[PATCH] ALSA: pcm: fix incorrect hw_base increase

[Greg Kroah-Hartman]

On Fri, May 15, 2020 at 12:09:39PM +0800, Brent Lu wrote:
> The hw_base will be increased by runtime->buffer_size frames
> unconditionally if the runtime->status->hw_ptr is not updated for over
> half of buffer time. As the hw_base increases, so does the
> runtime->status->hw_ptr which could lead to invalid return value when
> user space program calls snd_pcm_avail() function.
> 
> By updating runtime->hw_ptr_jiffies each time the HWSYNC is called,
> the hw_base will keep the same when buffer stall happens, so does the
> hw_ptr.
> 
> Signed-off-by: Brent Lu <brent.lu at intel.com>
> ---
>  sound/core/pcm_lib.c | 1 +
>  1 file changed, 1 insertion(+)

Is this a bugfix needed for older kernels as well?  When did this issue
show up?

thanks,

greg k-h