wpa-supplicant and scan sharing

Ben Greear greearb at candelatech.com
Sun Jun 4 07:32:42 PDT 2017

On 06/04/2017 01:34 AM, Otcheretianski, Andrei wrote:
>> -----Original Message-----
>> From: Hostap [mailto:hostap-bounces at lists.infradead.org] On Behalf Of Ben
>> Greear
>> Sent: Wednesday, May 31, 2017 00:45
>> To: hostap at lists.infradead.org
>> Subject: wpa-supplicant and scan sharing
>> [Sorry for previous email with bogus subject.]
>> Hello,
>> In wpa_supplicant/events.c, there is code similar to this below.
>> Is there any reason 'ret = 1' other than some drivers may have issues with
>> multiple association attempts?  I am pretty sure that I used to bring up many
>> ath9k and ath10k station vdevs at once, so maybe this is just for Intel NICs
>> (based on the comitter that changed that code last)?
> This is the same behavior as it was there before this patch. Previously if scan results triggered an operation, other interfaces wouldn't be updated at all.
> The patch you mention changed it to update scan results on other interfaces, but still prevents starting any operation.
> Anyway, in the "if" you mention wpa_s->scan_res_handler != NULL - so it's not an association flow - the association is happening in wpas_select_network_from_last_scan()
> I'm not sure what do you mean by "multiple association attempts" - concurrent connections on the same radio are serialized using radio_works anyway, and on different radios there is no scan results update from sibling.
> So, here is the flow when you connect multiple interfaces: the first one will trigger scan and connect + update the siblings. Other sibling interfaces will connect directly without scant through wpa_supplicant_fast_associate().

In my case, until I relaxed this, all station vdevs would scan before connecting.  Possibly this is due to other
patches I have in my supplicant...but I would be curious to see 'iw events' output if you could get multiple
station vdevs to associate w/out each of them scanning.


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

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