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  • Jarek Poplawski's avatar
    [AX25] af_ax25: remove sock lock in ax25_info_show() · 1105b5d1
    Jarek Poplawski authored
    This lockdep warning:
    
    > =======================================================
    > [ INFO: possible circular locking dependency detected ]
    > 2.6.24 #3
    
    
    > -------------------------------------------------------
    > swapper/0 is trying to acquire lock:
    >  (ax25_list_lock){-+..}, at: [<f91dd3b1>] ax25_destroy_socket+0x171/0x1f0 [ax25]
    >
    > but task is already holding lock:
    >  (slock-AF_AX25){-+..}, at: [<f91dbabc>] ax25_std_heartbeat_expiry+0x1c/0xe0 [ax25]
    >
    > which lock already depends on the new lock.
    ...
    
    shows that ax25_list_lock and slock-AF_AX25 are taken in different
    order: ax25_info_show() takes slock (bh_lock_sock(ax25->sk)) while
    ax25_list_lock is held, so reversely to other functions. To fix this
    the sock lock should be moved to ax25_info_start(), and there would
    be still problem with breaking ax25_list_lock (it seems this "proper"
    order isn't optimal yet). But, since it's only for reading proc info
    it seems this is not necessary (e.g.  ax25_send_to_raw() does similar
    reading without this lock too).
    
    So, this patch removes sock lock to avoid deadlock possibility; there
    is also used sock_i_ino() function, which reads sk_socket under proper
    read lock. Additionally printf format of this i_ino is changed to %lu.
    
    Reported-by: default avatarBernard Pidoux F6BVP <f6bvp@free.fr>
    Signed-off-by: default avatarJarek Poplawski <jarkao2@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    1105b5d1