[ovs-dev] [PATCH] dpif-netdev: Do not mix recirculation depth into RSS hash itself.

Jan Scheurich jan.scheurich at ericsson.com
Thu Oct 24 13:36:46 UTC 2019


Even simpler solution to the problem.
Acked-by: Jan Scheurich <jan.scheurich at ericsson.com>

BR, Jan

> -----Original Message-----
> From: Ilya Maximets <i.maximets at ovn.org>
> Sent: Thursday, 24 October, 2019 14:32
> To: ovs-dev at openvswitch.org
> Cc: Ian Stokes <ian.stokes at intel.com>; Kevin Traynor <ktraynor at redhat.com>;
> Jan Scheurich <jan.scheurich at ericsson.com>; ychen103103 at 163.com; Ilya
> Maximets <i.maximets at ovn.org>
> Subject: [PATCH] dpif-netdev: Do not mix recirculation depth into RSS hash
> itself.
> 
> Mixing of RSS hash with recirculation depth is useful for flow lookup because
> same packet after recirculation should match with different datapath rule.
> Setting of the mixed value back to the packet is completely unnecessary
> because recirculation depth is different on each recirculation, i.e. we will have
> different packet hash for flow lookup anyway.
> 
> This should fix the issue that packets from the same flow could be directed to
> different buckets based on a dp_hash or different ports of a balanced bonding
> in case they were recirculated different number of times (e.g. due to conntrack
> rules).
> With this change, the original RSS hash will remain the same making it possible
> to calculate equal dp_hash values for such packets.
> 
> Reported-at: https://protect2.fireeye.com/v1/url?k=0a51a6c3-56db840c-
> 0a51e658-0cc47ad93ea4-b7f1e9be8f7bbef8&q=1&e=c9f55798-de3c-45f4-afeb-
> 9a87d3d594ca&u=https%3A%2F%2Fmail.openvswitch.org%2Fpipermail%2Fovs-
> dev%2F2019-September%2F363127.html
> Fixes: 048963aa8507 ("dpif-netdev: Reset RSS hash when recirculating.")
> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
> ---
>  lib/dpif-netdev.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index 4546b55e8..c09b8fd95
> 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -6288,7 +6288,6 @@ dpif_netdev_packet_get_rss_hash(struct dp_packet
> *packet,
>      recirc_depth = *recirc_depth_get_unsafe();
>      if (OVS_UNLIKELY(recirc_depth)) {
>          hash = hash_finish(hash, recirc_depth);
> -        dp_packet_set_rss_hash(packet, hash);
>      }
>      return hash;
>  }
> --
> 2.17.1



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