[Bug build/13844] New: `nptl/sysdeps/unix/sysv/linux/sparc/sparc32/libc-lowlevellock.c' missing in glibc sources

["ilmalakhov at yandex dot ru" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=13844

             Bug #: 13844
           Summary: `nptl/sysdeps/unix/sysv/linux/sparc/sparc32/libc-lowle
                    vellock.c' missing in glibc sources
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: build
        AssignedTo: unassigned@sourceware.org
        ReportedBy: ilmalakhov@yandex.ru
                CC: carlos@systemhalted.org
    Classification: Unclassified


Hi.

 Because of the absence of the sparc32-linux specific version of this file,
`nptl/sysdeps/unix/sysv/linux/libc-lowlevellock.c' is fetched when building
`libc-lowlevellock.o{,s}'. The latter contains just
. . .
#include "lowlevellock.c"

which leads to `nptl/sysdeps/unix/sysv/linux/lowlevellock.c' being actually
compiled instead of
`nptl/sysdeps/unix/sysv/linux/sparc/sparc32/lowlevellock.c'.

 As a consequence a futex can be accessed in a non-atomic way when using libc's
internal locks, e.g. when performing output to the same stream from different
threads.

 For example, when the following test is run on a V8 host, this typically leads
to a deadlock when all threads are waiting for a futex to become free and there
is no one to release it. This happens particularly soon when it's executed this
way at a multi-CPU host:

$ ./test.sparc32 5 > /dev/null


$ cat test.c

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

void *
handler (void *arg)
{
  for (;;)
    printf ("Thread #%ld\n", (long) arg);

  return NULL;
}

int
main (int argc, char **argv)
{
  size_t i;
  size_t nthreads = (size_t) atoi (argv[1]);
  pthread_t *threads = (pthread_t *) malloc (nthreads * sizeof (pthread_t));

  for (i = 0; i < nthreads; i++)
    pthread_create (&threads[i], NULL, handler, (void *) i);

  for (i = 0; i < nthreads; i++)
    pthread_join (threads[i], NULL);

  free (threads);
  return 0;
}

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