RFR (XS) 8199012: JVM crash during LevelDB JNI access

[David Holmes]

Can I get a second review please.

Thanks,
David

On 7/03/2018 9:31 AM, David Holmes wrote:
> webrev: http://cr.openjdk.java.net/~dholmes/8199012/webrev/
> bug: https://bugs.openjdk.java.net/browse/JDK-8199012
> 
> JNI DetachCurrentThread is defined as a no-op if called by a thread that 
> is not attached. But the check for that was occurring after we called 
> VM_Exit::block_if_vm_exited(). If the thread was not in fact attached 
> then we have a NULL current thread and that can cause in crash in 
> VM_Exit::block_if_vm_exited() if we actually need to block - which 
> explains the scenario reported in the bug.
> 
> Simple, obvious, fix is to do the "not attached" check first.
> 
> Testing:
>    - Mach5 CI equivalent testing (tier1/2)
>    - internal JNI tests
> 
> I marked this noreg-hard as a regression test is difficult to set up due 
> to the need to coordinate with a VM shutdown.
> 
> Thanks,
> David