esp6_output_head
int esp6_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp);
EXPORT_SYMBOL_GPL(esp6_output_head);
esp.nfrags = esp6_output_head(x, skb, &esp);
esp.nfrags = esp6_output_head(x, skb, &esp);