Subject: kern/28385: ath(4) is unstable under load with DLink AG650 PCcard
To: None <,,>
From: None <>
List: netbsd-bugs
Date: 11/22/2004 10:56:00
>Number:         28385
>Category:       kern
>Synopsis:       ath(4) is unstable under load with DLink AG650 PCcard
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 22 10:56:00 +0000 2004
>Originator:     Steve Woodford
>Release:        NetBSD 2.99.10
System: NetBSD 2.99.10 NetBSD 2.99.10 (WULLIE) #1: Sun Nov 7 20:45:52 GMT 2004 i386
Architecture: i386
Machine: i386

ath0 at cardbus1 dev 0 function 0
ath0: mac 5.6 phy 4.1 5ghz radio 3.6
ath0: 11a rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
ath0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
ath0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps

My laptop is connected to my network using a DLink AG650 WLAN card and
the ath(4) driver. The actual packets traverse an IPsec tunnel to
another machine hard-wired to the Access Point (802.11g).

Periodically (and always when there is a lot of traffic crossing the WLAN
between a server and my laptop) the ath(4) card seems to lose its connection
with the AP. This is indicated by the card's two LEDs flashing alternately.

When this situation arises, the card refuses to re-establish the link by
itself. Other computers on the WLAN continue to operate normally.

It used to be the case that "ifconfig ath0 down up" cured the problem.
However in recent kernels, the above command wedges the laptop solid. As
the laptop runs X11, and the kernel message buffer is cleared on reset, I
have no clue as to why this occurs.

I also see, on occasion, an endless stream of

	ath0: hardware error; resetting

messages on the console when this ath(4) card is configured at boot time.

If this happens, the machine becomes unresponsive and the only cure is
to eject the card and hope the machine doesn't panic. If all goes well,
the card can be re-inserted and manually configured in most cases.

Sometimes the card will pull itself together after a few seconds without
needing to be ejected. The above messages stop spewing and the card will
associate with the AP.
The first bug is not repeatable on demand, although it seems to be a load
issue tickled by lots of small and/or fragmented packets.

The second happens much more readily and looks to be some form of reset
timing bug.

 ath(4) is unstable under load with a DLink AG650 PCcard, and can lead to crash.