1 files changed, 26 insertions, 3 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index b95d3c72ba21..2bbd9a73b54c 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -362,6 +362,29 @@ int unregister_reboot_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_reboot_notifier);
 
+/* Add backwards compatibility for stable trees. */
+#ifndef PF_NO_SETAFFINITY
+#define PF_NO_SETAFFINITY               PF_THREAD_BOUND
+#endif
+
+static void migrate_to_reboot_cpu(void)
+{
+        /* The boot cpu is always logical cpu 0 */
+        int cpu = 0;
+
+        cpu_hotplug_disable();
+
+        /* Make certain the cpu I'm about to reboot on is online */
+        if (!cpu_online(cpu))
+                cpu = cpumask_first(cpu_online_mask);
+
+        /* Prevent races with other tasks migrating this task */
+        current->flags |= PF_NO_SETAFFINITY;
+
+        /* Make certain I only run on the appropriate processor */
+        set_cpus_allowed_ptr(current, cpumask_of(cpu));
+}
+
 /**
  *      kernel_restart - reboot the system
  *      @cmd: pointer to buffer containing command to execute for restart
@@ -373,7 +396,7 @@ EXPORT_SYMBOL(unregister_reboot_notifier);
 void kernel_restart(char *cmd)
 {
         kernel_restart_prepare(cmd);
-        disable_nonboot_cpus();
+        migrate_to_reboot_cpu();
         syscore_shutdown();
         if (!cmd)
                 printk(KERN_EMERG "Restarting system.\n");
@@ -400,7 +423,7 @@ static void kernel_shutdown_prepare(enum system_states state)
 void kernel_halt(void)
 {
         kernel_shutdown_prepare(SYSTEM_HALT);
-        disable_nonboot_cpus();
+        migrate_to_reboot_cpu();
         syscore_shutdown();
         printk(KERN_EMERG "System halted.\n");
         kmsg_dump(KMSG_DUMP_HALT);
@@ -419,7 +442,7 @@ void kernel_power_off(void)
         kernel_shutdown_prepare(SYSTEM_POWER_OFF);
         if (pm_power_off_prepare)
                 pm_power_off_prepare();
-        disable_nonboot_cpus();
+        migrate_to_reboot_cpu();
         syscore_shutdown();
         printk(KERN_EMERG "Power down.\n");
         kmsg_dump(KMSG_DUMP_POWEROFF);