RFR (XS) 8202014: Possible to receive signal before signal semaphore created

[coleen.phillimore at oracle.com]

On 5/18/18 2:07 AM, Thomas Stüfe wrote:
> Hi Coleen,
>
> looks good, thanks for taking my suggestion.
>
> Thoughts for further improvements:
>
> - os::signal_init could be renamed to something more to the point,
> e.g. os::initialize_signal_dispatcher_thread() or
> os::initialize_jdk_signal_support() or similar

Okay os::signal_init => os::initialize_jdk_signal_support()
>
> - os::signal_init_pd could be removed from os.hpp altogether and made
> file scope static in the os_xxx.cpp file. It could also have a better
> name.

os::signal_init_pd => jdk_misc_signal_init().
> I leave it up to you if you do this in a follow up item, or even at
> all. The fix is fine to me in its current form.

I'll make these changes with this minor change.  Hopefully this is 
agreeable.

Thanks,
Coleen

>
> Thanks, Thomas
>
>
>
>
> On Thu, May 17, 2018 at 9:25 PM,  <coleen.phillimore at oracle.com> wrote:
>>
>> On 5/16/18 2:04 AM, Thomas Stüfe wrote:
>>> Hi,
>>>
>>> I agree with David. Signal handlers are installed in os::init_2(), but
>>> the semaphore sometime later in the (imho misleadingly named) void
>>> os::signal_init(). This looks like an initialization error.
>>>
>>> As a side note, can we make the "void signalHandler(int sig,
>>> siginfo_t* info, void* uc)" functions in os_xxx.cpp static, since they
>>> are only file local marshalling points?
>>
>> Okay, I've moved the initialization of the signal semaphore to os::init_2().
>> The signal handler for this signal_notify() case is set up by
>> JVM_RegisterSignal early in JDK initialization (initPhase1) which is before
>> os::signal_init() was run.  Now the semaphore is initialized before that.
>>
>> I also made signalHandler static in this change although not strictly
>> related.
>>
>> http://cr.openjdk.java.net/~coleenp/8202014.02/webrev/index.html
>>
>> Reran kill -INT script and mach5 hs_tiers 1 and 2.
>> test/hotspot/jtreg/runtime/signal tests and
>> test/jdk/sun/misc/SunMiscSignalTest.java.
>>
>> Thanks,
>> Coleen
>>
>>
>>> Kind Regards, Thomas
>>>
>>>
>>>
>>>
>>> On Wed, May 16, 2018 at 4:40 AM, David Holmes <david.holmes at oracle.com>
>>> wrote:
>>>> Hi Coleen,
>>>>
>>>> On 16/05/2018 11:23 AM, coleen.phillimore at oracle.com wrote:
>>>>> Summary: Don't assert for null semaphore because it can be null before
>>>>> initialization is complete.
>>>>
>>>> Sorry I don't agree with this. Surely we should not install our signal
>>>> handler until such time as everything is properly initialized? Or the
>>>> handler itself should have some kind of initialization check to guide how
>>>> it
>>>> responds.
>>>>
>>>> Thanks,
>>>> David
>>>>
>>>>
>>>>> Tested this with a shell script, thanks Robbin, and mach5 tier1,2 all
>>>>> Oracle platforms.  AIX doesn't use the semaphore class so doesn't have
>>>>> this
>>>>> bug.
>>>>>
>>>>> open webrev at http://cr.openjdk.java.net/~coleenp/8202014.01/webrev
>>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8202014
>>>>>
>>>>> Thanks,
>>>>> Coleen
>>