net: reorder dev_addr_sem lock
authorStanislav Fomichev <sdf@fomichev.me>
Wed, 12 Mar 2025 19:05:13 +0000 (12:05 -0700)
committerPaolo Abeni <pabeni@redhat.com>
Wed, 19 Mar 2025 17:52:00 +0000 (18:52 +0100)
commit6dd132516f8e467f144f7871ff2708ce827417a1
treedecb418263cf909476a8c5d33166e8477e58affb
parent8033d2aef51722fe74068b52553625ed91ea256c
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>
include/linux/netdevice.h
net/core/dev.c
net/core/dev_api.c
net/core/rtnetlink.c