• Cong Wang's avatar
    net: change addr_list_lock back to static key · 845e0ebb
    Cong Wang authored
    The dynamic key update for addr_list_lock still causes troubles,
    for example the following race condition still exists:
    
    CPU 0:				CPU 1:
    (RCU read lock)			(RTNL lock)
    dev_mc_seq_show()		netdev_update_lockdep_key()
    				  -> lockdep_unregister_key()
     -> netif_addr_lock_bh()
    
    because lockdep doesn't provide an API to update it atomically.
    Therefore, we have to move it back to static keys and use subclass
    for nest locking like before.
    
    In commit 1a33e10e ("net: partially revert dynamic lockdep key
    changes"), I already reverted most parts of commit ab92d68f
    ("net: core: add generic lockdep keys").
    
    This patch reverts the rest and also part of commit f3b0a18b
    ("net: remove unnecessary variables and callback"). After this
    patch, addr_list_lock changes back to using static keys and
    subclasses to satisfy lockdep. Thanks to dev->lower_level, we do
    not have to change back to ->ndo_get_lock_subclass().
    
    And hopefully this reduces some syzbot lockdep noises too.
    
    Reported-by: syzbot+f3a0e80c34b3fc28ac5e@syzkaller.appspotmail.com
    Cc: Taehee Yoo <ap420073@gmail.com>
    Cc: Dmitry Vyukov <dvyukov@google.com>
    Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    845e0ebb
netdevice.h 156 KB