MIN_DDP_HDR
if (srx->fpdu_part_rcvd < MIN_DDP_HDR) {
MIN_DDP_HDR - srx->fpdu_part_rcvd);
if (srx->fpdu_part_rcvd < MIN_DDP_HDR)
bytes = min_t(int, hdrlen - MIN_DDP_HDR, srx->skb_new);