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net: replace dev_addr_sem with netdev instance lock

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Lockdep reports possible circular dependency in [0]. Instead of
fixing the ordering, replace global dev_addr_sem with netdev
instance lock. Most of the paths that set/get mac are RTNL
protected. Two places where it's not, convert to explicit
locking:
- sysfs address_show
- dev_get_mac_address via dev_ioctl

0: https://netdev-3.bots.linux.dev/vmksft-forwarding-dbg/results/993321/24-router-bridge-1d-lag-sh/stderr

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250305163732.2766420-12-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Stanislav Fomichev
2025-03-05 08:37:29 -08:00
committed by Jakub Kicinski
parent 2bcf4772e4
commit df43d8bf10
9 changed files with 41 additions and 56 deletions
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52
net/core/dev.c
View File

@@ -1058,6 +1058,28 @@ struct net_device *netdev_get_by_index_lock(struct net *net, int ifindex)
return __netdev_put_lock(dev);
}
/**
* netdev_get_by_name_lock() - find a device by its name
* @net: the applicable net namespace
* @name: name of device
*
* Search for an interface by name. If a valid device
* with @name is found it will be returned with netdev->lock held.
* netdev_unlock() must be called to release it.
*
* Return: pointer to a device with lock held, NULL if not found.
*/
struct net_device *netdev_get_by_name_lock(struct net *net, const char *name)
{
struct net_device *dev;
dev = dev_get_by_name(net, name);
if (!dev)
return NULL;
return __netdev_put_lock(dev);
}
struct net_device *
netdev_xa_find_lock(struct net *net, struct net_device *dev,
unsigned long *index)
@@ -9589,44 +9611,24 @@ int netif_set_mac_address(struct net_device *dev, struct sockaddr *sa,
return 0;
}
DECLARE_RWSEM(dev_addr_sem);
int netif_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
struct netlink_ext_ack *extack)
{
int ret;
down_write(&dev_addr_sem);
ret = netif_set_mac_address(dev, sa, extack);
up_write(&dev_addr_sem);
return ret;
}
int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)
{
size_t size = sizeof(sa->sa_data_min);
struct net_device *dev;
int ret = 0;
down_read(&dev_addr_sem);
rcu_read_lock();
dev = netdev_get_by_name_lock(net, dev_name);
if (!dev)
return -ENODEV;
dev = dev_get_by_name_rcu(net, dev_name);
if (!dev) {
ret = -ENODEV;
goto unlock;
}
if (!dev->addr_len)
memset(sa->sa_data, 0, size);
else
memcpy(sa->sa_data, dev->dev_addr,
min_t(size_t, size, dev->addr_len));
sa->sa_family = dev->type;
netdev_unlock(dev);
unlock:
rcu_read_unlock();
up_read(&dev_addr_sem);
return ret;
return 0;
}
EXPORT_SYMBOL(dev_get_mac_address);