[lworld] RFR: 8323781: [lworld] Synchronization on inline type does not throw IllegalMonitorStateException with lightweight locking

[Tobias Hartmann]

On Thu, 18 Jan 2024 09:02:51 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

> [JDK-8315880](https://bugs.openjdk.org/browse/JDK-8315880) sets `LM_LIGHTWEIGHT` as new default locking mode which revealed an existing bug after the merge of jdk-22+16 (triggers already before the merge by explicitly setting `-XX:LockingMode=2`). JDK-8315880 was backed out again in jdk-22+24 ([JDK-8319253](https://bugs.openjdk.org/browse/JDK-8319253)). But the backout is not yet merged in. The REDO [JDK-8319251](https://bugs.openjdk.org/browse/JDK-8319251) is still open. Maybe we need to add some runs in the CI in the future which test all three locking modes.
> 
> This patch fixes a problem in the newly added lightweight locking code ([JDK-8291555](https://bugs.openjdk.org/browse/8291555)) where we forgot to mask the inline type bit in the mark word. This patch fixes that and unlists the problemlisted tests.
> 
> Thanks,
> Christian

That looks good to me. Thanks for fixing!

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Marked as reviewed by thartmann (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/972#pullrequestreview-1829202705