RFR 8171971: Fix timing bug in JVM management of package export lists

[harold seigel]

Hi Serguei,

Thanks for the review.

I think that Modules::add_module_exports_to_all_unnamed() and similar 
functions are okay because the functions that they call to set the new 
export states take out the module lock.

If you are concerned about them then maybe enter a new bug for them?

Thanks, Harold


On 1/19/2017 5:05 AM, serguei.spitsyn at oracle.com wrote:
> Hi Harold,
>
> It looks pretty good to me.
>
> One question though.
>
> || src/share/vm/classfile/modules.cpp
>
>   I wonder if a synchronization is needed for the functions like
>   Modules::add_module_exports_to_all_unnamed.
>   But this is unrelated to your particular fix.
> ||
>
> Thanks,
> Serguei
>
>
>
> On 1/18/17 07:05, harold seigel wrote:
>> Hi,
>>
>> Please review this fix for the package export timing holes discussed 
>> in JDK-8171971.  The fix reduces the number of PackageEntry fields 
>> that are used to maintain a package's export state and uses the 
>> Module_lock to protect all access to these fields.
>>
>> Also, in cases where a package transitions from having qualified 
>> exports to being unqualifiedly exported, it fixes the cleanup of its 
>> qualified export list by removing the _exported_pending_delete field 
>> and using just is_unqual_exported() to determine when the qualified 
>> exports list can be purged (at a safepoint).
>>
>> Open Webrev: http://cr.openjdk.java.net/~hseigel/bug_8171971/webrev/
>>
>> JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8171971
>>
>> The fix was tested with the hotspot, java/lang, java/util, java/io, 
>> JFR, and other JTReg tests, the JCK lang and VM tests, RBT tier2 - 
>> tier5 tests on LinuxX64, and the colocated and non-colocated NSK tests.
>>
>> Thanks, Harold
>>
>