reboot: move shutdown/reboot related functions to kernel/reboot.c

This patch is preparatory.  It moves reboot related syscall, etc
functions from kernel/sys.c to kernel/reboot.c.

Signed-off-by: Robin Holt <holt@sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/Makefile

@@ -9,7 +9,7 @@ obj-y     = fork.o exec_domain.o panic.o printk.o \
 	    rcupdate.o extable.o params.o posix-timers.o \
 	    kthread.o wait.o sys_ni.o posix-cpu-timers.o mutex.o \
 	    hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \
-	    notifier.o ksysfs.o cred.o \
+	    notifier.o ksysfs.o cred.o reboot.o \
 	    async.o range.o groups.o lglock.o smpboot.o
 
 ifdef CONFIG_FUNCTION_TRACER

kernel/reboot.c

@@ -0,0 +1,346 @@
+/*
+ *  linux/kernel/reboot.c
+ *
+ *  Copyright (C) 2013  Linus Torvalds
+ */
+
+#include <linux/export.h>
+#include <linux/kexec.h>
+#include <linux/kmod.h>
+#include <linux/kmsg_dump.h>
+#include <linux/reboot.h>
+#include <linux/suspend.h>
+#include <linux/syscalls.h>
+#include <linux/syscore_ops.h>
+#include <linux/uaccess.h>
+
+/*
+ * this indicates whether you can reboot with ctrl-alt-del: the default is yes
+ */
+
+int C_A_D = 1;
+struct pid *cad_pid;
+EXPORT_SYMBOL(cad_pid);
+
+/*
+ * If set, this is used for preparing the system to power off.
+ */
+
+void (*pm_power_off_prepare)(void);
+
+/**
+ *	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)
+{
+	kmsg_dump(KMSG_DUMP_EMERG);
+	machine_emergency_restart();
+}
+EXPORT_SYMBOL_GPL(emergency_restart);
+
+void kernel_restart_prepare(char *cmd)
+{
+	blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
+	system_state = SYSTEM_RESTART;
+	usermodehelper_disable();
+	device_shutdown();
+}
+
+/**
+ *	register_reboot_notifier - Register function to be called at reboot time
+ *	@nb: Info about notifier function to be called
+ *
+ *	Registers a function with the list of functions
+ *	to be called at reboot time.
+ *
+ *	Currently always returns zero, as blocking_notifier_chain_register()
+ *	always returns zero.
+ */
+int register_reboot_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&reboot_notifier_list, nb);
+}
+EXPORT_SYMBOL(register_reboot_notifier);
+
+/**
+ *	unregister_reboot_notifier - Unregister previously registered reboot notifier
+ *	@nb: Hook to be unregistered
+ *
+ *	Unregisters a previously registered reboot
+ *	notifier function.
+ *
+ *	Returns zero on success, or %-ENOENT on failure.
+ */
+int unregister_reboot_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
+}
+EXPORT_SYMBOL(unregister_reboot_notifier);
+
+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
+ *		or %NULL
+ *
+ *	Shutdown everything and perform a clean reboot.
+ *	This is not safe to call in interrupt context.
+ */
+void kernel_restart(char *cmd)
+{
+	kernel_restart_prepare(cmd);
+	migrate_to_reboot_cpu();
+	syscore_shutdown();
+	if (!cmd)
+		printk(KERN_EMERG "Restarting system.\n");
+	else
+		printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
+	kmsg_dump(KMSG_DUMP_RESTART);
+	machine_restart(cmd);
+}
+EXPORT_SYMBOL_GPL(kernel_restart);
+
+static void kernel_shutdown_prepare(enum system_states state)
+{
+	blocking_notifier_call_chain(&reboot_notifier_list,
+		(state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
+	system_state = state;
+	usermodehelper_disable();
+	device_shutdown();
+}
+/**
+ *	kernel_halt - halt the system
+ *
+ *	Shutdown everything and perform a clean system halt.
+ */
+void kernel_halt(void)
+{
+	kernel_shutdown_prepare(SYSTEM_HALT);
+	migrate_to_reboot_cpu();
+	syscore_shutdown();
+	printk(KERN_EMERG "System halted.\n");
+	kmsg_dump(KMSG_DUMP_HALT);
+	machine_halt();
+}
+
+EXPORT_SYMBOL_GPL(kernel_halt);
+
+/**
+ *	kernel_power_off - power_off the system
+ *
+ *	Shutdown everything and perform a clean system power_off.
+ */
+void kernel_power_off(void)
+{
+	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
+	if (pm_power_off_prepare)
+		pm_power_off_prepare();
+	migrate_to_reboot_cpu();
+	syscore_shutdown();
+	printk(KERN_EMERG "Power down.\n");
+	kmsg_dump(KMSG_DUMP_POWEROFF);
+	machine_power_off();
+}
+EXPORT_SYMBOL_GPL(kernel_power_off);
