[PATCH] wifi: mac80211: determine missing link_id in ieee80211_rx_for_interface() based on band

[Johannes Berg]

Hi,

[btw, you're sending HTML that looks like plain text, seems redundant
and also made the links non-clickable here? maybe try to change that]

> > Hm. Qualcomm has a similar thing with frequency, I think, and that
> > probably makes more sense for them since 'band' isn't unique for the
> > radio:
> > 
> > https://lore.kernel.org/linux-wireless/20250612121127.1960948-3-maharaja.kennadyrajan@oss.qualcomm.com/
> > 
> > Or is it not related?

> I think they're related but address different issues about group-
> addressed frames.

OK, fair.

> The Qualcomm patch seems to focus on preventing frames from getting
> processed on an interface running on a different band. (referred from
> their commit message)
> For example, a frame from frequency 6135 MHz should not be processed by
> an interface that does not have a link on frequency 6135 MHz.

Right, it's just in some way I thought many frames should be processed
for a link in the first place, though I guess you're thinking more
generally, and the other patch was explicitly about data frames for
which that of course isn't really true.

> On the other hand, the problem we encountered is that the interface is
> going to process the frame, but the "status->link_valid" is unset
> because the driver is incapable of determining the "link_id". The
> "link_id" remains its default value of -1, and the frame is handled by
> the interface's default link and is dropped because an AP MLD interface
> is not using its default link (sdata->deflink).

Right.

> In summary, the Qualcomm patch focuses on avoiding frames being
> processed by unsuitable interfaces, while our patch aims to determine
> the "link_id" so that the interface can correctly handle it.

OK.

> Additionally, we also think the 'link_id' can be determined based on
> 'freq' rather than 'band'. What do you think?

I'm starting to wonder if either should be in mac80211 at all, but I
guess if you both need it why not :)

I'd say we should be consistent, and use the frequency because there are
(likely? going to be?) devices with two separate low/high 5 GHz links.

johannes