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

[coleen.phillimore at oracle.com]

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