Re: [Jack-Devel] Jack 1.9.7 on ARM crashes when killing a client

Hi guys; thanks a lot for your invaluable support! The patch, unfortunately, 
does nothing to fix or even improve the problem, which appears being 
completely unrelated to killing  clients...

Let me explain. We did never try booting up our ARM box and just leaving JACK 
running without any clients connected, until yesterday. It happened by chance 
and we noticed that JACK *was already blocked*! We didn't connect any client 
to it yet!

I've tried to better pinpoint the problem, and here's what I've found:

First: ALSA docs specify error codes for some pcm_snd_* functions used by 
jacks' ALSA driver - that is -EPIPE, -EINTR and -ESTRPIPE - but in a couple 
occasions you use the defined values without the minus. I've attached a patch, 
"fix-ALSA-error-codes.patch", to fix this.

The actual problem wasn't fixed by this patch so I kept trying and adding 
debug messages. JACK starts up and hums away until an xrun occurs. As soon as 
this happens, the driver breaks. The reason is that it tries to perform 
recovery (by restarting the driver) but it makes no effect because it ends up 
in an infinite loop within JackAlsaDriver::Read() ! 
There, alsa_driver_wait returns 0, the "goto retry;" runs it again, the xrun 
code is ran again, and alsa_driver_wait returns 0 again, entering an infinite 
loop.

I'm attaching two patches, both with a lot of added log messages (and also the 
previously explained patch)  to help understand what was going on.
The first version ("without-recovery") only adds debugging. A test run with it 
is linked at Pastebin: http://jackd.pastebin.com/JTswYfLd . the second one 
also attempts to fix the issue using ALSA's snd_pcm_recover(), and a test run 
of it is linked here: http://jackd.pastebin.com/2iifw6Gh .
With the recovery in place the issue is still present, but seemingly better 
identifiable, because JackAlsaDriver simply gets stuck within the poll() call 
in alsa_driver_wait() .

At the moment this is as far as I've got with the debugging. Do you have any 
idea or suggestion?

Thanks - immensely - in advance.

* Attachment: 'fix-ALSA-error-codes.patch'
content-type: text/x-patch
* Attachment: 'with-recovery.patch'
content-type: text/x-patch
* Attachment: 'without-recovery.patch'
content-type: text/x-patch

1297781103.1912_0.ltw:2,a <201102151544.30373.valerio.pilo at akhela dot com>