RFR: 8285794: AsyncGetCallTrace might acquire a lock via JavaThread::thread_from_jni_environment [v4]

[Martin Doerr]

On Tue, 3 May 2022 08:02:57 GMT, Johannes Bechberger <duke at openjdk.java.net> wrote:

>> Calling JavaThread::thread_from_jni_environment for a terminated thread in AsyncGetCallTrace might cause the acquisition of a lock, making AsyncGetCallTrace non-signal-safe. 
>> 
>> AsyncGetCallTrace can only be called for the current threads (there are asserts for that), therefore using JavaThread::current directly and checking the termination status is semantically equivalent.
>
> Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Merge cast into condition

LGTM.

src/hotspot/share/prims/forte.cpp line 571:

> 569:   JavaThread* thread;
> 570: 
> 571:   if (trace->env_id == NULL || raw_thread == NULL || !raw_thread->is_Java_thread() || (thread = JavaThread::cast(raw_thread))->is_exiting()) {

Line is a bit long! (There are other long lines in this file, too, so, I can live with it.)

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Marked as reviewed by mdoerr (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/8446