skb_zerocopy - Zero copy skb to skb
int skb_zerocopy(struct sk_buff * to, struct sk_buff * from, int len, int hlen);
Copies up to `len` bytes from `from` to `to` by creating references to the frags in the source buffer.
The `hlen` as calculated by skb_zerocopy_headlen specifies the headroom in the `to` buffer.
Return value: 0: everything is OK -ENOMEM: couldn't orphan frags of from due to lack of memory -EFAULT: skb_copy_bits found some problem with skb geometry
|January 2017||Kernel Hackers Manual 4.8.|