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batman-adv: Avoid sysfs name collision for netns moves 

The kobject_put is only removing the sysfs entry and corresponding entries
when its reference counter becomes zero. This tends to lead to collisions
when a device is moved between two different network namespaces because
some of the sysfs files have to be removed first and then added again to
the already moved sysfs entry.

    WARNING: CPU: 0 PID: 290 at lib/kobject.c:240 kobject_add_internal+0x5ec/0x8a0
    kobject_add_internal failed for batman_adv with -EEXIST, don't try to register things with the same name in the same directory.

But the caller of kobject_put can already remove the sysfs entry before it
does the kobject_put. This removal is done even when the reference counter
is not yet zero and thus avoids the problem.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
This commit is contained in:
Sven Eckelmann 2016-06-13 07:41:32 +02:00 committed by Simon Wunderlich
parent 569c98504b
commit f4acb1086b
1 changed files with 14 additions and 0 deletions
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14
net/batman-adv/sysfs.c
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@ -713,6 +713,8 @@ rem_attr:
for (bat_attr = batadv_mesh_attrs; *bat_attr; ++bat_attr)
sysfs_remove_file(bat_priv->mesh_obj, &((*bat_attr)->attr));
kobject_uevent(bat_priv->mesh_obj, KOBJ_REMOVE);
kobject_del(bat_priv->mesh_obj);
kobject_put(bat_priv->mesh_obj);
bat_priv->mesh_obj = NULL;
out:
@ -727,6 +729,8 @@ void batadv_sysfs_del_meshif(struct net_device *dev)
for (bat_attr = batadv_mesh_attrs; *bat_attr; ++bat_attr)
sysfs_remove_file(bat_priv->mesh_obj, &((*bat_attr)->attr));
kobject_uevent(bat_priv->mesh_obj, KOBJ_REMOVE);
kobject_del(bat_priv->mesh_obj);
kobject_put(bat_priv->mesh_obj);
bat_priv->mesh_obj = NULL;
}
@ -782,6 +786,10 @@ rem_attr:
for (bat_attr = batadv_vlan_attrs; *bat_attr; ++bat_attr)
sysfs_remove_file(vlan->kobj, &((*bat_attr)->attr));
if (vlan->kobj != bat_priv->mesh_obj) {
kobject_uevent(vlan->kobj, KOBJ_REMOVE);
kobject_del(vlan->kobj);
}
kobject_put(vlan->kobj);
vlan->kobj = NULL;
out:
@ -801,6 +809,10 @@ void batadv_sysfs_del_vlan(struct batadv_priv *bat_priv,
for (bat_attr = batadv_vlan_attrs; *bat_attr; ++bat_attr)
sysfs_remove_file(vlan->kobj, &((*bat_attr)->attr));
if (vlan->kobj != bat_priv->mesh_obj) {
kobject_uevent(vlan->kobj, KOBJ_REMOVE);
kobject_del(vlan->kobj);
}
kobject_put(vlan->kobj);
vlan->kobj = NULL;
}
@ -1103,6 +1115,8 @@ out:
void batadv_sysfs_del_hardif(struct kobject **hardif_obj)
{
kobject_uevent(*hardif_obj, KOBJ_REMOVE);
kobject_del(*hardif_obj);
kobject_put(*hardif_obj);
*hardif_obj = NULL;
}