Re: [PATCH net-next v7 00/11] net: Improve netns handling in rtnetlink

On Tue, Jan 7, 2025 at 4:57 PM Kuniyuki Iwashima kuniyu@amazon.com wrote: [...]

We can fix this by linking the dev to the socket's netns and clean them up in __net_exit hook as done in bareudp and geneve.

---8<--- diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 89a996ad8cd0..77638a815873 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -70,6 +70,7 @@ struct pdp_ctx { /* One instance of the GTP device. */ struct gtp_dev { struct list_head list;

•   struct list_head        sock_list;
  
    struct sock             *sk0;
    struct sock             *sk1u;
  

@@ -102,6 +103,7 @@ static unsigned int gtp_net_id __read_mostly;

struct gtp_net { struct list_head gtp_dev_list;

•   struct list_head gtp_sock_list;
  

After a closer look at the GTP driver, I'm confused about the gtp_dev_list here. GTP device is linked to this list at creation time, but netns can be changed afterwards. The list is used in gtp_net_exit_batch_rtnl(), but to my understanding net devices can already be deleted in default_device_exit_batch() by default. And I wonder if the use in gtp_genl_dump_pdp() can be replaced by something like for_each_netdev_rcu().

};

static u32 gtp_h_initval; @@ -1526,6 +1528,10 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,

    gn = net_generic(dev_net(dev), gtp_net_id);
    list_add_rcu(&gtp->list, &gn->gtp_dev_list);

•   gn = net_generic(src_net, gtp_net_id);
  

•   list_add(&gtp->sock_list, &gn->gtp_sock_list);
  

•   dev->priv_destructor = gtp_destructor;
  
    netdev_dbg(dev, "registered new GTP interface\n");
  

@@ -1552,6 +1558,7 @@ static void gtp_dellink(struct net_device *dev, struct list_head *head) pdp_context_delete(pctx);

    list_del_rcu(&gtp->list);

•   list_del(&gtp->sock_list);
    unregister_netdevice_queue(dev, head);
  

}

@@ -2465,6 +2472,8 @@ static int __net_init gtp_net_init(struct net *net) struct gtp_net *gn = net_generic(net, gtp_net_id);

    INIT_LIST_HEAD(&gn->gtp_dev_list);

•   INIT_LIST_HEAD(&gn->gtp_sock_list);
  

•   return 0;
  

}

@@ -2475,9 +2484,12 @@ static void __net_exit gtp_net_exit_batch_rtnl(struct list_head *net_list,

    list_for_each_entry(net, net_list, exit_list) {
            struct gtp_net *gn = net_generic(net, gtp_net_id);

•           struct gtp_dev *gtp;
  

•           struct gtp_dev *gtp, *next;
  

•           list_for_each_entry_safe(gtp, next, &gn->gtp_dev_list, list)
  

•                   gtp_dellink(gtp->dev, dev_to_kill);
  
  

•           list_for_each_entry(gtp, &gn->gtp_dev_list, list)
  

•           list_for_each_entry_safe(gtp, next, &gn->gtp_sock_list, sock_list)
                    gtp_dellink(gtp->dev, dev_to_kill);
    }
  

} ---8<---