netdev - Re: [PATCH v2 net-next 0/2] net/sched: support tunnel options in cls_flower and act_tunnel

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Date:   Wed, 27 Sep 2017 17:46:37 +0200
From:   Jiri Benc <jbenc@...hat.com>
To:     Simon Horman <simon.horman@...ronome.com>
Cc:     David Miller <davem@...emloft.net>, Jiri Pirko <jiri@...lanox.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>, netdev@...r.kernel.org,
        oss-drivers@...ronome.com
Subject: Re: [PATCH v2 net-next 0/2] net/sched: support tunnel options in
 cls_flower and act_tunnel_key

On Wed, 27 Sep 2017 10:16:32 +0200, Simon Horman wrote:
> * Geneve
> 
>   In the case of Geneve options are TLVs[1]. My reading is that in collect
>   metadata mode the kernel does not appear to do anything other than pass
>   them around as a bytestring.
> 
>   [1] https://tools.ietf.org/html/draft-ietf-nvo3-geneve-05#section-3.5
[...]
> 
> Neither of the above appear to assume any structure for the data.

But that's not true. Geneve uses TLVs, you even mentioned that
yourself. Matching on a block of TLVs as a bytestring doesn't make
sense. The TLV fields may be in any order.

We need better matching here. Bytestring is useless for Geneve.

NACK for this direction of option matching. We'd need to introduce
matching on TLVs sooner or later anyway and this would be just a never
used compat cruft that we need to keep around forever.

 Jiri