<AWT Dev> Review Request For 8146230: Crash in JNI_ArgumentPusherVaArg::JNI_ArgumentPusherVaArg(_jmethodID*, __va_list_tag*)+0xa

[Semyon Sadetsky]

Hi Ambarish,

Why not simply initialize yieldMethodID separately? For example in 
Java_sun_awt_X11_XToolkit_initIDs.

--Semyon

On 06.07.2016 14:23, Ambarish Rapte wrote:
>
> Hi,
>
>                 Please review the fix for JDK9,
>
>                 Bug: https://bugs.openjdk.java.net/browse/JDK-8146230
>
>                 Webrev: 
> http://cr.openjdk.java.net/~arapte/8146230/webrev.00/ 
> <http://cr.openjdk.java.net/%7Earapte/8146230/webrev.00/>
>
> Issue:
>
> 1.Null pointer exception in JNI
>
> Cause:
>
> The code block was not multi thread safe.
>
> Issue occurs in  multi threaded , multi processor environment.
>
> Fix:
>
> 1.Changed the variable used for double checking, to use /yieldMethodID ./
>
> 2.Changed /yieldMethodID  to  volatile./
>
> 3.Added AWT_LOCK() over initialize block of code.
>
> 4.Removed unrequired  err variable.
>
> A drawback of Double Check Locking ( DCL ) is, if the resource 
> assignment is not an atomic operation, The DCL may fail.
>
> But here in the code of concern, is an atomic operation. Hence DCL 
> should work fine.
>
> Please check below reference link for more detailed discussion of DCL 
> with C++.
>
> Verification:
>
> 1.Tested Event tests which pass without any regression of this change.
>
> 2.As this change only corrects existing logic, there should be no side 
> effects.
>
> Reference:
>
>                 C++ and the Perils of Double-Checked Locking: 
> http://www.aristeia.com/Papers/DDJ_Jul_Aug_2004_revised.pdf
>
> Regards,
>
> Ambarish
>

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