[PATCH 1/3] hostapd: Fix VHT unsolicitated channel switching

Michal Kazior michal.kazior at tieto.com
Tue Mar 18 11:27:58 EDT 2014


On 18 March 2014 15:58, Peer, Ilan <ilan.peer at intel.com> wrote:
> Hi Michal,
>
>> -----Original Message-----
>> From: hostap-bounces at lists.shmoo.com [mailto:hostap-
>> bounces at lists.shmoo.com] On Behalf Of Michal Kazior
>> Sent: Tuesday, March 18, 2014 14:38
>> To: j at w1.fi
>> Cc: hostap at lists.shmoo.com
>> Subject: [PATCH 1/3] hostapd: Fix VHT unsolicitated channel switching
>>
>> The ieee80211ac config wasn't updated upon channel switch notification.
>> This led to inconsistent beacons in some cases.
>>
>> It's not possible to deduce VHT status for an unsolicitated channel switch
>> now in all cases.
>>
>
> [...]
>
>> +     /* FIXME: It's impossible to tell how exactly an unsolicitated channel
>> +      * switch downgraded channel definition in all cases. */
>> +     if (width == CHAN_WIDTH_80 ||
>> +         width == CHAN_WIDTH_80P80 ||
>> +         width == CHAN_WIDTH_160)
>> +             hapd->iconf->ieee80211ac = 1;
>> +     if (!ht)
>> +             hapd->iconf->ieee80211ac = 0;
>> +
>
> As far as I understand the ieee80211ac variable states weather 80211ac is enabled or not, and thus I do not think that it should be changed based on the actual operating mode/channel width.

You could apply this for ieee80211n, yet, it is possible for channel
switch to change it.


> Regardless, how is it possible that the CS ended with being on VHT if hostap did not ask to use VHT in the first place?
>
> Thanks in advance,

Technically a driver can call cfg80211_ch_switch_notify() with any
chandef. It's not a necessity for an actual CSA to be requested first.


Michał


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