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batman-adv: Set special lockdep classes to avoid lockdep warning

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Transmissions over batman-adv devices always start another nested transmission
over devices attached to the batman-adv interface. These devices usually use
the ethernet lockdep class for the tx_queue lock which is also set by default
for all batman-adv devices. Lockdep will detect a nested locking attempt of two
locks with the same class and warn about a possible deadlock.

This is the default and expected behavior and should not alarm the locking
correctness prove mechanism. Therefore, the locks for all netdevice specific tx
queues get a special batman-adv lock class to avoid a false positive for each
transmission.

Reported-by: Linus Luessing <linus.luessing@web.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
This commit is contained in:
Sven Eckelmann 2012-08-20 09:03:59 +02:00 committed by Antonio Quartulli
parent c10dba051a
commit 36c1d15311
1 changed files with 44 additions and 0 deletions
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44
net/batman-adv/soft-interface.c
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@ -347,7 +347,51 @@ void batadv_interface_rx(struct net_device *soft_iface,
return;
}
/* batman-adv network devices have devices nesting below it and are a special
* "super class" of normal network devices; split their locks off into a
* separate class since they always nest.
*/
static struct lock_class_key batadv_netdev_xmit_lock_key;
static struct lock_class_key batadv_netdev_addr_lock_key;
/**
* batadv_set_lockdep_class_one - Set lockdep class for a single tx queue
* @dev: device which owns the tx queue
* @txq: tx queue to modify
* @_unused: always NULL
*/
static void batadv_set_lockdep_class_one(struct net_device *dev,
struct netdev_queue *txq,
void *_unused)
{
lockdep_set_class(&txq->_xmit_lock, &batadv_netdev_xmit_lock_key);
}
/**
* batadv_set_lockdep_class - Set txq and addr_list lockdep class
* @dev: network device to modify
*/
static void batadv_set_lockdep_class(struct net_device *dev)
{
lockdep_set_class(&dev->addr_list_lock, &batadv_netdev_addr_lock_key);
netdev_for_each_tx_queue(dev, batadv_set_lockdep_class_one, NULL);
}
/**
* batadv_softif_init - Late stage initialization of soft interface
* @dev: registered network device to modify
*
* Returns error code on failures
*/
static int batadv_softif_init(struct net_device *dev)
{
batadv_set_lockdep_class(dev);
return 0;
}
static const struct net_device_ops batadv_netdev_ops = {
.ndo_init = batadv_softif_init,
.ndo_open = batadv_interface_open,
.ndo_stop = batadv_interface_release,
.ndo_get_stats = batadv_interface_stats,