struct sk_buff * skb_copy_expand (const struct sk_buff * skb, int newheadroom, int newtailroom, unsigned int __nocast gfp_mask);
Make a copy of both an &sk_buff and its data and while doing so allocate additional space.
This is used when the caller wishes to modify the data and needs a private copy of the data to alter as well as more space for new fields. Returns NULL on failure or the pointer to the buffer on success. The returned buffer has a reference count of 1.
You must pass GFP_ATOMIC as the allocation priority if this function is called from an interrupt.
ip_summed is not copied. Why does this work? Is it used only by netfilter in the cases when checksum is recalculated? --ANK