Re: [REGRESSION] aquantia: Sunshine/Moonlight UDP video streaming broken since 5b4015ad833c ("net: aquantia: Remove redundant UDP length adjustment with GSO_PARTIAL")

[Matthew Schwartz <matthew.schwartz@linux.dev>]

On 5/10/26 5:38 AM, Gal Pressman wrote:
> On 06/05/2026 17:20, Gal Pressman wrote:
>> On 06/05/2026 10:49, Matthew Schwartz wrote:
>>>
>>>
>>>> On May 5, 2026, at 8:05 AM, Gal Pressman <gal@nvidia.com> wrote:
>>>>
>>>> On 27/04/2026 21:26, Matthew Schwartz wrote:
>>>>>> On 4/27/26 11:09 AM, Gal Pressman wrote:
>>>>>> Hello Matthew,
>>>>>>
>>>>>> On 27/04/2026 2:20, Matthew Schwartz wrote:
>>>>>>> Hello,
>>>>>>>
>>>>>>> When using a previously working setup of remote streaming from my workstation to another device via Sunshine (the host server) and Moonlight (the client app) on my home network, I no longer receive any video output on the client app after upgrading my host workstation to kernel 7.0. Reverting back to kernel 6.19 on the host restored my setup to a working state.
>>>>>>>
>>>>>>> After bisecting, I landed on 5b4015ad833c ("net: aquantia: Remove redundant UDP length adjustment with GSO_PARTIAL") as the first bad commit. I confirmed this by moving the cable to my second on-board NIC (Intel) on the same workstation, which restored video output without any other kernel changes. My affected on-board NIC is Aquantia AQC113 [1d6a:04c0] (rev 03), atlantic driver, firmware 1.3.34, MTU 1500.
>>>>>>>
>>>>>>> Looking into it a bit further, ethtool -K enp97s0 tx-udp-segmentation off also serves as a workaround on my Aquantia port without changing to my other ethernet port. The working Intel NIC reports tx-udp-segmentation as "off [fixed]", so traffic falls back to software UDP segmentation on there.
>>>>>>>
>>>>>>> Please let me know if there's any additional info I can provide.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Matt
>>>>>>>
>>>>>>> #regzbot introduced: 5b4015ad833c
>>>>>>
>>>>>> Thank you for the report and the bisect!
>>>>>>
>>>>>> I will take a look and try to figure out what's wrong (though I don't
>>>>>> have real hardware to test on).
>>>>>> Is the userspace app open source? can I see its code and try to run it
>>>>>> myself?
>>>>>
>>>>> Thanks for the reply. The code for Sunshine is available here: https://github.com/LizardByte/Sunshine and the code for Moonlight is here: https://github.com/moonlight-stream/moonlight-qt.
>>>>>
>>>>> I have been using the Arch Linux Sunshine package which I installed by following the Linux instructions here: https://docs.lizardbyte.dev/projects/sunshine/latest/md_docs_2getting__started.html, but there are also binaries for other distros or it's buildable from source. For Moonlight, I have been using the Flatpak distributed on Flathub because the client device runs an atomic rootfs, but you can also use any other device that Moonlight supports.
>>>>>
>>>>>>
>>>>>> I will be OOO for the rest of the week, hope to have some meaningful
>>>>>> reply by the end of next week.
>>>>>
>>>>
>>>> I think I see the issue, do you mind testing the following diff?
>>>
>>> Sorry for the delay. I applied this diff and I’m able to stream from my host to clients again without any issues.
>>>
>>> If you send this version upstream, feel free to add my Tested-by to it.
>>
>> Thanks for verifying!
>>
>> I will finalize this and submit a proper patch soon.
> 
> Hey Matthew,
> 
> I made a small change to the patch, can you please verify it still fixes
> the issue?

Yes, this diff also fixes the issue.

> 
> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
> index a0813d425b71..71df45f9488a 100644
> --- a/net/ipv4/udp_offload.c
> +++ b/net/ipv4/udp_offload.c
> @@ -604,7 +604,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
>  		       seg->data_len);
>  	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
> 
> -	uh->len = newlen;
> +	uh->len = skb_is_gso(seg) ? msslen : newlen;
>  	uh->check = check;
> 
>  	if (seg->ip_summed == CHECKSUM_PARTIAL)