[PATCH Yakkety SRU] net: use net->count to check whether a netns is alive or not

[Joseph Salisbury]

Was this a backport versus a cherry-pick?

On 03/30/2017 07:28 PM, Tim Gardner wrote:
> From: Andrey Vagin <avagin at openvz.org>
>
> BugLink: http://bugs.launchpad.net/bugs/1672144
>
> 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 at gmail.com>
> Fixes: 002d8a1a6c11 ("net: skip genenerating uevents for network namespaces that are exiting")
> Signed-off-by: Andrei Vagin <avagin at openvz.org>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry picked from commit 91864f5852f9996210fad400cf70fb85af091243)
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
>
> Conflicts:
> 	net/core/net-sysfs.c
> ---
>  net/core/net-sysfs.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 6e4f347..dabd94c 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -950,6 +950,10 @@ 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 (!atomic_read(&dev_net(dev)->count))
> +			kobj->uevent_suppress = 1;
>  		if (dev->sysfs_rx_queue_group)
>  			sysfs_remove_group(&dev->_rx[i].kobj,
>  					   dev->sysfs_rx_queue_group);
> @@ -1340,6 +1344,8 @@ 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 (!atomic_read(&dev_net(dev)->count))
> +			queue->kobj.uevent_suppress = 1;
>  #ifdef CONFIG_BQL
>  		sysfs_remove_group(&queue->kobj, &dql_group);
>  #endif
> @@ -1525,6 +1531,9 @@ void netdev_unregister_kobject(struct net_device *ndev)
>  {
>  	struct device *dev = &(ndev->dev);
>  
> +	if (!atomic_read(&dev_net(ndev)->count))
> +		dev_set_uevent_suppress(dev, 1);
> +
>  	kobject_get(&dev->kobj);
>  
>  	remove_queue_kobjects(ndev);