[alsa-devel] Questions on locking, snd-usb-caiaq

Mark Hills mark at pogo.org.uk
Tue Sep 22 09:14:23 CEST 2009

On Tue, 22 Sep 2009, Daniel Mack wrote:

> On Mon, Sep 21, 2009 at 03:35:06PM +0200, Takashi Iwai wrote:
>> At Sun, 20 Sep 2009 13:07:05 +0100 (BST),
>> Mark Hills wrote:
>>> I fixed some race issues in snd-usb-caiaq, but have some questions on the
>>> interface between the driver and ALSA.
>>> First fix is a lock in pointer(), which caused snd_pcm_update_hw_ptr_pos()
>>> to report an out of range buffer position (even though it was sucessfully
>>> corrected to zero).
>>> Second is a lock as part of trigger(). On testing, this appears to fix an
>>> issue where white noise could sometimes be transferred by the driver.
>> Both look fine to me.
> To me as well, but I'm currently unable to test them. But I trust Mark - 
> he's been tracking that issue for a long time already and was the only 
> one so far observing this bug. If those patches fix it for him, they 
> should definitely go in. So assume my Acked-by: on them :)

Thanks, once I've done a little more widespread testing for visible bugs, 
I'll follow up with proper patches. I also made the change to spin_lock() 
where appropriate.


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