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net: remove type_check from dev_get_nest_level()

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The idea for type_check in dev_get_nest_level() was to count the number
of nested devices of the same type (currently, only macvlan or vlan
devices).
This prevented the false positive lockdep warning on configurations such
as:

eth0 <--- macvlan0 <--- vlan0 <--- macvlan1

However, this doesn't prevent a warning on a configuration such as:

eth0 <--- macvlan0 <--- vlan0
eth1 <--- vlan1 <--- macvlan1

In this case, all the locks end up with a nesting subclass of 1, so
lockdep thinks that there is still a deadlock:

- in the first case we have (macvlan_netdev_addr_lock_key, 1) and then
  take (vlan_netdev_xmit_lock_key, 1)
- in the second case, we have (vlan_netdev_xmit_lock_key, 1) and then
  take (macvlan_netdev_addr_lock_key, 1)

By removing the linktype check in dev_get_nest_level() and always
incrementing the nesting depth, lockdep considers this configuration
valid.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sabrina Dubroca 2016-08-12 16:10:33 +02:00 committed by David S. Miller
parent e200387245
commit 952fcfd08c
5 changed files with 7 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/macsec.c
View File

@ -3201,7 +3201,7 @@ static int macsec_newlink(struct net *net, struct net_device *dev,
dev_hold(real_dev);
macsec->nest_level = dev_get_nest_level(real_dev, netif_is_macsec) + 1;
macsec->nest_level = dev_get_nest_level(real_dev) + 1;
netdev_lockdep_set_classes(dev);
lockdep_set_class_and_subclass(&dev->addr_list_lock,
&macsec_netdev_addr_lock_key,

2
drivers/net/macvlan.c
View File

@ -1315,7 +1315,7 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev,
vlan->dev = dev;
vlan->port = port;
vlan->set_features = MACVLAN_FEATURES;
vlan->nest_level = dev_get_nest_level(lowerdev, netif_is_macvlan) + 1;
vlan->nest_level = dev_get_nest_level(lowerdev) + 1;
vlan->mode = MACVLAN_MODE_VEPA;
if (data && data[IFLA_MACVLAN_MODE])

3
include/linux/netdevice.h
View File

@ -3891,8 +3891,7 @@ void netdev_default_l2upper_neigh_destroy(struct net_device *dev,
extern u8 netdev_rss_key[NETDEV_RSS_KEY_LEN] __read_mostly;
void netdev_rss_key_fill(void *buffer, size_t len);
int dev_get_nest_level(struct net_device *dev,
bool (*type_check)(const struct net_device *dev));
int dev_get_nest_level(struct net_device *dev);
int skb_checksum_help(struct sk_buff *skb);
struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
netdev_features_t features, bool tx_path);

2
net/8021q/vlan.c
View File

@ -169,7 +169,7 @@ int register_vlan_dev(struct net_device *dev)
if (err < 0)
goto out_uninit_mvrp;
vlan->nest_level = dev_get_nest_level(real_dev, is_vlan_dev) + 1;
vlan->nest_level = dev_get_nest_level(real_dev) + 1;
err = register_netdevice(dev);
if (err < 0)
goto out_uninit_mvrp;

10
net/core/dev.c
View File

@ -6045,8 +6045,7 @@ void *netdev_lower_dev_get_private(struct net_device *dev,
EXPORT_SYMBOL(netdev_lower_dev_get_private);
int dev_get_nest_level(struct net_device *dev,
bool (*type_check)(const struct net_device *dev))
int dev_get_nest_level(struct net_device *dev)
{
struct net_device *lower = NULL;
struct list_head *iter;
@ -6056,15 +6055,12 @@ int dev_get_nest_level(struct net_device *dev,
ASSERT_RTNL();
netdev_for_each_lower_dev(dev, lower, iter) {
nest = dev_get_nest_level(lower, type_check);
nest = dev_get_nest_level(lower);
if (max_nest < nest)
max_nest = nest;
}
if (type_check(dev))
max_nest++;
return max_nest;
return max_nest + 1;
}
EXPORT_SYMBOL(dev_get_nest_level);