RFR: JDK-8255711: Fix and unify hotspot signal handlers [v3]

[Thomas Stuefe]

On Thu, 5 Nov 2020 17:39:02 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Feedback David
>
> Changes requested by gziemski (Committer).

Thanks for the review, Gerard! I'll wait for Davids feedback, since he may want more changes done.

> src/hotspot/os/posix/signals_posix.cpp line 587:
> 
>> 585:   // Call platform dependent signal handler.
>> 586:   if (!signal_was_handled) {
>> 587:     signal_was_handled = PosixSignals::pd_hotspot_signal_handler(sig, info, uc, jt);
> 
> Can we move:
> 
> JavaThread* const jt = (t != NULL && t->is_Java_thread()) ? (JavaThread*) t : NULL;
> 
> here? It's not used anywhere else.

Sure, I can do this. We can move it up again when/if later needed.

> src/hotspot/os/posix/signals_posix.cpp line 610:
> 
>> 608:     }
>> 609: #if defined(ZERO) && !defined(PRODUCT)
>> 610:     char buf[20];
> 
> How do we know 20 makes it big enough?

Its the signal name, plus possible additions in the form of numbers (e.g. "UNKNOWN (222)") . Now that I write this I see you are right, this could lead to truncation of the number are very long (MAX_INT is 10 digits long). I'll up this to 64.

> src/hotspot/os/posix/signals_posix.cpp line 1276:
> 
>> 1274:   set_signal_handler(SIGFPE, true);
>> 1275:   PPC64_ONLY(set_signal_handler(SIGTRAP, true);)
>> 1276:   set_signal_handler(SIGXFSZ, true);
> 
> Can we drop the last argument here, it's always true the way we use set_signal_handler() ?

Yes, we can do this.

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PR: https://git.openjdk.java.net/jdk/pull/1034