kernel: add functions to query the number of available/online CPUs

kernel/cpu.c

@@ -58,6 +58,16 @@ void cpu_set_online(unsigned int cpu_id)
 	bitmap_set(cpu_online, cpu_id);
 }
 
+unsigned int cpu_nr_available(void)
+{
+	return bitmap_count_set(cpu_available, CPU_MAX);
+}
+
+unsigned int cpu_nr_online(void)
+{
+	return bitmap_count_set(cpu_online, CPU_MAX);
+}
+
 void preempt_disable(void)
 {
 	ml_cpu_block *ml_cpu = ml_this_cpu();