[ALSA] Fix races in PCM OSS emulation

Fixed the race among multiple threads accessing the OSS PCM
instance concurrently by simply introducing a mutex for protecting
a setup of the PCM.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>
2 files changed