Dinakar,
can you try patch-2.6.15-rc7-rt3-rf1 on
http://source.mvista.com/~dsingleton/ and see if it works for your
tests?
This new patch creates a 'futex_deadlock' semaphore that we hang
applications that
are deadlocking themselves. This method will only hang the
application, not the system,
as no other locks are held, like the mmap_sem, just the futex_deadlock
semaphore.
NOTE: for pthread_mutexes that are robust but NOT POSIX priority
inheriting I return -EWOULDDEADLOCK,
since there is no POSIX specfication for robust pthread_mutexes yet.
POSIX PI pthread_mutexes will hang
on the futex_deadlock semaphore.
Let me know how it works.
David
On Dec 20, 2005, at 7:50 AM, Dinakar Guniguntala wrote:
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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