[pulseaudio-discuss] USB hotplug causes crash

Rick Bronson rick at efn.org
Wed Dec 17 10:57:54 PST 2008


  I have a need for USB hotplugging to work for pulse audio.  Normally
it works but sometimes I get this scenario:

snd_pcm_close(), then snd_pcm_drop(), snd_pcm_ioplug_drop(),
pulse_stop() is called with pcm->stream == 0, this causes a pointer
exception and a crash.  If I change pulse_stop() so that it tests for
a pcm->stream == 0 condition and returns an error, sound stops
working.  In this situation it looks like the main thread is in ->
snd_pcm_close(), pulse_free(), pa_threaded_mainloop_stop(),
pthread_join() and stuck there waiting for the "helper thread" to do
something.  Almost like a deadlock.

  Normally when you hotplug you see two threads, one is always the same
tid, the other (probably the "helper thread") gets killed and
restarted.  When it reaches the deadlock above hotplugging doesn't
cause the "helper thread" to restart, the two threads are always the
same tid.

  Any help or ideas would be greatly appreciated.

  Rick Bronson

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