Iain Lane authored Sep 10, 2018 and Philip Withnall committed Sep 13, 2018

`read_netlink_messages()` is the callback attached to the netlink socket
(G_IO_IN). It calls `g_socket_receive_message()`. There is a race
condition that if the socket is closed while there is a pending call, we
will try to receive on a closed socket, which fails.

To avoid this, we switch the order of the operations around: first
destroy the source and then close the socket.