SKB_HEADER_LEN
ALIGN(sizeof(struct message_data) + SKB_HEADER_LEN, 4)
struct sk_buff *skb = alloc_skb(len + SKB_HEADER_LEN, GFP_ATOMIC);
skb_reserve(skb, SKB_HEADER_LEN);
skb = alloc_skb(len + SKB_HEADER_LEN, GFP_ATOMIC);
skb_reserve(skb, SKB_HEADER_LEN);