RFR: 8373366: HandshakeState should disallow suspend ops for disabler threads [v4]

[Serguei Spitsyn]

On Tue, 23 Dec 2025 00:02:26 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

> Agreed. We had a private slack discussion with Patricio and decided to construct a test case to catch this situation. I've decided to postpone JBS and PR description changes while I'm working on test coverage. I had to place a comment about it.

Update: The issue was is reproducible with the new test (will add it to this PR shortly). Thanks to @pchilano for good ideas!
So, current approach is to keep the original fix and also add an assert to the function `SuspendResumeManager::do_owner_suspend()`.

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PR Comment: https://git.openjdk.org/jdk/pull/28740#issuecomment-3730324923