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

[Ben Greear]

On 02/25/2016 10:23 AM, Dan Williams wrote:
> On Thu, 2016-02-25 at 18:34 +0530, Johncy Bennette wrote:
>> Hi Jouni,
>>
>> My earlier logs were big in size. So not delivered. So I recaptured
>> and attaching only required logs.
>>
>> AP-Problem.log
>>
>> I switched off the router around the time
>> 1456401394.205710: dbus: flush_object_timeout_handler: Timeout -
>> sending changed properties of object
>> /fi/w1/wpa_supplicant1/Interfaces/1
>>
>> Around the time 1456401598.821077: wlan0: Setting scan request:
>> 1.000000 sec I gave the scan command.
>>
>> The dbus sequence I follow is,
>> AddNetwork
>> SelectNetwork
>> Then I wait for "completed" signal from dbus
>> udhcpc -iwlan0 to get IP once connected.
>>
>> When there is problem connecting ie at the time of reconnect,
>> SelectNetwork with the object obtained as part of AddNetwork
>> Then I wait for "completed" signal from dbus
>> udhcpc -iwlan0 if connected.
>>
>> I could see from the log,
>> 1456401549.760162: Fast associate: Old scan results
>> After this there is continous scan requests ignored.
>
> There are two bugs, it seems.
>
> 1) you don't have this patch:
>
> d38c7be0f013703639568a690af0394ceece1fca
> "Skip SELECT_NETWORK steps only if already connected or connecting"
>
> which would fix the issue where SelectNetwork doesn't attempt to
> associate.  Unfortunately this fix is not in a released version, not
> even hostapd 2.5.
>
> 2) a supplicant SCHED_SCAN never completes.  There is only one enabled
> network, and this is the first sched_scan, and apparently those are
> never timed out.  Since the AP is turned off, no scan results for that
> AP will ever be delivered.
>
> Jouni, this seems like a supplicant bug?  The code is pretty clear, the
> following block never gets run because ssid==NULL (because there's only
> one enabled network/SSID and max_sched_scan_ssids >= 1) and this is the
> first sched_scan:

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/913f01e9d0384ed5e99b396f050233d9204dd041

Thanks,
Ben

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