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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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