amt_skb_cb
tunnel = amt_skb_cb(skb)->tunnel;
amt_skb_cb(skb)->tunnel = tunnel;
static struct amt_skb_cb *amt_skb_cb(struct sk_buff *skb)
BUILD_BUG_ON(sizeof(struct amt_skb_cb) + sizeof(struct tc_skb_cb) >
return (struct amt_skb_cb *)((void *)skb->cb +
amt_skb_cb(skb)->tunnel = tunnel;