MT_SKB_HEAD_LEN
int len = min_t(int, data_len, MT_SKB_HEAD_LEN);
skb = alloc_skb(MT_SKB_HEAD_LEN, GFP_ATOMIC);
skb_put_data(skb, data + head_room, MT_SKB_HEAD_LEN);
data += head_room + MT_SKB_HEAD_LEN;
len - MT_SKB_HEAD_LEN, buf_size);