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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
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3
include/linux/netdevice.h
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@@ -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);