net: fib_notifier: make FIB notifier per-netns

Currently all users of FIB notifier only cares about events in init_net.
Later in this patchset, users get interested in other namespaces too.
However, for every registered block user is interested only about one
namespace. Make the FIB notifier registration per-netns and avoid
unnecessary calls of notifier block for other namespaces.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 39 insertions, 48 deletions

diff --git a/net/core/fib_notifier.c b/net/core/fib_notifier.c
index 470a606d5e8d..fbd029425638 100644
--- a/net/core/fib_notifier.c
+++ b/net/core/fib_notifier.c
@@ -12,17 +12,15 @@ static unsigned int fib_notifier_net_id;
 
 struct fib_notifier_net {
 	struct list_head fib_notifier_ops;
+	struct atomic_notifier_head fib_chain;
 };
 
-static ATOMIC_NOTIFIER_HEAD(fib_chain);
-
-int call_fib_notifier(struct notifier_block *nb, struct net *net,
+int call_fib_notifier(struct notifier_block *nb,
 		      enum fib_event_type event_type,
 		      struct fib_notifier_info *info)
 {
 	int err;
 
-	info->net = net;
 	err = nb->notifier_call(nb, event_type, info);
 	return notifier_to_errno(err);
 }
@@ -31,35 +29,29 @@ EXPORT_SYMBOL(call_fib_notifier);
 int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
 		       struct fib_notifier_info *info)
 {
+	struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
 	int err;
 
-	info->net = net;
-	err = atomic_notifier_call_chain(&fib_chain, event_type, info);
+	err = atomic_notifier_call_chain(&fn_net->fib_chain, event_type, info);
 	return notifier_to_errno(err);
 }
 EXPORT_SYMBOL(call_fib_notifiers);
 
-static unsigned int fib_seq_sum(void)
+static unsigned int fib_seq_sum(struct net *net)
 {
-	struct fib_notifier_net *fn_net;
+	struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
 	struct fib_notifier_ops *ops;
 	unsigned int fib_seq = 0;
-	struct net *net;
 
 	rtnl_lock();
-	down_read(&net_rwsem);
-	for_each_net(net) {
-		fn_net = net_generic(net, fib_notifier_net_id);
-		rcu_read_lock();
-		list_for_each_entry_rcu(ops, &fn_net->fib_notifier_ops, list) {
-			if (!try_module_get(ops->owner))
-				continue;
-			fib_seq += ops->fib_seq_read(net);
-			module_put(ops->owner);
-		}
-		rcu_read_unlock();
+	rcu_read_lock();
+	list_for_each_entry_rcu(ops, &fn_net->fib_notifier_ops, list) {
+		if (!try_module_get(ops->owner))
+			continue;
+		fib_seq += ops->fib_seq_read(net);
+		module_put(ops->owner);
 	}
-	up_read(&net_rwsem);
+	rcu_read_unlock();
 	rtnl_unlock();
 
 	return fib_seq;
@@ -69,68 +61,66 @@ static int fib_net_dump(struct net *net, struct notifier_block *nb)
 {
 	struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
 	struct fib_notifier_ops *ops;
+	int err = 0;
 
+	rcu_read_lock();
 	list_for_each_entry_rcu(ops, &fn_net->fib_notifier_ops, list) {
-		int err;
-
 		if (!try_module_get(ops->owner))
 			continue;
 		err = ops->fib_dump(net, nb);
 		module_put(ops->owner);
 		if (err)
-			return err;
+			goto unlock;
 	}
 
-	return 0;
+unlock:
+	rcu_read_unlock();
+
+	return err;
 }
 
-static bool fib_dump_is_consistent(struct notifier_block *nb,
+static bool fib_dump_is_consistent(struct net *net, struct notifier_block *nb,
 				   void (*cb)(struct notifier_block *nb),
 				   unsigned int fib_seq)
 {
-	atomic_notifier_chain_register(&fib_chain, nb);
-	if (fib_seq == fib_seq_sum())
+	struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
+
+	atomic_notifier_chain_register(&fn_net->fib_chain, nb);
+	if (fib_seq == fib_seq_sum(net))
 		return true;
-	atomic_notifier_chain_unregister(&fib_chain, nb);
+	atomic_notifier_chain_unregister(&fn_net->fib_chain, nb);
 	if (cb)
 		cb(nb);
 	return false;
 }
 
 #define FIB_DUMP_MAX_RETRIES 5
-int register_fib_notifier(struct notifier_block *nb,
+int register_fib_notifier(struct net *net, struct notifier_block *nb,
 			  void (*cb)(struct notifier_block *nb))
 {
 	int retries = 0;
 	int err;
 
 	do {
-		unsigned int fib_seq = fib_seq_sum();
-		struct net *net;
-
-		rcu_read_lock();
-		for_each_net_rcu(net) {
-			err = fib_net_dump(net, nb);
-			if (err)
-				goto err_fib_net_dump;
-		}
-		rcu_read_unlock();
-
-		if (fib_dump_is_consistent(nb, cb, fib_seq))
+		unsigned int fib_seq = fib_seq_sum(net);
+
+		err = fib_net_dump(net, nb);
+		if (err)
+			return err;
+
+		if (fib_dump_is_consistent(net, nb, cb, fib_seq))
 			return 0;
 	} while (++retries < FIB_DUMP_MAX_RETRIES);
 
 	return -EBUSY;
-
-err_fib_net_dump:
-	rcu_read_unlock();
-	return err;
 }
 EXPORT_SYMBOL(register_fib_notifier);
 
-int unregister_fib_notifier(struct notifier_block *nb)
+int unregister_fib_notifier(struct net *net, struct notifier_block *nb)
 {
-	return atomic_notifier_chain_unregister(&fib_chain, nb);
+	struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
+
+	return atomic_notifier_chain_unregister(&fn_net->fib_chain, nb);
 }
 EXPORT_SYMBOL(unregister_fib_notifier);
 
@@ -181,6 +171,7 @@ static int __net_init fib_notifier_net_init(struct net *net)
 	struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
 
 	INIT_LIST_HEAD(&fn_net->fib_notifier_ops);
+	ATOMIC_INIT_NOTIFIER_HEAD(&fn_net->fib_chain);
 	return 0;
 }