netdev - Re: [RFC] netfilter: nf_tables: ignore -EOPNOTSUPP on flowtable device offload setup

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Message-ID: <2575f329-7d95-46f8-ab88-2bcdf8b87d66@nbd.name>
Date: Fri, 1 Sep 2023 12:30:37 +0200
From: Felix Fietkau <nbd@....name>
To: Pablo Neira Ayuso <pablo@...filter.org>
Cc: netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC] netfilter: nf_tables: ignore -EOPNOTSUPP on flowtable
 device offload setup

On 01.09.23 10:39, Pablo Neira Ayuso wrote:
> Hi Felix,
> 
> On Thu, Aug 31, 2023 at 10:14:20PM +0200, Felix Fietkau wrote:
>> On many embedded devices, it is common to configure flowtable offloading for
>> a mix of different devices, some of which have hardware offload support and
>> some of which don't.
>> The current code limits the ability of user space to properly set up such a
>> configuration by only allowing adding devices with hardware offload support to
>> a offload-enabled flowtable.
>> Given that offload-enabled flowtables also imply fallback to pure software
>> offloading, this limitation makes little sense.
>> Fix it by not bailing out when the offload setup returns -EOPNOTSUPP
> 
> Would you send a v2 to untoggle the offload flag when listing the
> ruleset if EOPNOTSUPP is reported? Thus, the user knows that no
> hardware offload is being used.

Wouldn't that mess up further updates to the flowtable? From what I can 
tell, when updating a flow table, changing its offload flag is not 
supported.

- Felix