Messages in this thread | | | Subject | Re: [PATCH v2] lockdep: check the depth of subclass | From | Peter Zijlstra <> | Date | Wed, 13 Oct 2010 10:48:29 +0200 |
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On Wed, 2010-10-13 at 17:30 +0900, Hitoshi Mitake wrote: > 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 possibility to point > another key in different lock_class_key. > Of course this problem depends on the memory layout and > occurs with really low possibility. > > And mousedev_create() calles lockdep_set_subclass() and > sets class of mousedev->mutex as MOUSEDEV_MIX(== 31). > And if my understanding is correct, > this subclass doesn't have to be MOUSEDEV_MIX, > so I modified this value to SINGLE_DEPTH_NESTING. > > v2: Based on Peter Zijlstra's advice, I removed the > checking of the subclass value from __lock_acquire(). > Because this is already a redundant thing. > > # If you need devided version for mousedev.c and lockdep.c, > # feel free to tell me.
I've taken the patch without the mousedev hunk, as Dmitry said he'd take that.
Thanks!
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