[jdk21u-dev] Integrated: 8351933: Inaccurate masking of TC subfield decrement in ForkJoinPool

[Dmitry Chuyko]

On Thu, 13 Mar 2025 14:31:42 GMT, Dmitry Chuyko <dchuyko at openjdk.org> wrote:

> This a backport of JDK-8351933 [0] (PR [1]) for 21u. At one of code paths the TC subfield of ctl field is decremented and the result is not masked correctly. The target code is also in tryTrim() but the surrounding is different from the current master, as well as the original mask name. The core change is the same, candidate for compareAndSetCtl() is constructed using '(c & RC_MASK) | ((c - TC_UNIT) & TC_MASK)' instead of '(UC_MASK & (c - TC_UNIT))' to correctly preserve the RC subfield.
> 
> [0] https://bugs.openjdk.org/browse/JDK-8351933
> [1] https://github.com/openjdk/jdk/pull/24034

This pull request has now been integrated.

Changeset: e13da984
Author:    Dmitry Chuyko <dchuyko at openjdk.org>
Committer: Paul Hohensee <phh at openjdk.org>
URL:       https://git.openjdk.org/jdk21u-dev/commit/e13da984481b17fb5ba7a27a25112fa5fd6f7722
Stats:     1 line in 1 file changed: 0 ins; 0 del; 1 mod

8351933: Inaccurate masking of TC subfield decrement in ForkJoinPool

Reviewed-by: phh, dl

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PR: https://git.openjdk.org/jdk21u-dev/pull/1485