netdev - Re: [PATCH net-next 1/2] net: flow_offload: mangle 128-bit packet field with one action

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Message-ID: <f18d8369-f87d-5b9a-6c9d-daf48a3b95f1@solarflare.com>
Date:   Tue, 20 Aug 2019 15:15:16 +0100
From:   Edward Cree <ecree@...arflare.com>
To:     Pablo Neira Ayuso <pablo@...filter.org>,
        <netfilter-devel@...r.kernel.org>
CC:     <davem@...emloft.net>, <netdev@...r.kernel.org>,
        <jakub.kicinski@...ronome.com>, <jiri@...nulli.us>,
        <vladbu@...lanox.com>
Subject: Re: [PATCH net-next 1/2] net: flow_offload: mangle 128-bit packet
 field with one action

On 20/08/2019 11:52, Pablo Neira Ayuso wrote:
> The existing infrastructure needs the front-end to generate up to four
> actions (one for each 32-bit word) to mangle an IPv6 address. This patch
> allows you to mangle fields than are longer than 4-bytes with one single
> action. Drivers have been adapted to this new representation following a
> simple approach, that is, iterate over the array of words and configure
> the hardware IR to make the packet mangling. FLOW_ACTION_MANGLE_MAX_WORDS
> defines the maximum number of words from one given offset (currently 4
> words).
>
> Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
What's the point of this?
Why do you need to be able to do this with a single action?  It doesn't
 look like this extra 70 lines of code is actually buying you anything,
 and it makes more work for any other drivers that want to implement the
 offload API.