rwlock: Fix explicit hand-over (bug 21298)

Without this fix, the rwlock can fail to execute the explicit hand-over
in certain cases (e.g., empty critical sections that switch quickly between
read and write phases).  This can then lead to errors in how __wrphase_futex
is accessed, which in turn can lead to deadlocks.

8 files changed, 172 insertions, 0 deletions

diff --git a/support/Makefile b/support/Makefile
index 1eba34b..2ace3fa 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -106,6 +106,12 @@ libsupport-routines = \
   xpthread_mutexattr_setrobust \
   xpthread_mutexattr_settype \
   xpthread_once \
+  xpthread_rwlock_init \
+  xpthread_rwlock_rdlock \
+  xpthread_rwlock_wrlock \
+  xpthread_rwlock_unlock \
+  xpthread_rwlockattr_init \
+  xpthread_rwlockattr_setkind_np \
   xpthread_sigmask \
   xpthread_spin_lock \
   xpthread_spin_unlock \
diff --git a/support/xpthread_rwlock_init.c b/support/xpthread_rwlock_init.c
new file mode 100644
index 0000000..824288c
--- /dev/null
+++ b/support/xpthread_rwlock_init.c
@@ -0,0 +1,27 @@
+/* pthread_rwlock_init with error checking.
+   Copyright (C) 2017 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 <support/xthread.h>
+
+void
+xpthread_rwlock_init (pthread_rwlock_t *rwlock,
+		      const pthread_rwlockattr_t *attr)
+{
+  xpthread_check_return ("pthread_rwlock_init",
+                         pthread_rwlock_init (rwlock, attr));
+}
diff --git a/support/xpthread_rwlock_rdlock.c b/support/xpthread_rwlock_rdlock.c
new file mode 100644
index 0000000..96330a5
--- /dev/null
+++ b/support/xpthread_rwlock_rdlock.c
@@ -0,0 +1,26 @@
+/* pthread_rwlock_rdlock with error checking.
+   Copyright (C) 2017 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 <support/xthread.h>
+
+void
+xpthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
+{
+  xpthread_check_return ("pthread_rwlock_rdlock",
+			 pthread_rwlock_rdlock (rwlock));
+}
diff --git a/support/xpthread_rwlock_unlock.c b/support/xpthread_rwlock_unlock.c
new file mode 100644
index 0000000..eaa136b
--- /dev/null
+++ b/support/xpthread_rwlock_unlock.c
@@ -0,0 +1,26 @@
+/* pthread_rwlock_unlock with error checking.
+   Copyright (C) 2017 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 <support/xthread.h>
+
+void
+xpthread_rwlock_unlock (pthread_rwlock_t *rwlock)
+{
+  xpthread_check_return ("pthread_rwlock_unlock",
+			 pthread_rwlock_unlock (rwlock));
+}
diff --git a/support/xpthread_rwlock_wrlock.c b/support/xpthread_rwlock_wrlock.c
new file mode 100644
index 0000000..8d25d5b
--- /dev/null
+++ b/support/xpthread_rwlock_wrlock.c
@@ -0,0 +1,26 @@
+/* pthread_rwlock_wrlock with error checking.
+   Copyright (C) 2017 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 <support/xthread.h>
+
+void
+xpthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
+{
+  xpthread_check_return ("pthread_rwlock_wrlock",
+			 pthread_rwlock_wrlock (rwlock));
+}
diff --git a/support/xpthread_rwlockattr_init.c b/support/xpthread_rwlockattr_init.c
new file mode 100644
index 0000000..48baf24
--- /dev/null
+++ b/support/xpthread_rwlockattr_init.c
@@ -0,0 +1,26 @@
+/* pthread_rwlockattr_init with error checking.
+   Copyright (C) 2017 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 <support/xthread.h>
+
+void
+xpthread_rwlockattr_init (pthread_rwlockattr_t *attr)
+{
+  xpthread_check_return ("pthread_rwlockattr_init",
+                         pthread_rwlockattr_init (attr));
+}
diff --git a/support/xpthread_rwlockattr_setkind_np.c b/support/xpthread_rwlockattr_setkind_np.c
new file mode 100644
index 0000000..958aace
--- /dev/null
+++ b/support/xpthread_rwlockattr_setkind_np.c
@@ -0,0 +1,27 @@
+/* pthread_rwlockattr_setkind_np with error checking.
+   Copyright (C) 2017 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 <support/xthread.h>
+
+void
+xpthread_rwlockattr_setkind_np (pthread_rwlockattr_t *attr,
+				int pref)
+{
+  xpthread_check_return ("pthread_rwlockattr_setkind_np",
+                         pthread_rwlockattr_setkind_np (attr, pref));
+}
diff --git a/support/xthread.h b/support/xthread.h
index 3552a73..472763e 100644
--- a/support/xthread.h
+++ b/support/xthread.h
@@ -74,6 +74,14 @@ void xpthread_attr_setguardsize (pthread_attr_t *attr,
    PTHREAD_BARRIER_SERIAL_THREAD.  */
 int xpthread_barrier_wait (pthread_barrier_t *barrier);
 
+void xpthread_rwlock_init (pthread_rwlock_t *rwlock,
+			  const pthread_rwlockattr_t *attr);
+void xpthread_rwlockattr_init (pthread_rwlockattr_t *attr);
+void xpthread_rwlockattr_setkind_np (pthread_rwlockattr_t *attr, int pref);
+void xpthread_rwlock_wrlock (pthread_rwlock_t *rwlock);
+void xpthread_rwlock_rdlock (pthread_rwlock_t *rwlock);
+void xpthread_rwlock_unlock (pthread_rwlock_t *rwlock);
+
 __END_DECLS
 
 #endif /* SUPPORT_THREAD_H */