[linux-2.6-block.git] / kernel / reboot.c

/*
 *  linux/kernel/reboot.c
 *
 *  Copyright (C) 2013  Linus Torvalds
 */

#define pr_fmt(fmt)	"reboot: " fmt

#include <linux/ctype.h>
#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 defined(CONFIG_ARM) || defined(CONFIG_UNICORE32)
#define DEFAULT_REBOOT_MODE		= REBOOT_HARD
#else
#define DEFAULT_REBOOT_MODE
#endif
enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;

/*
 * This variable is used privately to keep track of whether or not
 * reboot_type is still set to its default value (i.e., reboot= hasn't
 * been set on the command line).  This is needed so that we can
 * suppress DMI scanning for reboot quirks.  Without it, it's
 * impossible to override a faulty reboot quirk without recompiling.
 */
int reboot_default = 1;
int reboot_cpu;
enum reboot_type reboot_type = BOOT_ACPI;
int reboot_force;

/*
 * If set, this is used for preparing the system to power off.
 */

void (*pm_power_off_prepare)(void);
EXPORT_SYMBOL_GPL(pm_power_off_prepare);

/**
 *	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 devm_unregister_reboot_notifier(struct device *dev, void *res)
{
	WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
}

int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
{
	struct notifier_block **rcnb;
	int ret;

	rcnb = devres_alloc(devm_unregister_reboot_notifier,
			    sizeof(*rcnb), GFP_KERNEL);
	if (!rcnb)
		return -ENOMEM;

	ret = register_reboot_notifier(nb);
	if (!ret) {
		*rcnb = nb;
		devres_add(dev, rcnb);
	} else {
		devres_free(rcnb);
	}

	return ret;
}
EXPORT_SYMBOL(devm_register_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 */
	int cpu = reboot_cpu;

	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)
		pr_emerg("Restarting system\n");
	else
		pr_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();
	pr_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();
	pr_emerg("Power down\n");
	kmsg_dump(KMSG_DUMP_POWEROFF);
	machine_power_off();
}
EXPORT_SYMBOL_GPL(kernel_power_off);

DEFINE_MUTEX(system_transition_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(&system_transition_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:
		ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
		if (ret < 0) {
			ret = -EFAULT;
			break;
		}
		buffer[sizeof(buffer) - 1] = '\0';

		kernel_restart(buffer);
		break;

#ifdef CONFIG_KEXEC_CORE
	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(&system_transition_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 const char reboot_cmd[] = "/sbin/reboot";

static int run_cmd(const char *cmd)
{
	char **argv;
	static char *envp[] = {
		"HOME=/",
		"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
		NULL
	};
	int ret;
	argv = argv_split(GFP_KERNEL, cmd, NULL);
	if (argv) {
		ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
		argv_free(argv);
	} else {
		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
		 * 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.
 */
void orderly_poweroff(bool force)
{
	if (force) /* do not override the pending "true" */
		poweroff_force = true;
	schedule_work(&poweroff_work);
}
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 (;;) {
		/*
		 * Having anything passed on the command line via
		 * reboot= will cause us to disable DMI checking
		 * below.
		 */
		reboot_default = 0;

		switch (*str) {
		case 'w':
			reboot_mode = REBOOT_WARM;
			break;

		case 'c':
			reboot_mode = REBOOT_COLD;
			break;

		case 'h':
			reboot_mode = REBOOT_HARD;
			break;

		case 's':
		{
			int rc;

			if (isdigit(*(str+1))) {
				rc = kstrtoint(str+1, 0, &reboot_cpu);
				if (rc)
					return rc;
			} else if (str[1] == 'm' && str[2] == 'p' &&
				   isdigit(*(str+3))) {
				rc = kstrtoint(str+3, 0, &reboot_cpu);
				if (rc)
					return rc;
			} else
				reboot_mode = REBOOT_SOFT;
			break;
		}
		case 'g':
			reboot_mode = REBOOT_GPIO;
			break;

		case 'b':
		case 'a':
		case 'k':
		case 't':
		case 'e':
		case 'p':
			reboot_type = *str;
			break;

