Merge branch 'tc-filter-cleanup-destroy-delete'

Cong Wang says:

====================
net_sched: clean up tc filter destroy and delete logic

The first patch fixes a potenial race condition, the second one
is pure cleanup.
====================
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

@@ -204,14 +204,14 @@ struct tcf_proto_ops {
 					    const struct tcf_proto *,
 					    struct tcf_result *);
 	int			(*init)(struct tcf_proto*);
-	bool			(*destroy)(struct tcf_proto*, bool);
+	void			(*destroy)(struct tcf_proto*);
 
 	unsigned long		(*get)(struct tcf_proto*, u32 handle);
 	int			(*change)(struct net *net, struct sk_buff *,
 					struct tcf_proto*, unsigned long,
 					u32 handle, struct nlattr **,
 					unsigned long *, bool);
-	int			(*delete)(struct tcf_proto*, unsigned long);
+	int			(*delete)(struct tcf_proto*, unsigned long, bool*);
 	void			(*walk)(struct tcf_proto*, struct tcf_walker *arg);
 
 	/* rtnetlink specific */

net/sched/cls_api.c

@@ -178,14 +178,11 @@ static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol,
 	return ERR_PTR(err);
 }
 
-static bool tcf_proto_destroy(struct tcf_proto *tp, bool force)
+static void tcf_proto_destroy(struct tcf_proto *tp)
 {
-	if (tp->ops->destroy(tp, force)) {
-		module_put(tp->ops->owner);
-		kfree_rcu(tp, rcu);
-		return true;
-	}
-	return false;
+	tp->ops->destroy(tp);
+	module_put(tp->ops->owner);
+	kfree_rcu(tp, rcu);
 }
 
 void tcf_destroy_chain(struct tcf_proto __rcu **fl)
@@ -194,7 +191,7 @@ void tcf_destroy_chain(struct tcf_proto __rcu **fl)
 
 	while ((tp = rtnl_dereference(*fl)) != NULL) {
 		RCU_INIT_POINTER(*fl, tp->next);
-		tcf_proto_destroy(tp, true);
+		tcf_proto_destroy(tp);
 	}
 }
 EXPORT_SYMBOL(tcf_destroy_chain);
@@ -361,7 +358,7 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
 			RCU_INIT_POINTER(*back, next);
 			tfilter_notify(net, skb, n, tp, fh,
 				       RTM_DELTFILTER, false);
-			tcf_proto_destroy(tp, true);
+			tcf_proto_destroy(tp);
 			err = 0;
 			goto errout;
 		}
@@ -372,24 +369,28 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
 			goto errout;
 		}
 	} else {
+		bool last;
+
 		switch (n->nlmsg_type) {
 		case RTM_NEWTFILTER:
 			if (n->nlmsg_flags & NLM_F_EXCL) {
 				if (tp_created)
-					tcf_proto_destroy(tp, true);
+					tcf_proto_destroy(tp);
 				err = -EEXIST;
 				goto errout;
 			}
 			break;
 		case RTM_DELTFILTER:
-			err = tp->ops->delete(tp, fh);
+			err = tp->ops->delete(tp, fh, &last);
 			if (err)
 				goto errout;
 			next = rtnl_dereference(tp->next);
 			tfilter_notify(net, skb, n, tp, t->tcm_handle,
 				       RTM_DELTFILTER, false);
-			if (tcf_proto_destroy(tp, false))
+			if (last) {
 				RCU_INIT_POINTER(*back, next);
+				tcf_proto_destroy(tp);
+			}
 			goto errout;
 		case RTM_GETTFILTER:
 			err = tfilter_notify(net, skb, n, tp, fh,
@@ -411,7 +412,7 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
 		tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER, false);
 	} else {
 		if (tp_created)
-			tcf_proto_destroy(tp, true);
+			tcf_proto_destroy(tp);
 	}
 
 errout:

net/sched/cls_basic.c

@@ -93,30 +93,28 @@ static void basic_delete_filter(struct rcu_head *head)
 	kfree(f);
 }
 
