Subject: Re: [Intel-wired-lan] [PATCH net v4 1/1] i40e: xsk: advance next_to_clean on status descriptors

From: Maciej Fijalkowski <[email-masked]>
Date: Wed, 19 Nov 2025 17:11:25 +0100

On Wed, Nov 19, 2025 at 11:49:44AM +1100, Alessandro Decina wrote:
> On Tue, Nov 18, 2025 at 07:45:24PM +0100, Maciej Fijalkowski wrote:
> > Repro steps would be nice to have, rest would be rather redundant to me.
> 
> Yeah unfortunately I don't really know how to _manually_ reproduce.
> 
> I don't know why I'm getting these status descriptors, but I'm getting
> them reproducibly every few minutes on ubuntu 24.04 across 3 machines

Might be a HW quirk, I don't remember. Other example I have handy is HW
that is served by ice driver can sometimes produce 0-length descriptors
for jumbo frames and we do handle this in driver.

Describing your setup in commit message would be enough, if you ask me.

> where I've hit this bug/tested the fix. The machines are doing ~300Mbps
> of UDP traffic, some of which is done using AF_XDP. The AF_XDP code is
> TX only, so it's executing the build-skb-in-zc-path all the time as all
> the ingress traffic goes to sockets. 
> 
> If you have any idea on how to reliably produce the descriptors I'm
> happy to give it a try.