[alsa-devel] Deadlock over semaphore issue with aplay while using dmix
abdulmateen.shaikh at gmail.com
Thu Apr 4 11:27:39 CEST 2013
I seeing sometimes deadlock issue with dmix when I press CTRL+C.
Aplay's signal handler calls snd_pcm_close() if an interrupt occurs.
snd_pcm_close() will internally call pcm->ops->close() which will fall to
snd_pcm_dmix_close() in case you are using dmix.
snd_pcm_dmix_close() will try to acquire the semaphore with
The same semaphore is acquired in snd_pcm_dmix_sync_area() with
dmix_down_sem() in case of non-concurrent access.
If semaphore is acquired in snd_pcm_dmix_sync_area() which is in thread
context and interrupt comes, which invokes the signal handler which is in
ISR context, which calls snd_pcm_close() which in turn calls
snd_pcm_dmix_close() then we see a deadlock since semaphore is not released
from thread context and ISR is waiting indefinitely on the same semaphore.
Please suggest a suitable solution for this.
Shaikh Mateen S.
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