Hi Peter On Thu, 2021-08-19 at 17:01 +0200, Marcel Holtmann wrote: > Hi Peter, > > > 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. > > I think you found a regression. Calling close() on the HCI User Channel should bring the device > back down. This used to work correctly, can you please bisect which kernel patch broke this. > > Back in the days I added tools/userchan-tester, but it seems I never included enough test cases to > catch this regression. > > Regards > > Marcel > Was bluetoothd running when you test? If then, try to run without running the bluetooth daemon and check to see if you have a same problem. If you have to use the daemon, change the "AutoEnable" flag in the /etc/bluetooth/main.conf to false and restart the bluetooth daemon. This will prevent the HCI interface from powering on after cloing socket. Regards, Tedd
