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: df43d8bf1031 ("net: replace dev_addr_sem with netdev instance lock")
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250312190513.1252045-3-sdf@fomichev.me
Tested-by: Lei Yang <leiyang@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 0db9fc0afe3605a0b7e92cef2b5330615ee1e7fd..0c5b1f7f8f3af8049ee7aa25817351e998bf6354 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -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);

diff --git a/net/core/dev.c b/net/core/dev.c
index 977a9946d39c5af5617b7adb1c9551fd5dd051ed..2355603417650fe10d075c8e85416a488e00626d 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -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);

diff --git a/net/core/dev_api.c b/net/core/dev_api.c
index 2e17548af685a48f81f79e8357a9dd17a86d8f25..8dbc6061210079f571713c6fbf456cba0baacf98 100644 (file)
--- a/net/core/dev_api.c
+++ b/net/core/dev_api.c
@@ -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;
 }

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 9355058bf996978b17a6c81eff1d9f47f1a8b368..5a24a30dfc2d13f8e113164a44082f90efe31ef3 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -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]) {