[PATCH net-next 0/2] net: rename device's sysfs symlinks on name change

[PATCH net-next 0/2] net: rename device's sysfs symlinks on name change

[Veaceslav Falico]

First patch only adds helper functions and cleans up the code a bit, second
one already does the renaming.

Reported-by: Ding Tianhong <dingtianhong@huawei.com>
CC: Ding Tianhong <dingtianhong@huawei.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
CC: Cong Wang <amwang@redhat.com>
CC: netdev@vger.kernel.org
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>

---
 include/linux/netdevice.h |  1 +
 net/core/dev.c            | 80 +++++++++++++++++++++++++++++++----------------
 2 files changed, 54 insertions(+), 27 deletions(-)

[PATCH net-next 1/2] net: add sysfs helpers for netdev_adjacent logic

[Veaceslav Falico]

They clean up the code a bit and can be used further.

CC: Ding Tianhong <dingtianhong@huawei.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
CC: Cong Wang <amwang@redhat.com>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---
 net/core/dev.c | 57 ++++++++++++++++++++++++++++++---------------------------
 1 file changed, 30 insertions(+), 27 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 87312dc..c578d4e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4595,13 +4595,36 @@ struct net_device *netdev_master_upper_dev_get_rcu(struct net_device *dev)
 }
 EXPORT_SYMBOL(netdev_master_upper_dev_get_rcu);
 
+int netdev_adjacent_sysfs_add(struct net_device *dev,
+			      struct net_device *adj_dev,
+			      struct list_head *dev_list)
+{
+	char linkname[IFNAMSIZ+7];
+	sprintf(linkname, dev_list == &dev->adj_list.upper ?
+		"upper_%s" : "lower_%s", adj_dev->name);
+	return sysfs_create_link(&(dev->dev.kobj), &(adj_dev->dev.kobj),
+				 linkname);
+}
+void netdev_adjacent_sysfs_del(struct net_device *dev,
+			       char *name,
+			       struct list_head *dev_list)
+{
+	char linkname[IFNAMSIZ+7];
+	sprintf(linkname, dev_list == &dev->adj_list.upper ?
+		"upper_%s" : "lower_%s", name);
+	sysfs_remove_link(&(dev->dev.kobj), linkname);
+}
+
+#define netdev_adjacent_is_neigh_list(dev, dev_list) \
+		(dev_list == &dev->adj_list.upper || \
+		 dev_list == &dev->adj_list.lower)
+
 static int __netdev_adjacent_dev_insert(struct net_device *dev,
 					struct net_device *adj_dev,
 					struct list_head *dev_list,
 					void *private, bool master)
 {
 	struct netdev_adjacent *adj;
-	char linkname[IFNAMSIZ+7];
 	int ret;
 
 	adj = __netdev_find_adj(dev, adj_dev, dev_list);
@@ -4624,16 +4647,8 @@ static int __netdev_adjacent_dev_insert(struct net_device *dev,
 	pr_debug("dev_hold for %s, because of link added from %s to %s\n",
 		 adj_dev->name, dev->name, adj_dev->name);
 
-	if (dev_list == &dev->adj_list.lower) {
-		sprintf(linkname, "lower_%s", adj_dev->name);
-		ret = sysfs_create_link(&(dev->dev.kobj),
-					&(adj_dev->dev.kobj), linkname);
-		if (ret)
-			goto free_adj;
-	} else if (dev_list == &dev->adj_list.upper) {
-		sprintf(linkname, "upper_%s", adj_dev->name);
-		ret = sysfs_create_link(&(dev->dev.kobj),
-					&(adj_dev->dev.kobj), linkname);
+	if (netdev_adjacent_is_neigh_list(dev, dev_list)) {
+		ret = netdev_adjacent_sysfs_add(dev, adj_dev, dev_list);
 		if (ret)
 			goto free_adj;
 	}
@@ -4653,14 +4668,8 @@ static int __netdev_adjacent_dev_insert(struct net_device *dev,
 	return 0;
 
