Re: [PATCH 3/3] wifi: cfg80211: check if AP has been started before adding new station

[Johannes Berg]

On Tue, 2026-09-08 at 13:59 +0200, Slawomir Stepien wrote:
> > 
> > Don't think you're missing anything, there's just the block handling
> > param->vlan in add_station, it's dead code now. But why not kill it?
> 
> For the reason explained below (in my previous message).
> There can still be a command from userspace with AP base interface (as wdev) with
> attrs[NL80211_ATTR_STA_VLAN] set and this block will be executed in such case. Right?

D'oh. Going too fast, I somehow managed to not connect the two things.
Sorry!

But it's another messy code path - if you have AP A and B, and VLANs A'
and B' belonging to A and B respectively, then you can

	add_station(A, vlan=B')

and it gets added on B/B', and B must be IFF_UP (because B' must be
IFF_UP) but doesn't need to be beaconing and we're back to the bug, it
seems? Maybe I'm missing something.

Since VLANs have to have the same local address as their AP (i.e. we
need addr(B') == addr(B)), I guess get_vlan() could check this though,
if it's indeed a problem, and that would avoid it through the chain of
other invariants (IFF_UP, beaconing, etc.)

johannes