x86: move prefill_possible_map calling early, fix, V2

Commit 4a701737 ("x86: move prefill_possible_map calling early, fix")
is the wrong fix: prefill_possible_map() needs to be available
even when CONFIG_HOTPLUG_CPU is not set. A followon patch will do that.

Fix this correctly by making prefill_possible_map() available even when
CONFIG_HOTPLUG_CPU is not set. The function is needed so that
the number of possible CPUs can be determined.

Tested on uniprocessor machine with CPU hotplug disabled.

From boot log:
  Before: NR_CPUS: 512, nr_cpu_ids: 512, nr_node_ids 1
  After: NR_CPUS: 512, nr_cpu_ids: 1, nr_node_ids 1
Signed-off-by: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/smpboot.c

@@ -1261,39 +1261,8 @@ void __init native_smp_cpus_done(unsigned int max_cpus)
 	check_nmi_watchdog();
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-
-static void remove_siblinginfo(int cpu)
-{
-	int sibling;
-	struct cpuinfo_x86 *c = &cpu_data(cpu);
-
-	for_each_cpu_mask_nr(sibling, per_cpu(cpu_core_map, cpu)) {
-		cpu_clear(cpu, per_cpu(cpu_core_map, sibling));
-		/*/
-		 * last thread sibling in this cpu core going down
-		 */
-		if (cpus_weight(per_cpu(cpu_sibling_map, cpu)) == 1)
-			cpu_data(sibling).booted_cores--;
-	}
-
-	for_each_cpu_mask_nr(sibling, per_cpu(cpu_sibling_map, cpu))
-		cpu_clear(cpu, per_cpu(cpu_sibling_map, sibling));
-	cpus_clear(per_cpu(cpu_sibling_map, cpu));
-	cpus_clear(per_cpu(cpu_core_map, cpu));
-	c->phys_proc_id = 0;
-	c->cpu_core_id = 0;
-	cpu_clear(cpu, cpu_sibling_setup_map);
-}
-
 static int additional_cpus __initdata = -1;
 
-static __init int setup_additional_cpus(char *s)
-{
-	return s && get_option(&s, &additional_cpus) ? 0 : -EINVAL;
-}
-early_param("additional_cpus", setup_additional_cpus);
-
 /*
  * cpu_possible_map should be static, it cannot change as cpu's
  * are onlined, or offlined. The reason is per-cpu data-structures
@@ -1340,6 +1309,37 @@ __init void prefill_possible_map(void)
 	nr_cpu_ids = possible;
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+
+static void remove_siblinginfo(int cpu)
+{
+	int sibling;
+	struct cpuinfo_x86 *c = &cpu_data(cpu);
+
+	for_each_cpu_mask_nr(sibling, per_cpu(cpu_core_map, cpu)) {
+		cpu_clear(cpu, per_cpu(cpu_core_map, sibling));
+		/*/
+		 * last thread sibling in this cpu core going down
+		 */
+		if (cpus_weight(per_cpu(cpu_sibling_map, cpu)) == 1)
+			cpu_data(sibling).booted_cores--;
+	}
+
+	for_each_cpu_mask_nr(sibling, per_cpu(cpu_sibling_map, cpu))
+		cpu_clear(cpu, per_cpu(cpu_sibling_map, sibling));
+	cpus_clear(per_cpu(cpu_sibling_map, cpu));
+	cpus_clear(per_cpu(cpu_core_map, cpu));
+	c->phys_proc_id = 0;
+	c->cpu_core_id = 0;
+	cpu_clear(cpu, cpu_sibling_setup_map);
+}
+
+static __init int setup_additional_cpus(char *s)
+{
+	return s && get_option(&s, &additional_cpus) ? 0 : -EINVAL;
+}
+early_param("additional_cpus", setup_additional_cpus);
+
 static void __ref remove_cpu_from_maps(int cpu)
 {
 	cpu_clear(cpu, cpu_online_map);

include/asm-x86/smp.h

@@ -141,6 +141,8 @@ void play_dead_common(void);
 void native_send_call_func_ipi(cpumask_t mask);
 void native_send_call_func_single_ipi(int cpu);
 
+extern void prefill_possible_map(void);
+
 void smp_store_cpu_info(int id);
 #define cpu_physical_id(cpu)	per_cpu(x86_cpu_to_apicid, cpu)
 
@@ -149,15 +151,11 @@ static inline int num_booting_cpus(void)
 {
 	return cpus_weight(cpu_callout_map);
 }
-#endif /* CONFIG_SMP */
-
-#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_CPU)
-extern void prefill_possible_map(void);
 #else
 static inline void prefill_possible_map(void)
 {
 }
-#endif
+#endif /* CONFIG_SMP */
 
 extern unsigned disabled_cpus __cpuinitdata;