[PATCH V0 0/1] ALSA: pcm: fix blocking while loop in

[Raghu Bankapur]

When period interrupts are disabled, while loop in snd_pcm_update_hw_ptr0()
results in the machine locking up if runtime->hw_ptr_buffer_jiffies is 0.
Validate runtime->hw_ptr_buffer_jiffies value before while loop to avoid
delta check.


when runtime->hw_ptr_buffer_jiffies is 0 then update of while condition 
hdelta > xrun_threshold will be always true because hdelta will not
change. This will lead to infinite loop causing lock-up

This issue found during stability test, below log explains CPU lock-up on CPU1

[ 922.249028] sched: RT throttling activated for rt_rq ffffffc0f9970778 (cpu 1)
[ 922.249028] potential CPU hogs:
[ 922.249028] **FastCapture (11426)
[ 922.249105] ------------[ cut here ]---------

To fix this lock-up issue, added new condition to check if runtime->
hw_ptr_buffer_jiffies is ZERO or negative.

Raghu Bankapur (1):
  ALSA: pcm: fix blocking while loop in snd_pcm_update_hw_ptr0()

 sound/core/pcm_lib.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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2.17.1