init: move setup of nr_cpu_ids to as early as possible

Move the setting of nr_cpu_ids from sched_init() to start_kernel()
so that it's available as early as possible.

Note that an arch has the option of setting it even earlier if need be,
but it should not result in a different value than the setup_nr_cpu_ids()
function.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

init/main.c

@@ -359,6 +359,7 @@ static void __init smp_init(void)
 #endif
 
 static inline void setup_per_cpu_areas(void) { }
+static inline void setup_nr_cpu_ids(void) { }
 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 
 #else
@@ -368,6 +369,21 @@ cpumask_t cpu_mask_all __read_mostly = CPU_MASK_ALL;
 EXPORT_SYMBOL(cpu_mask_all);
 #endif
 
+/* Setup number of possible processor ids */
+int nr_cpu_ids __read_mostly = NR_CPUS;
+EXPORT_SYMBOL(nr_cpu_ids);
+
+/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
+static void __init setup_nr_cpu_ids(void)
+{
+	int cpu, highest_cpu = 0;
+
+	for_each_possible_cpu(cpu)
+		highest_cpu = cpu;
+
+	nr_cpu_ids = highest_cpu + 1;
+}
+
 #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
 
@@ -542,6 +558,7 @@ asmlinkage void __init start_kernel(void)
 	setup_command_line(command_line);
 	unwind_setup();
 	setup_per_cpu_areas();
+	setup_nr_cpu_ids();
 	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
 
 	/*

kernel/sched.c

@@ -6116,10 +6116,6 @@ void __init migration_init(void)
 
 #ifdef CONFIG_SMP
 
-/* Number of possible processor ids */
-int nr_cpu_ids __read_mostly = NR_CPUS;
-EXPORT_SYMBOL(nr_cpu_ids);
-
 #ifdef CONFIG_SCHED_DEBUG
 
 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
@@ -7478,7 +7474,6 @@ static void init_tg_rt_entry(struct rq *rq, struct task_group *tg,
 
 void __init sched_init(void)
 {
-	int highest_cpu = 0;
 	int i, j;
 	unsigned long alloc_size = 0, ptr;
 
@@ -7569,7 +7564,6 @@ void __init sched_init(void)
 #endif
 		init_rq_hrtick(rq);
 		atomic_set(&rq->nr_iowait, 0);
-		highest_cpu = i;
 	}
 
 	set_load_weight(&init_task);
@@ -7579,7 +7573,6 @@ void __init sched_init(void)
 #endif
 
 #ifdef CONFIG_SMP
-	nr_cpu_ids = highest_cpu + 1;
 	open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
 #endif