-static bool basic_destroy(struct tcf_proto *tp, bool force)
+static void basic_destroy(struct tcf_proto *tp)
 {
 	struct basic_head *head = rtnl_dereference(tp->root);
 	struct basic_filter *f, *n;
 
-	if (!force && !list_empty(&head->flist))
-		return false;
-
 	list_for_each_entry_safe(f, n, &head->flist, link) {
 		list_del_rcu(&f->link);
 		tcf_unbind_filter(tp, &f->res);
 		call_rcu(&f->rcu, basic_delete_filter);
 	}
 	kfree_rcu(head, rcu);
-	return true;
 }
 
-static int basic_delete(struct tcf_proto *tp, unsigned long arg)
+static int basic_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
+	struct basic_head *head = rtnl_dereference(tp->root);
 	struct basic_filter *f = (struct basic_filter *) arg;
 
 	list_del_rcu(&f->link);
 	tcf_unbind_filter(tp, &f->res);
 	call_rcu(&f->rcu, basic_delete_filter);
+	*last = list_empty(&head->flist);
 	return 0;
 }
 

net/sched/cls_bpf.c

@@ -274,25 +274,24 @@ static void __cls_bpf_delete(struct tcf_proto *tp, struct cls_bpf_prog *prog)
 	call_rcu(&prog->rcu, cls_bpf_delete_prog_rcu);
 }
 
-static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
+static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
+	struct cls_bpf_head *head = rtnl_dereference(tp->root);
+
 	__cls_bpf_delete(tp, (struct cls_bpf_prog *) arg);
+	*last = list_empty(&head->plist);
 	return 0;
 }
 
-static bool cls_bpf_destroy(struct tcf_proto *tp, bool force)
+static void cls_bpf_destroy(struct tcf_proto *tp)
 {
 	struct cls_bpf_head *head = rtnl_dereference(tp->root);
 	struct cls_bpf_prog *prog, *tmp;
 
-	if (!force && !list_empty(&head->plist))
-		return false;
-
 	list_for_each_entry_safe(prog, tmp, &head->plist, link)
 		__cls_bpf_delete(tp, prog);
 
 	kfree_rcu(head, rcu);
-	return true;
 }
 
 static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle)

net/sched/cls_cgroup.c

@@ -131,20 +131,16 @@ static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
 	return err;
 }
 
-static bool cls_cgroup_destroy(struct tcf_proto *tp, bool force)
+static void cls_cgroup_destroy(struct tcf_proto *tp)
 {
 	struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 
-	if (!force)
-		return false;
 	/* Head can still be NULL due to cls_cgroup_init(). */
 	if (head)
 		call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
-
-	return true;
 }
 
-static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
+static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
 	return -EOPNOTSUPP;
 }

net/sched/cls_flow.c

@@ -562,12 +562,14 @@ static int flow_change(struct net *net, struct sk_buff *in_skb,
 	return err;
 }
 
-static int flow_delete(struct tcf_proto *tp, unsigned long arg)
+static int flow_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
+	struct flow_head *head = rtnl_dereference(tp->root);
 	struct flow_filter *f = (struct flow_filter *)arg;
 
 	list_del_rcu(&f->list);
 	call_rcu(&f->rcu, flow_destroy_filter);
+	*last = list_empty(&head->filters);
 	return 0;
 }
 
@@ -583,20 +585,16 @@ static int flow_init(struct tcf_proto *tp)
 	return 0;
 }
 
-static bool flow_destroy(struct tcf_proto *tp, bool force)
+static void flow_destroy(struct tcf_proto *tp)
 {
 	struct flow_head *head = rtnl_dereference(tp->root);
 	struct flow_filter *f, *next;
 
-	if (!force && !list_empty(&head->filters))
-		return false;
-
 	list_for_each_entry_safe(f, next, &head->filters, list) {
 		list_del_rcu(&f->list);
 		call_rcu(&f->rcu, flow_destroy_filter);
 	}
 	kfree_rcu(head, rcu);
-	return true;
 }
 
 static unsigned long flow_get(struct tcf_proto *tp, u32 handle)

net/sched/cls_flower.c

@@ -328,21 +328,16 @@ static void fl_destroy_rcu(struct rcu_head *rcu)
 	schedule_work(&head->work);
 }
 
