ipv6: Avoid redoing fib6_lookup() with reachable = 0 by saving fn

This patch save the fn before doing rt6_backtrack.
Hence, without redo-ing the fib6_lookup(), saved_fn can be used
to redo rt6_select() with RT6_LOOKUP_F_REACHABLE off.

Some minor changes I think make sense to review as a single patch:
* Remove the 'out:' goto label.
* Remove the 'reachable' variable. Only use the 'strict' variable instead.

After this patch, "failing ip6_ins_rt()" should be the only case that
requires a redo of fib6_lookup().

Cc: David Miller <davem@davemloft.net>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 98c523f..c910831 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -917,31 +917,40 @@ static struct rt6_info *rt6_alloc_clone(struct rt6_info *ort,
 static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table, int oif,
                                      struct flowi6 *fl6, int flags)
 {
-       struct fib6_node *fn;
+       struct fib6_node *fn, *saved_fn;
        struct rt6_info *rt, *nrt;
        int strict = 0;
        int attempts = 3;
        int err;
-       int reachable = net->ipv6.devconf_all->forwarding ? 0 : RT6_LOOKUP_F_REACHABLE;
 
        strict |= flags & RT6_LOOKUP_F_IFACE;
+       if (net->ipv6.devconf_all->forwarding == 0)
+               strict |= RT6_LOOKUP_F_REACHABLE;
 
 redo_fib6_lookup_lock:
        read_lock_bh(&table->tb6_lock);
 
-redo_fib6_lookup:
        fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
+       saved_fn = fn;
 
 redo_rt6_select:
-       rt = rt6_select(fn, oif, strict | reachable);
+       rt = rt6_select(fn, oif, strict);
        if (rt->rt6i_nsiblings)
-               rt = rt6_multipath_select(rt, fl6, oif, strict | reachable);
+               rt = rt6_multipath_select(rt, fl6, oif, strict);
        if (rt == net->ipv6.ip6_null_entry) {
                fn = fib6_backtrack(fn, &fl6->saddr);
                if (fn)
                        goto redo_rt6_select;
-               else
-                       goto out;
+               else if (strict & RT6_LOOKUP_F_REACHABLE) {
+                       /* also consider unreachable route */
+                       strict &= ~RT6_LOOKUP_F_REACHABLE;
+                       fn = saved_fn;
+                       goto redo_rt6_select;
+               } else {
+                       dst_hold(&rt->dst);
+                       read_unlock_bh(&table->tb6_lock);
+                       goto out2;
+               }
        }
 
        dst_hold(&rt->dst);
@@ -977,13 +986,6 @@ redo_rt6_select:
        ip6_rt_put(rt);
        goto redo_fib6_lookup_lock;
 
-out:
-       if (reachable) {
-               reachable = 0;
-               goto redo_fib6_lookup;
-       }
-       dst_hold(&rt->dst);
-       read_unlock_bh(&table->tb6_lock);
 out2:
        rt->dst.lastuse = jiffies;
        rt->dst.__use++;