RFR: 8253833: mutexLocker assert_locked_or_safepoint should not access VMThread state from non-VM-thread

Coleen Phillimore coleenp at openjdk.java.net
Thu Oct 8 14:54:46 UTC 2020


On Thu, 8 Oct 2020 13:08:51 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> It's unsafe for all threads except VM thread to access the current vm operation.
> This part of the assert is also faulty:
> If we are not at safepoint and the operation requester (calling thread) would be the owner of the lock do not mean it
> is safe for current thread.
> Passes t1-5. (also note VMThread::vm_operation() assert current thread is VM thread, and I have seen no such assert)
> 
> Thanks

Marked as reviewed by coleenp (Reviewer).

src/hotspot/share/runtime/mutexLocker.cpp line 173:

> 171:   if (!Universe::is_fully_initialized()) return;
> 172:   fatal("must own lock %s", lock->name());
> 173: }

You could refactor this like:
assert_locked_or_safepoint(lock) {
if (lock->owned_by_self()) return;
assert_locked_or_safepoint_weak(lock);
}

-------------

PR: https://git.openjdk.java.net/jdk/pull/563


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