Hi,
> > > + if (sdata && sdata->vif.type == NL80211_IFTYPE_AP) {
> > > + if (sdata->vif.multiple_bssid.flags &
> > > IEEE80211_VIF_MBSS_TRANSMITTING) {
> > > + struct ieee80211_sub_if_data *child;
> > > +
> > > + rcu_read_lock();
> > > + list_for_each_entry_rcu(child, &sdata->local->interfaces, list)
> > > + if (child->vif.multiple_bssid.parent == &sdata->vif)
> > > + dev_close(child->wdev.netdev);
> > > + rcu_read_unlock();
> This was added for graceful shutdown of non-transmitting interfaces
> whenever the transmitting one is being brought down.
>
I know, I asked you to.
> But I see that
> dev_close() is happening twice now.
>
That wouldn't be an issue.
The issue is that dev_close() needs to be able to sleep, and it even
contains a might_sleep(), so you can't do it under the RCU protection
you used here.
> Inclining towards removing this and just return error to application if
> it tries to remove transmitting before all non-transmitting are deleted.
> However, currently the "parent" pointer to indicate the transmitting
> interface is maintained in mac80211, nothing in cfg80211.
That seems kinda awkward, considering e.g. if hostapd crashes and then a
new instance has to clean up, it might not really have much knowledge of
the order in which it should be doing that.
I think it's better if you just fix the locking here?
johannes
