ip_tunnel: use exit_batch_rtnl() method

exit_batch_rtnl() is called while RTNL is held,
and devices to be unregistered can be queued in the dev_kill_list.

This saves one rtnl_lock()/rtnl_unlock() pair
and one unregister_netdevice_many() call.

This patch takes care of ipip, ip_vti, and ip_gre tunnels.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Antoine Tenart <atenart@kernel.org>
Link: https://lore.kernel.org/r/20240206144313.2050392-15-edumazet@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/ip_tunnels.h

@@ -284,7 +284,8 @@ int ip_tunnel_init_net(struct net *net, unsigned int ip_tnl_net_id,
 		       struct rtnl_link_ops *ops, char *devname);
 
 void ip_tunnel_delete_nets(struct list_head *list_net, unsigned int id,
-			   struct rtnl_link_ops *ops);
+			   struct rtnl_link_ops *ops,
+			   struct list_head *dev_to_kill);
 
 void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 		    const struct iphdr *tnl_params, const u8 protocol);

net/ipv4/ip_gre.c

@@ -1025,14 +1025,16 @@ static int __net_init ipgre_init_net(struct net *net)
 	return ip_tunnel_init_net(net, ipgre_net_id, &ipgre_link_ops, NULL);
 }
 
-static void __net_exit ipgre_exit_batch_net(struct list_head *list_net)
+static void __net_exit ipgre_exit_batch_rtnl(struct list_head *list_net,
+					     struct list_head *dev_to_kill)
 {
-	ip_tunnel_delete_nets(list_net, ipgre_net_id, &ipgre_link_ops);
+	ip_tunnel_delete_nets(list_net, ipgre_net_id, &ipgre_link_ops,
+			      dev_to_kill);
 }
 
 static struct pernet_operations ipgre_net_ops = {
 	.init = ipgre_init_net,
-	.exit_batch = ipgre_exit_batch_net,
+	.exit_batch_rtnl = ipgre_exit_batch_rtnl,
 	.id   = &ipgre_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };
@@ -1697,14 +1699,16 @@ static int __net_init ipgre_tap_init_net(struct net *net)
 	return ip_tunnel_init_net(net, gre_tap_net_id, &ipgre_tap_ops, "gretap0");
 }
 
-static void __net_exit ipgre_tap_exit_batch_net(struct list_head *list_net)
+static void __net_exit ipgre_tap_exit_batch_rtnl(struct list_head *list_net,
+						 struct list_head *dev_to_kill)
 {
-	ip_tunnel_delete_nets(list_net, gre_tap_net_id, &ipgre_tap_ops);
+	ip_tunnel_delete_nets(list_net, gre_tap_net_id, &ipgre_tap_ops,
+			      dev_to_kill);
 }
 
 static struct pernet_operations ipgre_tap_net_ops = {
 	.init = ipgre_tap_init_net,
-	.exit_batch = ipgre_tap_exit_batch_net,
+	.exit_batch_rtnl = ipgre_tap_exit_batch_rtnl,
 	.id   = &gre_tap_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };
@@ -1715,14 +1719,16 @@ static int __net_init erspan_init_net(struct net *net)
 				  &erspan_link_ops, "erspan0");
 }
 
-static void __net_exit erspan_exit_batch_net(struct list_head *net_list)
+static void __net_exit erspan_exit_batch_rtnl(struct list_head *net_list,
+					      struct list_head *dev_to_kill)
 {
-	ip_tunnel_delete_nets(net_list, erspan_net_id, &erspan_link_ops);
+	ip_tunnel_delete_nets(net_list, erspan_net_id, &erspan_link_ops,
+			      dev_to_kill);
 }
 
 static struct pernet_operations erspan_net_ops = {
 	.init = erspan_init_net,
-	.exit_batch = erspan_exit_batch_net,
+	.exit_batch_rtnl = erspan_exit_batch_rtnl,
 	.id   = &erspan_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };

net/ipv4/ip_tunnel.c

@@ -1130,19 +1130,17 @@ static void ip_tunnel_destroy(struct net *net, struct ip_tunnel_net *itn,
 }
 
 void ip_tunnel_delete_nets(struct list_head *net_list, unsigned int id,
-			   struct rtnl_link_ops *ops)
+			   struct rtnl_link_ops *ops,
+			   struct list_head *dev_to_kill)
 {
 	struct ip_tunnel_net *itn;
 	struct net *net;
-	LIST_HEAD(list);
 
-	rtnl_lock();
+	ASSERT_RTNL();
 	list_for_each_entry(net, net_list, exit_list) {
 		itn = net_generic(net, id);
-		ip_tunnel_destroy(net, itn, &list, ops);
+		ip_tunnel_destroy(net, itn, dev_to_kill, ops);
 	}
-	unregister_netdevice_many(&list);
-	rtnl_unlock();
 }
 EXPORT_SYMBOL_GPL(ip_tunnel_delete_nets);
 

net/ipv4/ip_vti.c

@@ -510,14 +510,16 @@ static int __net_init vti_init_net(struct net *net)
 	return 0;
 }
 
-static void __net_exit vti_exit_batch_net(struct list_head *list_net)
+static void __net_exit vti_exit_batch_rtnl(struct list_head *list_net,
+					   struct list_head *dev_to_kill)
 {
-	ip_tunnel_delete_nets(list_net, vti_net_id, &vti_link_ops);
+	ip_tunnel_delete_nets(list_net, vti_net_id, &vti_link_ops,
+			      dev_to_kill);
 }
 
 static struct pernet_operations vti_net_ops = {
 	.init = vti_init_net,
-	.exit_batch = vti_exit_batch_net,
+	.exit_batch_rtnl = vti_exit_batch_rtnl,
 	.id   = &vti_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };

net/ipv4/ipip.c

@@ -592,14 +592,16 @@ static int __net_init ipip_init_net(struct net *net)
 	return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0");
 }
 
-static void __net_exit ipip_exit_batch_net(struct list_head *list_net)
+static void __net_exit ipip_exit_batch_rtnl(struct list_head *list_net,
+					    struct list_head *dev_to_kill)
 {
-	ip_tunnel_delete_nets(list_net, ipip_net_id, &ipip_link_ops);
+	ip_tunnel_delete_nets(list_net, ipip_net_id, &ipip_link_ops,
+			      dev_to_kill);
 }
 
 static struct pernet_operations ipip_net_ops = {
 	.init = ipip_init_net,
-	.exit_batch = ipip_exit_batch_net,
+	.exit_batch_rtnl = ipip_exit_batch_rtnl,
 	.id   = &ipip_net_id,
 	.size = sizeof(struct ip_tunnel_net),
 };