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    SubjectRe: Recursion bug in -rt
    On Tue, Dec 20, 2005 at 02:19:56PM +0100, Ingo Molnar wrote:
    >
    > hm, i'm looking at -rf4 - these changes look fishy:
    >
    > - _raw_spin_lock(&lock_owner(lock)->task->pi_lock);
    > + if (current != lock_owner(lock)->task)
    > + _raw_spin_lock(&lock_owner(lock)->task->pi_lock);
    >
    > why is this done?
    >

    Ingo, this is to prevent a kernel hang due to application error.

    Basically when an application does a pthread_mutex_lock twice on a
    _nonrecursive_ mutex with robust/PI attributes the whole system hangs.
    Ofcourse the application clearly should not be doing anything like
    that, but it should not end up hanging the system either

    -Dinakar

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