#include <linux/highmem.h>
  
  static inline void *kmap_skb_frag(const skb_frag_t *frag)
  {
  #ifdef CONFIG_HIGHMEM
  	BUG_ON(in_irq());
  
  	local_bh_disable();
  #endif

  	return kmap_atomic(skb_frag_page(frag), KM_SKB_DATA_SOFTIRQ);

  }
  
  static inline void kunmap_skb_frag(void *vaddr)
  {
  	kunmap_atomic(vaddr, KM_SKB_DATA_SOFTIRQ);
  #ifdef CONFIG_HIGHMEM
  	local_bh_enable();
  #endif
  }