[IPV6]: Use time_after() etc. for comparing jiffies.

net/ipv6/ip6_fib.c

@@ -1179,14 +1179,14 @@ static int fib6_age(struct rt6_info *rt, void *arg)
 	 */
 
 	if (rt->rt6i_flags&RTF_EXPIRES && rt->rt6i_expires) {
-		if ((long)(now - rt->rt6i_expires) > 0) {
+		if (time_after(now, rt->rt6i_expires)) {
 			RT6_TRACE("expiring %p\n", rt);
 			return -1;
 		}
 		gc_args.more++;
 	} else if (rt->rt6i_flags & RTF_CACHE) {
 		if (atomic_read(&rt->u.dst.__refcnt) == 0 &&
-		    (long)(now - rt->u.dst.lastuse) >= gc_args.timeout) {
+		    time_after_eq(now, rt->u.dst.lastuse + gc_args.timeout)) {
 			RT6_TRACE("aging clone %p\n", rt);
 			return -1;
 		}

net/ipv6/route.c

@@ -565,7 +565,7 @@ static int ip6_dst_gc()
 	static unsigned long last_gc;
 	unsigned long now = jiffies;
 
-	if ((long)(now - last_gc) < ip6_rt_gc_min_interval &&
+	if (time_after(last_gc + ip6_rt_gc_min_interval, now) &&
 	    atomic_read(&ip6_dst_ops.entries) <= ip6_rt_max_size)
 		goto out;