Re: [PATCH wireless] wifi: mac80211: Fix ADDBA update when HW supports reordering

[Johannes Berg]

On Sun, 2026-02-22 at 17:06 +0100, Remi Pommarel wrote:
> > > That does make sense. However, if I understand correctly, it means that
> > > even if we end up storing the timeout for drivers that support
> > > reordering, a new IEEE80211_AMPDU_RX_UPDATE should still be introduced,
> > > right?
> > 
> > I guess in order to do a no-op update that doesn't change the timeout,
> > we could? But not sure it's all worth it?
> 
> I was going to say it would not be a no-op for a buf_size update but,
> if I understand correctly, even when SUPPORTS_REORDERING_BUFFER is not
> set the buf_size update is ignored completely and the reorder_buf is
> not resized yet a successful addba response is sent. Don't we need to
> check for buf_size change as well as timeout also?

I was going to say that I thought buf_size is not allowed to change, but
(re)reading the spec doesn't seem to bear that out.

I guess we could just unconditionally reject any updates. I'm not sure
now why we ever added the update in the first place. Perhaps some
implementation was doing no-op updates and failing on negative
responses?

> > Pablo seems to have looked up that it _is_ supported - which I didn't
> > expect because it's not part of the API contract, so the drivers
> > implemented something that can't actually ever get hit? Seems odd. And
> > I'm pretty sure e.g. iwlwifi wouldn't support it.
> > 
> > But I basically also think it's not worth it in practice; why try to
> > support something that's never going to happen?
> 
> Just to confirm, you mean that updating the timeout is not worth it, but
> fixing this issue is still needed right?

Right.

johannes