x86: convert cpumask_of_cpu macro to allocated array

  * Here is a simple patch to use an allocated array of cpumasks to
    represent cpumask_of_cpu() instead of constructing one on the stack.
    It's based on the Kconfig option "HAVE_CPUMASK_OF_CPU_MAP" which is
    currently only set for x86_64 SMP.  Otherwise the the existing
    cpumask_of_cpu() is used but has been changed to produce an lvalue
    so a pointer to it can be used.

Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 30 insertions, 1 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2a59dbb28248..7f30b754bfc3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -117,6 +117,9 @@ config ARCH_HAS_CPU_RELAX
 config HAVE_SETUP_PER_CPU_AREA
         def_bool X86_64 || (X86_SMP && !X86_VOYAGER)
 
+config HAVE_CPUMASK_OF_CPU_MAP
+        def_bool X86_64_SMP
+
 config ARCH_HIBERNATION_POSSIBLE
         def_bool y
         depends on !SMP || !X86_VOYAGER
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index ed157c90412e..0d1f44ae6eea 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -54,6 +54,24 @@ static void __init setup_per_cpu_maps(void)
 #endif
 }
 
+#ifdef CONFIG_HAVE_CPUMASK_OF_CPU_MAP
+cpumask_t *cpumask_of_cpu_map __read_mostly;
+EXPORT_SYMBOL(cpumask_of_cpu_map);
+
+/* requires nr_cpu_ids to be initialized */
+static void __init setup_cpumask_of_cpu(void)
+{
+        int i;
+
+        /* alloc_bootmem zeroes memory */
+        cpumask_of_cpu_map = alloc_bootmem_low(sizeof(cpumask_t) * nr_cpu_ids);
+        for (i = 0; i < nr_cpu_ids; i++)
+                cpu_set(i, cpumask_of_cpu_map[i]);
+}
+#else
+static inline void setup_cpumask_of_cpu(void) { }
+#endif
+
 #ifdef CONFIG_X86_32
 /*
  * Great future not-so-futuristic plan: make i386 and x86_64 do it
@@ -70,7 +88,7 @@ EXPORT_SYMBOL(__per_cpu_offset);
  */
 void __init setup_per_cpu_areas(void)
 {
-        int i;
+        int i, highest_cpu = 0;
         unsigned long size;
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -104,10 +122,18 @@ void __init setup_per_cpu_areas(void)
                 __per_cpu_offset[i] = ptr - __per_cpu_start;
 #endif
                 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
+
+                highest_cpu = i;
         }
 
+        nr_cpu_ids = highest_cpu + 1;
+        printk(KERN_DEBUG "NR_CPUS: %d, nr_cpu_ids: %d\n", NR_CPUS, nr_cpu_ids);
+
         /* Setup percpu data maps */
         setup_per_cpu_maps();
+
+        /* Setup cpumask_of_cpu map */
+        setup_cpumask_of_cpu();
 }
 
 #endif