RFR: 8370314: Update signals_posix with new Linux signal codes [v2]

[Aleksey Shipilev]

On Thu, 8 Jan 2026 06:19:56 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> There are a few "new" si_codes defined on Linux that we did not support for error reporting. Some of these are only exposed in more recent glibc versions so we have to hard-wire them for older build environments.
>> 
>> The changes are all conditional on Linux, except the POLL_IN addition which is conditional on SIGPOLL, which is turn only exists on Linux.
>> 
>> Tested with local Linux environments, plus our CI plus GHA.
>> 
>> Thanks.
>
> David Holmes has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'master' into 8370314-posix-signals
>  -  8370314: Update signals_posix with new Linux signal codes

Looks reasonable, thanks.

I wish we could check the hard-coded values with the actual exported values (when available in building with newer GCC), but that is likely hard to do at preprocessor level.

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29105#pullrequestreview-3638119868