[Commotion-dev] Alternate mac80211 / hostapd from nbd for ath9k driver freeze issue

[Ben West]

No problem.  Seemed like the driver freeze could be a rather difficult
problem to diagnose (it was for me).

If you find node which seems to have one of its vif's locked up like this,
but still have access to a local SSH/serial console, this command could
tell if you if the driver is indeed stuck:

cat /sys/kernel/debug/ieee80211/phy*/ath9k/queues


On Thu, Jan 16, 2014 at 9:13 AM, Dan Staples <
danstaples at opentechinstitute.org> wrote:

> Thanks very much for this heads up, Ben! I can't say we've seen this
> ourselves, but we also don't run a network with heavy load. If we get
> reports about this from our testbed networks, we'll definitely look into
> whether this is the cause.
>
> Dan
>
> On 01/14/2014 04:05 PM, Ben West wrote:
> > Howdy,
> >
> > Giving you a heads up about a problem I've encountered on UBNT
> > Nanostation Loco M2, Nanostation M5, and TP-Link TL-MR3020.  WLAN
> > Slovenija also saw it on other TP-Link products.  Good chance
> > Commotion-OpenWRT might be seeing this driver freeze, too.
> >
> > Under heavy load conditions, the ath9k driver bundled with recent
> > versions of AA may freeze, and all broadcast SSIDs disappear.  For me,
> > this was also causing additional weird side-effects like
> > hostapd/wpa_supplicant crashing, and olsrd complaining "OLSR: sendto
> > IPv4 Resource temporarily unavailable," depending on which vif happened
> > to lock up.
> >
> > The lockup does appear to correlate well with heavy traffic load, i.e.
> > never see this problem on nodes with very light traffic.  Also, it's
> > very intermittent.  Nodes with a weekly reboot schedule might see this
> > lockup a couple times a month or so, in my experience.
> >
> > This is the ticket filed in OpenWRT issue queue:
> > https://dev.openwrt.org/ticket/13681
> >
> > This is the updated version of mac80211 and hostapd which nbd has
> > offered to address the driver lockup issue under AA.  I've reflashed my
> > affected problem nodes over the past couple weeks (AA r39154), and so
> > far so good.  I presume these versions will eventually be backported
> > into AA.
> > http://nbd.name/gitweb.cgi?p=aa-mac80211.git;a=summary
> >
> > Finally, this is the script from WLAN Slovenija to detect the freeze and
> > trigger a reboot.  I've incorporated this script as-is in WasabiNet
> > firmware for Nanostation Loco M2s and the TL-MR3020s.
> >
> https://github.com/wlanslovenija/firmware-packages-opkg/blob/master/util/nodewatcher-watchdog/files/check_ath9k_freeze
> >
> > For Nanostation M5s, the string the check for is "qdepth: 0 ampdu-depth:
> > 0 pending: 124 stopped: 1".
> >
> > --
> > Ben West
> > http://gowasabi.net
> > ben at gowasabi.net <mailto:ben at gowasabi.net>
> > 314-246-9434
> >
> >
> > _______________________________________________
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> > Commotion-dev at lists.chambana.net
> > https://lists.chambana.net/mailman/listinfo/commotion-dev
> >
>
> --
> Dan Staples
>
> Open Technology Institute
> https://commotionwireless.net
> OpenPGP key: http://disman.tl/pgp.asc
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>
>


-- 
Ben West
http://gowasabi.net
ben at gowasabi.net
314-246-9434
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