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From: Johannes Berg <johannes@sipsolutions.net>
To: Denis Kenzior <denkenz@gmail.com>,
	Tim Kourt <tim.a.kourt@linux.intel.com>
Cc: linux-wireless@vger.kernel.org
Subject: Re: [PATCH] cfg80211: Fix support for flushing old scan results
Date: Tue, 22 May 2018 22:40:08 +0200	[thread overview]
Message-ID: <1527021608.6787.47.camel@sipsolutions.net> (raw)
In-Reply-To: <114ca20b-7b20-7a3e-75bd-8c336d26b9c0@gmail.com> (sfid-20180522_223752_743447_70AB98E8)

Hi,

> So I need to absorb all of this some more, but I'm still wondering why 
> we are seeing two separate scan entries (with hidden & plain ssid) when 
> we requested a flush?  Is there a way to force the kernel to only show 
> us the probe responses.

Oh. I didn't even think about this part, but that's just a consequence
of having a hidden SSID. We need one entry to track the beacon, and then
we add another entry for each hidden SSID it may have. Some APs
implement multiple SSIDs that way (old Cisco equipment, IIRC, though
then with zero-length SSID instead of zero-bytes), so you can't lump
them together into a single BSS entry.

> It would seem that even with the flush flag set, there could still be 
> spurious beacons getting in causing these results to appear in the scan 
> result set, right?

In general anything can, there's no filtering. So you might do a flush
scan for a specific SSID and still get 20 (different) results, if 20
beacons happened to be received while you were scanning.

johannes

  reply	other threads:[~2018-05-22 20:40 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-11 16:48 [PATCH] cfg80211: Fix support for flushing old scan results Tim Kourt
2018-05-18  8:13 ` Johannes Berg
2018-05-18 16:47   ` Denis Kenzior
2018-05-18 18:54     ` Arend van Spriel
2018-05-18 19:00       ` Denis Kenzior
2018-05-22  7:24         ` Arend van Spriel
2018-05-22 14:48           ` Denis Kenzior
2018-05-22 14:50             ` Johannes Berg
2018-05-22 14:51               ` Johannes Berg
2018-05-22 15:03                 ` Denis Kenzior
2018-05-22  8:12     ` Johannes Berg
2018-05-22 14:50       ` Denis Kenzior
2018-05-22 20:12     ` Johannes Berg
2018-05-22 20:37       ` Denis Kenzior
2018-05-22 20:40         ` Johannes Berg [this message]
2018-05-22 20:49           ` Denis Kenzior
2018-05-22 20:52             ` Johannes Berg
2018-05-22 21:00               ` Denis Kenzior
2018-05-22 21:11                 ` Johannes Berg
2018-05-22 21:25                   ` Denis Kenzior
2018-05-22 21:28                     ` Johannes Berg
2018-05-22 21:45                       ` Denis Kenzior
2018-05-23  7:08                         ` Johannes Berg

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