Re: Connection issues with BW Tracking in mac80211

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2015-03-11 at 21:45 +0530, Krishna Chaitanya wrote:

> I did some experiments on this and found the root cause.
> 
> We are using 5GHz in WORLD Mode, so only passive scan is allowed.
> So when connecting the very first time, the mac80211 MLME sees that
> there are no probe_resp ies (only beacon_ies are present) and it sends
> a directed probe and updates the probe_resp ies. (and also the "ies").
> 
> But when config is changed and we get disconnected, beacon_ies are updated
> with the new config, but the probe_resp ies are not.
> cfg80211_bss_update assigns
> probe_resp ies to "ies' and mac80211 updates its bss info based on the
> probe_resp
> ies which have old config causing the issue.
> 
> Solution:
> 
> 1) Make the directed probe mandatory.
> 2) As you suggested maintain timestamps for probe_resp_ies and beacon_ies
> and use the latest.
> 
> Any takes?

What's the operational problem here? I don't really see it. Are you
afraid users will reconfigure their APs often enough for this to be an
issue?

johannes