Hi Xin,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on ipsec-next/master]

url:    https://github.com/0day-ci/linux/commits/Xin-Long/xfrm-support-ipip-and-ipv6-tunnels-in-vti-and-xfrmi/20200630-154042
base:   https://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next.git master
config: x86_64-randconfig-a012-20200701 (attached as .config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build):
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   ld: net/xfrm/xfrm_interface.o: in function `xfrmi6_rcv_tunnel':
>> net/xfrm/xfrm_interface.c:807: undefined reference to `xfrm6_tunnel_spi_lookup'

vim +807 net/xfrm/xfrm_interface.c

   800	
   801	static int xfrmi6_rcv_tunnel(struct sk_buff *skb)
   802	{
   803		const xfrm_address_t *saddr;
   804		__be32 spi;
   805	
   806		saddr = (const xfrm_address_t *)&ipv6_hdr(skb)->saddr;
 > 807		spi = xfrm6_tunnel_spi_lookup(dev_net(skb->dev), saddr);
   808	
   809		return xfrm6_rcv_spi(skb, IPPROTO_IPV6, spi, NULL);
   810	}
   811	

---
0-DAY CI Kernel Test Service, Intel Corporation
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