+
+static DEFINE_MUTEX(reboot_mutex);
+
+/*
+ * Reboot system call: for obvious reasons only root may call it,
+ * and even root needs to set up some magic numbers in the registers
+ * so that some mistake won't make this reboot the whole machine.
+ * You can also set the meaning of the ctrl-alt-del-key here.
+ *
+ * reboot doesn't sync: do that yourself before calling this.
+ */
+SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
+		void __user *, arg)
+{
+	struct pid_namespace *pid_ns = task_active_pid_ns(current);
+	char buffer[256];
+	int ret = 0;
+
+	/* We only trust the superuser with rebooting the system. */
+	if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
+		return -EPERM;
+
+	/* For safety, we require "magic" arguments. */
+	if (magic1 != LINUX_REBOOT_MAGIC1 ||
+	    (magic2 != LINUX_REBOOT_MAGIC2 &&
+	                magic2 != LINUX_REBOOT_MAGIC2A &&
+			magic2 != LINUX_REBOOT_MAGIC2B &&
+	                magic2 != LINUX_REBOOT_MAGIC2C))
+		return -EINVAL;
+
+	/*
+	 * If pid namespaces are enabled and the current task is in a child
+	 * pid_namespace, the command is handled by reboot_pid_ns() which will
+	 * call do_exit().
+	 */
+	ret = reboot_pid_ns(pid_ns, cmd);
+	if (ret)
+		return ret;
+
+	/* Instead of trying to make the power_off code look like
+	 * halt when pm_power_off is not set do it the easy way.
+	 */
+	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
+		cmd = LINUX_REBOOT_CMD_HALT;
+
+	mutex_lock(&reboot_mutex);
+	switch (cmd) {
+	case LINUX_REBOOT_CMD_RESTART:
+		kernel_restart(NULL);
+		break;
+
+	case LINUX_REBOOT_CMD_CAD_ON:
+		C_A_D = 1;
+		break;
+
+	case LINUX_REBOOT_CMD_CAD_OFF:
+		C_A_D = 0;
+		break;
+
+	case LINUX_REBOOT_CMD_HALT:
+		kernel_halt();
+		do_exit(0);
+		panic("cannot halt");
+
+	case LINUX_REBOOT_CMD_POWER_OFF:
+		kernel_power_off();
+		do_exit(0);
+		break;
+
+	case LINUX_REBOOT_CMD_RESTART2:
+		if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
+			ret = -EFAULT;
+			break;
+		}
+		buffer[sizeof(buffer) - 1] = '\0';
+
+		kernel_restart(buffer);
+		break;
+
+#ifdef CONFIG_KEXEC
+	case LINUX_REBOOT_CMD_KEXEC:
+		ret = kernel_kexec();
+		break;
+#endif
+
+#ifdef CONFIG_HIBERNATION
+	case LINUX_REBOOT_CMD_SW_SUSPEND:
+		ret = hibernate();
+		break;
+#endif
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&reboot_mutex);
+	return ret;
+}
+
+static void deferred_cad(struct work_struct *dummy)
+{
+	kernel_restart(NULL);
+}
+
+/*
+ * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
+ * As it's called within an interrupt, it may NOT sync: the only choice
+ * is whether to reboot at once, or just ignore the ctrl-alt-del.
+ */
+void ctrl_alt_del(void)
+{
+	static DECLARE_WORK(cad_work, deferred_cad);
+
+	if (C_A_D)
+		schedule_work(&cad_work);
+	else
+		kill_cad_pid(SIGINT, 1);
+}
+
+char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
+
+static int __orderly_poweroff(bool force)
+{
+	char **argv;
+	static char *envp[] = {
+		"HOME=/",
+		"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
+		NULL
+	};
+	int ret;
+
+	argv = argv_split(GFP_KERNEL, poweroff_cmd, NULL);
+	if (argv) {
+		ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+		argv_free(argv);
+	} else {
+		printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
+					 __func__, poweroff_cmd);
+		ret = -ENOMEM;
+	}
+
+	if (ret && force) {
+		printk(KERN_WARNING "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
+		 * emergency shutdown?
+		 */
+		emergency_sync();
+		kernel_power_off();
+	}
+
+	return ret;
+}
+
+static bool poweroff_force;
+
+static void poweroff_work_func(struct work_struct *work)
+{
+	__orderly_poweroff(poweroff_force);
+}
+
+static DECLARE_WORK(poweroff_work, poweroff_work_func);
+
+/**
+ * orderly_poweroff - Trigger an orderly system poweroff
+ * @force: force poweroff if command execution fails
+ *
+ * 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)
+{
+	if (force) /* do not override the pending "true" */
+		poweroff_force = true;
+	schedule_work(&poweroff_work);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(orderly_poweroff);