RFR: 8261660: AArch64: Race condition in stub code generation for LSE Atomics

[Andrew Dinn]

On Fri, 12 Feb 2021 16:55:01 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Temporary fix for race condition.
>> 
>> There's a narrow race condition in the code which generates LSE Atomic stubs and enables them for use by the runtime. DIsable LSE stub generation for now.
>
> Thanks for the explanation. Thumbs up.
> 
> This is a trivial fix and does not have to wait for 24 hours.

@dcubed-ojdk A complete fix merely requires writing the generated stub code before updating the stub function pointers. With this change all that happens is that those pointers continue pointing to the default routines. There is no point backing out the rest of the code given that it will almost all be needed.

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PR: https://git.openjdk.java.net/jdk/pull/2553