commit 6dc9da4a9c99524d5d6deb841811f1a8cc37c5b2
Author: Stefan Liebler <stli@linux.vnet.ibm.com>
Date:   Wed Feb 15 17:22:38 2017 +0100

    S390: Use generic spinlock code.
    
    This patch removes the s390 specific implementation of spinlock code
    and is now using the generic one.
    
    For pthread_spin_trylock an explicit load and test before executing
    compare and swap instruction is done as it is an interlock update even
    if the lock is already acquired.
    
    The macros in s390 specific atomic-machine.h are aligned in order to
    omit the storing to and loading from stack.
    
    ChangeLog:
    
    	* sysdeps/s390/atomic-machine.h:
    	(__arch_compare_and_exchange_val_32_acq):
    	Cast type to omit volatile qualifier.
    	(__arch_compare_and_exchange_val_64_acq): Likewise.
    	(atomic_exchange_acq): Likewise.
    	* sysdeps/s390/nptl/pthread_spin_init.c: Delete File.
    	* sysdeps/s390/nptl/pthread_spin_lock.c: Likewise.
    	* sysdeps/s390/nptl/pthread_spin_trylock.c: Likewise.
    	* sysdeps/s390/nptl/pthread_spin_unlock.c: Likewise.
    	* sysdeps/s390/nptl/pthread_spin_parameters.h: New File.

diff --git a/sysdeps/s390/atomic-machine.h b/sysdeps/s390/atomic-machine.h
index 211d3d6..d98c836 100644
--- a/sysdeps/s390/atomic-machine.h
+++ b/sysdeps/s390/atomic-machine.h
@@ -54,7 +54,7 @@ typedef uintmax_t uatomic_max_t;
 
