panic in AcpiExReleaseMutex

[Andriy Gapon]

on 04/12/2009 23:24 Moore, Robert said the following:
>> This  thread has a fixed tid of 100000.
> 
> This is ok.
> 
> Well, I don't see anything obvious. You will probably need to step through
> the calls to AcpiExAcquireMutex and AcpiExReleaseMutex, or at least add some
> printfs to monitor the value of WalkState->Thread->AcquiredMutexList.

I see.

> Another question, however: is the global lock involved in any way?

Yes.  EC querying is performed under global lock.  That is, it gets locked and
unlocked in EcGpeQueryHandler function before _Qxx evaluation.
I am actually curious why you asked this question.

Thank you!

>> -----Original Message----- From: Andriy Gapon [mailto:avg at icyb.net.ua] 
>> Sent: Friday, December 04, 2009 1:20 PM To: Moore, Robert Cc:
>> freebsd-acpi at freebsd.org; Tarick Subject: Re: panic in AcpiExReleaseMutex
>> 
>> on 04/12/2009 22:59 Moore, Robert said the following:
>>> It would appear that a GPE is taken, for the EC device, thus invoking 
>>> EcGpeQueryHandler. In what context is _Q20 or _Q09 executed?
>> It's invoked in "polling mode" at that stage.  Interrupts are not enabled 
>> yet at that point.  Let me quote my original report: [quote] _REG method
>> seems to access some registers in EC address space (with 
>> \_SB.PCI0.LPC0.EC0.MUT1 mutex locked).  That access triggers a call to 
>> EcSpaceHandler.  Now, we have a code in EcSpaceHandler that makes a direct 
>> call to EcGpeQueryHandler during a cold boot phase if SCI bit is set in CSR
>>  register. EcGpeQueryHandler performs an EC query and executes _Qxx method
>> if need. [/quote]
>> 
>> So, everything happens in the same thread with the same context and stack.
>> 
>>> This might be an important question: What is the thread_id of this
>> initial
>>> thread?
>> This  thread has a fixed tid of 100000.
>> 
>>>> -----Original Message----- From: Andriy Gapon [mailto:avg at icyb.net.ua] 
>>>> Sent: Friday, December 04, 2009 12:50 PM To: Moore, Robert Cc: 
>>>> freebsd-acpi at freebsd.org; Tarick Subject: Re: panic in
>> AcpiExReleaseMutex
>>>> on 04/12/2009 20:45 Moore, Robert said the following:
>>>>> Yes, you are correct. I did not have the code in front of me at the
>> time.
>>>>> 
>>>>> 
>>>>> 
>>>>> When AcpiExReleaseMutex is called, apparently the mutex is in fact
>> held,
>>>>> otherwise the function would have aborted immediately.
>>>>> 
>>>>> When the mutex is held, the Thread->AcquiredMutexList is expected to
>> hold
>>>>> 
>>>>> 
>>>> (at
>>>>> the minimum) the mutex object being released. Something is very wrong
>>>>> 
>> if
>>>> this
>>>>> list is NULL when releasing the mutex.
>>>>> 
>>>>> Just to make sure: All of this is happening in the same thread?
>>>> Yes, this happens when there is only the initial thread running on BSP,
>>>> 
>> no
>>>> other threads are started yet.
>>>> 
>>>> 
>>>> -- Andriy Gapon
>> 
>> -- Andriy Gapon


-- 
Andriy Gapon