Commit 952fcfd0 authored by Sabrina Dubroca's avatar Sabrina Dubroca Committed by David S. Miller
Browse files

net: remove type_check from dev_get_nest_level() 



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: default avatarSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e2003872

drivers/net/macsec.c

+1 −1
Original line number Diff line number Diff line
@@ -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,

drivers/net/macvlan.c

+1 −1
Original line number Diff line number Diff line
@@ -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])

include/linux/netdevice.h

+1 −2
Original line number Diff line number Diff line
@@ -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);

net/8021q/vlan.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

net/core/dev.c

+3 −7
Original line number Diff line number Diff line
@@ -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);

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