 remove_symlinks:
-	if (dev_list == &dev->adj_list.lower) {
-		sprintf(linkname, "lower_%s", adj_dev->name);
-		sysfs_remove_link(&(dev->dev.kobj), linkname);
-	} else if (dev_list == &dev->adj_list.upper) {
-		sprintf(linkname, "upper_%s", adj_dev->name);
-		sysfs_remove_link(&(dev->dev.kobj), linkname);
-	}
-
+	if (netdev_adjacent_is_neigh_list(dev, dev_list))
+		netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
 free_adj:
 	kfree(adj);
 	dev_put(adj_dev);
@@ -4673,7 +4682,6 @@ static void __netdev_adjacent_dev_remove(struct net_device *dev,
 					 struct list_head *dev_list)
 {
 	struct netdev_adjacent *adj;
-	char linkname[IFNAMSIZ+7];
 
 	adj = __netdev_find_adj(dev, adj_dev, dev_list);
 
@@ -4693,13 +4701,8 @@ static void __netdev_adjacent_dev_remove(struct net_device *dev,
 	if (adj->master)
 		sysfs_remove_link(&(dev->dev.kobj), "master");
 
-	if (dev_list == &dev->adj_list.lower) {
-		sprintf(linkname, "lower_%s", adj_dev->name);
-		sysfs_remove_link(&(dev->dev.kobj), linkname);
-	} else if (dev_list == &dev->adj_list.upper) {
-		sprintf(linkname, "upper_%s", adj_dev->name);
-		sysfs_remove_link(&(dev->dev.kobj), linkname);
-	}
+	if (netdev_adjacent_is_neigh_list(dev, dev_list))
+		netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
 
 	list_del_rcu(&adj->list);
 	pr_debug("dev_put for %s, because link removed from %s to %s\n",
-- 
1.8.4

[PATCH net-next 2/2] net: rename sysfs symlinks on device name change

[Veaceslav Falico]

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@huawei.com>
CC: Ding Tianhong <dingtianhong@huawei.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
CC: Cong Wang <amwang@redhat.com>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---
 include/linux/netdevice.h |  1 +
 net/core/dev.c            | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a2a70cc..61f8338 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(struct net_device *dev,
 				   struct net_device *lower_dev);
 int skb_checksum_help(struct sk_buff *skb);
diff --git a/net/core/dev.c b/net/core/dev.c
index c578d4e..5bf0950 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1117,6 +1117,8 @@ 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);
@@ -1136,6 +1138,7 @@ 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",
@@ -4971,6 +4974,26 @@ 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);
+	}
+}
+EXPORT_SYMBOL(netdev_adjacent_rename_links);
+
 void *netdev_lower_dev_get_private(struct net_device *dev,
 				   struct net_device *lower_dev)
 {
-- 
1.8.4

Re: [PATCH net-next 2/2] net: rename sysfs symlinks on device name change

[Cong Wang]

On Tue, Jan 14, 2014 at 8:36 AM, Veaceslav Falico <vfalico@redhat.com> wrote:
> +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);
> +       }
> +}
> +EXPORT_SYMBOL(netdev_adjacent_rename_links);

Since it is only used within net/core/dev.c, why do you make it extern
and export it? It can become static.

Re: [PATCH net-next 2/2] net: rename sysfs symlinks on device name change

[Veaceslav Falico]

On Tue, Jan 14, 2014 at 10:30:56AM -0800, Cong Wang wrote:
>On Tue, Jan 14, 2014 at 8:36 AM, Veaceslav Falico <vfalico@redhat.com> wrote:
>> +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);
>> +       }
>> +}
>> +EXPORT_SYMBOL(netdev_adjacent_rename_links);
>
>Since it is only used within net/core/dev.c, why do you make it extern
>and export it? It can become static.

Hm, good point, exported it automatically, didn't realise that dev_rename()
is also in dev.c.

Will send v2.