RFR: 8253742: POSIX signal code cleanup [v9]

[David Holmes]

On Tue, 17 Nov 2020 15:59:19 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 one additional commit since the last revision:
> 
>   last tweaks

Marked as reviewed by dholmes (Reviewer).

src/hotspot/os/posix/signals_posix.cpp line 1721:

> 1719:   // initialize suspend/resume support - must do this before signal_sets_init()
> 1720:   if (SR_initialize() != 0) {
> 1721:     vm_exit_during_initialization("SR_initialize failed");

You've lost the failure reason (errno) that perror would have provided. SR_initalize only returns non-zero if sigaction fails, which leaves errno set - hence perror() would report it. That said there are only two errors for sigaction (EFAULT or EINVAL) so we really haven't lost anything that useful.
Arguably the vm_exit... should be inside SR_initialize.
But I'm fine with this as-is so we can conclude this PR.

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