[PATCH] Remove custom pthread_once implementation on s390.

[Torvald Riegel <triegel at redhat dot com>]

This patch removes the custom implementation of pthread_once on s390.  I
have not tested this, but the generic implementation in
nptl/pthread_once.c works well on several architectures.  The custom
implementation is a C implementation of essentially the same algorithm
the generic implementation uses (but with fixes) -- the only difference
is that inline asm is used for the atomic ops instead of using the
atomic.h atomic ops.

OK to commit?

commit ebab418a50900f5ce1d995bbb99f5ee6987457a8
Author: Torvald Riegel <triegel@redhat.com>
Date:   Mon Dec 8 18:32:14 2014 +0100

    Remove custom pthread_once implementation on s390.

diff --git a/sysdeps/unix/sysv/linux/s390/pthread_once.c b/sysdeps/unix/sysv/linux/s390/pthread_once.c
deleted file mode 100644
index ce02206..0000000
--- a/sysdeps/unix/sysv/linux/s390/pthread_once.c
+++ /dev/null
@@ -1,110 +0,0 @@
-/* Copyright (C) 2003-2014 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"
-#include <lowlevellock.h>
-
-
-unsigned long int __fork_generation attribute_hidden;
-
-
-static void
-clear_once_control (void *arg)
-{
-  pthread_once_t *once_control = (pthread_once_t *) arg;
-
-  *once_control = 0;
-  lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
-}
-
-
-int
-__pthread_once (once_control, init_routine)
-     pthread_once_t *once_control;
-     void (*init_routine) (void);
-{
-  while (1)
-    {
-      int oldval;
-      int newval;
-
-      /* Pseudo code:
-	   oldval = *once_control;
-	   if ((oldval & 2) == 0)
-	    {
-	      newval = (oldval & 3) | __fork_generation | 1;
-	      *once_control = newval;
-	    }
-	 Do this atomically.  */
-      __asm __volatile ("   l	 %1,%0\n"
-			"0: lhi	 %2,2\n"
-			"   tml	 %1,2\n"
-			"   jnz	 1f\n"
-			"   nr	 %2,%1\n"
-			"   ahi	 %2,1\n"
-			"   o	 %2,%3\n"
-			"   cs	 %1,%2,%0\n"
-			"   jl	 0b\n"
-			"1:"
-			: "=Q" (*once_control), "=&d" (oldval), "=&d" (newval)
-			: "m" (__fork_generation), "m" (*once_control)
-			: "cc" );
-      /* Check if the initialized has already been done.  */
-      if ((oldval & 2) != 0)
-	  break;
-      /* Check if another thread already runs the initializer.	*/
-      if ((oldval & 1) != 0)
-	{
-	  /* Check whether the initializer execution was interrupted
-	     by a fork.	 */
-	  if (((oldval ^ newval) & -4) == 0)
-	    {
-	      /* Same generation, some other thread was faster. Wait.  */
-	      lll_futex_wait (once_control, newval, LLL_PRIVATE);
-	      continue;
-	    }
-	}
-
-      /* This thread is the first here.  Do the initialization.
-	 Register a cleanup handler so that in case the thread gets
-	 interrupted the initialization can be restarted.  */
-      pthread_cleanup_push (clear_once_control, once_control);
-
-      init_routine ();
-
-      pthread_cleanup_pop (0);
-
-
-      /* Add one to *once_control.  */
-      __asm __volatile ("   l	 %1,%0\n"
-			"0: lr	 %2,%1\n"
-			"   ahi	 %2,1\n"
-			"   cs	 %1,%2,%0\n"
-			"   jl	 0b\n"
-			: "=Q" (*once_control), "=&d" (oldval), "=&d" (newval)
-			: "m" (*once_control) : "cc" );
-
-      /* Wake up all other threads.  */
-      lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
-      break;
-    }
-
-  return 0;
-}
-weak_alias (__pthread_once, pthread_once)
-hidden_def (__pthread_once)