[Bluetooth] Signal user-space for HIDP and BNEP socket errors

When using the HIDP or BNEP kernel support, the user-space needs to
know if the connection has been terminated for some reasons. Wake up
the application if that happens. Otherwise kernel and user-space are
no longer on the same page and weird behaviors can happen.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/bnep/core.c

@@ -507,6 +507,11 @@ static int bnep_session(void *arg)
 	/* Delete network device */
 	unregister_netdev(dev);
 
+	/* Wakeup user-space polling for socket errors */
+	s->sock->sk->sk_err = EUNATCH;
+
+	wake_up_interruptible(s->sock->sk->sk_sleep);
+
 	/* Release the socket */
 	fput(s->sock->file);