static int bpf_skb_generic_pop(struct sk_buff *skb, u32 off, u32 len)
{
	/* skb_ensure_writable() is not needed here, as we're
	 * already working on an uncloned skb.
	 */
	if (unlikely(!pskb_may_pull(skb, off + len)))
		return -ENOMEM;

	skb_postpull_rcsum(skb, skb->data + off, len);
	memmove(skb->data + len, skb->data, off);
	__skb_pull(skb, len);

	return 0;
}
static int bpf_skb_generic_pop(struct sk_buff *skb, u32 off, u32 len)
{
	 
	if (unlikely(!pskb_may_pull(skb, off + len)))
		return -ENOMEM;

	skb_postpull_rcsum(skb, skb->data + off, len);
	memmove(skb->data + len, skb->data, off);
	__skb_pull(skb, len);

	return 0;
}