linux-kernel - Re: ath9k becon loss messages

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Date:	Mon, 6 Apr 2009 12:17:30 +0200
From:	Michael Buesch <mb@...sch.de>
To:	Helmut Schaa <helmut.schaa@...glemail.com>
Cc:	Kalle Valo <kalle.valo@....fi>,
	Jaswinder Singh Rajput <jaswinder@...nel.org>,
	Sujith <Sujith.Manoharan@...eros.com>,
	wireless <linux-wireless@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: ath9k becon loss messages

On Monday 06 April 2009 09:14:31 Helmut Schaa wrote:
> Am Sonntag, 5. April 2009 schrieb Kalle Valo:
> > Jaswinder Singh Rajput <jaswinder@...nel.org> writes:
> > 
> > >> And besides that, I think one can easily remotely trigger this
> > >> message and flood the logs. So it should probably _also_ be
> > >> ratelimited.
> > >
> > > normally it prints after 120 seconds:
> > >
> > > [ 1078.848434] wlan0: beacon loss from AP 00:11:95:9e:df:f6 - sending probe request
> > > [ 1198.822913] wlan0: beacon loss from AP 00:11:95:9e:df:f6 - sending probe request
> > > [ 1318.824931] wlan0: beacon loss from AP 00:11:95:9e:df:f6 - sending probe request
> 
> > Then there is something happening in ath9k or your AP which prevents
> > ath9k from receiving beacons. Try pinging your AP with 100 ms
> > interval. Do you see anything happening in 120 s intervals?
> 
> NetworkManager typically scans every 120 seconds and I can also trigger
> the messages by a manual scan with iwlist. I did not dig any further but
> the messages seem to appear right at the end of the scan. Tried with iwlagn
> and both sw_scan and hw_scan.

Yeah OK. While scanning it's expected to lose some frames.

However, the driver should probably protect against this by using the scan notification
callbacks. It could disable beacon-loss reporting while scanning.

-- 
Greetings, Michael.
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