[NET_SCHED] cls_u32: refcounting fix for u32_delete()

Deleting of nonroot hnodes mostly doesn't work in u32_delete():
refcnt == 1 is expected, but such hnodes' refcnts are initialized
with 0 and charged only with "link" nodes. Now they'll start with
1 like usual. Thanks to Patrick McHardy for an improving suggestion.
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_u32.c

@@ -411,8 +411,10 @@ static void u32_destroy(struct tcf_proto *tp)
 			}
 		}
 
-		for (ht=tp_c->hlist; ht; ht = ht->next)
+		for (ht = tp_c->hlist; ht; ht = ht->next) {
+			ht->refcnt--;
 			u32_clear_hnode(tp, ht);
+		}
 
 		while ((ht = tp_c->hlist) != NULL) {
 			tp_c->hlist = ht->next;
@@ -441,8 +443,12 @@ static int u32_delete(struct tcf_proto *tp, unsigned long arg)
 	if (tp->root == ht)
 		return -EINVAL;
 
-	if (--ht->refcnt == 0)
+	if (ht->refcnt == 1) {
+		ht->refcnt--;
 		u32_destroy_hnode(tp, ht);
+	} else {
+		return -EBUSY;
+	}
 
 	return 0;
 }
@@ -568,7 +574,7 @@ static int u32_change(struct tcf_proto *tp, unsigned long base, u32 handle,
 		if (ht == NULL)
 			return -ENOBUFS;
 		ht->tp_c = tp_c;
-		ht->refcnt = 0;
+		ht->refcnt = 1;
 		ht->divisor = divisor;
 		ht->handle = handle;
 		ht->prio = tp->prio;