are received in burst mode,
> 	P1 contains PSH flag and since it does not contain any prior packets in the flow
> 	we copy it to unprocess_packets and P2(ACK) and P3(ACK) are merged together.
> 	In the existing case the  P2,P3 would be delivered as single segment first and the
> 	unprocess_packets will be copied later which will cause reordering. With the patch
> 	copy the unprocess packets first and then the packets from the GRO table.
>
> 	Testing done
> 	The csum test-pmd was modified to support the following
> 	GET request of 10MB from client to server via test-pmd (static arp entries added in client
> 	and server). Enable GRO and TSO in test-pmd where the packets recived from the client mac
> 	would be sent to server mac and vice versa.
> 	In above testing, without the patch the client observerd re-ordering of 25 packets
> 	and with the patch there were no packet re-ordering observerd.
>
> v2:
> 	Fix warnings in commit and comment.
> 	Do not consider packet as candidate to merge if it contains SYN/RST flag.
>
> v3:
> 	Fix warnings.
>
> v4:
> 	Rebase with master.
>
> v5:
> 	Adding co-author email
> v6:
> 	Address review comments from the maintainer to restructure the code
> 	and handle only special flags PSH,FIN
>
> v7:
> 	Fix warnings and errors
>
> v8:
> 	Fix warnings and errors
>
> v9:
> 	Fix commit message
>
> v10:
>      Update tcp header flags and address review comments
>
> v11:
>      Fix warnings
>
> v12:
>      Fix nit review comments
>
> v13:
>      Fix warnings
>
>   lib/gro/gro_tcp.h          |  9 +++++++++
>   lib/gro/gro_tcp4.c         | 36 +++++++++++++++++++++++++++---------
>   lib/gro/gro_tcp_internal.h |  2 +-
>   lib/gro/gro_vxlan_tcp4.c   |  5 +++--
>   4 files changed, 40 insertions(+), 12 deletions(-)
>

Reviewed-by: Jiayu Hu <hujiayu.hu@foxmail.com>

Thanks,

Jiayu