skb_cow(9) centos man page | unix.com

SKB_COW(9)							 Linux Networking							SKB_COW(9)

NAME
       skb_cow - copy header of skb when it is required

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

ARGUMENTS
       skb
	   buffer to cow

       headroom
	   needed headroom

DESCRIPTION
       If the skb passed lacks sufficient headroom or its data part is shared, data is reallocated. If reallocation fails, an error is returned
       and original skb is not changed.

       The result is skb with writable area skb->head...skb->tail and at least headroom of space at head.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014								SKB_COW(9)