netdev - [PATCH net v2 4/5] net: move altnames together with the netdevice

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Date: Tue, 17 Oct 2023 18:38:16 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	jiri@...nulli.us,
	przemyslaw.kitszel@...el.com,
	daniel@...earbox.net,
	Jakub Kicinski <kuba@...nel.org>,
	Jiri Pirko <jiri@...dia.com>
Subject: [PATCH net v2 4/5] net: move altnames together with the netdevice

The altname nodes are currently not moved to the new netns
when netdevice itself moves:

  [ ~]# ip netns add test
  [ ~]# ip -netns test link add name eth0 type dummy
  [ ~]# ip -netns test link property add dev eth0 altname some-name
  [ ~]# ip -netns test link show dev some-name
  2: eth0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
      link/ether 1e:67:ed:19:3d:24 brd ff:ff:ff:ff:ff:ff
      altname some-name
  [ ~]# ip -netns test link set dev eth0 netns 1
  [ ~]# ip link
  ...
  3: eth0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
      link/ether 02:40:88:62:ec:b8 brd ff:ff:ff:ff:ff:ff
      altname some-name
  [ ~]# ip li show dev some-name
  Device "some-name" does not exist.

Remove them from the hash table when device is unlisted
and add back when listed again.

Fixes: 36fbf1e52bd3 ("net: rtnetlink: add linkprop commands to add and delete alternative ifnames")
Reviewed-by: Jiri Pirko <jiri@...dia.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 net/core/dev.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 559705aeefe4..9f3f8930c691 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -381,6 +381,7 @@ static void netdev_name_node_alt_flush(struct net_device *dev)
 /* Device list insertion */
 static void list_netdevice(struct net_device *dev)
 {
+	struct netdev_name_node *name_node;
 	struct net *net = dev_net(dev);
 
 	ASSERT_RTNL();
@@ -391,6 +392,10 @@ static void list_netdevice(struct net_device *dev)
 	hlist_add_head_rcu(&dev->index_hlist,
 			   dev_index_hash(net, dev->ifindex));
 	write_unlock(&dev_base_lock);
+
+	netdev_for_each_altname(dev, name_node)
+		netdev_name_node_add(net, name_node);
+
 	/* We reserved the ifindex, this can't fail */
 	WARN_ON(xa_store(&net->dev_by_index, dev->ifindex, dev, GFP_KERNEL));
 
@@ -402,12 +407,16 @@ static void list_netdevice(struct net_device *dev)
  */
 static void unlist_netdevice(struct net_device *dev, bool lock)
 {
+	struct netdev_name_node *name_node;
 	struct net *net = dev_net(dev);
 
 	ASSERT_RTNL();
 
 	xa_erase(&net->dev_by_index, dev->ifindex);
 
+	netdev_for_each_altname(dev, name_node)
+		netdev_name_node_del(name_node);
+
 	/* Unlink dev from the device chain */
 	if (lock)
 		write_lock(&dev_base_lock);
@@ -10942,7 +10951,6 @@ void unregister_netdevice_many_notify(struct list_head *head,
 	synchronize_net();
 
 	list_for_each_entry(dev, head, unreg_list) {
-		struct netdev_name_node *name_node;
 		struct sk_buff *skb = NULL;
 
 		/* Shutdown queueing discipline. */
@@ -10970,9 +10978,6 @@ void unregister_netdevice_many_notify(struct list_head *head,
 		dev_uc_flush(dev);
 		dev_mc_flush(dev);
 
-		netdev_for_each_altname(dev, name_node)
-			netdev_name_node_del(name_node);
-		synchronize_rcu();
 		netdev_name_node_alt_flush(dev);
 		netdev_name_node_free(dev->name_node);
 
-- 
2.41.0