netdev - Re: [PATCH net 0/2] Lift UDP_SEGMENT restriction for egress via device w/o csum offload

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Message-ID: <87r0cmwpd3.fsf@cloudflare.com>
Date: Mon, 24 Jun 2024 13:29:28 +0200
From: Jakub Sitnicki <jakub@...udflare.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: netdev@...r.kernel.org,  "David S. Miller" <davem@...emloft.net>,  Eric
 Dumazet <edumazet@...gle.com>,  Jakub Kicinski <kuba@...nel.org>,  Paolo
 Abeni <pabeni@...hat.com>,  Willem de Bruijn <willemb@...gle.com>,
  kernel-team@...udflare.com
Subject: Re: [PATCH net 0/2] Lift UDP_SEGMENT restriction for egress via
 device w/o csum offload

On Sun, Jun 23, 2024 at 04:18 AM -04, Willem de Bruijn wrote:
> Jakub Sitnicki wrote:
>> This is a follow-up to an earlier question [1] if we can make UDP GSO work with
>> any egress device, even those with no checksum offload capability. That's the
>> default setup for TUN/TAP.
>> 
>> I leave it to the maintainers to decide if it qualifies as a fix. We plan to
>> backport it to our v6.6 either way, hence the submission to -net.
>> 
>> [1] https://lore.kernel.org/netdev/87jzqsld6q.fsf@cloudflare.com/
>
> Agreed with the change to allow UDP_SEGMENT to work regardless of
> device capabilities.

Thanks for the stamp.

> In my opinion this is a new feature with sufficient risk of unintended
> side effects to be net-next material.

OK, I will resubmit for net-next.

> Maybe worth recording in patch 1 the reason for the original check:
> that UDP_SEGMENT with software checksumming in the GSO stack may be
> a regression vs copy_and_checksum in the send syscall.

Will expand the description.