RFR: 8253742: POSIX signal code cleanup [v3]

[David Holmes]

On Tue, 3 Nov 2020 21:35:08 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> hi all,
>> 
>> Please review this followup to [JDK-8252324 Signal related code should be shared among POSIX platforms](https://bugs.openjdk.java.net/browse/JDK-8252324), where several issues were identified for a cleanup. This change addresses them all:
>> 
>> #1 David's feedback - removed non POSIX SIGNIFICANT_SIGNAL_MASK code
>> 
>> #2 David's feedback - used unblock_program_error_signals() on all platforms (reverted for JDK-8252533)
>> 
>> #3 David's feedback - used single JVM_handle_posix_signal API for all POSIX platforms (reverted for JDK-8255711)
>> 
>> #4 Coleen's feedback - cleanup header files in src/hotspot/os/posix/signals_posix.hpp
>> 
>> #5 Coleen's feedback - hid SR_signum assignment in src/hotspot/os/posix/signals_posix.hpp to avoid having to include <signal.h>
>> 
>> #6 Coleen's feedback - factored out print_signal_handlers()
>> 
>> #7 Thomas' feedback - factored out common POSIX os::SuspendedThreadTask::internal_do_task()
>> 
>> #8 Thomas's feedback - factored out common POSIX signal initialization code
>> 
>> #9 YaSuenag's feedback - used JVM_handle_posix_signal for the common API
>> 
>> #10 YaSuenag's feedback - unified logging out of the scope for this fix
>> 
>> #11 YaSuenag's feedback - memset usage in PosixSignals::jdk_misc_signal_init() correct?
>
> Gerard Ziemski has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - use ifdef(SIGDANGER) and ifdef(SIGTRAP)
>  - revert unblock_program_error_signals change

Hi Gerard,

Overall looking good. Some changes still to be finalized e.g ucontext_t related functions in os.hpp.

I flagged some os functions that are implemented in os_foo.cpp but which just call the Posix helper, which can be deleted from os_foo.cpp and simply added to os_posix.cpp. That can't be a further cleanup RFE if you want to limit changes in this PR.

A few minor nits below.

Thanks,
David

src/hotspot/os/aix/os_aix.cpp line 2578:

> 2576: }
> 2577: 
> 2578: void os::SuspendedThreadTask::internal_do_task() {

We should be able to have a single definition of this function in os_posix.cpp too.

src/hotspot/os/posix/signals_posix.cpp line 1286:

> 1284: void PosixSignals::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
> 1285:   st->print_cr("Signal Handlers:");
> 1286:   PosixSignals::print_signal_handler(st, SIGSEGV, buf, buflen);

You shouldn't need the PosixSignals:: prefix in this method.

src/hotspot/os/posix/signals_posix.cpp line 1349:

> 1347:     sigaddset(&unblocked_sigs, SIGTRAP);
> 1348:   #endif
> 1349:   sigaddset(&unblocked_sigs, PosixSignals::SR_signum);

Shouldn't need the PosixSignals::prefix in this method

src/hotspot/os/posix/signals_posix.cpp line 1642:

> 1640: 
> 1641: void PosixSignals::do_task(Thread* thread, os::SuspendedThreadTask* task) {
> 1642:   if (PosixSignals::do_suspend(thread->osthread())) {

Shouldn't need PosixSignals:: prefix in this method.

src/hotspot/os/posix/signals_posix.hpp line 33:

> 31: 
> 32: typedef siginfo_t siginfo_t;
> 33: typedef sigset_t sigset_t;

I don't see why this is needed/wanted. We can include signal.h without a problem.

I'm not even sure what these typedefs means ??

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PR: https://git.openjdk.java.net/jdk/pull/636