-static bool fl_destroy(struct tcf_proto *tp, bool force)
+static void fl_destroy(struct tcf_proto *tp)
 {
 	struct cls_fl_head *head = rtnl_dereference(tp->root);
 	struct cls_fl_filter *f, *next;
 
-	if (!force && !list_empty(&head->filters))
-		return false;
-
 	list_for_each_entry_safe(f, next, &head->filters, list)
 		__fl_delete(tp, f);
 
 	__module_get(THIS_MODULE);
 	call_rcu(&head->rcu, fl_destroy_rcu);
-
-	return true;
 }
 
 static unsigned long fl_get(struct tcf_proto *tp, u32 handle)
@@ -947,7 +942,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 	return err;
 }
 
-static int fl_delete(struct tcf_proto *tp, unsigned long arg)
+static int fl_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
 	struct cls_fl_head *head = rtnl_dereference(tp->root);
 	struct cls_fl_filter *f = (struct cls_fl_filter *) arg;
@@ -956,6 +951,7 @@ static int fl_delete(struct tcf_proto *tp, unsigned long arg)
 		rhashtable_remove_fast(&head->ht, &f->ht_node,
 				       head->ht_params);
 	__fl_delete(tp, f);
+	*last = list_empty(&head->filters);
 	return 0;
 }
 

net/sched/cls_fw.c

@@ -127,20 +127,14 @@ static void fw_delete_filter(struct rcu_head *head)
 	kfree(f);
 }
 
-static bool fw_destroy(struct tcf_proto *tp, bool force)
+static void fw_destroy(struct tcf_proto *tp)
 {
 	struct fw_head *head = rtnl_dereference(tp->root);
 	struct fw_filter *f;
 	int h;
 
 	if (head == NULL)
-		return true;
-
-	if (!force) {
-		for (h = 0; h < HTSIZE; h++)
-			if (rcu_access_pointer(head->ht[h]))
-				return false;
-	}
+		return;
 
 	for (h = 0; h < HTSIZE; h++) {
 		while ((f = rtnl_dereference(head->ht[h])) != NULL) {
@@ -150,17 +144,17 @@ static bool fw_destroy(struct tcf_proto *tp, bool force)
 			call_rcu(&f->rcu, fw_delete_filter);
 		}
 	}
-	RCU_INIT_POINTER(tp->root, NULL);
 	kfree_rcu(head, rcu);
-	return true;
 }
 
-static int fw_delete(struct tcf_proto *tp, unsigned long arg)
+static int fw_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
 	struct fw_head *head = rtnl_dereference(tp->root);
 	struct fw_filter *f = (struct fw_filter *)arg;
 	struct fw_filter __rcu **fp;
 	struct fw_filter *pfp;
+	int ret = -EINVAL;
+	int h;
 
 	if (head == NULL || f == NULL)
 		goto out;
@@ -173,11 +167,21 @@ static int fw_delete(struct tcf_proto *tp, unsigned long arg)
 			RCU_INIT_POINTER(*fp, rtnl_dereference(f->next));
 			tcf_unbind_filter(tp, &f->res);
 			call_rcu(&f->rcu, fw_delete_filter);
-			return 0;
+			ret = 0;
+			break;
 		}
 	}
+
+	*last = true;
+	for (h = 0; h < HTSIZE; h++) {
+		if (rcu_access_pointer(head->ht[h])) {
+			*last = false;
+			break;
+		}
+	}
+
 out:
-	return -EINVAL;
+	return ret;
 }
 
 static const struct nla_policy fw_policy[TCA_FW_MAX + 1] = {

net/sched/cls_matchall.c

@@ -90,19 +90,18 @@ static void mall_destroy_hw_filter(struct tcf_proto *tp,
 					     &offload);
 }
 
