sound/pcm/* bugs (was: Re: page fault panic tracked down (selwakeuppri()) - really sound/pcm/*)

Don Lewis truckman at
Fri Jan 16 17:27:10 PST 2004

On 16 Jan, Stefan Ehmann wrote:
> On Fri, 2004-01-16 at 10:31, Don Lewis wrote:

>> The following patch seems to be at least somewhat stable on my machine.
>> I did get one last panic in feed_vchan_s16() that I haven't been able to
>> reproduce since I added some more sanity checks. Since it was caught in
>> the interrupt routine, it's not easy to track down to its root cause.  I
>> think there is still a bug somewhere, but it's not easy to trigger.
> Good news: no panic so far.
> Bad news: sound stopped working after some time (Chances are that the
> system would have panicked on the unpatched kernel at the same time)
> /dev/dsp: Operation not supported by device

The only thing I found that would return this error appears to be the
code in chn_buildfeeder() that gets invoked when you change the speed or
format of a channel and you attempted to change to a speed or format
this is not supported.  I don't know why you would just start seeing
this now.

> I'm not sure why this happened.
> I tried to increase vchans to 5 and got this on printed
> cnt 4, newcnt 1, busy 2

Newcnt is the number of vchans that you have requested.  It looks more
like you tried to reduce the number of vchans to one but the request was
rejected because two were currently in use.

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