[PATCH net-next 07/10] ipv6: Be smarter with null_entry handling in ip6_pol_route_lookup

[David Ahern]

From: David Ahern <dsah...@gmail.com>

Clean up the fib6_null_entry handling in ip6_pol_route_lookup.
rt6_device_match can return fib6_null_entry, but fib6_multipath_select
can not. Consolidate the fib6_null_entry handling and on the final
null_entry check set rt and goto out - no need to defer to a second
check after rt6_find_cached_rt.

Signed-off-by: David Ahern <dsah...@gmail.com>
---
 net/ipv6/route.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 52aa48a8dbda..0745ed872e5b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1062,36 +1062,37 @@ static struct rt6_info *ip6_pol_route_lookup(struct net 
*net,
        fn = fib6_node_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
 restart:
        f6i = rcu_dereference(fn->leaf);
-       if (!f6i) {
+       if (!f6i)
                f6i = net->ipv6.fib6_null_entry;
-       } else {
+       else
                f6i = rt6_device_match(net, f6i, &fl6->saddr,
                                      fl6->flowi6_oif, flags);
-               if (f6i->fib6_nsiblings && fl6->flowi6_oif == 0)
-                       f6i = fib6_multipath_select(net, f6i, fl6,
-                                                   fl6->flowi6_oif, skb,
-                                                   flags);
-       }
+
        if (f6i == net->ipv6.fib6_null_entry) {
                fn = fib6_backtrack(fn, &fl6->saddr);
                if (fn)
                        goto restart;
-       }
 
-       trace_fib6_table_lookup(net, f6i, table, fl6);
+               rt = net->ipv6.ip6_null_entry;
+               dst_hold(&rt->dst);
+               goto out;
+       }
 
+       if (f6i->fib6_nsiblings && fl6->flowi6_oif == 0)
+               f6i = fib6_multipath_select(net, f6i, fl6, fl6->flowi6_oif, skb,
+                                           flags);
        /* Search through exception table */
        rt = rt6_find_cached_rt(f6i, &fl6->daddr, &fl6->saddr);
        if (rt) {
                if (ip6_hold_safe(net, &rt))
                        dst_use_noref(&rt->dst, jiffies);
-       } else if (f6i == net->ipv6.fib6_null_entry) {
-               rt = net->ipv6.ip6_null_entry;
-               dst_hold(&rt->dst);
        } else {
                rt = ip6_create_rt_rcu(f6i);
        }
 
+out:
+       trace_fib6_table_lookup(net, f6i, table, fl6);
+
        rcu_read_unlock();
 
        return rt;
-- 
2.11.0