batadv_skb_head_push
if (batadv_skb_head_push(skb, sizeof(*bcast_packet)) < 0)
int batadv_skb_head_push(struct sk_buff *skb, unsigned int len);
if (batadv_skb_head_push(skb, hdr_size) < 0)
if (batadv_skb_head_push(skb, ETH_HLEN) < 0)