text: #ifndef _XFRM_HASH_H
  #define _XFRM_HASH_H
  
  #include <linux/xfrm.h>
  #include <linux/socket.h>
  
  static inline unsigned int __xfrm4_addr_hash(const xfrm_address_t *addr)
  {
  	return ntohl(addr->a4);
  }
  
  static inline unsigned int __xfrm6_addr_hash(const xfrm_address_t *addr)
  {
  	return ntohl(addr->a6[2] ^ addr->a6[3]);
  }
  
  static inline unsigned int __xfrm4_daddr_saddr_hash(const xfrm_address_t *daddr,
  						    const xfrm_address_t *saddr)
  {
  	u32 sum = (__force u32)daddr->a4 + (__force u32)saddr->a4;
  	return ntohl((__force __be32)sum);
  }
  
  static inline unsigned int __xfrm6_daddr_saddr_hash(const xfrm_address_t *daddr,
  						    const xfrm_address_t *saddr)
  {
  	return ntohl(daddr->a6[2] ^ daddr->a6[3] ^
  		     saddr->a6[2] ^ saddr->a6[3]);
  }
  
  static inline unsigned int __xfrm_dst_hash(const xfrm_address_t *daddr,
  					   const xfrm_address_t *saddr,
  					   u32 reqid, unsigned short family,
  					   unsigned int hmask)
  {
  	unsigned int h = family ^ reqid;
  	switch (family) {
  	case AF_INET:
  		h ^= __xfrm4_daddr_saddr_hash(daddr, saddr);
  		break;
  	case AF_INET6:
  		h ^= __xfrm6_daddr_saddr_hash(daddr, saddr);
  		break;
  	}
  	return (h ^ (h >> 16)) & hmask;
  }
  
  static inline unsigned int __xfrm_src_hash(const xfrm_address_t *daddr,
  					   const xfrm_address_t *saddr,
  					   unsigned short family,
  					   unsigned int hmask)
  {
  	unsigned int h = family;
  	switch (family) {
  	case AF_INET:
  		h ^= __xfrm4_daddr_saddr_hash(daddr, saddr);
  		break;
  	case AF_INET6:
  		h ^= __xfrm6_daddr_saddr_hash(daddr, saddr);
  		break;
  	}
  	return (h ^ (h >> 16)) & hmask;
  }
  
  static inline unsigned int
  __xfrm_spi_hash(const xfrm_address_t *daddr, __be32 spi, u8 proto,
  		unsigned short family, unsigned int hmask)
  {
  	unsigned int h = (__force u32)spi ^ proto;
  	switch (family) {
  	case AF_INET:
  		h ^= __xfrm4_addr_hash(daddr);
  		break;
  	case AF_INET6:
  		h ^= __xfrm6_addr_hash(daddr);
  		break;
  	}
  	return (h ^ (h >> 10) ^ (h >> 20)) & hmask;
  }
  
  static inline unsigned int __idx_hash(u32 index, unsigned int hmask)
  {
  	return (index ^ (index >> 8)) & hmask;
  }
  
  static inline unsigned int __sel_hash(const struct xfrm_selector *sel,
  				      unsigned short family, unsigned int hmask)
  {
  	const xfrm_address_t *daddr = &sel->daddr;
  	const xfrm_address_t *saddr = &sel->saddr;
  	unsigned int h = 0;
  
  	switch (family) {
  	case AF_INET:
  		if (sel->prefixlen_d != 32 ||
  		    sel->prefixlen_s != 32)
  			return hmask + 1;
  
  		h = __xfrm4_daddr_saddr_hash(daddr, saddr);
  		break;
  
  	case AF_INET6:
  		if (sel->prefixlen_d != 128 ||
  		    sel->prefixlen_s != 128)
  			return hmask + 1;
  
  		h = __xfrm6_daddr_saddr_hash(daddr, saddr);
  		break;
  	}
  	h ^= (h >> 16);
  	return h & hmask;
  }
  
  static inline unsigned int __addr_hash(const xfrm_address_t *daddr,
  				       const xfrm_address_t *saddr,
  				       unsigned short family, unsigned int hmask)
  {
  	unsigned int h = 0;
  
  	switch (family) {
  	case AF_INET:
  		h = __xfrm4_daddr_saddr_hash(daddr, saddr);
  		break;
  
  	case AF_INET6:
  		h = __xfrm6_daddr_saddr_hash(daddr, saddr);
  		break;
  	}
  	h ^= (h >> 16);
  	return h & hmask;
  }
  
  struct hlist_head *xfrm_hash_alloc(unsigned int sz);
  void xfrm_hash_free(struct hlist_head *n, unsigned int sz);
  
  #endif /* _XFRM_HASH_H */
  