Scan request looks ignored when wpa_state is in scanning state with dbus interface

[Ben Greear]

On 02/29/2016 02:20 PM, Johannes Berg wrote:
> On Thu, 2016-02-25 at 10:36 -0800, Ben Greear wrote:

>> At least with ath10k, I've seen cases where scan-complete is never
>> sent
>> back to supplicant.  I added a timeout at that time that dealt with
>> the issue,
>> not sure it would fix this problem or not.
>>
>> https://github.com/greearb/hostap-ct/commit/913f01e9d0384ed5e99b396f0
>> 50233d9204dd041
>>
>
> That won't actually help you much, unless somehow the event got lost
> between cfg80211 and wpa_s; if it never arrived you'll never be allowed
> to scan again and really need to fix ath10k instead.
>
> There's a very slight chance of us failing to allocate memory when
> sending the event; we could attempt to fix that by preallocating? But
> it cannot actually happen since small GFP_KERNEL apparently can't
> actually fail.

It's been a year or two, but I think the issue was that firmware crashed
during scan, and the ath10k driver didn't do some sort of cleanup properly.

Note that supplicant RX buffers for netlink socket in supplicant could also overflow
and cause pkt loss there, but I don't know if that was what was
happening in my case.

Either way, I haven't had this problem any time recently, so either
the firmware/driver/stack is fixed (I don't see any firmware scan
crashes anymore, for instance), or my work-around in supplicant
is sufficient.

Thanks,
Ben


-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com