I have found what seems to be a bug in ALSA (CVS of this afternoon).
When a program opens certain PCM devices for capture the program blocks
forever in snd_pcm_open (both the library function and the kernel
function actually). The PCM device I have been testing it with is
surround40 on a emu10k1 (SBLive Value). I am trying to capture on this
device because I want to have jack use surround40 (actually a route
plugin device pointing to it) so that I can use all 4 outs and both ins
at the same time.
Below is a minimal setup that reproduces the problem for me.
alsa_freeze.c
------------------
#include <alsa/asoundlib.h>
int main( int argc, char* argv[] )
{
snd_pcm_t *pcm;
snd_pcm_open(&pcm, "surround40", SND_PCM_STREAM_CAPTURE, 0);
return 0;
}
------------------
.asoundrc
------------------
<confdir:cards/EMU10K1.conf>
------------------
using SysRq-T I captured a kernel stack trace
------------------
Using defaults from ksymoops -t elf32-i386 -a i386
Call Trace: [<e094908e>] [<e0922b20>] [<e0948f60>] [<e091b220>]
[<c018c325>]
[<c014bf59>] [<c013ea43>] [<c013e968>] [<c013ed43>] [<c010774f>]
Warning (Oops_read): Code line not seen, dumping what data is available
Proc; alsa_test_sim
>>EIP; 00000000 Before first symbol
Trace; e094908e <[snd-pcm]snd_pcm_open+12e/190>
Trace; e0922b20 <[snd]snd_fops+0/48>
Trace; e0948f60 <[snd-pcm]snd_pcm_open+0/190>
Trace; e091b220 <[snd]snd_open+e0/160>
Trace; c018c325 <devfs_open+195/210>
Trace; c014bf59 <path_lookup+39/40>
Trace; c013ea43 <dentry_open+d3/1e0>
Trace; c013e968 <filp_open+68/70>
Trace; c013ed43 <sys_open+53/c0>
Trace; c010774f <system_call+33/38>
------------------
I suspect that snd_pcm_open+12e is line 1974 in pcm_native.c. Everytime
I checked it was at this address.
------------------
set_current_state(TASK_INTERRUPTIBLE);
schedule();
>>>> if (signal_pending(current)) { <<<
err = -ERESTARTSYS;
break;
}
------------------
Please tell me you need anymore info or if you want me to try anything.
-Arthur
--
Arthur Peters <[EMAIL PROTECTED]>
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