[Acked/cmt] [PATCH 3/3] net: rename sysfs symlinks on device name change

[Andy Whitcroft]

On Mon, Mar 02, 2015 at 05:04:44PM +0100, Stefan Bader wrote:
> From: Veaceslav Falico <vfalico at redhat.com>
> 
> Currently, we don't rename the upper/lower_ifc symlinks in
> /sys/class/net/*/ , which might result stale/duplicate links/names.
> 
> Fix this by adding netdev_adjacent_rename_links(dev, oldname) which renames
> all the upper/lower interface's links to dev from the upper/lower_oldname
> to the new name.
> 
> We don't need a rollback because only we control these symlinks and if we
> fail to rename them - sysfs will anyway complain.
> 
> Reported-by: Ding Tianhong <dingtianhong at huawei.com>
> CC: Ding Tianhong <dingtianhong at huawei.com>
> CC: "David S. Miller" <davem at davemloft.net>
> CC: Eric Dumazet <edumazet at google.com>
> CC: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
> CC: Cong Wang <amwang at redhat.com>
> Signed-off-by: Veaceslav Falico <vfalico at redhat.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> 
> BugLink: http://bugs.launchpad.net/bugs/1410852
> 
> (backported from commit 5bb025fae53889cc99a21058c5dd369bf8cce820 upstream)
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  include/linux/netdevice.h |  1 +
>  net/core/dev.c            | 23 ++++++++++++++++++++++-
>  2 files changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index c46b3b2..caa5563 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -2937,6 +2937,7 @@ int netdev_master_upper_dev_link_private(struct net_device *dev,
>  					 void *private);
>  void netdev_upper_dev_unlink(struct net_device *dev,
>  			     struct net_device *upper_dev);
> +void netdev_adjacent_rename_links(struct net_device *dev, char *oldname);
>  void *netdev_lower_dev_get_private_rcu(struct net_device *dev,
>  				       struct net_device *lower_dev);
>  void *netdev_lower_dev_get_private(struct net_device *dev,
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 588548c..0974a0f 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1118,6 +1118,8 @@ rollback:
>  
>  	write_seqcount_end(&devnet_rename_seq);
>  
> +	netdev_adjacent_rename_links(dev, oldname);
> +
>  	write_lock_bh(&dev_base_lock);
>  	hlist_del_rcu(&dev->name_hlist);
>  	write_unlock_bh(&dev_base_lock);
> @@ -1137,6 +1139,7 @@ rollback:
>  			err = ret;
>  			write_seqcount_begin(&devnet_rename_seq);
>  			memcpy(dev->name, oldname, IFNAMSIZ);
> +			memcpy(oldname, newname, IFNAMSIZ);
>  			goto rollback;
>  		} else {
>  			pr_err("%s: name change rollback failed: %d\n",
> @@ -5039,6 +5042,25 @@ void netdev_upper_dev_unlink(struct net_device *dev,
>  }
>  EXPORT_SYMBOL(netdev_upper_dev_unlink);
>  
> +void netdev_adjacent_rename_links(struct net_device *dev, char *oldname)
> +{
> +	struct netdev_adjacent *iter;
> +
> +	list_for_each_entry(iter, &dev->adj_list.upper, list) {
> +		netdev_adjacent_sysfs_del(iter->dev, oldname,
> +					  &iter->dev->adj_list.lower);
> +		netdev_adjacent_sysfs_add(iter->dev, dev,
> +					  &iter->dev->adj_list.lower);
> +	}
> +
> +	list_for_each_entry(iter, &dev->adj_list.lower, list) {
> +		netdev_adjacent_sysfs_del(iter->dev, oldname,
> +					  &iter->dev->adj_list.upper);
> +		netdev_adjacent_sysfs_add(iter->dev, dev,
> +					  &iter->dev->adj_list.upper);
> +	}
> +}
> +
>  void *netdev_lower_dev_get_private_rcu(struct net_device *dev,
>  				       struct net_device *lower_dev)
>  {
> @@ -5069,7 +5091,6 @@ void *netdev_lower_dev_get_private(struct net_device *dev,
>  }
>  EXPORT_SYMBOL(netdev_lower_dev_get_private);
>  
> -

Erp.

>  int dev_get_nest_level(struct net_device *dev,
>  		       bool (*type_check)(struct net_device *dev))
>  {

Other than the blank line which should be elided, this looks to be as
near as dammit a cherry-pick too.  Looks to do what is claimed and is
easy to test.

Acked-by: Andy Whitcroft <apw at canonical.com>

-apw