		case 'f':
			reboot_force = 1;
			break;
		}

		str = strchr(str, ',');
		if (str)
			str++;
		else
			break;
	}
	return 1;
}
__setup("reboot=", reboot_setup);
Commit	Line	Data
15d94b82 RH	1	/*
	2	* linux/kernel/reboot.c
	3	*
	4	* Copyright (C) 2013 Linus Torvalds
	5	*/
	6
972ee83d RH	7	#define pr_fmt(fmt) "reboot: " fmt
972ee83d RH	8
1b3a5d02	9	#include <linux/ctype.h>
15d94b82 RH	10	#include <linux/export.h>
	11	#include <linux/kexec.h>
	12	#include <linux/kmod.h>
	13	#include <linux/kmsg_dump.h>
	14	#include <linux/reboot.h>
	15	#include <linux/suspend.h>
	16	#include <linux/syscalls.h>
	17	#include <linux/syscore_ops.h>
	18	#include <linux/uaccess.h>
	19
	20	/*
	21	* this indicates whether you can reboot with ctrl-alt-del: the default is yes
	22	*/
	23
	24	int C_A_D = 1;
	25	struct pid *cad_pid;
	26	EXPORT_SYMBOL(cad_pid);
	27
1b3a5d02 RH	28	#if defined(CONFIG_ARM) \|\| defined(CONFIG_UNICORE32)
	29	#define DEFAULT_REBOOT_MODE = REBOOT_HARD
	30	#else
	31	#define DEFAULT_REBOOT_MODE
	32	#endif
	33	enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
	34
e2f0b88e CL	35	/*
	36	* This variable is used privately to keep track of whether or not
	37	* reboot_type is still set to its default value (i.e., reboot= hasn't
	38	* been set on the command line). This is needed so that we can
	39	* suppress DMI scanning for reboot quirks. Without it, it's
	40	* impossible to override a faulty reboot quirk without recompiling.
	41	*/
	42	int reboot_default = 1;
1b3a5d02 RH	43	int reboot_cpu;
	44	enum reboot_type reboot_type = BOOT_ACPI;
	45	int reboot_force;
	46
15d94b82 RH	47	/*
	48	* If set, this is used for preparing the system to power off.
	49	*/
	50
	51	void (*pm_power_off_prepare)(void);
74f008f2	52	EXPORT_SYMBOL_GPL(pm_power_off_prepare);
15d94b82 RH	53
	54	/**
	55	* emergency_restart - reboot the system
	56	*
	57	* Without shutting down any hardware or taking any locks
	58	* reboot the system. This is called when we know we are in
	59	* trouble so this is our best effort to reboot. This is
	60	* safe to call in interrupt context.
	61	*/
	62	void emergency_restart(void)
	63	{
	64	kmsg_dump(KMSG_DUMP_EMERG);
	65	machine_emergency_restart();
	66	}
	67	EXPORT_SYMBOL_GPL(emergency_restart);
	68
	69	void kernel_restart_prepare(char *cmd)
	70	{
	71	blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
	72	system_state = SYSTEM_RESTART;
	73	usermodehelper_disable();
	74	device_shutdown();
	75	}
	76
	77	/**
	78	* register_reboot_notifier - Register function to be called at reboot time
	79	* @nb: Info about notifier function to be called
	80	*
	81	* Registers a function with the list of functions
	82	* to be called at reboot time.
	83	*
	84	* Currently always returns zero, as blocking_notifier_chain_register()
	85	* always returns zero.
	86	*/
	87	int register_reboot_notifier(struct notifier_block *nb)
	88	{
	89	return blocking_notifier_chain_register(&reboot_notifier_list, nb);
	90	}
	91	EXPORT_SYMBOL(register_reboot_notifier);
	92
	93	/**
	94	* unregister_reboot_notifier - Unregister previously registered reboot notifier
	95	* @nb: Hook to be unregistered
	96	*
	97	* Unregisters a previously registered reboot
	98	* notifier function.
	99	*
	100	* Returns zero on success, or %-ENOENT on failure.
	101	*/
	102	int unregister_reboot_notifier(struct notifier_block *nb)
	103	{
	104	return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
	105	}
	106	EXPORT_SYMBOL(unregister_reboot_notifier);
	107
2d8364ba AS	108	static void devm_unregister_reboot_notifier(struct device dev, void res)
	109	{
	110	WARN_ON(unregister_reboot_notifier((struct notifier_block *)res));
	111	}
	112
	113	int devm_register_reboot_notifier(struct device dev, struct notifier_block nb)
	114	{
	115	struct notifier_block **rcnb;
	116	int ret;
	117
