[PATCH] Refactor sys_reboot into reusable parts

Because the factors of sys_reboot don't exist people calling
into the reboot path duplicate the code badly, leading to
inconsistent expectations of code in the reboot path.

This patch should is just code motion.

Signed-off-by: Eric W. Biederman <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/reboot.h

···
 struct pt_regs;
 extern void machine_crash_shutdown(struct pt_regs *);
 
+/* 
+ * Architecture independent implemenations of sys_reboot commands.
+ */
+
+extern void kernel_restart(char *cmd);
+extern void kernel_halt(void);
+extern void kernel_power_off(void);
+extern void kernel_kexec(void);
+
 #endif
 
 #endif /* _LINUX_REBOOT_H */

kernel/sys.c

···
 	return retval;
 }
 
+void kernel_restart(char *cmd)
+{
+	notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
+	system_state = SYSTEM_RESTART;
+	device_suspend(PMSG_FREEZE);
+	device_shutdown();
+	if (!cmd) {
+		printk(KERN_EMERG "Restarting system.\n");
+	} else {
+		printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
+	}
+	printk(".\n");
+	machine_restart(cmd);
+}
+EXPORT_SYMBOL_GPL(kernel_restart);
+
+void kernel_kexec(void)
+{
+#ifdef CONFIG_KEXEC
+	struct kimage *image;
+	image = xchg(&kexec_image, 0);
+	if (!image) {
+		return;
+	}
+	notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL);
+	system_state = SYSTEM_RESTART;
+	device_suspend(PMSG_FREEZE);
+	device_shutdown();
+	printk(KERN_EMERG "Starting new kernel\n");
+	machine_shutdown();
+	machine_kexec(image);
+#endif
+}
+EXPORT_SYMBOL_GPL(kernel_kexec);
+
+void kernel_halt(void)
+{
+	notifier_call_chain(&reboot_notifier_list, SYS_HALT, NULL);
+	system_state = SYSTEM_HALT;
+	device_suspend(PMSG_SUSPEND);
+	device_shutdown();
+	printk(KERN_EMERG "System halted.\n");
+	machine_halt();
+}
+EXPORT_SYMBOL_GPL(kernel_halt);
+
+void kernel_power_off(void)
+{
+	notifier_call_chain(&reboot_notifier_list, SYS_POWER_OFF, NULL);
+	system_state = SYSTEM_POWER_OFF;
+	device_suspend(PMSG_SUSPEND);
+	device_shutdown();
+	printk(KERN_EMERG "Power down.\n");
+	machine_power_off();
+}
+EXPORT_SYMBOL_GPL(kernel_power_off);
 
 /*
  * Reboot system call: for obvious reasons only root may call it,
···
 	lock_kernel();
 	switch (cmd) {
 	case LINUX_REBOOT_CMD_RESTART:
-		notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL);
-		system_state = SYSTEM_RESTART;
-		device_suspend(PMSG_FREEZE);
-		device_shutdown();
-		printk(KERN_EMERG "Restarting system.\n");
-		machine_restart(NULL);
+		kernel_restart(NULL);
 		break;
 
 	case LINUX_REBOOT_CMD_CAD_ON:
···
 		break;
 
 	case LINUX_REBOOT_CMD_HALT:
-		notifier_call_chain(&reboot_notifier_list, SYS_HALT, NULL);
-		system_state = SYSTEM_HALT;
-		device_suspend(PMSG_SUSPEND);
-		device_shutdown();
-		printk(KERN_EMERG "System halted.\n");
-		machine_halt();
+		kernel_halt();
 		unlock_kernel();
 		do_exit(0);
 		break;
 
 	case LINUX_REBOOT_CMD_POWER_OFF:
-		notifier_call_chain(&reboot_notifier_list, SYS_POWER_OFF, NULL);
-		system_state = SYSTEM_POWER_OFF;
-		device_suspend(PMSG_SUSPEND);
-		device_shutdown();
-		printk(KERN_EMERG "Power down.\n");
-		machine_power_off();
+		kernel_power_off();
 		unlock_kernel();
 		do_exit(0);
 		break;
···
 		}
 		buffer[sizeof(buffer) - 1] = '\0';
 
-		notifier_call_chain(&reboot_notifier_list, SYS_RESTART, buffer);
-		system_state = SYSTEM_RESTART;
-		device_suspend(PMSG_FREEZE);
-		device_shutdown();
-		printk(KERN_EMERG "Restarting system with command '%s'.\n", buffer);
-		machine_restart(buffer);
+		kernel_restart(buffer);
 		break;
 
-#ifdef CONFIG_KEXEC
 	case LINUX_REBOOT_CMD_KEXEC:
-	{
-		struct kimage *image;
-		image = xchg(&kexec_image, 0);
-		if (!image) {
-			unlock_kernel();
-			return -EINVAL;
-		}
-		notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL);
-		system_state = SYSTEM_RESTART;
-		device_suspend(PMSG_FREEZE);
-		device_shutdown();
-		printk(KERN_EMERG "Starting new kernel\n");
-		machine_shutdown();
-		machine_kexec(image);
-		break;
-	}
-#endif
+		kernel_kexec();
+		unlock_kernel();
+		return -EINVAL;
+
 #ifdef CONFIG_SOFTWARE_SUSPEND
 	case LINUX_REBOOT_CMD_SW_SUSPEND:
 		{