Commit 6dd13251 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Paolo Abeni
Browse files

net: reorder dev_addr_sem lock 



Lockdep complains about circular lock in 1 -> 2 -> 3 (see below).

Change the lock ordering to be:
- rtnl_lock
- dev_addr_sem
- netdev_ops (only for lower devices!)
- team_lock (or other per-upper device lock)

1. rtnl_lock -> netdev_ops -> dev_addr_sem

rtnl_setlink
  rtnl_lock
    do_setlink IFLA_ADDRESS on lower
      netdev_ops
        dev_addr_sem

2. rtnl_lock -> team_lock -> netdev_ops

rtnl_newlink
  rtnl_lock
    do_setlink IFLA_MASTER on lower
      do_set_master
        team_add_slave
          team_lock
            team_port_add
	      dev_set_mtu
	        netdev_ops

3. rtnl_lock -> dev_addr_sem -> team_lock

rtnl_newlink
  rtnl_lock
    do_setlink IFLA_ADDRESS on upper
      dev_addr_sem
        netif_set_mac_address
          team_set_mac_address
            team_lock

4. rtnl_lock -> netdev_ops -> dev_addr_sem

rtnl_lock
  dev_ifsioc
    dev_set_mac_address_user

__tun_chr_ioctl
  rtnl_lock
    dev_set_mac_address_user

tap_ioctl
  rtnl_lock
    dev_set_mac_address_user

dev_set_mac_address_user
  netdev_lock_ops
    netif_set_mac_address_user
      dev_addr_sem

v2:
- move lock reorder to happen after kmalloc (Kuniyuki)

Cc: Kohei Enju <enjuk@amazon.com>
Fixes: df43d8bf ("net: replace dev_addr_sem with netdev instance lock")
Signed-off-by: default avatarStanislav Fomichev <sdf@fomichev.me>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250312190513.1252045-3-sdf@fomichev.me


Tested-by: default avatarLei Yang <leiyang@redhat.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 8033d2ae

include/linux/netdevice.h

+0 −2
Original line number Diff line number Diff line
@@ -4196,8 +4196,6 @@ int netif_set_mac_address(struct net_device *dev, struct sockaddr *sa, 
			  struct netlink_ext_ack *extack);

int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,

			struct netlink_ext_ack *extack);

int netif_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,

			       struct netlink_ext_ack *extack);

int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,

			     struct netlink_ext_ack *extack);

int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name);

net/core/dev.c

+0 −11
Original line number Diff line number Diff line
@@ -9577,17 +9577,6 @@ int netif_set_mac_address(struct net_device *dev, struct sockaddr *sa, 


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);

net/core/dev_api.c

+3 −1
Original line number Diff line number Diff line
@@ -89,9 +89,11 @@ int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa, 
{

	int ret;



	down_write(&dev_addr_sem);

	netdev_lock_ops(dev);

	ret = netif_set_mac_address_user(dev, sa, extack);

	ret = netif_set_mac_address(dev, sa, extack);

	netdev_unlock_ops(dev);

	up_write(&dev_addr_sem);



	return ret;

}

net/core/rtnetlink.c

+13 −2
Original line number Diff line number Diff line
@@ -3088,13 +3088,24 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev, 
			goto errout;

		}

		sa->sa_family = dev->type;



		netdev_unlock_ops(dev);



		/* dev_addr_sem is an outer lock, enforce proper ordering */

		down_write(&dev_addr_sem);

		netdev_lock_ops(dev);



		memcpy(sa->sa_data, nla_data(tb[IFLA_ADDRESS]),

		       dev->addr_len);

		err = netif_set_mac_address_user(dev, sa, extack);

		err = netif_set_mac_address(dev, sa, extack);

		kfree(sa);

		if (err)

		if (err) {

			up_write(&dev_addr_sem);

			goto errout;

		}

		status |= DO_SETLINK_MODIFIED;



		up_write(&dev_addr_sem);

	}



	if (tb[IFLA_MTU]) {