Re: [PATCH] cfg80211: Fix support for flushing old scan results

[Denis Kenzior <denkenz@gmail.com>]

Hi Johannes,

On 05/18/2018 03:13 AM, Johannes Berg wrote:
> On Fri, 2018-05-11 at 09:48 -0700, Tim Kourt wrote:
>> __cfg80211_bss_expire function was incorrectly used to flush the BSS
>> entries from the previous scan results, causing NL80211_SCAN_FLAG_FLUSH
>> flag to have no effect.
> 
> Hmm. I guess I'm not convinced - what's the bug?
> 
> We flush anything that's older than our start, so that should work just
> fine?
> 

Just FYI, there's definitely something funny with the scanning code:

denkenz@iwd-test ~ $ sudo iw dev wlp2s0 scan flush
BSS 10:c3:7b:54:74:d4(on wlp2s0)
	last seen: 274.815s [boottime]
	freq: 5765
	beacon interval: 100 TUs
	signal: -35.00 dBm
	last seen: 349 ms ago
	Information elements from Probe Response frame:
	SSID: \x00\x00\x00\x00\x00\x00\x00\x00\x00


Then if I try:
denkenz@iwd-test ~ $ sudo iw dev wlp2s0 scan flush ssid myssid
BSS 10:c3:7b:54:74:d4(on wlp2s0)
	last seen: 319.667s [boottime]
	freq: 5765
	beacon interval: 100 TUs
	signal: -42.00 dBm
	last seen: 350 ms ago
	Information elements from Probe Response frame:
	SSID: \x00\x00\x00\x00\x00\x00\x00\x00\x00
....
BSS 10:c3:7b:54:74:d4(on wlp2s0)
	last seen: 319.662s [boottime]
	freq: 5765
	beacon interval: 100 TUs
	signal: -37.00 dBm
	last seen: 355 ms ago
	Information elements from Probe Response frame:
	SSID: myssid

Shouldn't the second scan give a single result from that one BSS?

Regards,
-Denis