centos man page for skb_cow_head

SKB_COW_HEAD(9) 						 Linux Networking						   SKB_COW_HEAD(9)

NAME
       skb_cow_head - skb_cow but only making the head writable

SYNOPSIS
       int skb_cow_head(struct sk_buff * skb, unsigned int headroom);

ARGUMENTS
       skb
	   buffer to cow

       headroom
	   needed headroom

DESCRIPTION
       This function is identical to skb_cow except that we replace the skb_cloned check by skb_header_cloned. It should be used when you only
       need to push on some header and do not need to modify the data.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							   SKB_COW_HEAD(9)