bonding: switch bond_net_exit() to batch mode

cleanup_net() is competing with other rtnl users.

Batching bond_net_exit() factorizes all rtnl acquistions
to a single one, giving chance for cleanup_net()
to progress much faster, holding rtnl a bit longer.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/bonding/bond_main.c

@@ -6048,27 +6048,38 @@ static int __net_init bond_net_init(struct net *net)
 	return 0;
 }
 
-static void __net_exit bond_net_exit(struct net *net)
+static void __net_exit bond_net_exit_batch(struct list_head *net_list)
 {
-	struct bond_net *bn = net_generic(net, bond_net_id);
-	struct bonding *bond, *tmp_bond;
+	struct bond_net *bn;
+	struct net *net;
 	LIST_HEAD(list);
 
+	list_for_each_entry(net, net_list, exit_list) {
+		bn = net_generic(net, bond_net_id);
 		bond_destroy_sysfs(bn);
+	}
 
 	/* Kill off any bonds created after unregistering bond rtnl ops */
 	rtnl_lock();
+	list_for_each_entry(net, net_list, exit_list) {
+		struct bonding *bond, *tmp_bond;
+
+		bn = net_generic(net, bond_net_id);
 		list_for_each_entry_safe(bond, tmp_bond, &bn->dev_list, bond_list)
 			unregister_netdevice_queue(bond->dev, &list);
+	}
 	unregister_netdevice_many(&list);
 	rtnl_unlock();
 
+	list_for_each_entry(net, net_list, exit_list) {
+		bn = net_generic(net, bond_net_id);
 		bond_destroy_proc_dir(bn);
+	}
 }
 
 static struct pernet_operations bond_net_ops = {
 	.init = bond_net_init,
-	.exit = bond_net_exit,
+	.exit_batch = bond_net_exit_batch,
 	.id   = &bond_net_id,
 	.size = sizeof(struct bond_net),
 };

drivers/net/bonding/bond_procfs.c

@@ -307,7 +307,6 @@ void __net_init bond_create_proc_dir(struct bond_net *bn)
 }
 
 /* Destroy the bonding directory under /proc/net, if empty.
- * Caller must hold rtnl_lock.
  */
 void __net_exit bond_destroy_proc_dir(struct bond_net *bn)
 {