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    lockdep: Check the depth of subclass · 4ba053c0
    Hitoshi Mitake 提交于
    Current look_up_lock_class() doesn't check the parameter "subclass".
    This rarely rises problems because the main caller of this function,
    register_lock_class(), checks it.
    
    But register_lock_class() is not the only function which calls
    look_up_lock_class(). lock_set_class() and its callees also call it.
    And lock_set_class() doesn't check this parameter.
    
    This will rise problems when the the value of subclass is larger than
    MAX_LOCKDEP_SUBCLASSES. Because the address (used as the key of class)
    caliculated with too large subclass has a probability to point
    another key in different lock_class_key.
    
    Of course this problem depends on the memory layout and
    occurs with really low probability.
    Signed-off-by: NHitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
    Cc: Dmitry Torokhov <dtor@mail.ru>
    Cc: Vojtech Pavlik <vojtech@ucw.cz>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
    LKML-Reference: <1286958626-986-1-git-send-email-mitake@dcl.info.waseda.ac.jp>
    Signed-off-by: NIngo Molnar <mingo@elte.hu>
    4ba053c0
lockdep.c 91.6 KB