Re: mac80211: holding sta_info for non associated stations

["Tomas Winkler" <tomasw@gmail.com>]

On Tue, Apr 1, 2008 at 3:28 PM, Johannes Berg <johannes@sipsolutions.net> wrote:
> Hi,
>
>
>  > If i associate to a random AP "x" (what happened automatically as i
>  > was configured by ifup scripts to do that), and then scan and
>  > associate to my desired AP "y", i notice that AP "x" was not removed
>  > from the mac80211 station table. Then, what happened was that during
>  > ieee80211_stop, when we reach
>  >
>  > list_for_each_entry_rcu(sta, &local->sta_list, list) {
>  >     if (sta->sdata == sdata)
>  >     ieee80211_sta_tear_down_BA_sessions(dev, sta->addr);
>  > }
>  >
>  > we try to tear down sessions to irrelevant stations (AP "x" in my
>  > example), which leads to bugs.
>
>  Why would that lead to bugs? That station was known, and there are no
>  sessions for that AP.

It's like freeing twice the same a pointer. On what level will you
check that there are no BA session with this ghost  AP?

>
>  > did i miss something, or is there really a problem in the state
>  > machine in the described scenario?
>
>  There might be a problem in that we forget to remove that AP under some
>  circumstances but it shouldn't matter, we always can have multiple
>  stations in our table.

Not in STA mode, should be associated only to one AP at a time. (Hope
this also cover roaming).

Tomas