linux-kernel - Re: [PATCH -tip/cpus4096-v2] cpumask: fix cpumask of call_function

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Date:	Mon, 27 Oct 2008 14:02:25 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>,
	Mike Travis <travis@....com>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH -tip/cpus4096-v2] cpumask: fix cpumask of
	call_function_data


* Ingo Molnar <mingo@...e.hu> wrote:

> > If there's any chance for this in v2.6.28 then only if we disable 
> > the dynamic API branch altogether [CONFIG_MAXCPUS] and keep that 
> > for v2.6.29. This means we'd bring in the API changes which should 
> > have trivial impact only - and none of the riskier changes.
> 
> in any case, i've started testing tip/cpus4096-v2 again on x86 - the 
> problem with d4de5a above was the only outstanding known issue, 
> right?

plus there are also the fixlets below.

	Ingo

-------------->
>From a14b735fb7a82bb6561449dda4067365af7ee95c Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@...tcorp.com.au>
Date: Thu, 23 Oct 2008 14:35:31 -0700
Subject: [PATCH] cpumask: fixlets

[ from Mike ]

Here are the only changes I could find from Rusty's last patches that
apply to tip/cpus4096-v2.

* Fix NR_CPUS reference in arch/powerpc/platforms/cell/spu_base.c

* modify arch/x86/Kconfig so CONFIG_NR_CPUS is always defined.  Also it
  does not prompt if MAXSMP is set.

* change include/linux/threads.h so CONFIG_NR_CPUS is defined for those
  arch's that do not define it.

Signed-of-by: Rusty Russell <rusty@...tcorp.com.au>
Signed-of-by: Mike Travis <travis@....com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/powerpc/platforms/cell/spu_base.c |    9 ++++++---
 arch/x86/Kconfig                       |    2 +-
 include/linux/threads.h                |   16 ++++++++--------
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spu_base.c b/arch/powerpc/platforms/cell/spu_base.c
index a5bdb89..a876904 100644
--- a/arch/powerpc/platforms/cell/spu_base.c
+++ b/arch/powerpc/platforms/cell/spu_base.c
@@ -111,10 +111,13 @@ void spu_flush_all_slbs(struct mm_struct *mm)
  */
 static inline void mm_needs_global_tlbie(struct mm_struct *mm)
 {
-	int nr = (NR_CPUS > 1) ? NR_CPUS : NR_CPUS + 1;
-
 	/* Global TLBIE broadcast required with SPEs. */
-	__cpus_setall(&mm->cpu_vm_mask, nr);
+	if (NR_CPUS > 1)
+		cpumask_setall(&mm->cpu_vm_mask);
+	else {
+		cpumask_set_cpu(0, &mm->cpu_vm_mask);
+		cpumask_set_cpu(1, &mm->cpu_vm_mask);
+	}
 }
 
 void spu_associate_mm(struct spu *spu, struct mm_struct *mm)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d574cd6..a901f59 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -585,9 +585,9 @@ config MAXSMP
 	  If unsure, say N.
 
 config NR_CPUS
-	depends on SMP
  	int "Maximum number of CPUs" if SMP && !MAXSMP
  	range 2 512 if SMP && !MAXSMP
+	default "1" if !SMP
 	default "4096" if MAXSMP
  	default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
 	default "8"
diff --git a/include/linux/threads.h b/include/linux/threads.h
index 38d1a5d..052b12b 100644
--- a/include/linux/threads.h
+++ b/include/linux/threads.h
@@ -8,17 +8,17 @@
  */
 
 /*
- * Maximum supported processors that can run under SMP.  This value is
- * set via configure setting.  The maximum is equal to the size of the
- * bitmasks used on that platform, i.e. 32 or 64.  Setting this smaller
- * saves quite a bit of memory.
+ * Maximum supported processors.  Setting this smaller saves quite a
+ * bit of memory.  Use nr_cpu_ids instead of this except for static bitmaps.
  */
-#ifdef CONFIG_SMP
-#define NR_CPUS		CONFIG_NR_CPUS
-#else
-#define NR_CPUS		1
+#ifndef CONFIG_NR_CPUS
+/* FIXME: This should be fixed in the arch's Kconfig */
+#define CONFIG_NR_CPUS	1
 #endif
 
+/* Places which use this should consider cpumask_var_t. */
+#define NR_CPUS		CONFIG_NR_CPUS
+
 #define MIN_THREADS_LEFT_FOR_ROOT 4
 
 /*
--
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