I'm using an AF_BLUETOOTH socket bound with HCI_CHANNEL_USER from a user-mode application with cap_net_admin=ep. As expected this requires the device be down, and brings the device up automatically. When I close that socket and exit the application, the device appears to remain up forever. Which prevents me from re-starting the application. I tried to issue HCIDEVDOWN before closing, but that produces EBADFD because ioctls cannot be performed with HCI_CHANNEL_RAW. I can bring the interface down from within the application if, after closing the socket, I wait a second or so, then create a new bound HCI_CHANNEL_RAW socket and issue HCIDEVDOWN on it. Is there some other way to cleanly shut down an application that used HCI_CHANNEL_USER so that the device is returned to down state on exit? Or is this supposed to happen automatically (I see code that suggests it should)? Kernel version is 5.11.0-7620-generic (System76), and I'm using go 1.16, if that's relevant. Thanks! Peter
