1 files changed, 129 insertions, 5 deletions

diff --git a/kernel/reboot.c b/kernel/reboot.c
index a3a9e240fcdb..d20c85d9f8c0 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -104,6 +104,87 @@ int unregister_reboot_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_reboot_notifier);
 
+/*
+ *      Notifier list for kernel code which wants to be called
+ *      to restart the system.
+ */
+static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
+
+/**
+ *      register_restart_handler - Register function to be called to reset
+ *                                 the system
+ *      @nb: Info about handler function to be called
+ *      @nb->priority:  Handler priority. Handlers should follow the
+ *                      following guidelines for setting priorities.
+ *                      0:      Restart handler of last resort,
+ *                              with limited restart capabilities
+ *                      128:    Default restart handler; use if no other
+ *                              restart handler is expected to be available,
+ *                              and/or if restart functionality is
+ *                              sufficient to restart the entire system
+ *                      255:    Highest priority restart handler, will
+ *                              preempt all other restart handlers
+ *
+ *      Registers a function with code to be called to restart the
+ *      system.
+ *
+ *      Registered functions will be called from machine_restart as last
+ *      step of the restart sequence (if the architecture specific
+ *      machine_restart function calls do_kernel_restart - see below
+ *      for details).
+ *      Registered functions are expected to restart the system immediately.
+ *      If more than one function is registered, the restart handler priority
+ *      selects which function will be called first.
+ *
+ *      Restart handlers are expected to be registered from non-architecture
+ *      code, typically from drivers. A typical use case would be a system
+ *      where restart functionality is provided through a watchdog. Multiple
+ *      restart handlers may exist; for example, one restart handler might
+ *      restart the entire system, while another only restarts the CPU.
+ *      In such cases, the restart handler which only restarts part of the
+ *      hardware is expected to register with low priority to ensure that
+ *      it only runs if no other means to restart the system is available.
+ *
+ *      Currently always returns zero, as atomic_notifier_chain_register()
+ *      always returns zero.
+ */
+int register_restart_handler(struct notifier_block *nb)
+{
+        return atomic_notifier_chain_register(&restart_handler_list, nb);
+}
+EXPORT_SYMBOL(register_restart_handler);
+
+/**
+ *      unregister_restart_handler - Unregister previously registered
+ *                                   restart handler
+ *      @nb: Hook to be unregistered
+ *
+ *      Unregisters a previously registered restart handler function.
+ *
+ *      Returns zero on success, or %-ENOENT on failure.
+ */
+int unregister_restart_handler(struct notifier_block *nb)
+{
+        return atomic_notifier_chain_unregister(&restart_handler_list, nb);
+}
+EXPORT_SYMBOL(unregister_restart_handler);
+
+/**
+ *      do_kernel_restart - Execute kernel restart handler call chain
+ *
+ *      Calls functions registered with register_restart_handler.
+ *
+ *      Expected to be called from machine_restart as last step of the restart
+ *      sequence.
+ *
+ *      Restarts the system immediately if a restart handler function has been
+ *      registered. Otherwise does nothing.
+ */
+void do_kernel_restart(char *cmd)
+{
+        atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
+}
+
 void migrate_to_reboot_cpu(void)
 {
         /* The boot cpu is always logical cpu 0 */
@@ -306,8 +387,9 @@ void ctrl_alt_del(void)
 }
 
 char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
+static const char reboot_cmd[] = "/sbin/reboot";
 
-static int __orderly_poweroff(bool force)
+static int run_cmd(const char *cmd)
 {
         char **argv;
         static char *envp[] = {
@@ -316,8 +398,7 @@ static int __orderly_poweroff(bool force)
                 NULL
         };
         int ret;
-
-        argv = argv_split(GFP_KERNEL, poweroff_cmd, NULL);
+        argv = argv_split(GFP_KERNEL, cmd, NULL);
         if (argv) {
                 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
                 argv_free(argv);
@@ -325,8 +406,33 @@ static int __orderly_poweroff(bool force)
                 ret = -ENOMEM;
         }
 
+        return ret;
+}
+
+static int __orderly_reboot(void)
+{
+        int ret;
+
+        ret = run_cmd(reboot_cmd);
+
+        if (ret) {
+                pr_warn("Failed to start orderly reboot: forcing the issue\n");
+                emergency_sync();
+                kernel_restart(NULL);
+        }
+
+        return ret;
+}
+
+static int __orderly_poweroff(bool force)
+{
+        int ret;
+
+        ret = run_cmd(poweroff_cmd);
+
         if (ret && force) {
                 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
+
                 /*
                  * I guess this should try to kick off some daemon to sync and
                  * poweroff asap.  Or not even bother syncing if we're doing an
@@ -355,15 +461,33 @@ static DECLARE_WORK(poweroff_work, poweroff_work_func);
  * This may be called from any context to trigger a system shutdown.
  * If the orderly shutdown fails, it will force an immediate shutdown.
  */
-int orderly_poweroff(bool force)
+void orderly_poweroff(bool force)
 {
         if (force) /* do not override the pending "true" */
                 poweroff_force = true;
         schedule_work(&poweroff_work);
-        return 0;
 }
 EXPORT_SYMBOL_GPL(orderly_poweroff);
 
+static void reboot_work_func(struct work_struct *work)
+{
+        __orderly_reboot();
+}
+
+static DECLARE_WORK(reboot_work, reboot_work_func);
+
+/**
+ * orderly_reboot - Trigger an orderly system reboot
+ *
+ * This may be called from any context to trigger a system reboot.
+ * If the orderly reboot fails, it will force an immediate reboot.
+ */
+void orderly_reboot(void)
+{
+        schedule_work(&reboot_work);
+}
+EXPORT_SYMBOL_GPL(orderly_reboot);
+
 static int __init reboot_setup(char *str)
 {
         for (;;) {