2 files changed, 50 insertions, 6 deletions

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 3b3266ff1a95..7ab2cdb83ef0 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -59,6 +59,10 @@ extern void machine_crash_shutdown(struct pt_regs *);
  * Architecture independent implemenations of sys_reboot commands.
  */
 
+extern void kernel_restart_prepare(char *cmd);
+extern void kernel_halt_prepare(void);
+extern void kernel_power_off_prepare(void);
+
 extern void kernel_restart(char *cmd);
 extern void kernel_halt(void);
 extern void kernel_power_off(void);
diff --git a/kernel/sys.c b/kernel/sys.c
index f723522e6986..2fa1ed18123c 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -361,17 +361,35 @@ out_unlock:
         return retval;
 }
 
+/**
+ *      emergency_restart - reboot the system
+ *
+ *      Without shutting down any hardware or taking any locks
+ *      reboot the system.  This is called when we know we are in
+ *      trouble so this is our best effort to reboot.  This is
+ *      safe to call in interrupt context.
+ */
 void emergency_restart(void)
 {
         machine_emergency_restart();
 }
 EXPORT_SYMBOL_GPL(emergency_restart);
 
-void kernel_restart(char *cmd)
+/**
+ *      kernel_restart - reboot the system
+ *
+ *      Shutdown everything and perform a clean reboot.
+ *      This is not safe to call in interrupt context.
+ */
+void kernel_restart_prepare(char *cmd)
 {
         notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
         system_state = SYSTEM_RESTART;
         device_shutdown();
+}
+void kernel_restart(char *cmd)
+{
+        kernel_restart_prepare(cmd);
         if (!cmd) {
                 printk(KERN_EMERG "Restarting system.\n");
         } else {
@@ -382,6 +400,12 @@ void kernel_restart(char *cmd)
 }
 EXPORT_SYMBOL_GPL(kernel_restart);
 
+/**
+ *      kernel_kexec - reboot the system
+ *
+ *      Move into place and start executing a preloaded standalone
+ *      executable.  If nothing was preloaded return an error.
+ */
 void kernel_kexec(void)
 {
 #ifdef CONFIG_KEXEC
@@ -390,9 +414,7 @@ void kernel_kexec(void)
         if (!image) {
                 return;
         }
-        notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL);
-        system_state = SYSTEM_RESTART;
-        device_shutdown();
+        kernel_restart_prepare(NULL);
         printk(KERN_EMERG "Starting new kernel\n");
         machine_shutdown();
         machine_kexec(image);
@@ -400,21 +422,39 @@ void kernel_kexec(void)
 }
 EXPORT_SYMBOL_GPL(kernel_kexec);
 
-void kernel_halt(void)
+/**
+ *      kernel_halt - halt the system
+ *
+ *      Shutdown everything and perform a clean system halt.
+ */
+void kernel_halt_prepare(void)
 {
         notifier_call_chain(&reboot_notifier_list, SYS_HALT, NULL);
         system_state = SYSTEM_HALT;
         device_shutdown();
+}
+void kernel_halt(void)
+{
+        kernel_halt_prepare();
         printk(KERN_EMERG "System halted.\n");
         machine_halt();
 }
 EXPORT_SYMBOL_GPL(kernel_halt);
 
-void kernel_power_off(void)
+/**
+ *      kernel_power_off - power_off the system
+ *
+ *      Shutdown everything and perform a clean system power_off.
+ */
+void kernel_power_off_prepare(void)
 {
         notifier_call_chain(&reboot_notifier_list, SYS_POWER_OFF, NULL);
         system_state = SYSTEM_POWER_OFF;
         device_shutdown();
+}
+void kernel_power_off(void)
+{
+        kernel_power_off_prepare();
         printk(KERN_EMERG "Power down.\n");
         machine_power_off();
 }