1 files changed, 73 insertions, 0 deletions
diff --git a/libpthread/nptl/pthread_rwlock_init.c b/libpthread/nptl/pthread_rwlock_init.c
new file mode 100644
index 000000000..aab832eea
--- /dev/null
+++ b/libpthread/nptl/pthread_rwlock_init.c
@@ -0,0 +1,73 @@
+/* Copyright (C) 2002, 2007, 2009 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include "pthreadP.h"
+#include <bits/kernel-features.h>
+
+
+static const struct pthread_rwlockattr default_attr =
+  {
+    .lockkind = PTHREAD_RWLOCK_DEFAULT_NP,
+    .pshared = PTHREAD_PROCESS_PRIVATE
+  };
+
+
+int
+__pthread_rwlock_init (
+     pthread_rwlock_t *rwlock,
+     const pthread_rwlockattr_t *attr)
+{
+  const struct pthread_rwlockattr *iattr;
+
+  iattr = ((const struct pthread_rwlockattr *) attr) ?: &default_attr;
+
+  memset (rwlock, '\0', sizeof (*rwlock));
+
+  rwlock->__data.__flags
+    = iattr->lockkind == PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP;
+
+  /* The __SHARED field is computed to minimize the work that needs to
+     be done while handling the futex.  There are two inputs: the
+     availability of private futexes and whether the rwlock is shared
+     or private.  Unfortunately the value of a private rwlock is
+     fixed: it must be zero.  The PRIVATE_FUTEX flag has the value
+     0x80 in case private futexes are available and zero otherwise.
+     This leads to the following table:
+
+		 |     pshared     |     result
+		 | shared  private | shared  private |
+     ------------+-----------------+-----------------+
+     !avail 0    |     0       0   |     0       0   |
+      avail 0x80 |  0x80       0   |     0    0x80   |
+
+     If the pshared value is in locking functions XORed with avail
+     we get the expected result.  */
+#ifdef __ASSUME_PRIVATE_FUTEX
+  rwlock->__data.__shared = (iattr->pshared == PTHREAD_PROCESS_PRIVATE
+			     ? 0 : FUTEX_PRIVATE_FLAG);
+#else
+  rwlock->__data.__shared = (iattr->pshared == PTHREAD_PROCESS_PRIVATE
+			     ? 0
+			     : THREAD_GETMEM (THREAD_SELF,
+					      header.private_futex));
+#endif
+
+  return 0;
+}
+strong_alias (__pthread_rwlock_init, pthread_rwlock_init)