`ni6501_detach()` is the Comedi "detach" handler for the ni_usb6501
driver. It is called when the private data for the device is about to
be freed. The private data contains a mutex `devpriv->mut` that was
initialized when the private data was allocated. Call `mutex_destroy()`
to mark it as invalid.
Also remove the calls to `mutex_lock()` and `mutex_unlock()` from
`ni6501_detach()`. The only other locks of the mutex are by some of the
Comedi instruction handlers that cannot contend with the "detach"
handler for this mutex.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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