Re: [LAU] Segfault using zita-j2a

On 10/25/2012 04:54 PM, Jannis Achstetter wrote:
> Hi Fons, hi list,
>
> I've been trying to get zita-a2jbridge working on my laptop. JACK is
> running with the internal Intel HDA-card via ALSA backend.
> Using the Edirol UA-101 as JACK's main-backend works w/o problems and
> using alsa_out & alsa_in works, too.
> Software versions I am using:
> media-libs/zita-alsa-pcmi-0.2.0
> media-libs/zita-resampler-1.2.0
> media-sound/zita-ajbridge-0.2.2
> media-sound/jack-audio-connection-kit-1.9.8
>
> Here's the output of gdb trying to run zita-j2a:
> kripton@email-addr-hidden ~ $ cat /proc/asound/cards
> 0 [Intel ]: HDA-Intel - HDA Intel
> HDA Intel at 0xfc020000 irq 46
> 1 [Loopback ]: Loopback - Loopback
> Loopback 1
> 2 [UA101 ]: UA-101 - UA-101
> EDIROL UA-101 (serial ZT40539), 48000 Hz at
> usb-0000:00:1d.7-2, high speed
> 29 [ThinkPadEC ]: ThinkPad EC - ThinkPad Console Audio Control
> ThinkPad Console Audio Control at EC reg 0x30, fw
> 7VHT16WW-1.06
> kripton@email-addr-hidden ~ $ gdb zita-j2a
> GNU gdb (Gentoo 7.5 p1) 7.5
> Copyright (C) 2012 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law. Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-pc-linux-gnu".
> For bug reporting instructions, please see:
> <http://bugs.gentoo.org/>...
> Reading symbols from /usr/bin/zita-j2a...done.
> (gdb) r -j UA101 -d hw:UA101 -c 10 -v
> Starting program: /usr/bin/zita-j2a -j UA101 -d hw:UA101 -c 10 -v
> warning: Could not load shared library symbols for linux-vdso.so.1.
> Do you need "set solib-search-path" or "set sysroot"?
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> playback :
> nchan : 10
> fsamp : 48000
> fsize : 256
> nfrag : 2
> format : S32_LE
> capture : not enabled
> [New Thread 0x7ffff7f9f700 (LWP 15169)]
> [New Thread 0x7ffff7f1e700 (LWP 15170)]
> [New Thread 0x7ffff7e9d700 (LWP 15171)]
> [New Thread 0x7ffff7fce700 (LWP 15172)]
> Starting synchronisation.
>
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0x7ffff7e9d700 (LWP 15171)]
> 0x00007ffff7bd8760 in VResampler::process (this=0x6265a0) at
> vresampler.cc:217
> 217 vresampler.cc: No such file or directory.
> (gdb) bt
> #0 0x00007ffff7bd8760 in VResampler::process (this=0x6265a0) at
> vresampler.cc:217
> #1 0x0000000000403951 in Jackclient::playback (this=0x6262d0,
> nframes=128) at jackclient.cc:222
> #2 0x00000000004042eb in Jackclient::jack_process (this=0x6262d0,
> nframes=128) at jackclient.cc:467
> #3 0x00007ffff779c61a in ?? () from /usr/lib64/libjack.so.0
> #4 0x00007ffff77af760 in ?? () from /usr/lib64/libjack.so.0
> #5 0x00007ffff7575ec6 in start_thread () from /lib64/libpthread.so.0
> #6 0x00007ffff6aa08ad in clone () from /lib64/libc.so.6
> (gdb) q
> A debugging session is active.
>
> Inferior 1 [process 15160] will be killed.
>
> Quit anyway? (y or n) y
>
> Any ideas?
>
Classic race condition. The jack_client is activated before the
resampler is initialized.

zita-j2a.cc:200 creates the jack-client and calls jack_activate.
process_callbacks can arrive starting now.

but not until zita-j2a.cc:211 calls J->start() the data-structures
required to do the processing are initialized.

Easiest solution is probably to check if start() has been called in the
process callback:

--- a/jackclient.cc
+++ b/jackclient.cc
@@ -301,6 +301,8 @@ int Jackclient::jack_process (int nframes)
     jack_nframes_t ft;
     double tj, err, d1, d2;

+ if (_state == INIT) return 0;
+
     // Buffer size change or other evil.
     if (_state == TERM)

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Received on Thu Oct 25 20:15:02 2012