Of course. Not only does this page say so: http://www.alsa-project.org/main/index.php/SMP_Design

Ah, I read this, but that's probably just if two threads would share one handle:

"The use of returned handles must be serialized in the application using own locking scheme."

One more question: You said snd_pcm_wait() was real time safe. I guess that's also true for similar functions, like snd_pcm_htimestamp(), snd_pcm_readi(), ..., correct?