Re: [linux-usb-devel] USB deadlock after resume

On 11/21/07, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
On Wed, 21 Nov 2007, Markus Rechberger wrote:

it's not just usb_set_interface that hangs actually.
It seems to hang at

wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);

in drivers/usb/core/urb.c after resuming. I disabled access to the usb
subsystem in the uvc driver, although connecting any other usb storage
fails too, just at the same point.

Which URB is usb_kill_urb() called for?


it's the usb_control_message which calls usb_kill_urb if I haven't got
it wrong. (if you're looking for some other information please let me
know)
Although, I got a bit further with it. The error seems to happen
earlier already.
If I load the driver, and do not access the device after suspending
all usb_control commands fail with -71 eproto.

That's very strange. Getting -71 errors is understandable; it
indicates that the device can't handle being suspended. But the
wait_event() line still shouldn't hang. If it does, it indicates that
there's something wrong with the USB host controller, not just the
device.

Can you try testing this on a different sort of computer?


Not really, suspending doesn't work at all on my other notebook it
just freezes..
I'm basically trying to get that driver work on my eee PC [1], it's
cheap and tiny so I don't expect anything special in there..
The system is preloaded with Xandros (it's debian etch with a few
custom applications) and linux 2.6.21.4.

The system still locks up, although only if I leave the video
application running during suspending. I don't have to reload the
driver anymore after resuming if the video node doesn't get accessed
(I'm looking for races in the uvc driver at the moment).

thanks,
Markus

[1] http://eeepc.asus.com
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