isert_get_iser_hdr
struct iser_ctrl *iser_ctrl = isert_get_iser_hdr(rx_desc);
return isert_get_iser_hdr(desc) - (void *)desc->buf;
return isert_get_iser_hdr(desc) + sizeof(struct iser_ctrl);
void *data = isert_get_iser_hdr(desc) + ISER_HEADERS_LEN;