Hi Wei,

Thank you for the patch! Yet something to improve:

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

url:    https://github.com/0day-ci/linux/commits/Wei-Wang/ipv6-avoid-taking-refcnt-on-dst-during-route-lookup/20190621-052244
config: i386-randconfig-x077-201924 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

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

All errors (new ones prefixed by >>):

   In file included from drivers/net/ipvlan/ipvlan.h:23:0,
                    from drivers/net/ipvlan/ipvlan_main.c:5:
   include/net/ip6_route.h: In function 'ip6_route_output_flags':
>> include/net/ip6_route.h:103:15: error: 'struct net' has no member named 'ipv6'; did you mean 'ipv4'?
      dst = &net->ipv6.ip6_null_entry->dst;
                  ^~~~
                  ipv4

vim +103 include/net/ip6_route.h

    80	
    81	void ip6_route_input(struct sk_buff *skb);
    82	struct dst_entry *ip6_route_input_lookup(struct net *net,
    83						 struct net_device *dev,
    84						 struct flowi6 *fl6,
    85						 const struct sk_buff *skb, int flags);
    86	
    87	struct dst_entry *ip6_route_output_flags_noref(struct net *net,
    88						       const struct sock *sk,
    89						       struct flowi6 *fl6, int flags);
    90	
    91	static inline struct dst_entry *ip6_route_output_flags(struct net *net,
    92							       const struct sock *sk,
    93							       struct flowi6 *fl6,
    94							       int flags) {
    95		struct dst_entry *dst;
    96		struct rt6_info *rt6;
    97	
    98		rcu_read_lock();
    99		dst = ip6_route_output_flags_noref(net, sk, fl6, flags);
   100		rt6 = (struct rt6_info *)dst;
   101		/* For dst cached in uncached_list, refcnt is already taken. */
   102		if (list_empty(&rt6->rt6i_uncached) && !dst_hold_safe(dst)) {
 > 103			dst = &net->ipv6.ip6_null_entry->dst;
   104			dst_hold(dst);
   105		}
   106		rcu_read_unlock();
   107	
   108		return dst;
   109	}
   110	

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