net: fib_notifier: propagate possible error during fib notifier registration

Unlike events for registered notifier, during the registration, the
errors that happened for the block being registered are not propagated
up to the caller. Make sure the error is propagated for FIB rules and
entries.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_fib.h

@@ -229,7 +229,7 @@ int __net_init fib4_notifier_init(struct net *net);
 void __net_exit fib4_notifier_exit(struct net *net);
 
 void fib_info_notify_update(struct net *net, struct nl_info *info);
-void fib_notify(struct net *net, struct notifier_block *nb);
+int fib_notify(struct net *net, struct notifier_block *nb);
 
 struct fib_table {
 	struct hlist_node	tb_hlist;

net/core/fib_rules.c

@@ -354,15 +354,20 @@ int fib_rules_dump(struct net *net, struct notifier_block *nb, int family)
 {
 	struct fib_rules_ops *ops;
 	struct fib_rule *rule;
+	int err = 0;
 
 	ops = lookup_rules_ops(net, family);
 	if (!ops)
 		return -EAFNOSUPPORT;
-	list_for_each_entry_rcu(rule, &ops->rules_list, list)
-		call_fib_rule_notifier(nb, FIB_EVENT_RULE_ADD, rule, family);
+	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
+		err = call_fib_rule_notifier(nb, FIB_EVENT_RULE_ADD,
+					     rule, family);
+		if (err)
+			break;
+	}
 	rules_ops_put(ops);
 
-	return 0;
+	return err;
 }
 EXPORT_SYMBOL_GPL(fib_rules_dump);
 

net/ipv4/fib_notifier.c

@@ -42,9 +42,7 @@ static int fib4_dump(struct net *net, struct notifier_block *nb)
 	if (err)
 		return err;
 
-	fib_notify(net, nb);
-
-	return 0;
+	return fib_notify(net, nb);
 }
 
 static const struct fib_notifier_ops fib4_notifier_ops_template = {

net/ipv4/fib_trie.c

@@ -2015,10 +2015,11 @@ void fib_info_notify_update(struct net *net, struct nl_info *info)
 	}
 }
 
-static void fib_leaf_notify(struct key_vector *l, struct fib_table *tb,
-			    struct notifier_block *nb)
+static int fib_leaf_notify(struct key_vector *l, struct fib_table *tb,
+			   struct notifier_block *nb)
 {
 	struct fib_alias *fa;
+	int err;
 
 	hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
 		struct fib_info *fi = fa->fa_info;
@@ -2032,38 +2033,50 @@ static void fib_leaf_notify(struct key_vector *l, struct fib_table *tb,
 		if (tb->tb_id != fa->tb_id)
 			continue;
 
-		call_fib_entry_notifier(nb, FIB_EVENT_ENTRY_ADD, l->key,
-					KEYLENGTH - fa->fa_slen, fa);
+		err = call_fib_entry_notifier(nb, FIB_EVENT_ENTRY_ADD, l->key,
+					      KEYLENGTH - fa->fa_slen, fa);
+		if (err)
+			return err;
 	}
+	return 0;
 }
 
-static void fib_table_notify(struct fib_table *tb, struct notifier_block *nb)
+static int fib_table_notify(struct fib_table *tb, struct notifier_block *nb)
 {
 	struct trie *t = (struct trie *)tb->tb_data;
 	struct key_vector *l, *tp = t->kv;
 	t_key key = 0;
+	int err;
 
 	while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
-		fib_leaf_notify(l, tb, nb);
+		err = fib_leaf_notify(l, tb, nb);
+		if (err)
+			return err;
 
 		key = l->key + 1;
 		/* stop in case of wrap around */
 		if (key < l->key)
 			break;
 	}
+	return 0;
 }
 
-void fib_notify(struct net *net, struct notifier_block *nb)
+int fib_notify(struct net *net, struct notifier_block *nb)
 {
 	unsigned int h;
+	int err;
 
 	for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
 		struct hlist_head *head = &net->ipv4.fib_table_hash[h];
 		struct fib_table *tb;
 
