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

[David Holmes]

On Thu, 8 Oct 2020 16:03:07 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> src/hotspot/share/runtime/mutexLocker.cpp line 171:
>> 
>>> 169:   if (lock->owned_by_self()) return;
>>> 170:   if (SafepointSynchronize::is_at_safepoint()) return;
>>> 171:   if (!Universe::is_fully_initialized()) return;
>> 
>> Is this bailout on L171 for the code you are deleting (old L172-4)
>> or for the fatal() on old L175?
>
> I was hope that "git blame" would help, but most of this code is ancient:
> 
> da18495f385b (Coleen Phillimore 2019-08-22 09:51:36 -0400 166) void assert_locked_or_safepoint(const Mutex* lock) {
> 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 167)   // check if this thread owns the lock (common case)
> 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 168)   assert(lock != NULL, "Need non-NULL lock");
> 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 169)   if (lock->owned_by_self()) return;
> 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 170)   if (SafepointSynchronize::is_at_safepoint()) return;
> 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 171)   if (!Universe::is_fully_initialized()) return;
> 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 172)   // see if invoker of VM operation owns it
> 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 173)   VM_Operation* op = VMThread::vm_operation();
> 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 174)   if (op != NULL && op->calling_thread() ==
> lock->owner()) return; 1e71f6773659 (David Lindholm    2015-09-29 11:02:08 +0200 175)   fatal("must own lock %s",
> lock->name()); 8153779ad32d (J. Duke           2007-12-01 00:00:00 +0000 176) }
> 
> Update: Stripped the filename from the "git blame" output so it wasn't quite so wide...
> Update: Changing to a `code` quote helped the formatting a bit...

The initialization bail-out was added "1.86 99/02/19 17:05:07", but no comments or associated bug report.

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