Revert "ipv4: restore rt->fi for reference counting"

This reverts commit 82486aa6.

As implemented, this causes dangling netdevice refs.
Reported-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/route.h

@@ -69,7 +69,6 @@ struct rtable {
 
 	struct list_head	rt_uncached;
 	struct uncached_list	*rt_uncached_list;
-	struct fib_info		*fi; /* for refcnt to shared metrics */
 };
 
 static inline bool rt_is_input_route(const struct rtable *rt)

net/ipv4/route.c

@@ -1387,11 +1387,6 @@ static void ipv4_dst_destroy(struct dst_entry *dst)
 {
 	struct rtable *rt = (struct rtable *) dst;
 
-	if (rt->fi) {
-		fib_info_put(rt->fi);
-		rt->fi = NULL;
-	}
-
 	if (!list_empty(&rt->rt_uncached)) {
 		struct uncached_list *ul = rt->rt_uncached_list;
 
@@ -1429,16 +1424,6 @@ static bool rt_cache_valid(const struct rtable *rt)
 		!rt_is_expired(rt);
 }
 
-static void rt_init_metrics(struct rtable *rt, struct fib_info *fi)
-{
-	if (fi->fib_metrics != (u32 *)dst_default_metrics) {
-		fib_info_hold(fi);
-		rt->fi = fi;
-	}
-
-	dst_init_metrics(&rt->dst, fi->fib_metrics, true);
-}
-
 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
 			   const struct fib_result *res,
 			   struct fib_nh_exception *fnhe,
@@ -1453,7 +1438,7 @@ static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
 			rt->rt_gateway = nh->nh_gw;
 			rt->rt_uses_gateway = 1;
 		}
-		rt_init_metrics(rt, fi);
+		dst_init_metrics(&rt->dst, fi->fib_metrics, true);
 #ifdef CONFIG_IP_ROUTE_CLASSID
 		rt->dst.tclassid = nh->nh_tclassid;
 #endif
@@ -1505,7 +1490,6 @@ struct rtable *rt_dst_alloc(struct net_device *dev,
 		rt->rt_gateway = 0;
 		rt->rt_uses_gateway = 0;
 		rt->rt_table_id = 0;
-		rt->fi = NULL;
 		INIT_LIST_HEAD(&rt->rt_uncached);
 
 		rt->dst.output = ip_output;