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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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Sabrina Dubroca 2016-08-12 16:10:33 +02:00 • committed by David S. Miller
commit 952fcfd08c
5 changed files with 7 additions and 12 deletions
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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;