RFR: 8183925: Decouple crash protection from watcher thread

[Daniel D. Daugherty]

On 7/6/17 4:33 AM, Robbin Ehn wrote:
> Hi all, please review:
>
> While looking into:
> java_lang_Thread::get_thread_status(oop java_thread) {
>      4802:   assert(Thread::current()->is_Watcher_thread()
> As: 
> http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2017-July/023863.html
>
> I saw that I have missed that crash protection doesn't work for the 
> upcoming trace backend changes.
> Main reason for not seeing this is that the trace backend haven't 
> crashed (yet).
>
> This code is not used in the open-jdk, compiled tested linux and windows.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8183925
> Webrev: http://cr.openjdk.java.net/~rehn/8183925/webrev/index.html

General comments
   - Please update copyright years as needed before pushing.

src/os/posix/vm/os_posix.hpp
     No comments.

src/os/posix/vm/os_posix.cpp
     L1306:   assert(_protected_thread != NULL, "Cannot crash protect a 
none Thread");
         Typo: 'none Thread' -> 'NULL thread'

src/os/windows/vm/os_windows.hpp
     No comments.

src/os/windows/vm/os_windows.cpp
     L4842:   assert(_protected_thread != NULL, "Cannot crash protect a 
none Thread");
         Typo: 'none Thread' -> 'NULL thread'

     Really don't like the variable named 'success', but that
     pre-dates these changes.

src/os_cpu/bsd_x86/vm/os_bsd_x86.cpp
src/os_cpu/linux_aarch64/vm/os_linux_aarch64.cpp
src/os_cpu/linux_arm/vm/os_linux_arm.cpp
src/os_cpu/linux_s390/vm/os_linux_s390.cpp
src/os_cpu/linux_sparc/vm/os_linux_sparc.cpp
src/os_cpu/linux_x86/vm/os_linux_x86.cpp
src/os_cpu/solaris_sparc/vm/os_solaris_sparc.cpp
src/os_cpu/solaris_x86/vm/os_solaris_x86.cpp
     Same change to this set of files; no comments.

src/share/vm/runtime/mutex.cpp
     L1392: assert(!os::ThreadCrashProtection::is_crash_protected(thread),
     L1393:            "locking not allowed when crash protection is set");
         nit - two extra spaces before '"' on L1393.

src/share/vm/runtime/os.cpp
     L576:   // checking for the WatcherThread and crash_protection first
     L579:   // try to find the thread after we see that the watcher thread
         These comments mention "WatcherThread" and "watcher thread"
         so they need to be updated.

     L582:          "Can't malloc with crash protection from 
WatcherThread");
         "from WatcherThread" should be "from crash protected thread"
         or something similar.

         Or you could do something like the mutex.cpp mesg:

         "locking not allowed when crash protection is set"
         "malloc() not allowed when crash protection is set"

src/share/vm/runtime/thread.hpp
     No comments.

src/share/vm/runtime/thread.cpp
     No comments.


Thumbs up! I don't need to see another webrev if you make
the above minor changes...

Dan


>
> Thanks!
>
> /Robbin