Panic in rum(4) on 8.0-BETA2

[Florent Thoumie]

On Fri, Aug 14, 2009 at 7:02 PM, Sam Leffler <sam at errno.com> wrote:

> Hans Petter Selasky wrote:
>
>  This looks like a WLAN problem rather than an USB problem. Some months
>> back the WLAN statemachine was converted to taskqueues. In that regard I've
>> seen 100% reproducable panics, but I did not have time to investigate. If
>> you put some delay between the "ifconfig" commands on your wlan device, does
>> the problem disappear?
>>
>
> The rum driver violates locking requirements by dropping the net80211 lock
> in the driver's newstate method in order to pickup the driver softc to do
> usb operations.  This opens a race whereby wpa_supplicant makes a request
> that clocks the state machine again causing a state transition to be lost:
>
> wlan0: ieee80211_new_state_locked: pending SCAN -> AUTH transition lost
>
> This in turns causes net80211 state to be wrong and causes the crash.
>
> I will need to understand why the above is done to see if the driver can be
> changed to do what is required.  I also note other bugs in this routine that
> can cause further problems.


I've filed a PR: kern/137776, as suggested by Sam.

We should probably move the discussion there.

-- 
Florent Thoumie
flz at FreeBSD.org
FreeBSD Committer