ipv6: Create RTF_CACHE clone when FLOWI_FLAG_KNOWN_NH is set

This patch always creates RTF_CACHE clone with DST_NOCACHE
when FLOWI_FLAG_KNOWN_NH is set so that the rt6i_dst is set to
the fl6->daddr.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Tested-by: Julian Anastasov <ja@ssi.bg>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index a4bece6797da217edf561c1099ae9d02de14a4e7..5556111022eba601781ec7cff0b963b7d72584dc 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -161,6 +161,9 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout)
 
 static inline u32 rt6_get_cookie(const struct rt6_info *rt)
 {
+       if (unlikely(rt->dst.flags & DST_NOCACHE))
+               rt = (struct rt6_info *)(rt->dst.from);
+
        return rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
 }
 

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index e7ae2430dfed805985e9390069b64c093a486cbb..9e4c3c5d159163443b8b06c902dab9ac97e7a721 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -901,13 +901,34 @@ redo_rt6_select:
                }
        }
 
-       dst_hold(&rt->dst);
+       dst_use(&rt->dst, jiffies);
        read_unlock_bh(&table->tb6_lock);
 
-       rt6_dst_from_metrics_check(rt);
-       rt->dst.lastuse = jiffies;
-       rt->dst.__use++;
+       if (rt == net->ipv6.ip6_null_entry || (rt->rt6i_flags & RTF_CACHE)) {
+               goto done;
+       } else if (unlikely((fl6->flowi6_flags & FLOWI_FLAG_KNOWN_NH) &&
+                           !(rt->rt6i_flags & RTF_GATEWAY))) {
+               /* Create a RTF_CACHE clone which will not be
+                * owned by the fib6 tree.  It is for the special case where
+                * the daddr in the skb during the neighbor look-up is different
+                * from the fl6->daddr used to look-up route here.
+                */
+
+               struct rt6_info *uncached_rt;
+
+               uncached_rt = ip6_rt_cache_alloc(rt, &fl6->daddr, NULL);
+               dst_release(&rt->dst);
+
+               if (uncached_rt)
+                       uncached_rt->dst.flags |= DST_NOCACHE;
+               else
+                       uncached_rt = net->ipv6.ip6_null_entry;
+               dst_hold(&uncached_rt->dst);
+               return uncached_rt;
+       }
 
+done:
+       rt6_dst_from_metrics_check(rt);
        return rt;
 }
 
@@ -1019,6 +1040,26 @@ static void rt6_dst_from_metrics_check(struct rt6_info *rt)
                dst_init_metrics(&rt->dst, dst_metrics_ptr(rt->dst.from), true);
 }
 
+static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie)
+{
+       if (!rt->rt6i_node || (rt->rt6i_node->fn_sernum != cookie))
+               return NULL;
+
+       if (rt6_check_expired(rt))
+               return NULL;
+
+       return &rt->dst;
+}
+
+static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt, u32 cookie)
+{
+       if (rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
+           rt6_check((struct rt6_info *)(rt->dst.from), cookie))
+               return &rt->dst;
+       else
+               return NULL;
+}
+
 static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
 {
        struct rt6_info *rt;
@@ -1029,15 +1070,13 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
         * DST_OBSOLETE_FORCE_CHK which forces validation calls down
         * into this function always.
         */
-       if (!rt->rt6i_node || (rt->rt6i_node->fn_sernum != cookie))
-               return NULL;
-
-       if (rt6_check_expired(rt))
-               return NULL;
 
        rt6_dst_from_metrics_check(rt);
 
-       return dst;
+       if (unlikely(dst->flags & DST_NOCACHE))
+               return rt6_dst_from_check(rt, cookie);
+       else
+               return rt6_check(rt, cookie);
 }
 
 static struct dst_entry *ip6_negative_advice(struct dst_entry *dst)