sched: domain sysctl fixes: use for_each_online_cpu()

init_sched_domain_sysctl was walking cpus 0-n and referencing per_cpu
variables.  If the cpus_possible mask is not contigious this will result
in a crash referencing unallocated data.  If the online mask is not
contigious then we would show offline cpus and miss online ones.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -5326,11 +5326,12 @@ static void init_sched_domain_sysctl(void)
 
 	sd_ctl_dir[0].child = entry;
 
-	for (i = 0; i < cpu_num; i++, entry++) {
+	for_each_online_cpu(i) {
 		snprintf(buf, 32, "cpu%d", i);
 		entry->procname = kstrdup(buf, GFP_KERNEL);
 		entry->mode = 0555;
 		entry->child = sd_alloc_ctl_cpu_table(i);
+		entry++;
 	}
 	sd_sysctl_header = register_sysctl_table(sd_ctl_root);
 }