panic: bogus long slot station count 0

[Sam Leffler]

Michal Mertl wrote:
> I'm getting easy to reproduce INVARIANTS panics on fresh CURRENT.
> 
> The panicing machine has ath0 configured like this: "ifconfig ath0
> 192.168.0.1/24 media auto mode 11b mediaopt hostap ssid mig_ap_xx".
> 
> When I associate to it with a notebook with an ipw card I get later
> several panics with the same INVARIANTS cause - line 2073 in
> src/sys/net80211/ieee80211_node.c.
> 
> The "normal" panic is this scenario - a station connects and then leaves
> (is turned off or something).
> 
> I run '80211debug assoc' and this is what I get before the panic:
> 
> ath0: [00:0c:f1:3e:8b:07] recv probe req
> ath0: [00:0c:f1:3e:8b:07] station associated at aid 1: short preamble,
> long slot time
> ath0: [00:0c:f1:3e:8b:07] station with aid 1 leaves
> 
> After the association was formed I put the ipw0 card 'down' and after
> short while (a minute or so) I received the third message above and the
> panic with the traceback below. I don't understand much what 'short
> preamble' means but I'd expect to see 'S' character in 'ifconfig ath0
> list sta' command output on the AP if the station was really doing
> shoart preamble. 
> 
> Output of 'ifconfig ath0 list sta' on the AP before the crash is this:
> 
> ADDR               AID CHAN RATE RSSI IDLE  TXSEQ  RXSEQ CAPS ERP
> 00:0c:f1:3e:8b:07    1    1   1M   25  210      2    208 E      0

Sigh, guess we need to still reference ic_curmode instead of looking at 
the channel characteristics (this was a recent change to deal with your 
problem with switching mode from 11a->11g w/ a station associated).  The 
problem is that ic_curmode needs to be completely removed.  I've done 
this in p4 but the changes are too extensive to commit at this time. 
I'll backout the change for now.

Separately, I recently learned that 11g ap mode w/ a mixed bss is 
broken.  I forgot to update the ERP ie in the beacon frame so 11g 
stations are not informed when an 11b sta joins the bss and slot time 
and/or protection are altered.  I won't get to fix this for a few weeks.

	Sam