tuntap: attach queue 0 before registering netdevice

We attach queue 0 after registering netdevice currently. This leads to call
netif_set_real_num_{tx|rx}_queues() after registering the netdevice. Since we
allow tun/tap has a maximum of 1024 queues, this may lead a huge number of
uevents to be injected to userspace since we create 2048 kobjects and then
remove 2046. Solve this problem by attaching queue 0 and set the real number of
queues before registering netdevice.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 607a3a5981c6628a738ca47929a6ad45af51eec2..71f6874d804825ac922c613b327c4d8e1d4181de 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -493,9 +493,6 @@ static int tun_attach(struct tun_struct *tun, struct file *file)
 
        tun_set_real_num_queues(tun);
 
-       if (tun->numqueues == 1)
-               netif_carrier_on(tun->dev);
-
        /* device is allowed to go away first, so no need to hold extra
         * refcnt.
         */
@@ -1612,6 +1609,10 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
                        TUN_USER_FEATURES;
                dev->features = dev->hw_features;
 
+               err = tun_attach(tun, file);
+               if (err < 0)
+                       goto err_free_dev;
+
                err = register_netdevice(tun->dev);
                if (err < 0)
                        goto err_free_dev;
@@ -1621,9 +1622,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
                    device_create_file(&tun->dev->dev, &dev_attr_group))
                        pr_err("Failed to create tun sysfs files\n");
 
-               err = tun_attach(tun, file);
-               if (err < 0)
-                       goto err_free_dev;
+               netif_carrier_on(tun->dev);
        }
 
        tun_debug(KERN_INFO, tun, "tun_set_iff\n");