On Thu, 28 Apr 2022 09:38:30 GMT, Johannes Bechberger <[email protected]>
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.
Changes requested by dholmes (Reviewer).
src/hotspot/share/prims/forte.cpp line 566:
> 564: void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void*
> ucontext) {
> 565:
> 566: JavaThread* thread = JavaThread::current_or_null();
As this can be in a signal handling context it needs to be
Thread::current_or_null_safe().
src/hotspot/share/prims/forte.cpp line 568:
> 566: JavaThread* thread = JavaThread::current_or_null();
> 567:
> 568: if (trace->env_id == NULL || thread == NULL || thread->is_terminated()
> || thread->is_exiting()) {
`is_exiting()` also covers `is_terminated()`.
src/hotspot/share/prims/forte.cpp line 580:
> 578: }
> 579:
> 580: assert(thread ==
> JavaThread::thread_from_jni_environment(trace->env_id),
Please add a comment before the assert:
// This is safe now as the thread has not terminated and so no VM exit check
occurs.
-------------
PR: https://git.openjdk.java.net/jdk/pull/8446
