Re: ar9170usb crashes during iwconfig for ad-hoc mode

[Joerg Albert <jal2@gmx.de>]

Hi Christian,

On 08/03/2009 03:09 PM, Christian Lamparter wrote:
> On Monday 03 August 2009 14:36:42 Joerg Albert wrote:
>>> On Mon, 2009-08-03 at 10:44 +0200, Johannes Berg wrote:
>>>
>>>>>>     ifconfig wlan1 down
>>>>>>     iwconfig wlan1 mode managed essid huhu
>>>>>>     ifconfig wlan1 up
>>>>>>     ifconfig wlan1 down
>>>>>>     iwconfig wlan1 mode ad-hoc essid huhu_a channel 1
>>>> No, it's a bug in cfg80211 :)
>>> But it's not making sense to me. I'll have to try to reproduce it. In
>>> any case, we shouldn't be calling in to mac80211 from cfg80211 while the
>>> interface is down.
>> I guess this is caused by the call to __cfg80211_leave_ibss()
>> in  net/wireless/ibss.c::cfg80211_ibss_wext_siwfreq() trying to
>> disable the beacon via net/mac80211::ieee80211_ibss_leave().

> what about this? (only compiled so far, don't have the device here...)

 > diff --git a/drivers/net/wireless/ath/ar9170/main.c b/drivers/net/wireless/ath/ar9170/main.c
 > index 099ed3c..9c97ad7 100644
 > --- a/drivers/net/wireless/ath/ar9170/main.c
 > +++ b/drivers/net/wireless/ath/ar9170/main.c
 > @@ -2177,7 +2177,7 @@ static void ar9170_op_bss_info_changed(struct ieee80211_hw *hw,
 >                         goto out;
 >         }
 >
 > -       if (changed & (BSS_CHANGED_BEACON | BSS_CHANGED_BEACON_ENABLED)) {
 > +       if (changed & BSS_CHANGED_BEACON_ENABLED) {
 >                 err = ar9170_update_beacon(ar);
 >               if (err)
 >                         goto out;

Thanks for the patch,  but I think it won't help. ar9170_op_bss_info_changed() is called
with BSS_CHANGED_BEACON_ENABLED set in changed, while ar->vif is NULL as _op_remove_interface() was called before
(by "ifconfig down"). This triggers the crash.

I've got a patch ready here, which uses the vif parameter of ar9170_op_bss_info_changed() instead of ar->vif.
I'll try Johannes' patch first.

Regards,
Joerg.