nptl: Eliminate <smp.h> and __is_smp

Most systems are SMP, so optimizing for the UP case is no longer
approriate.  A dynamic check based on the kernel identification
has been only implemented for i386 anyway.

To disable adaptive mutexes on sh, define DEFAULT_ADAPTIVE_COUNT
as zero for this architecture.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

nptl/nptl-init.c

@@ -32,7 +32,6 @@
 #include <fork.h>
 #include <version.h>
 #include <shlib-compat.h>
-#include <smp.h>
 #include <lowlevellock.h>
 #include <futex-internal.h>
 #include <kernel-features.h>
@@ -346,9 +345,6 @@ __pthread_initialize_minimal_internal (void)
     __libc_pthread_init (&__fork_generation, __reclaim_stacks,
 			 ptr_pthread_functions);
 
-  /* Determine whether the machine is SMP or not.  */
-  __is_smp = is_smp_system ();
-
 #if HAVE_TUNABLES
   __pthread_tunables_init ();
 #endif

nptl/pthreadP.h

@@ -208,9 +208,6 @@ extern void __default_pthread_attr_freeres (void) attribute_hidden;
 extern size_t __static_tls_size attribute_hidden;
 extern size_t __static_tls_align_m1 attribute_hidden;
 
-/* Flag whether the machine is SMP or not.  */
-extern int __is_smp attribute_hidden;
-
 /* Thread descriptor handling.  */
 extern list_t __stack_user;
 hidden_proto (__stack_user)

nptl/pthread_mutex_lock.c

@@ -120,9 +120,6 @@ __pthread_mutex_lock (pthread_mutex_t *mutex)
   else if (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex)
 			  == PTHREAD_MUTEX_ADAPTIVE_NP, 1))
     {
-      if (! __is_smp)
-	goto simple;
-
       if (LLL_MUTEX_TRYLOCK (mutex) != 0)
 	{
 	  int cnt = 0;

nptl/pthread_mutex_timedlock.c

@@ -113,9 +113,6 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
 
 
     case PTHREAD_MUTEX_ADAPTIVE_NP:
-      if (! __is_smp)
-	goto simple;
-
       if (lll_trylock (mutex->__data.__lock) != 0)
 	{
 	  int cnt = 0;

nptl/smp.h

@@ -1,27 +0,0 @@
-/* Determine whether the host has multiple processors.  Stub version.
-   Copyright (C) 1996-2020 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 Library General Public License as
-   published by the Free Software Foundation; either version 2 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
-   Library General Public License for more details.
-
-   You should have received a copy of the GNU Library General Public
-   License along with the GNU C Library; see the file COPYING.LIB.  If
-   not, see <https://www.gnu.org/licenses/>.  */
-
-/* Test whether the machine has more than one processor.  This is not the
-   best test but good enough.  More complicated tests would require `malloc'
-   which is not available at that time.  */
-static inline int
-is_smp_system (void)
-{
-  /* Assume all machines are SMP and/or CMT and/or SMT.  */
-  return 1;
-}

nptl/vars.c

@@ -27,9 +27,6 @@ union pthread_attr_transparent __default_pthread_attr attribute_hidden;
 /* Mutex protecting __default_pthread_attr.  */
 int __default_pthread_attr_lock = LLL_LOCK_INITIALIZER;
 
-/* Flag whether the machine is SMP or not.  */
-int __is_smp attribute_hidden;
-
 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
 /* Variable set to a nonzero value either if more than one thread runs or ran,
    or if a single-threaded process is trying to cancel itself.  See

sysdeps/unix/sysv/linux/i386/smp.h

@@ -1,55 +0,0 @@
-/* Determine whether the host has multiple processors.  Linux version.
-   Copyright (C) 1996-2020 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 Library General Public License as
-   published by the Free Software Foundation; either version 2 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
-   Library General Public License for more details.
-
-   You should have received a copy of the GNU Library General Public
-   License along with the GNU C Library; see the file COPYING.LIB.  If
-   not, see <https://www.gnu.org/licenses/>.  */
-
-#include <errno.h>
-#include <fcntl.h>
-#include <string.h>
-#include <sys/utsname.h>
-#include <not-cancel.h>
-
-/* Test whether the machine has more than one processor.  This is not the
-   best test but good enough.  More complicated tests would require `malloc'
-   which is not available at that time.  */
-static inline int
-is_smp_system (void)
-{
-  union
-  {
-    struct utsname uts;
-    char buf[512];
-  } u;
-  char *cp;
-
-  /* Try reading the number using `sysctl' first.  */
-  if (__uname (&u.uts) == 0)
-    cp = u.uts.version;
-  else
-    {
-      /* This was not successful.  Now try reading the /proc filesystem.  */
-      int fd = __open64_nocancel ("/proc/sys/kernel/version", O_RDONLY);
-      if (__builtin_expect (fd, 0) == -1
-	  || __read_nocancel (fd, u.buf, sizeof (u.buf)) <= 0)
-	/* This also didn't work.  We give up and say it's a UP machine.  */
-	u.buf[0] = '\0';
-
-      __close_nocancel_nostatus (fd);
-      cp = u.buf;
-    }
-
-  return strstr (cp, "SMP") != NULL;
-}

sysdeps/unix/sysv/linux/sh/adaptive_spin_count.h

@@ -0,0 +1,20 @@
+/* Maximum adaptive spin count default for sh.
+   Copyright (C) 2020 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
+   <https://www.gnu.org/licenses/>.  */
+
+/* Disable spinning because sh is always uniprocessor.  */
+#define DEFAULT_ADAPTIVE_COUNT 0

sysdeps/unix/sysv/linux/sh/smp.h

@@ -1,23 +0,0 @@
-/* Determine whether the host has multiple processors.  SH version.
-   Copyright (C) 2002-2020 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 Library General Public License as
-   published by the Free Software Foundation; either version 2 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
-   Library General Public License for more details.
-
-   You should have received a copy of the GNU Library General Public
-   License along with the GNU C Library; see the file COPYING.LIB.  If
-   not, see <https://www.gnu.org/licenses/>.  */
-
-static inline int
-is_smp_system (void)
-{
-  return 0;
-}