classic_can
hf_size_rx = struct_size(hf, classic_can, 1);
DECLARE_FLEX_ARRAY(struct classic_can, classic_can);
memcpy(cf->data, hf->classic_can->data, data_length);
memcpy(hf->classic_can->data, cf->data, cf->len);
dev->hf_size_tx = struct_size(hf, classic_can, 1);