RFR: 8253833: mutexLocker assert_locked_or_safepoint should not access VMThread state from non-VM-thread

[Robbin Ehn]

On Thu, 8 Oct 2020 13:22:55 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> It's unsafe for all threads except VM thread to access the current vm operation.
>> This part of the assert is also faulty:
>> If we are not at safepoint and the operation requester (calling thread) would be the owner of the lock do not mean it
>> is safe for current thread.
>> Passes t1-5. (also note VMThread::vm_operation() assert current thread is VM thread, and I have seen no such assert)
>> 
>> Thanks
>
> Looks okay to me. Is it significantly different from `assert_locked_or_safepoint_weak` now?

@shipilev and @dholmes-ora you are not listed under "Reviewers" commit message part, can you press the magic button(s)
(approve?) so you get the credit!

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PR: https://git.openjdk.java.net/jdk/pull/563