[Bug libfortran/39176] New: [4.4 Regression] -static and -fopenmp and io causes segfault

[Bug libfortran/39176] New: [4.4 Regression] -static and -fopenmp and io causes segfault

[jv244 at cam dot ac dot uk]

I noticed this running mixed mpi/openmp on a system that required an executable
without dynamics libraries. Don't know if the Fortran IO is supposed to be
thread safe (i.e. serialized thread safe), but this seems to work without
-static. It also appears to work with 4.3.1 but not 4.4 (trunk)

> cat test.f90
!$OMP PARALLEL
!$OMP CRITICAL
 write(6,*) "Hello world"
!$OMP END CRITICAL
!$OMP END PARALLEL
 write(6,*) "Done!"
END

> gfortran -static -fopenmp test.f90
> ./a.out
Segmentation fault
> gdb ./a.out
GNU gdb 6.4
Copyright 2005 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-suse-linux"...Using host libthread_db
library                            "/lib64/libthread_db.so.1".

(gdb) run
Starting program: /data/vondele/omptest/a.out

Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x000000000040642f in get_external_unit (n=6, do_create=1)
    at /data/vondele/gcc_trunk/gcc/libgfortran/../gcc/gthr-posix.h:704
#2  0x0000000000404c01 in data_transfer_init (dtp=0x7fff047208c0, read_flag=0)
    at /data/vondele/gcc_trunk/gcc/libgfortran/io/transfer.c:1828
#3  0x00000000004003d6 in MAIN__.omp_fn.0 ()
#4  0x000000000040032c in MAIN__ ()
#5  0x000000000040042c in main (argc=1, argv=0x7fff04720fa8)
    at /data/vondele/gcc_trunk/gcc/libgfortran/fmain.c:21
(gdb)


-- 
           Summary: [4.4 Regression] -static and -fopenmp and io causes
                    segfault
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: libfortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jv244 at cam dot ac dot uk
GCC target triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libfortran/39176] [4.4 Regression] -static and -fopenmp and io causes segfault

[jv244 at cam dot ac dot uk]

------- Comment #1 from jv244 at cam dot ac dot uk  2009-02-13 11:42 -------
adding Jakub


-- 

jv244 at cam dot ac dot uk changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at redhat dot com
      Known to fail|                            |4.4.0
      Known to work|                            |4.3.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libfortran/39176] [4.4 Regression] -static and -fopenmp and io causes segfault

[jv244 at cam dot ac dot uk]

-- 

jv244 at cam dot ac dot uk changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libfortran/39176] [4.4 Regression] -static and -fopenmp and io causes segfault

[jakub at gcc dot gnu dot org]

------- Comment #2 from jakub at gcc dot gnu dot org  2009-02-13 11:50 -------
This has been repeated many times.  Don't use -static for threaded programs, it
is really bad idea, and if you really have to, you need to link the whole
libpthread.a in (-Wl,--whole-archive -lpthread -Wl,--no-whole-archive),
otherwise if it works, it is by pure luck.
This certainly isn't a regression.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID
   Target Milestone|4.4.0                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libfortran/39176] [4.4 Regression] -static and -fopenmp and io causes segfault

[jv244 at cam dot ac dot uk]

------- Comment #3 from jv244 at cam dot ac dot uk  2009-02-13 12:19 -------
(In reply to comment #2)
> This has been repeated many times.  Don't use -static for threaded programs, it
> is really bad idea, and if you really have to, you need to link the whole
> libpthread.a in (-Wl,--whole-archive -lpthread -Wl,--no-whole-archive),
> otherwise if it works, it is by pure luck.
> This certainly isn't a regression.
> 

Thanks for your reply, this was unknown to me, and I think for many occassional
omp users. Do you think this could be documented near the -fopenmp flag (I can
write something if you wish). Or could one have gcc warn if both -fopenmp and
-static are present ?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libfortran/39176] [4.4 Regression] -static and -fopenmp and io causes segfault

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2009-02-13 12:35 -------
It is glibc specific, on the other hand it isn't particularly -fopenmp related.
I guess easiest will be if glibc stops shipping libpthread.a.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libgomp/39176] -static and -fopenmp and io causes segfault

[jv244 at cam dot ac dot uk]

------- Comment #5 from jv244 at cam dot ac dot uk  2009-02-13 14:01 -------
(In reply to comment #4)
> It is glibc specific, on the other hand it isn't particularly -fopenmp related.
> I guess easiest will be if glibc stops shipping libpthread.a.

but if -fopenmp automatically adds -lpthread maybe it should do it in the
'proper' way if -static is also on the command line (eventually bailing out if
libpthread.a can not be found)? 

Note, e.g. a warning is produced for similar issues already, e.g. I see:

/home/u1/vondele/gcc_trunk/build/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.4.0/../../../../lib64/libgfortran.a(getlog.o):
In function `_gfortran_getlog':
/home/u1/vondele/gcc_trunk/gcc/libgfortran/intrinsics/getlog.c:82: warning:
Using 'getpwuid' in statically linked applications requires at runtime the
shared libraries from the glibc version used for linking

let me reopen the bug, removing the regression marker, and as an enhancement. I
think that a warning, or adding -lpthread in the 'proper' way if -static will
save many other users from loosing time on this one.


-- 

jv244 at cam dot ac dot uk changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
             Status|RESOLVED                    |UNCONFIRMED
          Component|libfortran                  |libgomp
         Resolution|INVALID                     |
            Summary|[4.4 Regression] -static and|-static and -fopenmp and io
                   |-fopenmp and io causes      |causes segfault
                   |segfault                    |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libgomp/39176] -static and -fopenmp and io causes segfault

[pinskia at gcc dot gnu dot org]

------- Comment #6 from pinskia at gcc dot gnu dot org  2009-02-13 20:18 -------
Not a gcc bug so closing as invalid.  That warning comes from glibc anyways.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libgomp/39176] -static and -fopenmp and io causes segfault

[jv244 at cam dot ac dot uk]

------- Comment #7 from jv244 at cam dot ac dot uk  2009-02-13 21:00 -------
(In reply to comment #6)
> Not a gcc bug so closing as invalid.  

The gcc  'bug' is that -fopenmp -static should link to pthreads as 
-Wl,--whole-archive -lpthread -Wl,--no-whole-archive, if that is required, or
error out if that is not possible. 

The current way of just adding -lpthread and hoping it is correct (even in the
presence of -static) is leading to wrong code.


-- 

jv244 at cam dot ac dot uk changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176

[Bug libgomp/39176] -static and -fopenmp and io causes segfault

[jakub at gcc dot gnu dot org]

------- Comment #8 from jakub at gcc dot gnu dot org  2009-02-13 21:10 -------
This is not a gcc bug, glibc either should not ship libpthread.a at all or
mv libpthread.a libpthreadx.a; gcc -r -nostdlib -o libpthread.a --whole-archive
libpthreadx.a; rm libpthreadx.a
I'll try the latter in Fedora soon.
In any case, users really shouldn't use -static except for a few system
recovery tools, see
http://people.redhat.com/drepper/no_static_linking.html


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39176