[IPV4]: Fix rt_score() and usage when purging rtcache hash chains.

net/ipv4/route.c

@@ -463,7 +463,9 @@ out:	return ret;
  */
 static inline u32 rt_score(struct rtable *rt)
 {
-	u32 score = rt->u.dst.__use;
+	u32 score = jiffies - rt->u.dst.lastuse;
+
+	score = ~score & ~(3<<30);
 
 	if (rt_valuable(rt))
 		score |= (1<<31);
@@ -805,8 +807,7 @@ static int rt_intern_hash(unsigned hash, struct rtable *rt, struct rtable **rp)
 		 * The second limit is less certain. At the moment it allows
 		 * only 2 entries per bucket. We will see.
 		 */
-		if (chain_length > ip_rt_gc_elasticity ||
-		    (chain_length > 1 && !(min_score & (1<<31)))) {
+		if (chain_length > ip_rt_gc_elasticity) {
 			*candp = cand->u.rt_next;
 			rt_free(cand);
 		}