[Bug libgomp/51376] libgomp taskwait failure

[Bug libgomp/51376] libgomp taskwait failure

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51376

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |powerpc-linux
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011-12-01
         AssignedTo|unassigned at gcc dot       |amodra at gmail dot com
                   |gnu.org                     |
   Target Milestone|---                         |4.7.0
     Ever Confirmed|0                           |1

--- Comment #1 from Alan Modra <amodra at gmail dot com> 2011-12-01 09:23:38 UTC ---
Investigating possible fix

[Bug libgomp/51376] New: libgomp taskwait failure

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51376

             Bug #: 51376
           Summary: libgomp taskwait failure
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgomp
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: amodra@gmail.com


libgomp.c++/task-6 occasionally aborts on power7 with symptoms that indicate
"#pragma omp taskwait" is failing to wait for a child thread.  On replacing the
abort() with an asm illegal insn to get a core with the register state at the
failure point, you see "a" or "n" has been loaded to regs with their original
value.  By the time the core dump is written, the memory value for "a" and "n"
is correct.

[Bug libgomp/51376] libgomp taskwait failure

[amodra at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51376

--- Comment #2 from Alan Modra <amodra at gcc dot gnu.org> 2011-12-09 02:21:46 UTC ---
Author: amodra
Date: Fri Dec  9 02:21:43 2011
New Revision: 182151

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182151
Log:
    PR libgomp/51376
    * task.c (GOMP_taskwait): Don't access task->children outside of
    task_lock mutex region.
    (GOMP_task): Likewise.


Modified:
    trunk/libgomp/ChangeLog
    trunk/libgomp/task.c

[Bug libgomp/51376] libgomp taskwait failure

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51376

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #3 from Alan Modra <amodra at gmail dot com> 2011-12-09 05:20:25 UTC ---
Fixed

[Bug libgomp/51376] libgomp taskwait failure

[amodra at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51376

--- Comment #4 from Alan Modra <amodra at gcc dot gnu.org> 2013-01-22 11:41:56 UTC ---
Author: amodra
Date: Tue Jan 22 11:41:53 2013
New Revision: 195370

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=195370
Log:
    PR libgomp/51376
    PR libgomp/56073
    * task.c (GOMP_task): Revert 2011-12-09 change.
    (GOMP_taskwait): Likewise.  Instead use atomic load with acquire
    barrier to read task->children..
    (gomp_barrier_handle_tasks): ..and matching atomic store with
    release barrier here when setting parent->children to NULL.


Modified:
    trunk/libgomp/ChangeLog
    trunk/libgomp/task.c

[Bug libgomp/51376] libgomp taskwait failure

[amodra at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51376

--- Comment #5 from Alan Modra <amodra at gcc dot gnu.org> 2013-01-24 21:52:03 UTC ---
Author: amodra
Date: Thu Jan 24 21:51:58 2013
New Revision: 195444

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=195444
Log:
    PR libgomp/51376
    PR libgomp/56073
    * task.c (GOMP_task): Revert 2011-12-09 change.
    (GOMP_taskwait): Likewise.  Instead use atomic load with acquire
    barrier to read task->children..
    (gomp_barrier_handle_tasks): ..and matching atomic store with
    release barrier here when setting parent->children to NULL.


Added:
    branches/ibm/gcc-4_7-branch/libgomp/ChangeLog.ibm
Modified:
    branches/ibm/gcc-4_7-branch/libgomp/task.c

[Bug libgomp/51376] libgomp taskwait failure

[amodra at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51376

--- Comment #6 from Alan Modra <amodra at gcc dot gnu.org> 2013-02-05 13:40:35 UTC ---
Author: amodra
Date: Tue Feb  5 13:40:25 2013
New Revision: 195756

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=195756
Log:
    PR libgomp/51376
    PR libgomp/56073
    * task.c (GOMP_task): Revert 2011-12-09 change.
    (GOMP_taskwait): Likewise.  Instead use atomic load with acquire
    barrier to read task->children..
    (gomp_barrier_handle_tasks): ..and matching atomic store with
    release barrier here when setting parent->children to NULL.


Modified:
    branches/gcc-4_7-branch/libgomp/ChangeLog
    branches/gcc-4_7-branch/libgomp/task.c