1 files changed, 123 insertions, 0 deletions
diff --git a/nptl/sem_wait.c b/nptl/sem_wait.c
new file mode 100644
index 0000000000..b12babb596
--- /dev/null
+++ b/nptl/sem_wait.c
@@ -0,0 +1,123 @@
+/* sem_wait -- wait on a semaphore.  Generic futex-using version.
+   Copyright (C) 2003-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
+
+   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 <errno.h>
+#include <sysdep.h>
+#include <lowlevellock.h>
+#include <internaltypes.h>
+#include <semaphore.h>
+
+#include <pthreadP.h>
+#include <shlib-compat.h>
+#include <atomic.h>
+
+
+void
+attribute_hidden
+__sem_wait_cleanup (void *arg)
+{
+  struct new_sem *isem = (struct new_sem *) arg;
+
+  atomic_decrement (&isem->nwaiters);
+}
+
+/* This is in a seperate function in order to make sure gcc
+   puts the call site into an exception region, and thus the
+   cleanups get properly run.  */
+static int
+__attribute__ ((noinline))
+do_futex_wait (struct new_sem *isem)
+{
+  int err, oldtype = __pthread_enable_asynccancel ();
+
+  err = lll_futex_wait (&isem->value, 0, isem->private ^ FUTEX_PRIVATE_FLAG);
+
+  __pthread_disable_asynccancel (oldtype);
+  return err;
+}
+
+int
+__new_sem_wait (sem_t *sem)
+{
+  struct new_sem *isem = (struct new_sem *) sem;
+  int err;
+
+  if (atomic_decrement_if_positive (&isem->value) > 0)
+    return 0;
+
+  atomic_increment (&isem->nwaiters);
+
+  pthread_cleanup_push (__sem_wait_cleanup, isem);
+
+  while (1)
+    {
+      err = do_futex_wait(isem);
+      if (err != 0 && err != -EWOULDBLOCK)
+	{
+	  __set_errno (-err);
+	  err = -1;
+	  break;
+	}
+
+      if (atomic_decrement_if_positive (&isem->value) > 0)
+	{
+	  err = 0;
+	  break;
+	}
+    }
+
+  pthread_cleanup_pop (0);
+
+  atomic_decrement (&isem->nwaiters);
+
+  return err;
+}
+versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1);
+
+
+#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
+int
+attribute_compat_text_section
+__old_sem_wait (sem_t *sem)
+{
+  int *futex = (int *) sem;
+  int err;
+
+  do
+    {
+      if (atomic_decrement_if_positive (futex) > 0)
+	return 0;
+
+      /* Enable asynchronous cancellation.  Required by the standard.  */
+      int oldtype = __pthread_enable_asynccancel ();
+
+      /* Always assume the semaphore is shared.  */
+      err = lll_futex_wait (futex, 0, LLL_SHARED);
+
+      /* Disable asynchronous cancellation.  */
+      __pthread_disable_asynccancel (oldtype);
+    }
+  while (err == 0 || err == -EWOULDBLOCK);
+
+  __set_errno (-err);
+  return -1;
+}
+
+compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0);
+#endif