Re: [PATCH v2 2/6] mac80211: Support getting sta_info stats via ethtool.

[Johannes Berg <johannes@sipsolutions.net>]

On Tue, 2012-04-17 at 20:46 -0700, Ben Greear wrote:

> >> +	rcu_read_lock();
> >> +	list_for_each_entry_rcu(sta,&local->sta_list, list) {
> >
> > This doesn't seem right -- shouldn't it look up the BSSID or something
> > and only work on managed interfaces? What if there really are two
> > stations on this interface -- then it'll just overwrite it and return a
> > random station's data? That's useless.
> 
> Well, its weird at least.
> 
> But, if there are multiple stations, like for APs??, then it will
> add the station's stats together.  Perhaps not horribly useful, but better
> than nothing.

Oh, right, it's adding, I missed that. But is that really useful?

> For managed interface, I *think* they don't have more than one station, right?

You can't rely on it. Typically they will, but with TDLS there might be
multiple.

> And, as for the underlying driver stats and survey stats (in later patches),
> that is only probed once.  I guess if you somehow had two
> stations on different channels on the same network device,
> the survey stats would be a bit dodgy, but it does return
> the freq for the stats in question, so at least you know
> what you are getting.

A single netdev is always going to be on a single channel. Actually, I
take that back, I think TDLS can work out of channel too, but we don't
support that right now.

johannes