net: use net->count to check whether a netns is alive or not

[ Upstream commit 91864f5852f9996210fad400cf70fb85af091243 ]

The previous idea was to check whether a net namespace is in
net_exit_list or not. It doesn't work, because net->exit_list is used in
__register_pernet_operations and __unregister_pernet_operations where
all namespaces are added to a temporary list to make cleanup in a error
case, so list_empty(&net->exit_list) always returns false.

Reported-by: Mantas Mikulėnas <grawity@gmail.com>
Fixes: 002d8a1a6c11 ("net: skip genenerating uevents for network namespaces that are exiting")
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index b0c04cf4851d67b58c541fa602c6d53009cc9bee..1004418d937ede4123c8164ac6ecc6889d0927c3 100644 (file)
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -952,7 +952,7 @@ net_rx_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
        while (--i >= new_num) {
                struct kobject *kobj = &dev->_rx[i].kobj;
 
-               if (!list_empty(&dev_net(dev)->exit_list))
+               if (!atomic_read(&dev_net(dev)->count))
                        kobj->uevent_suppress = 1;
                if (dev->sysfs_rx_queue_group)
                        sysfs_remove_group(kobj, dev->sysfs_rx_queue_group);
@@ -1370,7 +1370,7 @@ netdev_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
        while (--i >= new_num) {
                struct netdev_queue *queue = dev->_tx + i;
 
-               if (!list_empty(&dev_net(dev)->exit_list))
+               if (!atomic_read(&dev_net(dev)->count))
                        queue->kobj.uevent_suppress = 1;
 #ifdef CONFIG_BQL
                sysfs_remove_group(&queue->kobj, &dql_group);
@@ -1557,7 +1557,7 @@ void netdev_unregister_kobject(struct net_device *ndev)
 {
        struct device *dev = &(ndev->dev);
 
-       if (!list_empty(&dev_net(ndev)->exit_list))
+       if (!atomic_read(&dev_net(ndev)->count))
                dev_set_uevent_suppress(dev, 1);
 
        kobject_get(&dev->kobj);