-static bool mall_destroy(struct tcf_proto *tp, bool force)
+static void mall_destroy(struct tcf_proto *tp)
 {
 	struct cls_mall_head *head = rtnl_dereference(tp->root);
 	struct net_device *dev = tp->q->dev_queue->dev;
 
 	if (!head)
-		return true;
+		return;
 
 	if (tc_should_offload(dev, tp, head->flags))
 		mall_destroy_hw_filter(tp, head, (unsigned long) head);
 
 	call_rcu(&head->rcu, mall_destroy_rcu);
-	return true;
 }
 
 static unsigned long mall_get(struct tcf_proto *tp, u32 handle)
@@ -216,7 +215,7 @@ static int mall_change(struct net *net, struct sk_buff *in_skb,
 	return err;
 }
 
-static int mall_delete(struct tcf_proto *tp, unsigned long arg)
+static int mall_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
 	return -EOPNOTSUPP;
 }

net/sched/cls_route.c

@@ -140,8 +140,6 @@ static int route4_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 		goto failure;
 
 	id = dst->tclassid;
-	if (head == NULL)
-		goto old_method;
 
 	iif = inet_iif(skb);
 
@@ -194,15 +192,6 @@ static int route4_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 		route4_set_fastmap(head, id, iif, ROUTE4_FAILURE);
 failure:
 	return -1;
-
-old_method:
-	if (id && (TC_H_MAJ(id) == 0 ||
-		   !(TC_H_MAJ(id^tp->q->handle)))) {
-		res->classid = id;
-		res->class = 0;
-		return 0;
-	}
-	return -1;
 }
 
 static inline u32 to_hash(u32 id)
@@ -234,9 +223,6 @@ static unsigned long route4_get(struct tcf_proto *tp, u32 handle)
 	struct route4_filter *f;
 	unsigned int h1, h2;
 
-	if (!head)
-		return 0;
-
 	h1 = to_hash(handle);
 	if (h1 > 256)
 		return 0;
@@ -276,20 +262,13 @@ static void route4_delete_filter(struct rcu_head *head)
 	kfree(f);
 }
 
-static bool route4_destroy(struct tcf_proto *tp, bool force)
+static void route4_destroy(struct tcf_proto *tp)
 {
 	struct route4_head *head = rtnl_dereference(tp->root);
 	int h1, h2;
 
 	if (head == NULL)
-		return true;
-
-	if (!force) {
-		for (h1 = 0; h1 <= 256; h1++) {
-			if (rcu_access_pointer(head->table[h1]))
-				return false;
-		}
-	}
+		return;
 
 	for (h1 = 0; h1 <= 256; h1++) {
 		struct route4_bucket *b;
@@ -312,12 +291,10 @@ static bool route4_destroy(struct tcf_proto *tp, bool force)
 			kfree_rcu(b, rcu);
 		}
 	}
-	RCU_INIT_POINTER(tp->root, NULL);
 	kfree_rcu(head, rcu);
-	return true;
 }
 
-static int route4_delete(struct tcf_proto *tp, unsigned long arg)
+static int route4_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
 	struct route4_head *head = rtnl_dereference(tp->root);
 	struct route4_filter *f = (struct route4_filter *)arg;
@@ -325,7 +302,7 @@ static int route4_delete(struct tcf_proto *tp, unsigned long arg)
 	struct route4_filter *nf;
 	struct route4_bucket *b;
 	unsigned int h = 0;
-	int i;
+	int i, h1;
 
 	if (!head || !f)
 		return -EINVAL;
@@ -356,16 +333,25 @@ static int route4_delete(struct tcf_proto *tp, unsigned long arg)
 
 				rt = rtnl_dereference(b->ht[i]);
 				if (rt)
-					return 0;
+					goto out;
 			}
 
 			/* OK, session has no flows */
 			RCU_INIT_POINTER(head->table[to_hash(h)], NULL);
 			kfree_rcu(b, rcu);
+			break;
+		}
+	}
 
-			return 0;
+out:
+	*last = true;
+	for (h1 = 0; h1 <= 256; h1++) {
+		if (rcu_access_pointer(head->table[h1])) {
+			*last = false;
+			break;
 		}
 	}
+
 	return 0;
 }
 

net/sched/cls_rsvp.h

@@ -152,8 +152,6 @@ static int rsvp_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 		return -1;
 	nhptr = ip_hdr(skb);
 #endif
-	if (unlikely(!head))
-		return -1;
 restart:
 
