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67a7b5a993
The root cause is that alsa-lib is not thread safe for the same handle. There are two threads in the gstreamer accessing alsa-lib not serilized. The race condition happens when one thread holds the old framebuffer app_ptr position in the kernel, another thread advances the framebuffer app_ptr. when the former thread is scheduled to run again, it overwrites the app_ptr to old value by copying from kernel.Thus,the app_ptr in the upper alsa-lib(pcm_rate) become one period size more advanced than the lower alsa-lib(pcm_hw & kernel). gstreamer uses noblock and poll method to communicate with the alsa-lib. The app_ptr unsync situation as described above makes the poll return immediately because it concludes there is enough space for the ring-buffer via the low-level alsa-lib. The write function returns immediately because it concludes there is not enough space for the ring-buffer from the upper-level alsa-lib. Then the loop of poll and write runs again and again until another period size is available for ring-buffer.This leads to the cpu 100 problem. delay_lock is used to avoid the race condition. Fixes: https://bugzilla.gnome.org/show_bug.cgi?id=690937 |
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| .. | ||
| gstalsa.c | ||
| gstalsa.h | ||
| gstalsadeviceprobe.c | ||
| gstalsadeviceprobe.h | ||
| gstalsaplugin.c | ||
| gstalsasink.c | ||
| gstalsasink.h | ||
| gstalsasrc.c | ||
| gstalsasrc.h | ||
| Makefile.am | ||