From: david singleton <dsingleton@mvista.com>
To: dino@in.ibm.com
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org, robustmutexes@lists.osdl.org
Subject: Re: Recursion bug in -rt
Date: Mon, 2 Jan 2006 17:54:43 -0800 [thread overview]
Message-ID: <E8B90C30-7BFB-11DA-8CAD-000A959BB91E@mvista.com> (raw)
In-Reply-To: <20051220155004.GA3906@in.ibm.com>
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
>
next prev parent reply other threads:[~2006-01-03 1:54 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-14 22:39 Recursion bug in -rt Dinakar Guniguntala
2005-12-15 1:03 ` david singleton
2005-12-15 19:44 ` Dinakar Guniguntala
2005-12-15 20:40 ` David Singleton
2005-12-16 0:02 ` david singleton
2005-12-16 18:42 ` Dinakar Guniguntala
2005-12-16 21:26 ` David Singleton
2005-12-19 11:56 ` Dinakar Guniguntala
2005-12-19 20:11 ` David Singleton
2005-12-15 19:00 ` David Singleton
2005-12-15 19:52 ` Dinakar Guniguntala
2005-12-20 13:19 ` Ingo Molnar
2005-12-20 15:50 ` Dinakar Guniguntala
2005-12-20 17:43 ` Esben Nielsen
2005-12-20 19:33 ` Steven Rostedt
2005-12-20 20:42 ` Esben Nielsen
2005-12-20 21:20 ` Steven Rostedt
2005-12-20 21:55 ` david singleton
2005-12-20 22:56 ` Esben Nielsen
2005-12-20 23:12 ` Steven Rostedt
2005-12-20 23:55 ` Esben Nielsen
2005-12-22 4:37 ` david singleton
2005-12-20 22:43 ` Esben Nielsen
2005-12-20 22:59 ` Steven Rostedt
2006-01-03 1:54 ` david singleton [this message]
2006-01-05 2:14 ` david singleton
2006-01-05 9:43 ` Esben Nielsen
2006-01-05 17:11 ` david singleton
2006-01-05 17:47 ` Esben Nielsen
2006-01-05 18:26 ` david singleton
2006-01-07 2:40 ` robust futex deadlock detection patch david singleton
[not found] ` <a36005b50601071145y7e2ead9an4a4ca7896f35a85e@mail.gmail.com>
2006-01-07 19:49 ` Ulrich Drepper
2006-01-09 9:23 ` Esben Nielsen
2006-01-09 20:01 ` David Singleton
2006-01-09 20:16 ` Esben Nielsen
2006-01-09 21:08 ` Steven Rostedt
2006-01-09 21:19 ` Esben Nielsen
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