 #if RSVP_DST_LEN == 4
@@ -302,22 +300,13 @@ static void rsvp_delete_filter(struct tcf_proto *tp, struct rsvp_filter *f)
 	call_rcu(&f->rcu, rsvp_delete_filter_rcu);
 }
 
-static bool rsvp_destroy(struct tcf_proto *tp, bool force)
+static void rsvp_destroy(struct tcf_proto *tp)
 {
 	struct rsvp_head *data = rtnl_dereference(tp->root);
 	int h1, h2;
 
 	if (data == NULL)
-		return true;
-
-	if (!force) {
-		for (h1 = 0; h1 < 256; h1++) {
-			if (rcu_access_pointer(data->ht[h1]))
-				return false;
-		}
-	}
-
-	RCU_INIT_POINTER(tp->root, NULL);
+		return;
 
 	for (h1 = 0; h1 < 256; h1++) {
 		struct rsvp_session *s;
@@ -337,10 +326,9 @@ static bool rsvp_destroy(struct tcf_proto *tp, bool force)
 		}
 	}
 	kfree_rcu(data, rcu);
-	return true;
 }
 
-static int rsvp_delete(struct tcf_proto *tp, unsigned long arg)
+static int rsvp_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
 	struct rsvp_head *head = rtnl_dereference(tp->root);
 	struct rsvp_filter *nfp, *f = (struct rsvp_filter *)arg;
@@ -348,7 +336,7 @@ static int rsvp_delete(struct tcf_proto *tp, unsigned long arg)
 	unsigned int h = f->handle;
 	struct rsvp_session __rcu **sp;
 	struct rsvp_session *nsp, *s = f->sess;
-	int i;
+	int i, h1;
 
 	fp = &s->ht[(h >> 8) & 0xFF];
 	for (nfp = rtnl_dereference(*fp); nfp;
@@ -361,7 +349,7 @@ static int rsvp_delete(struct tcf_proto *tp, unsigned long arg)
 
 			for (i = 0; i <= 16; i++)
 				if (s->ht[i])
-					return 0;
+					goto out;
 
 			/* OK, session has no flows */
 			sp = &head->ht[h & 0xFF];
@@ -370,13 +358,23 @@ static int rsvp_delete(struct tcf_proto *tp, unsigned long arg)
 				if (nsp == s) {
 					RCU_INIT_POINTER(*sp, s->next);
 					kfree_rcu(s, rcu);
-					return 0;
+					goto out;
 				}
 			}
 
-			return 0;
+			break;
 		}
 	}
+
+out:
+	*last = true;
+	for (h1 = 0; h1 < 256; h1++) {
+		if (rcu_access_pointer(head->ht[h1])) {
+			*last = false;
+			break;
+		}
+	}
+
 	return 0;
 }
 

net/sched/cls_tcindex.c

@@ -150,7 +150,7 @@ static void tcindex_destroy_fexts(struct rcu_head *head)
 	kfree(f);
 }
 
-static int tcindex_delete(struct tcf_proto *tp, unsigned long arg)
+static int tcindex_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
 	struct tcindex_data *p = rtnl_dereference(tp->root);
 	struct tcindex_filter_result *r = (struct tcindex_filter_result *) arg;
@@ -186,6 +186,8 @@ static int tcindex_delete(struct tcf_proto *tp, unsigned long arg)
 		call_rcu(&f->rcu, tcindex_destroy_fexts);
 	else
 		call_rcu(&r->rcu, tcindex_destroy_rexts);
+
+	*last = false;
 	return 0;
 }
 
@@ -193,7 +195,9 @@ static int tcindex_destroy_element(struct tcf_proto *tp,
 				   unsigned long arg,
 				   struct tcf_walker *walker)
 {
-	return tcindex_delete(tp, arg);
+	bool last;
+
+	return tcindex_delete(tp, arg, &last);
 }
 
 static void __tcindex_destroy(struct rcu_head *head)
@@ -529,14 +533,11 @@ static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker)
 	}
 }
 
