[pvrusb2] Random hang during 'modprobe -r pvrusb2'

[Mike Isely]

On Thu, 22 Jul 2010, devsk wrote:

> Mike,
> 
> This is with 2.6.34.1 and latest driver snapshot:
> 
> [18693.055000] pvrusb2: 20100708 (from www.isely.net):Hauppauge WinTV-PVR-USB2 
> MPEG2 Encoder/Tuner
> 
> I did modprobe -r pvrusb2 and it hung.
> 
> This is what it shows in dmesg:
> 
> [32118.444000] usbcore: deregistering interface driver pvrusb2
> [32118.444000] pvrusb2: Device being rendered inoperable
> 
> Its still hung here. How can I collect more information for you to debug this 
> issue. Its very intermittent. So, since we have it hung there, this is our 
> chance to nail this bugger.

Getting that to always work correctly is not easy.  Lots of opportunity 
for race conditions, and I have seen some issues with this.  There were 
a round of bug fixes a few months ago that address race conditions on 
removal.

Given the sporadic nature of an issue like this it's going to be hard to 
nail down.  Some things that will help:

1. Being able to demonstrate that the problem is affected by kernel 
version, i.e. if it only happens under 2.6.34.1 or if you can also get 
it to fail under an earlier kernel.  Either way the answer to that may 
help narrow the search.

2. Did an application have the device node open at the time?  That's a 
big factor?

3. If after it jams, can you unplug the device and does that unjam the 
removal process?

Another fun race to try is to run an application which talks to the 
driver and then unplug the device WHILE this is running.  This should 
also work out OK.

  -Mike

-- 

Mike Isely
isely @ isely (dot) net
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