2 files changed, 23 insertions, 9 deletions

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 4b29e508a0b6..f770039344c5 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -396,6 +396,12 @@ extern cpumask_t cpu_present_map;
 #define cpu_present(cpu)        ((cpu) == 0)
 #endif
 
+#ifdef CONFIG_SMP
+int highest_possible_processor_id(void);
+#else
+#define highest_possible_processor_id() 0
+#endif
+
 #define any_online_cpu(mask)                    \
 ({                                              \
         int cpu;                                \
@@ -409,14 +415,5 @@ extern cpumask_t cpu_present_map;
 #define for_each_online_cpu(cpu)  for_each_cpu_mask((cpu), cpu_online_map)
 #define for_each_present_cpu(cpu) for_each_cpu_mask((cpu), cpu_present_map)
 
-/* Find the highest possible smp_processor_id() */
-#define highest_possible_processor_id() \
-({ \
-        unsigned int cpu, highest = 0; \
-        for_each_cpu_mask(cpu, cpu_possible_map) \
-                highest = cpu; \
-        highest; \
-})
-
 
 #endif /* __LINUX_CPUMASK_H */
diff --git a/lib/cpumask.c b/lib/cpumask.c
index ba2f8543052c..ea25a034276c 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -14,3 +14,20 @@ int __next_cpu(int n, const cpumask_t *srcp)
         return min_t(int, NR_CPUS, find_next_bit(srcp->bits, NR_CPUS, n+1));
 }
 EXPORT_SYMBOL(__next_cpu);
+
+/*
+ * Find the highest possible smp_processor_id()
+ *
+ * Note: if we're prepared to assume that cpu_possible_map never changes
+ * (reasonable) then this function should cache its return value.
+ */
+int highest_possible_processor_id(void)
+{
+        unsigned int cpu;
+        unsigned highest = 0;
+
+        for_each_cpu_mask(cpu, cpu_possible_map)
+                highest = cpu;
+        return highest;
+}
+EXPORT_SYMBOL(highest_possible_processor_id);