kernel/reboot.c: add orderly_reboot for graceful reboot

The kernel has orderly_poweroff which allows the kernel to initiate a
graceful shutdown of userspace, by running /sbin/poweroff.  This adds
orderly_reboot that will cause userspace to shut itself down by calling
/sbin/reboot.

This will be used for shutdown initiated by a system controller on
platforms that do not use ACPI.

orderly_reboot() should be used when the system wants to allow userspace
to gracefully shut itself down.  For cases where the system may imminently
catch on fire, the existing emergency_restart() provides an immediate
reboot without involving userspace.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 48 insertions, 5 deletions

diff --git a/kernel/reboot.c b/kernel/reboot.c
index 5925f5ae8dff..d20c85d9f8c0 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -387,8 +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[] = {
@@ -397,8 +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);
@@ -406,8 +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
@@ -436,15 +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 (;;) {