-		hlist_for_each_entry_rcu(tb, head, tb_hlist)
-			fib_table_notify(tb, nb);
+		hlist_for_each_entry_rcu(tb, head, tb_hlist) {
+			err = fib_table_notify(tb, nb);
+			if (err)
+				return err;
+		}
 	}
+	return 0;
 }
 
 static void __trie_free_rcu(struct rcu_head *head)

net/ipv4/ipmr_base.c

@@ -409,17 +409,25 @@ int mr_dump(struct net *net, struct notifier_block *nb, unsigned short family,
 			if (!v->dev)
 				continue;
 
-			mr_call_vif_notifier(nb, family,
-					     FIB_EVENT_VIF_ADD,
-					     v, vifi, mrt->id);
+			err = mr_call_vif_notifier(nb, family,
+						   FIB_EVENT_VIF_ADD,
+						   v, vifi, mrt->id);
+			if (err)
+				break;
 		}
 		read_unlock(mrt_lock);
 
+		if (err)
+			return err;
+
 		/* Notify on table MFC entries */
-		list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list)
-			mr_call_mfc_notifier(nb, family,
-					     FIB_EVENT_ENTRY_ADD,
-					     mfc, mrt->id);
+		list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list) {
+			err = mr_call_mfc_notifier(nb, family,
+						   FIB_EVENT_ENTRY_ADD,
+						   mfc, mrt->id);
+			if (err)
+				return err;
+		}
 	}
 
 	return 0;

net/ipv6/ip6_fib.c

@@ -403,30 +403,37 @@ struct fib6_dump_arg {
 	struct notifier_block *nb;
 };
 
-static void fib6_rt_dump(struct fib6_info *rt, struct fib6_dump_arg *arg)
+static int fib6_rt_dump(struct fib6_info *rt, struct fib6_dump_arg *arg)
 {
 	if (rt == arg->net->ipv6.fib6_null_entry)
-		return;
-	call_fib6_entry_notifier(arg->nb, FIB_EVENT_ENTRY_ADD, rt);
+		return 0;
+	return call_fib6_entry_notifier(arg->nb, FIB_EVENT_ENTRY_ADD, rt);
 }
 
 static int fib6_node_dump(struct fib6_walker *w)
 {
 	struct fib6_info *rt;
+	int err = 0;
 
-	for_each_fib6_walker_rt(w)
-		fib6_rt_dump(rt, w->args);
+	for_each_fib6_walker_rt(w) {
+		err = fib6_rt_dump(rt, w->args);
+		if (err)
+			break;
+	}
 	w->leaf = NULL;
-	return 0;
+	return err;
 }
 
-static void fib6_table_dump(struct net *net, struct fib6_table *tb,
-			    struct fib6_walker *w)
+static int fib6_table_dump(struct net *net, struct fib6_table *tb,
+			   struct fib6_walker *w)
 {
+	int err;
+
 	w->root = &tb->tb6_root;
 	spin_lock_bh(&tb->tb6_lock);
-	fib6_walk(net, w);
+	err = fib6_walk(net, w);
 	spin_unlock_bh(&tb->tb6_lock);
+	return err;
 }
 
 /* Called with rcu_read_lock() */
@@ -435,6 +442,7 @@ int fib6_tables_dump(struct net *net, struct notifier_block *nb)
 	struct fib6_dump_arg arg;
 	struct fib6_walker *w;
 	unsigned int h;
+	int err = 0;
 
 	w = kzalloc(sizeof(*w), GFP_ATOMIC);
 	if (!w)
@@ -449,13 +457,17 @@ int fib6_tables_dump(struct net *net, struct notifier_block *nb)
 		struct hlist_head *head = &net->ipv6.fib_table_hash[h];
 		struct fib6_table *tb;
 
-		hlist_for_each_entry_rcu(tb, head, tb6_hlist)
-			fib6_table_dump(net, tb, w);
+		hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
+			err = fib6_table_dump(net, tb, w);
+			if (err < 0)
+				goto out;
+		}
 	}
 
+out:
 	kfree(w);
 
-	return 0;
+	return err;
 }
 
 static int fib6_dump_node(struct fib6_walker *w)