RFR: 8273695: Safepoint deadlock on VMOperation_lock

[Robbin Ehn]

On Tue, 21 Sep 2021 16:21:20 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> src/hotspot/share/runtime/safepointMechanism.inline.hpp line 83:
>> 
>>> 81:   // 3: The JavaThread wakes-up from blocked and do not allow suspend.
>>> 82:   // We are now about to avoid processing and thus no cross modify fence will be executed.
>>> 83:   // Therefore we executed it here.
>> 
>> typo: s/executed/execute/
>
> Also, do you need a call to `update_poll_values(thread)` here
> before the `cross_modify_fence()` call?

Fixed.

No, we do not need to update it.
But maybe we want to, to avoid hitting poll-sites.
The reason not to do it is that it is preferable to have the plain query should_process() not having side-effects.

I need to think about that, thanks for bringing that up.

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

PR: https://git.openjdk.java.net/jdk/pull/5613