[BUG] au0828: dev->lock in au0828_usb_probe()

[Alexey Khoroshilov]

It is not quite clear what does mutex_lock(&dev->lock) defend against.

If there is a chance that some other code can try to lock the mutex during probe(),
then 
  mutex_unlock(&dev->lock);
  kfree(dev);
looks suspicious, because when that code get control form mutex_lock(dev->lock)
the dev could be already freed.

Otherwise, dev->lock should not be acquired so early.

Another problem is that on the path going via goto done
there is no mutex_unlock(&dev->lock).

Found by Linux Driver Verification project (linuxtesting.org).

--
Alexey Khoroshilov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org