 #define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
   ({ __typeof (mem) __archmem = (mem);					      \
-     __typeof (*mem) __archold = (oldval);				      \
+     __typeof ((__typeof (*(mem))) *(mem)) __archold = (oldval);	      \
      __asm__ __volatile__ ("cs %0,%2,%1"				      \
 			   : "+d" (__archold), "=Q" (*__archmem)	      \
 			   : "d" (newval), "m" (*__archmem) : "cc", "memory" );	\
@@ -64,7 +64,7 @@ typedef uintmax_t uatomic_max_t;
 # define __HAVE_64B_ATOMICS 1
 # define __arch_compare_and_exchange_val_64_acq(mem, newval, oldval) \
   ({ __typeof (mem) __archmem = (mem);					      \
-     __typeof (*mem) __archold = (oldval);				      \
+     __typeof ((__typeof (*(mem))) *(mem)) __archold = (oldval);	      \
      __asm__ __volatile__ ("csg %0,%2,%1"				      \
 			   : "+d" (__archold), "=Q" (*__archmem)	      \
 			   : "d" ((long) (newval)), "m" (*__archmem) : "cc", "memory" ); \
@@ -86,8 +86,8 @@ typedef uintmax_t uatomic_max_t;
 #ifdef __s390x__
 # define atomic_exchange_acq(mem, newvalue)				\
   ({ __typeof (mem) __atg5_memp = (mem);				\
-    __typeof (*(mem)) __atg5_oldval = *__atg5_memp;			\
-    __typeof (*(mem)) __atg5_value = (newvalue);			\
+    __typeof ((__typeof (*(mem))) *(mem)) __atg5_oldval = *__atg5_memp;	\
+    __typeof ((__typeof (*(mem))) *(mem)) __atg5_value = (newvalue);	\
     if (sizeof (*mem) == 4)						\
       __asm__ __volatile__ ("0: cs %0,%2,%1\n"				\
 			    "   jl 0b"					\
@@ -106,8 +106,8 @@ typedef uintmax_t uatomic_max_t;
 #else
 # define atomic_exchange_acq(mem, newvalue)				\
   ({ __typeof (mem) __atg5_memp = (mem);				\
-    __typeof (*(mem)) __atg5_oldval = *__atg5_memp;			\
-    __typeof (*(mem)) __atg5_value = (newvalue);			\
+    __typeof ((__typeof (*(mem))) *(mem)) __atg5_oldval = *__atg5_memp;	\
+    __typeof ((__typeof (*(mem))) *(mem)) __atg5_value = (newvalue);	\
     if (sizeof (*mem) == 4)						\
       __asm__ __volatile__ ("0: cs %0,%2,%1\n"				\
 			    "   jl 0b"					\
diff --git a/sysdeps/s390/nptl/pthread_spin_init.c b/sysdeps/s390/nptl/pthread_spin_init.c
deleted file mode 100644
index d826871..0000000
--- a/sysdeps/s390/nptl/pthread_spin_init.c
+++ /dev/null
@@ -1,19 +0,0 @@
-/* Copyright (C) 2003-2017 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
-
-   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/>.  */
-
-/* Not needed.  pthread_spin_init is an alias for pthread_spin_unlock.  */
diff --git a/sysdeps/s390/nptl/pthread_spin_lock.c b/sysdeps/s390/nptl/pthread_spin_lock.c
deleted file mode 100644
index 7349940..0000000
--- a/sysdeps/s390/nptl/pthread_spin_lock.c
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Copyright (C) 2003-2017 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
-
-   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 "pthreadP.h"
-
-int
-pthread_spin_lock (pthread_spinlock_t *lock)
-{
-  int oldval;
-
-  __asm__ __volatile__ ("0: lhi %0,0\n"
-			"   cs  %0,%2,%1\n"
-			"   jl  0b"
-			: "=&d" (oldval), "=Q" (*lock)
-			: "d" (1), "m" (*lock) : "cc" );
-  return 0;
-}
diff --git a/sysdeps/s390/nptl/pthread_spin_parameters.h b/sysdeps/s390/nptl/pthread_spin_parameters.h
new file mode 100644
index 0000000..b2ff166
--- /dev/null
+++ b/sysdeps/s390/nptl/pthread_spin_parameters.h
@@ -0,0 +1,36 @@
+/* Parameters for generic pthread_spinlock_t implementation.  s390 version.
+   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/>.  */
+
+/* FIXME: Re-evaluate the defines below once we have an appropriate
+   microbenchmark.
+   See e.g. "RFC: shared-memory synchronization benchmarking in glibc"
+   (https://sourceware.org/ml/libc-alpha/2017-01/msg00168.html)  */
+
+/* An own benchmark shows no difference between defining to '1000'
+   and '-1', but a positive result compared to '0' as a CAS instruction
+   would be used in a loop, which should be avoided on s390 due to cache-line
+   ping-pong.  */
+#define SPIN_LOCK_READS_BETWEEN_CMPXCHG 1000
+
+/* An own benchmark showed a positive result if defined to '1'
+   and trylock is called often by different CPUs.
+   If the lock is not acquired and no other CPU is trying to
+   acquire the lock, then the additional load does not hurt.  */
+#define SPIN_TRYLOCK_LOAD_AND_TEST_BEFORE_XCHG 1
+
+#include_next <pthread_spin_parameters.h>
diff --git a/sysdeps/s390/nptl/pthread_spin_trylock.c b/sysdeps/s390/nptl/pthread_spin_trylock.c
deleted file mode 100644
index 0e848da..0000000
--- a/sysdeps/s390/nptl/pthread_spin_trylock.c
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Copyright (C) 2003-2017 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
-
-   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 <errno.h>
-#include "pthreadP.h"
-
-int
-pthread_spin_trylock (pthread_spinlock_t *lock)
-{
-  int old;
-
-  __asm__ __volatile__ ("cs %0,%3,%1"
-			: "=d" (old), "=Q" (*lock)
-			: "0" (0), "d" (1), "m" (*lock) : "cc" );
-
-  return old != 0 ? EBUSY : 0;
-}
diff --git a/sysdeps/s390/nptl/pthread_spin_unlock.c b/sysdeps/s390/nptl/pthread_spin_unlock.c
deleted file mode 100644
index 54e7378..0000000
--- a/sysdeps/s390/nptl/pthread_spin_unlock.c
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Copyright (C) 2003-2017 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
-
-   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/>.  */
-
-/* Ugly hack to avoid the declaration of pthread_spin_init.  */
-#define pthread_spin_init pthread_spin_init_XXX
-#include "pthreadP.h"
-#undef pthread_spin_init
-
-int
-pthread_spin_unlock (pthread_spinlock_t *lock)
-{
-  __asm__ __volatile__ ("   xc  %O0(4,%R0),%0\n"
-			"   bcr 15,0"
-			: "=Q" (*lock) : "m" (*lock) : "cc" );
-  return 0;
-}
-strong_alias (pthread_spin_unlock, pthread_spin_init)
