We lock the socket when both releasing and getting a disconnected
notification. In the latter case, we also ste the socket as orphan.
This fixes a potential kernel bug that can be triggered when we get the
disconnection notification before closing the socket.
Signed-off-by: NSamuel Ortiz <samuel@sortiz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>