-static bool tcindex_destroy(struct tcf_proto *tp, bool force)
+static void tcindex_destroy(struct tcf_proto *tp)
 {
 	struct tcindex_data *p = rtnl_dereference(tp->root);
 	struct tcf_walker walker;
 
-	if (!force)
-		return false;
-
 	pr_debug("tcindex_destroy(tp %p),p %p\n", tp, p);
 	walker.count = 0;
 	walker.skip = 0;
@@ -544,7 +545,6 @@ static bool tcindex_destroy(struct tcf_proto *tp, bool force)
 	tcindex_walk(tp, &walker);
 
 	call_rcu(&p->rcu, __tcindex_destroy);
-	return true;
 }
 
 

net/sched/cls_u32.c

@@ -585,37 +585,13 @@ static bool ht_empty(struct tc_u_hnode *ht)
 	return true;
 }
 
-static bool u32_destroy(struct tcf_proto *tp, bool force)
+static void u32_destroy(struct tcf_proto *tp)
 {
 	struct tc_u_common *tp_c = tp->data;
 	struct tc_u_hnode *root_ht = rtnl_dereference(tp->root);
 
 	WARN_ON(root_ht == NULL);
 
-	if (!force) {
-		if (root_ht) {
-			if (root_ht->refcnt > 1)
-				return false;
-			if (root_ht->refcnt == 1) {
-				if (!ht_empty(root_ht))
-					return false;
-			}
-		}
-
-		if (tp_c->refcnt > 1)
-			return false;
-
-		if (tp_c->refcnt == 1) {
-			struct tc_u_hnode *ht;
-
-			for (ht = rtnl_dereference(tp_c->hlist);
-			     ht;
-			     ht = rtnl_dereference(ht->next))
-				if (!ht_empty(ht))
-					return false;
-		}
-	}
-
 	if (root_ht && --root_ht->refcnt == 0)
 		u32_destroy_hnode(tp, root_ht);
 
@@ -640,20 +616,22 @@ static bool u32_destroy(struct tcf_proto *tp, bool force)
 	}
 
 	tp->data = NULL;
-	return true;
 }
 
-static int u32_delete(struct tcf_proto *tp, unsigned long arg)
+static int u32_delete(struct tcf_proto *tp, unsigned long arg, bool *last)
 {
 	struct tc_u_hnode *ht = (struct tc_u_hnode *)arg;
 	struct tc_u_hnode *root_ht = rtnl_dereference(tp->root);
+	struct tc_u_common *tp_c = tp->data;
+	int ret = 0;
 
 	if (ht == NULL)
-		return 0;
+		goto out;
 
 	if (TC_U32_KEY(ht->handle)) {
 		u32_remove_hw_knode(tp, ht->handle);
-		return u32_delete_key(tp, (struct tc_u_knode *)ht);
+		ret = u32_delete_key(tp, (struct tc_u_knode *)ht);
+		goto out;
 	}
 
 	if (root_ht == ht)
@@ -666,7 +644,40 @@ static int u32_delete(struct tcf_proto *tp, unsigned long arg)
 		return -EBUSY;
 	}
 
-	return 0;
+out:
+	*last = true;
+	if (root_ht) {
+		if (root_ht->refcnt > 1) {
+			*last = false;
+			goto ret;
+		}
+		if (root_ht->refcnt == 1) {
+			if (!ht_empty(root_ht)) {
+				*last = false;
+				goto ret;
+			}
+		}
+	}
+
+	if (tp_c->refcnt > 1) {
+		*last = false;
+		goto ret;
+	}
+
+	if (tp_c->refcnt == 1) {
+		struct tc_u_hnode *ht;
+
+		for (ht = rtnl_dereference(tp_c->hlist);
+		     ht;
+		     ht = rtnl_dereference(ht->next))
+			if (!ht_empty(ht)) {
+				*last = false;
+				break;
+			}
+	}
+
+ret:
+	return ret;
 }
 
 #define NR_U32_NODE (1<<12)