GPE handler livelock

[Moore, Robert]

This sounds suspiciously like the changes we made to the Notify()
handling last year. We attempted to make the notify handler run
synchronously with the caller to Notify(), but this created more
problems than it solved. We ended up returning the behavior of Notify
handlers to be asynchronous:



19 October 2007. Summary of changes for version 20071019:

1) ACPI CA Core Subsystem:

Reverted a change to Notify handling that was introduced in version 
20070508. This version changed the Notify handling from asynchronous to 
fully synchronous (Device driver Notify handling with respect to the
Notify 
ASL operator). It was found that this change caused more problems than
it 
solved and was removed by most users.




>-----Original Message-----
>From: owner-freebsd-acpi at freebsd.org [mailto:owner-freebsd-
>acpi at freebsd.org] On Behalf Of Yousif Hassan
>Sent: Sunday, January 06, 2008 12:18 PM
>To: Nate Lawson
>Cc: freebsd-acpi at FreeBSD.org
>Subject: Re: GPE handler livelock
>
>Nate wrote:
>> Thanks for digging into this.  I reviewed this and am trying to
figure
>> out why the _L00 handler never completes.  It keeps getting preempted
by
>> the next one.  To help track this down, try removing these two lines
>> from the _L00 method and recompile your ASL:
>>
>>    Acquire (\_TZ.C173, 0xFFFF)
>>    ...
>>    Release (\_TZ.C173)
>>
>> For others who have this problem, instructions on how to recompile
and
>> load your custom ASL can be found here (11.16.4 and 5):
>>
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/acpi-debug.htm
l
>
>I'm not sure if my situation is exactly what you're referring to in
>this note, but since my laptop is also an HP (nx6110), and since it
also
>hangs during thermal zone changes, I tried your suggestion.  It didn't
>help, unfortunately.  I still get mutex problems when the thermal zone
>increases.  My ASL did not have precisely the Acquire call you listed,
>but it did have a similar one in method _L00 called
>Acquire (\_TZ.C170, 0xFFFF) and Release (\_TZ.C170).  Also this pair
>of calls was also found in one other place (further down) in the ASL.
>I only removed the first pair in the method you instructed.
>FWIW, here are the debug error messages when the machine hangs:
>
>ACPI Exception (utmutex-0376): AE_TIME, Thread 28 could not acquire
Mutex
> [0] [20070320]
>ACPI Error (exutils-0180): Could not acquire AML Interpreter mutex
> [20070320]
>ACPI Error (utmutex-0421): Mutex [0] is not acquired, cannot release
> [20070320]
>ACPI Error (exutils-0250): Could not release AML Interpreter mutex
> [20070320]
>ACPI Exception (utmutex-0376): AE_TIME, Thread 28 could not acquire
Mutex
> [0] [20070320]
>ACPI Error (exutils-0180): Could not acquire AML Interpreter mutex
> [20070320]
>ACPI Error (psparse-0626): Method parse/execution failed [\_TZ_.C242]
(Node
> 0xc321c220), AE_TIME
>ACPI Error (psparse-0626): Method parse/execution failed
[\_TZ_.TZ1_._TMP]
> (Node 0xc321b9c0), AE_TIME
>... etc ...
>
>I put more info into PR 79080.
>
>Let me know if you want me to try anything else.
>--Yousif
>
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