RFR (S) 8164692: InstanceKlass::_previous_version_count goes negative

[Daniel D. Daugherty]

On 8/30/16 2:49 PM, Coleen Phillimore wrote:
> Summary: decrement previous_version_count when it's removed from the 
> list.
>
> The previous_version_count was decremented in the wrong place. This 
> contributed to the bug that Dean's just sent out the RFR and the fix 
> is essentially contributed by Dean.
>
> Ran jdk/test/java/lang/instrument, and internal closed (colocated and 
> non-colocated) redefinition tests.
>
> open webrev at http://cr.openjdk.java.net/~coleenp/8164692.01/webrev

src/share/vm/classfile/classLoaderData.cpp
     L965: // and only if class redefinition and if there are previous 
versions of
         Perhaps:

         // and only if class redefinition occurred and if there are 
previous versions of

src/share/vm/oops/instanceKlass.cpp
     No comments.

src/share/vm/oops/instanceKlass.hpp
     No comments.

test/runtime/RedefineTests/RedefineCount.java
     L48: // previous_version_list and the count should stay zero, but 
not go negative

         Perhaps:

             "should stay zero and not go negative"

         for that last part.

Does the new test (RedefineCount.java) reproduce the crash that Dean L
is chasing in https://bugs.openjdk.java.net/browse/JDK-8156137?

Thumbs up!

Dan


> bug link https://bugs.openjdk.java.net/browse/JDK-8164692
>
>
> Thanks,
> Coleen