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ip_tunnel: Support per-netns device unregistration.

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ip_tunnel_delete_net() iterates ip_tunnel devices whose link_net
is dying and queues them for destruction.

The devices may reside in different netns.

Let's use unregister_netdevice_queue_net() to support per-netns
device unregistration.

Even after ip_tunnel_delete_net() queues a cross-netns ip_tunnel
device, ip_tunnel_changelink(), ip_tunnel_dellink(), and
ip_tunnel_ctl() could be called concurrently for it (once RTNL is
removed).  In such a case, __rtnl_net_unlock() will perform the
unregistration.

Also, ip_tunnel_ctl() needs to check check_net(t->net), otherwise
it could create a new dev in dying netns after ip_tunnel_delete_net().

In the example below, we can see the fallback tunnel device (gre0)
and the cross-netns device (gre1) are unregistered by different
processes:

  # bpftrace -e '#include <linux/netdevice.h>
  kprobe:ip_tunnel_uninit {
      $dev = (struct net_device *)arg0;
      printf("PID: %d | DEV: %s%s\n", pid, $dev->name, kstack());
  }
  kprobe:ipgre_exit_rtnl {
      printf("PID: %d%s\n", pid, kstack());
  }' &

  # ip netns add ns1
  # ip netns add ns2
  # ip -n ns1 link add name gre1 link-netns ns2 \
    type gre local 192.168.0.1 remote 192.168.1.1
  # ip netns del ns2

  PID: 12
          ipgre_exit_rtnl+5
          ops_undo_list+702
          cleanup_net+1122
          process_scheduled_works+2538
  ...
  PID: 12 | DEV: gre0  <------ fallback device (itn->fb_tunnel_dev).
          ip_tunnel_uninit+5
          unregister_netdevice_many_notify+7129
          unregister_netdevice_many_net+1050
          __rtnl_net_unlock+37
          ops_undo_list+754
          cleanup_net+1122
          process_scheduled_works+2538
  ...
  PID: 10 | DEV: gre1
          ip_tunnel_uninit+5
          unregister_netdevice_many_notify+7129
          unregister_netdevice_many_net+1050
          rtnl_net_work_func+136
          process_scheduled_works+2538

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260912230043.2586313-8-kuniyu@google.com
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Kuniyuki Iwashima 2026-09-12 23:00:33 +00:00 committed by Paolo Abeni
parent 6724a7baf1
commit 8f3c724202
1 changed files with 26 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
net/ipv4/ip_tunnel.c
View File

@ -205,6 +205,11 @@ static void ip_tunnel_del(struct ip_tunnel_net *itn, struct ip_tunnel *t)
hlist_del_init_rcu(&t->hash_node);
}
static bool ip_tunnel_unregistering(struct ip_tunnel *t)
{
return hlist_unhashed(&t->hash_node);
}
static struct ip_tunnel *ip_tunnel_find(struct ip_tunnel_net *itn,
struct ip_tunnel_parm_kern *parms,
int type)
@ -893,20 +898,22 @@ static void ip_tunnel_update(struct ip_tunnel_net *itn,
netdev_state_change(dev);
}
static void __ip_tunnel_dellink(struct net_device *dev, struct list_head *head)
static void __ip_tunnel_dellink(struct net *net, struct net_device *dev,
struct list_head *head)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
struct ip_tunnel_net *itn;
itn = net_generic(tunnel->net, tunnel->ip_tnl_net_id);
ip_tunnel_del(itn, tunnel);
unregister_netdevice_queue(dev, head);
unregister_netdevice_queue_net(net, dev, head);
}
int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p,
int cmd)
{
struct ip_tunnel *t = netdev_priv(dev);
struct net *orig_net = dev_net(dev);
struct ip_tunnel_net *itn;
LIST_HEAD(dev_kill_list);
struct net *net = t->net;
@ -918,6 +925,11 @@ int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p,
mutex_lock(&itn->tunnels_lock);
if (!check_net(net)) {
err = -EBUSY;
goto done;
}
switch (cmd) {
case SIOCGETTUNNEL:
if (dev == itn->fb_tunnel_dev) {
@ -977,7 +989,7 @@ int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p,
}
}
if (t) {
if (t && !ip_tunnel_unregistering(t)) {
err = 0;
ip_tunnel_update(itn, t, dev, p, true, 0);
} else {
@ -1001,7 +1013,9 @@ int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p,
dev = t->dev;
}
__ip_tunnel_dellink(dev, &dev_kill_list);
if (!ip_tunnel_unregistering(t))
__ip_tunnel_dellink(orig_net, dev, &dev_kill_list);
err = 0;
break;
@ -1109,7 +1123,8 @@ void ip_tunnel_dellink(struct net_device *dev, struct list_head *head)
if (itn->fb_tunnel_dev != dev) {
mutex_lock(&itn->tunnels_lock);
__ip_tunnel_dellink(dev, head);
if (!ip_tunnel_unregistering(tunnel))
__ip_tunnel_dellink(dev_net(dev), dev, head);
mutex_unlock(&itn->tunnels_lock);
}
}
@ -1192,7 +1207,7 @@ void ip_tunnel_delete_net(struct net *net, unsigned int id,
struct ip_tunnel *t;
hlist_for_each_entry_safe(t, n, thead, hash_node)
__ip_tunnel_dellink(t->dev, head);
__ip_tunnel_dellink(net, t->dev, head);
}
mutex_unlock(&itn->tunnels_lock);
@ -1302,6 +1317,11 @@ int ip_tunnel_changelink(struct net_device *dev, struct nlattr *tb[],
}
}
if (ip_tunnel_unregistering(t)) {
err = -ENODEV;
goto out;
}
ip_tunnel_update(itn, t, dev, p, !tb[IFLA_MTU], fwmark);
out:
mutex_unlock(&itn->tunnels_lock);