nptl: Add C11 threads mtx_* functions

This patch adds the mtx_* definitions from C11 threads (ISO/IEC 9899:2011),
more specifically mtx_init, mtx_destroy, mtx_lock, mtx_timedlock, mtx_trylock,
mtx_unlock, and required types.

Mostly of the definitions are composed based on POSIX conterparts, and mtx_t
is also based on internal pthread fields, but with a distinct internal layout
to avoid possible issues with code interchange (such as trying to pass POSIX
structure on C11 functions and to avoid inclusion of pthread.h).  The idea
is to make possible to share POSIX internal implementations for mostly of
the code (and making adjustment only when required).

Checked with a build for all major ABI (aarch64-linux-gnu, alpha-linux-gnu,
arm-linux-gnueabi, i386-linux-gnu, ia64-linux-gnu, m68k-linux-gnu,
microblaze-linux-gnu [1], mips{64}-linux-gnu, nios2-linux-gnu,
powerpc{64le}-linux-gnu, s390{x}-linux-gnu, sparc{64}-linux-gnu,
and x86_64-linux-gnu).

Also ran a full check on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu,
arm-linux-gnueabhf, and powerpc64le-linux-gnu.

	[BZ #14092]
	* conform/data/threads.h-data (mtx_plain): New constant.
	(mtx_recursive): Likewise.
	(mtx_timed): Likewise.
	(mtx_t): New type.
	(mtx_init): New function.
	(mtx_lock): Likewise.
	(mtx_timedlock): Likewise.
	(mtx_trylock): Likewise.
	(mtx_unlock): Likewise.
	(mtx_destroy): Likewise.
	* nptl/Makefile (libpthread-routines): Add mtx_destroy, mtx_init,
	mtx_lock, mtx_timedlock, mtx_trylock, and mtx_unlock object.
	* nptl/Versions (libpthread) [GLIBC_2.28]): Add mtx_init, mtx_lock,
	mtx_timedlock, mtx_trylock, mtx_unlock, and mtx_destroy.
	* nptl/mtx_destroy.c: New file.
	* nptl/mtx_init.c: Likewise.
	* nptl/mtx_lock.c: Likewise.
	* nptl/mtx_timedlock.c: Likewise.
	* nptl/mtx_trylock.c: Likewise.
	* nptl/mtx_unlock.c: Likewise.
	* sysdeps/nptl/threads.h (mtx_plain): New enumeration.
	(mtx_recursive): Likewise.
	(mtx_timed): Likewise.
	(mtx_t): New type.
	(mtx_init): New prototype.
	(mtx_lock): Likewise.
	(mtx_timedlock): Likewise.
	(mtx_trylock): Likewise.
	(mtx_unlock): Likewise.
	(mtx_destroy): Likewise.

1 files changed, 53 insertions, 0 deletions

diff --git a/nptl/mtx_init.c b/nptl/mtx_init.c
new file mode 100644
index 0000000000..8f27478c77
--- /dev/null
+++ b/nptl/mtx_init.c
@@ -0,0 +1,53 @@
+/* C11 threads mutex initialization implementation.
+   Copyright (C) 2018 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 <stdalign.h>
+
+#include "thrd_priv.h"
+
+int
+mtx_init (mtx_t *mutex, int type)
+{
+  _Static_assert (sizeof (mtx_t) == sizeof (pthread_mutex_t),
+		  "sizeof (mtx_t) != sizeof (pthread_mutex_t)");
+  _Static_assert (alignof (mtx_t) == alignof (pthread_mutex_t),
+		  "alignof (mtx_t) != alignof (pthread_mutex_t)");
+
+  pthread_mutexattr_t attr;
+
+  __pthread_mutexattr_init (&attr);
+
+  /* Another possible solution would be to set the flags directly in
+     mutex object. */
+  switch (type)
+  {
+    case mtx_plain | mtx_recursive:
+    case mtx_timed | mtx_recursive:
+      __pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
+      break;
+    case mtx_plain:
+    case mtx_timed: /* No difference between both in standard */
+    default:
+      __pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_NORMAL);
+      break;
+  }
+
+  int err_code = __pthread_mutex_init ((pthread_mutex_t *) mutex, &attr);
+  /* pthread_mutexattr_destroy implementation is a noop.  */
+  return thrd_err_map (err_code);
+}