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, 44 insertions, 0 deletions

diff --git a/nptl/threads.h b/nptl/threads.h
index 5258e23919..13d0075ea9 100644
--- a/nptl/threads.h
+++ b/nptl/threads.h
@@ -24,6 +24,7 @@
 
 __BEGIN_DECLS
 
+#include <bits/pthreadtypes-arch.h>
 #include <bits/types/struct_timespec.h>
 
 typedef unsigned long int thrd_t;
@@ -39,6 +40,20 @@ enum
   thrd_timedout = 4
 };
 
+/* Mutex types.  */
+enum
+{
+  mtx_plain     = 0,
+  mtx_recursive = 1,
+  mtx_timed     = 2
+};
+
+typedef union
+{
+  char __size[__SIZEOF_PTHREAD_MUTEX_T];
+  long int __align __LOCK_ALIGNMENT;
+} mtx_t;
+
 /* Threads functions.  */
 
 /* Create a new thread executing the function __FUNC.  Arguments for __FUNC
@@ -85,6 +100,35 @@ thrd_equal (thrd_t __thread1, thrd_t __thread2)
 }
 #endif
 
+
+/* Mutex functions.  */
+
+/* Creates a new mutex object with type __TYPE.  If successful the new
+   object is pointed by __MUTEX.  */
+extern int mtx_init (mtx_t *__mutex, int __type);
+
+/* Block the current thread until the mutex pointed to by __MUTEX is
+   unlocked.  In that case current thread will not be blocked.  */
+extern int mtx_lock (mtx_t *__mutex);
+
+/* Block the current thread until the mutex pointed by __MUTEX is unlocked
+   or time pointed by __TIME_POINT is reached.  In case the mutex is unlock,
+   the current thread will not be blocked.  */
+extern int mtx_timedlock (mtx_t *__restrict __mutex,
+			  const struct timespec *__restrict __time_point);
+
+/* Try to lock the mutex pointed by __MUTEX without blocking.  If the mutex
+   is free the current threads takes control of it, otherwise it returns
+   immediately.  */
+extern int mtx_trylock (mtx_t *__mutex);
+
+/* Unlock the mutex pointed by __MUTEX.  It may potentially awake other
+   threads waiting on this mutex.  */
+extern int mtx_unlock (mtx_t *__mutex);
+
+/* Destroy the mutex object pointed by __MUTEX.  */
+extern void mtx_destroy (mtx_t *__mutex);
+
 __END_DECLS
 
 #endif /* _THREADS_H */