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

[Gal Pressman]

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@xxxxxxxxxx> 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?

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)