nptl: Add struct_mutex.h

The current way of defining the common mutex definition for POSIX and
C11 on pthreadtypes-arch.h (added by commit 06be6368da16104be5) is
not really the best options for newer ports.  It requires define some
misleading flags that should be always defined as 0
(__PTHREAD_COMPAT_PADDING_MID and __PTHREAD_COMPAT_PADDING_END), it
exposes options used solely for linuxthreads compat mode
(__PTHREAD_MUTEX_USE_UNION and __PTHREAD_MUTEX_NUSERS_AFTER_KIND), and
requires newer ports to explicit define them (adding more boilerplate
code).

This patch adds a new default __pthread_mutex_s definition meant to
be used by newer ports.  Its layout mimics the current usage on both
32 and 64 bits ports and it allows most ports to use the generic
definition.  Only ports that use some arch-specific definition (such
as hardware lock-elision or linuxthreads compat) requires specific
headers.

For 32 bit, the generic definitions mimic the other 32-bit ports
of using an union to define the fields uses on adaptive and robust
mutexes (thus not allowing both usage at same time) and by using a
single linked-list for robust mutexes.  Both decisions seemed to
follow what recent ports have done and make the resulting
pthread_mutex_t/mtx_t object smaller.

Also the static intialization macro for pthread_mutex_t is set to use
a macro __PTHREAD_MUTEX_INITIALIZER where the architecture can redefine
in its struct_mutex.h if it requires additional fields to be
initialized.

Checked with a build on affected abis.

Change-Id: I30a22c3e3497805fd6e52994c5925897cffcfe13

2 files changed, 53 insertions, 11 deletions

diff --git a/sysdeps/hppa/nptl/bits/pthreadtypes-arch.h b/sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
index 7c97b89..c11add1 100644
--- a/sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
@@ -40,17 +40,6 @@
 #define __SIZEOF_PTHREAD_RWLOCK_T 64
 #define __SIZEOF_PTHREAD_RWLOCKATTR_T 8
 
-/* The old 4-word 16-byte aligned lock. This is initalized
-   to all ones by the Linuxthreads PTHREAD_MUTEX_INITIALIZER.
-   Unused in NPTL.  */
-#define __PTHREAD_COMPAT_PADDING_MID  int __compat_padding[4];
-/* Two more words are left before the NPTL
-   pthread_mutex_t is larger than Linuxthreads.  */
-#define __PTHREAD_COMPAT_PADDING_END  int __reserved[2];
-#define __PTHREAD_MUTEX_LOCK_ELISION    0
-#define __PTHREAD_MUTEX_NUSERS_AFTER_KIND  1
-#define __PTHREAD_MUTEX_USE_UNION          1
-
 #define __LOCK_ALIGNMENT __attribute__ ((__aligned__(16)))
 #define __ONCE_ALIGNMENT
 
diff --git a/sysdeps/hppa/nptl/bits/struct_mutex.h b/sysdeps/hppa/nptl/bits/struct_mutex.h
new file mode 100644
index 0000000..7f81256
--- /dev/null
+++ b/sysdeps/hppa/nptl/bits/struct_mutex.h
@@ -0,0 +1,53 @@
+/* HPPA internal mutex struct definitions.
+   Copyright (C) 2019 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/>.  */
+
+#ifndef _THREAD_MUTEX_INTERNAL_H
+#define _THREAD_MUTEX_INTERNAL_H 1
+
+struct __pthread_mutex_s
+{
+  int __lock __LOCK_ALIGNMENT;
+  unsigned int __count;
+  int __owner;
+  /* KIND must stay at this position in the structure to maintain
+     binary compatibility with static initializers.  */
+  int __kind;
+  /* The old 4-word 16-byte aligned lock. This is initalized
+     to all ones by the Linuxthreads PTHREAD_MUTEX_INITIALIZER.
+     Unused in NPTL.  */
+  int __glibc_compat_padding[4];
+  /* In the old structure there are 4 words left due to alignment.
+     In NPTL two words are used.  */
+  unsigned int __nusers;
+  __extension__ union
+  {
+    int __spins;
+    __pthread_slist_t __list;
+  };
+  /* Two more words are left before the NPTL
+     pthread_mutex_t is larger than Linuxthreads.  */
+  int __glibc_reserved1;
+  int __glibc_reserved2;
+};
+
+#define __PTHREAD_MUTEX_HAVE_PREV       0
+
+#define __PTHREAD_MUTEX_INITIALIZER(__kind) \
+  0, 0, 0, __kind, { 0, 0, 0, 0 }, 0, { 0 }, 0, 0
+
+#endif