RFR: 8280832: Update usage docs for NonblockingQueue [v2]

[Kim Barrett]

On Thu, 10 Feb 2022 06:50:42 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Kim Barrett has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   walulyai review
>
> src/hotspot/share/utilities/nonblockingQueue.inline.hpp line 122:
> 
>> 120:     // concurrent try_pop could take old_tail before our update, it gets
>> 121:     // recycled and re-added to the end, and then we successfully cmpxchg,
>> 122:     // rendering the list in _tail circular.
> 
> Suggestions:
> 
> 1. start the new comment on a new line
> 2.  "Note that ABA would be possible if a concurrent try_pop takes old_tail before our update, ...
> 
> Cheers,
> David

OK, I separated the note and reworded it a bit.  Better?

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PR: https://git.openjdk.java.net/jdk/pull/7393