RFR (S) 8225681: vmTestbase/nsk/jvmti/RedefineClasses/StressRedefine fails due a) MT-unsafe modification of inline cache

[erik.osterlund at oracle.com]

Hi Coleen,

I don't understand this. It makes the frame-local variable volatile. But 
surely the frame local variable is accessed only by the current thread. 
And the whole thing is protected by the CompiledICLocker. Would you mind 
explaining what we are worried about here?

Thanks,
/Erik

On 9/26/19 5:59 PM, coleen.phillimore at oracle.com wrote:
>
> For the record, I added volatiles after discussions with Goetz:
>
> http://cr.openjdk.java.net/~coleenp/2019/8225681.02/webrev
>
> Which builds on s390 and ppc, and verified on Oracle platforms as well.
>
> Coleen
>
> On 9/26/19 7:24 AM, coleen.phillimore at oracle.com wrote:
>> Thanks Erik!
>> Coleen
>>
>> On 9/26/19 5:47 AM, erik.osterlund at oracle.com wrote:
>>> Hi Coleen,
>>>
>>> Looks good.
>>>
>>> Thanks,
>>> /Erik
>>>
>>> On 9/25/19 11:22 PM, coleen.phillimore at oracle.com wrote:
>>>> Summary: allow old methods in 
>>>> CompiledStaticDirectCall::set_to_interpreted
>>>>
>>>> This is the comment in the bug that describes this race and this fix:
>>>> https://bugs.openjdk.java.net/browse/JDK-8225681?focusedCommentId=14278441&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14278441 
>>>>
>>>>
>>>> The rest of the bug and sightings are actually caused by 
>>>> https://bugs.openjdk.java.net/browse/JDK-8226690,
>>>> and this one might have been caused by it also, but the race that 
>>>> Erik describes is possible as well.
>>>>
>>>> The s390 code had an exception for 
>>>> callee->is_compiled_lambda_form() which should probably apply to 
>>>> all the platforms, so the code is the same on all the platforms 
>>>> with this change.
>>>>
>>>> Tested with tier1-6.
>>>>
>>>> open webrev at 
>>>> http://cr.openjdk.java.net/~coleenp/2019/8225681.01/webrev
>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8225681
>>>>
>>>> Thanks,
>>>> Coleen
>>
>