centos man page for skb_head_is_locked

SKB_HEAD_IS_LOCKED(9)						 Linux Networking					     SKB_HEAD_IS_LOCKED(9)

NAME
       skb_head_is_locked - Determine if the skb->head is locked down

SYNOPSIS
       bool skb_head_is_locked(const struct sk_buff * skb);

ARGUMENTS
       skb
	   skb to check

DESCRIPTION
       The head on skbs build around a head frag can be removed if they are not cloned. This function returns true if the skb head is locked down
       due to either being allocated via kmalloc, or by being a clone with multiple references to the head.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						     SKB_HEAD_IS_LOCKED(9)