x86: change _node_to_cpumask_ptr to return const ptr

  * Strengthen the return type for the _node_to_cpumask_ptr to be
    a const pointer.  This adds compiler checking to insure that
    node_to_cpumask_map[] is not changed inadvertently.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Acked-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/topology.h b/include/asm-x86/topology.h
index 98e5f17..90ac771 100644
--- a/include/asm-x86/topology.h
+++ b/include/asm-x86/topology.h
@@ -82,7 +82,7 @@
 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
 extern int cpu_to_node(int cpu);
 extern int early_cpu_to_node(int cpu);
-extern cpumask_t *_node_to_cpumask_ptr(int node);
+extern const cpumask_t *_node_to_cpumask_ptr(int node);
 extern cpumask_t node_to_cpumask(int node);
 
 #else	/* !CONFIG_DEBUG_PER_CPU_MAPS */
@@ -103,7 +103,7 @@
 }
 
 /* Returns a pointer to the cpumask of CPUs on Node 'node'. */
-static inline cpumask_t *_node_to_cpumask_ptr(int node)
+static inline const cpumask_t *_node_to_cpumask_ptr(int node)
 {
 	return &node_to_cpumask_map[node];
 }
@@ -118,7 +118,7 @@
 
 /* Replace default node_to_cpumask_ptr with optimized version */
 #define node_to_cpumask_ptr(v, node)		\
-		cpumask_t *v = _node_to_cpumask_ptr(node)
+		const cpumask_t *v = _node_to_cpumask_ptr(node)
 
 #define node_to_cpumask_ptr_next(v, node)	\
 			   v = _node_to_cpumask_ptr(node)
@@ -186,7 +186,7 @@
 #define	cpu_to_node(cpu)	0
 #define	early_cpu_to_node(cpu)	0
 
-static inline cpumask_t *_node_to_cpumask_ptr(int node)
+static inline const cpumask_t *_node_to_cpumask_ptr(int node)
 {
 	return &cpu_online_map;
 }
@@ -201,7 +201,7 @@
 
 /* Replace default node_to_cpumask_ptr with optimized version */
 #define node_to_cpumask_ptr(v, node)		\
-		cpumask_t *v = _node_to_cpumask_ptr(node)
+		const cpumask_t *v = _node_to_cpumask_ptr(node)
 
 #define node_to_cpumask_ptr_next(v, node)	\
 			   v = _node_to_cpumask_ptr(node)