RFR: 8358821: patch_verified_entry causes problems, use nmethod entry barriers instead [v4]

[Erik Österlund]

On Mon, 23 Jun 2025 19:10:03 GMT, Dean Long <dlong at openjdk.org> wrote:

> I think it's OK if there is a race to have a point of no return, and if one thread gets there first, it wins, and we don't need to check again.  It's tempting to want to do an extra check when we disarm under the lock, but then it would need a comment explaining why we do it, even though the make_not_entrant could come in right after and we would miss it.  And we have already done the work of healing the oops by this point.  Finally, I like the encapsulation that only nmethod_stub_entry_barrier needs to know about not_entrant, and nmethod_entry_barrier doesn't need to know. 

Fair enough!

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PR Review Comment: https://git.openjdk.org/jdk/pull/25764#discussion_r2164467913