Regression since 2.6.25 kernel: Crash of userspace program leaves DVB device unusable

[Brendon Higgins <blhiggins@gmail.com>]

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Hi,

I wrote to linux-dvb (2009-01-03 12:00 pm):
> I've been coming up against a problem that seems to be with the DVB drivers
> that occurs when a program using them, usually VDR in my case, terminates
> uncleanly (segfault, general protection fault). Linux 2.6.25 doesn't have
> this problem, but 2.6.26, 2.6.27, and 2.6.28 do, though 2.6.28 manifests
> slightly differently to the others. I'll focus on what 2.6.28 does. I have
> a DViCO FusionHDTV DVB-T Plus, running on an amd64 Debian Testing (mostly)
> dual-core machine.
>
> After VDR crashes it attemps to restart itself. This was fine on 2.6.25,
> but on later kernels the crash seems to leave the device in some unusable
> state, where no program can subsequently use it - the device files
> (/dev/dvb) no longer exist. (In 2.6.2[67], the files existed, but accessing
> /dev/dvb/adapter0/dvr0 resulted in "No such device".) I had figured out
> that in order to get the device working again it is necessary to "rmmod
> cx88_dvb cx8802; modprobe cx88_dvb". This worked in 2.6.2[67] without
> trouble, but in 2.6.28, it's as if the cx88_dvb module gets lost somehow.
> It doesn't appear in lsmod, however:
> phi:~# modprobe cx88_dvb
> FATAL: Error inserting cx88_dvb
> (/lib/modules/2.6.28/kernel/drivers/media/video/cx88/cx88-dvb.ko): No such
> device
> phi:~# rmmod cx88_dvb cx8802
> ERROR: Module cx88_dvb does not exist in /proc/modules
> phi:~# modprobe cx88_dvb
>
> Note that probing it works only *after* cx8802 was unloaded. As before, now
> the device is accessible.
>
> So it seems something is wrong in the cx8802 module. Something is not being
> cleaned up after a userspace program crashes while using it, leaving the
> DVB system in a broken state.
>
> I'd very much like this to not be the case, since on my system a VDR crash
> is somewhat inevitable, and the automatic restart *was* very handy, back in
> 2.6.25.

Deafening silence. Does nobody have a clue? Or care? I just noticed I posted 
to the linux-dvb list which has been deprecated, so I'm quoting it here in 
its entirety in case relevent people missed it. Is there anything else I can 
do?

Peace,
Brendon

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