is_valid_state
rv = is_valid_state(device, ns);
if (is_valid_state(device, os) == rv)
rv = is_valid_state(device, ns);
if (is_valid_state(device, os) == rv)
static enum drbd_state_rv is_valid_state(struct drbd_device *, union drbd_state);
rv = is_valid_state(device, ns);
rv = is_valid_state(device, ns);