zd_ctrlset
hw->extra_tx_headroom = sizeof(struct zd_ctrlset);
skb_pull(skb, sizeof(struct zd_ctrlset));
static void cs_set_control(struct zd_mac *mac, struct zd_ctrlset *cs,
struct zd_ctrlset *cs = skb_push(skb, sizeof(struct zd_ctrlset));
packet_length = frag_len + sizeof(struct zd_ctrlset) + 10;