Fix sem_post race (bug 14532).

diff --git a/NEWS b/NEWS
index b2800e2f120d653a4328f8a7f206bbd5853b93cc..6ff950f7e2ba33ec356052032ae1e2b32c6af692 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -12,7 +12,7 @@ Version 2.17
   3479, 5400, 6778, 6808, 9685, 11607, 13717, 13696, 13939, 14042, 14090,
   14166, 14150, 14151, 14154, 14157, 14166, 14173, 14195, 14252, 14283,
   14298, 14303, 14307, 14328, 14331, 14336, 14337, 14347, 14349, 14459,
-  14476, 14505, 14516, 14519
+  14476, 14505, 14516, 14519, 14532
 
 * Support for STT_GNU_IFUNC symbols added for s390 and s390x.
   Optimized versions of memcpy, memset, and memcmp added for System z10 and

diff --git a/nptl/ChangeLog b/nptl/ChangeLog
index eb84863588f6ed1c3dfa3b1e55c2791209ec9485..f59c3d720e0603a1ca04cd253ef2f199a16d6f2c 100644 (file)
--- a/nptl/ChangeLog
+++ b/nptl/ChangeLog
@@ -1,6 +1,10 @@
-2012-08-15  Roland McGrath  <roland@hack.frob.com>
+2012-08-31  Joseph Myers  <joseph@codesourcery.com>
 
-2012-08-15  Roland McGrath  <roland@hack.frob.com>
+       [BZ #14532]
+       * sysdeps/unix/sysv/linux/sem_post.c (__new_sem_post): Use
+       atomic_compare_and_exchange_bool_rel.
+       * tst-sem14.c: New file.
+       * Makefile (tests): Add tst-sem14.
 
 2012-08-15  Roland McGrath  <roland@hack.frob.com>
 

diff --git a/nptl/Makefile b/nptl/Makefile
index 8cd168d4514757e736bd277aded1145cad4fd5da..614f0ceea919922c959daa1a42e9d5ebd95273e5 100644 (file)
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -217,7 +217,7 @@ tests = tst-typesizes \
        tst-once1 tst-once2 tst-once3 tst-once4 \
        tst-key1 tst-key2 tst-key3 tst-key4 \
        tst-sem1 tst-sem2 tst-sem3 tst-sem4 tst-sem5 tst-sem6 tst-sem7 \
-       tst-sem8 tst-sem9 tst-sem10 tst-sem11 tst-sem12 tst-sem13 \
+       tst-sem8 tst-sem9 tst-sem10 tst-sem11 tst-sem12 tst-sem13 tst-sem14 \
        tst-barrier1 tst-barrier2 tst-barrier3 tst-barrier4 \
        tst-align tst-align2 tst-align3 \
        tst-basic1 tst-basic2 tst-basic3 tst-basic4 tst-basic5 tst-basic6 \

diff --git a/nptl/sysdeps/unix/sysv/linux/sem_post.c b/nptl/sysdeps/unix/sysv/linux/sem_post.c
index 56f27e977e08aaa2d1d16c8c2b4f10c020078749..67e8cc5429abd9b942cdad056254aeb610fcc7d7 100644 (file)
--- a/nptl/sysdeps/unix/sysv/linux/sem_post.c
+++ b/nptl/sysdeps/unix/sysv/linux/sem_post.c
@@ -1,5 +1,5 @@
 /* sem_post -- post to a POSIX semaphore.  Generic futex-using version.
-   Copyright (C) 2003, 2004, 2007, 2008 Free Software Foundation, Inc.
+   Copyright (C) 2003-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
 
@@ -40,7 +40,7 @@ __new_sem_post (sem_t *sem)
          return -1;
        }
     }
-  while (atomic_compare_and_exchange_bool_acq (&isem->value, cur + 1, cur));
+  while (atomic_compare_and_exchange_bool_rel (&isem->value, cur + 1, cur));
 
   atomic_full_barrier ();
   if (isem->nwaiters > 0)

diff --git a/nptl/tst-sem14.c b/nptl/tst-sem14.c
new file mode 100644 (file)
index 0000000..949c03f
--- /dev/null
+++ b/nptl/tst-sem14.c
@@ -0,0 +1,91 @@
+/* Test for sem_post race: bug 14532.
+   Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <pthread.h>
+#include <semaphore.h>
+#include <stdio.h>
+
+#define NTHREADS 10
+#define NITER 100000
+
+sem_t sem;
+int c;
+volatile int thread_fail;
+
+static void *
+tf (void *arg)
+{
+  for (int i = 0; i < NITER; i++)
+    {
+      if (sem_wait (&sem) != 0)
+       {
+         perror ("sem_wait");
+         thread_fail = 1;
+       }
+      ++c;
+      if (sem_post (&sem) != 0)
+       {
+         perror ("sem_post");
+         thread_fail = 1;
+       }
+    }
+  return NULL;
+}
+
+static int
+do_test (void)
+{
+  if (sem_init (&sem, 0, 0) != 0)
+    {
+      perror ("sem_init");
+      return 1;
+    }
+
+  pthread_t th[NTHREADS];
+  for (int i = 0; i < NTHREADS; i++)
+    {
+      if (pthread_create (&th[i], NULL, tf, NULL) != 0)
+       {
+         puts ("pthread_create failed");
+         return 1;
+       }
+    }
+
+  if (sem_post (&sem) != 0)
+    {
+      perror ("sem_post");
+      return 1;
+    }
+
+  for (int i = 0; i < NTHREADS; i++)
+    if (pthread_join (th[i], NULL) != 0)
+      {
+       puts ("pthread_join failed");
+       return 1;
+      }
+
+  if (c != NTHREADS * NITER)
+    {
+      printf ("c = %d, should be %d\n", c, NTHREADS * NITER);
+      return 1;
+    }
+  return thread_fail;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"