Re: USB locks up system -- WAS Re: shutdown or acpi problem

On Sun, Nov 16, 2014 at 08:16:36PM +0100, Hans Petter Selasky wrote:
> On 11/16/14 20:03, Steve Kargl wrote:
> > On Sun, Nov 16, 2014 at 06:55:53PM +0000, Mark R V Murray wrote:
> >>
> >>> On 16 Nov 2014, at 18:51, Steve Kargl <sgk_at_troutmask.apl.washington.edu> wrote:
> >>>
> >>> If you have not read the entire thread, once the laptop keyboard and
> >>> video output lock up, I can ssh into the laptop.  If I run usbconfig,
> >>> it hangs, ^T tells me it is stuck in SX Lock, and the /dev/da0* devices
> >>> have not been destroyed.
> >>
> >> Weirder and weirder :-(.
> >>
> >> Something with SX locks? Hmm. I do use those for attach and detach for
> >> RNG sources. Could it be that that stick of yours is somehow getting
> >> involved in the RNG source locks?
> >>
> >
> > It's not limited to a single usb device.  Plugging in/Unplugging
> > a logitech mouse dongle, the memstick, a Western Digital MY Passport
> > external usb hard drive, all lead to the locked keyboard and video.
> >
> > I tried adding both RANDOM_DEBUG and USBDEBUG to the kernel, but the
> > mount of output is mind numbing.
> >
> 
> 
> Can you enter kgdb when the usbconfig is froozen, and backtrace all 
> kernel threads. You should see exactly what locks are the problem.
> 
> Maybe some lock didn't get properly unlocked!
> 

I haven't tried kgdb.  I did try to attach gdb to the usbconfig
process via its pid, but gdb dumped core.

I haven't looked at locks in kgdb, what command or commands should
I try.
 
-- 
Steve