Re: [RFC 07/14] cfg80211: track monitor interfaces count

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2012-06-06 at 13:40 +0200, Michal Kazior wrote:
> Johannes Berg wrote:
> > The other thing we might then want to is make this more general and not
> > just inform the driver about the monitor/no-monitor layout change, but
> > also tell it which interface combination we're in right now? Might look
> > a bit more like
> >
> > set_iface_combination(wiphy, dev, combination);
> >
> > or even
> > set_iface_combination(wiphy, dev, combination, have_monitor);
> >
> >
> > Then pure monitor would be "combination == NULL, have_monitor=True",
> > etc. The only downside is that we don't have combinations advertised for
> > when there's a single interface only, so we'd have to point to some
> > internal single-interface combinations then (static in cfg80211).
> > Thoughts?
> 
> I'm afraid we can't simply tell which combination we're in. I imagine 
> there may be two or three combinations matching at the same time. Take 
> this for example:
> 
>    comb1: 1xSTA + 1xAP (max channels = 1)
>    comb2: 2xSTA (max channels = 2)
> 
>    wlan0 is running as STA @ chan=1
> 
> Which combination are we in? Which one should we report to the driver?

Doesn't matter, right? Pick the one with most channels or something? :-)

> I don't see what passing current interface combination would be useful 
> for. Do you have something particular in mind?

I'm thinking about # of channels in the combination mostly, in
particular in combination with IBSS. OTOH, if we always reserve one
channel for IBSS in cfg80211 (unless it's fixed & driver supports that)
then it won't matter.

But then again, what about say 2xSTA being active and drivers with
connect() API?

johannes