	118	rcnb = devres_alloc(devm_unregister_reboot_notifier,
	119	sizeof(*rcnb), GFP_KERNEL);
	120	if (!rcnb)
	121	return -ENOMEM;
	122
	123	ret = register_reboot_notifier(nb);
	124	if (!ret) {
	125	*rcnb = nb;
	126	devres_add(dev, rcnb);
	127	} else {
	128	devres_free(rcnb);
	129	}
	130
	131	return ret;
	132	}
	133	EXPORT_SYMBOL(devm_register_reboot_notifier);
	134
b63adb97 GR	135	/*
	136	* Notifier list for kernel code which wants to be called
	137	* to restart the system.
	138	*/
	139	static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
	140
	141	/**
	142	* register_restart_handler - Register function to be called to reset
	143	* the system
	144	* @nb: Info about handler function to be called
	145	* @nb->priority: Handler priority. Handlers should follow the
	146	* following guidelines for setting priorities.
	147	* 0: Restart handler of last resort,
	148	* with limited restart capabilities
	149	* 128: Default restart handler; use if no other
	150	* restart handler is expected to be available,
	151	* and/or if restart functionality is
	152	* sufficient to restart the entire system
	153	* 255: Highest priority restart handler, will
	154	* preempt all other restart handlers
	155	*
	156	* Registers a function with code to be called to restart the
	157	* system.
	158	*
	159	* Registered functions will be called from machine_restart as last
	160	* step of the restart sequence (if the architecture specific
	161	* machine_restart function calls do_kernel_restart - see below
	162	* for details).
	163	* Registered functions are expected to restart the system immediately.
	164	* If more than one function is registered, the restart handler priority
	165	* selects which function will be called first.
	166	*
	167	* Restart handlers are expected to be registered from non-architecture
	168	* code, typically from drivers. A typical use case would be a system
	169	* where restart functionality is provided through a watchdog. Multiple
	170	* restart handlers may exist; for example, one restart handler might
	171	* restart the entire system, while another only restarts the CPU.
	172	* In such cases, the restart handler which only restarts part of the
	173	* hardware is expected to register with low priority to ensure that
	174	* it only runs if no other means to restart the system is available.
	175	*
	176	* Currently always returns zero, as atomic_notifier_chain_register()
	177	* always returns zero.
	178	*/
	179	int register_restart_handler(struct notifier_block *nb)
	180	{
	181	return atomic_notifier_chain_register(&restart_handler_list, nb);
	182	}
	183	EXPORT_SYMBOL(register_restart_handler);
	184
	185	/**
	186	* unregister_restart_handler - Unregister previously registered
	187	* restart handler
	188	* @nb: Hook to be unregistered
	189	*
	190	* Unregisters a previously registered restart handler function.
	191	*
	192	* Returns zero on success, or %-ENOENT on failure.
	193	*/
	194	int unregister_restart_handler(struct notifier_block *nb)
	195	{
	196	return atomic_notifier_chain_unregister(&restart_handler_list, nb);
	197	}
	198	EXPORT_SYMBOL(unregister_restart_handler);
199
200	/**
201	* do_kernel_restart - Execute kernel restart handler call chain
202	*
203	* Calls functions registered with register_restart_handler.
204	*
205	* Expected to be called from machine_restart as last step of the restart
206	* sequence.
207	*
208	* Restarts the system immediately if a restart handler function has been
209	* registered. Otherwise does nothing.
210	*/
211	void do_kernel_restart(char *cmd)
212	{
213	atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
214	}
215
c97102ba	216	void migrate_to_reboot_cpu(void)
15d94b82 RH	217	{
15d94b82 RH	218	/* The boot cpu is always logical cpu 0 */
1b3a5d02	219	int cpu = reboot_cpu;
15d94b82 RH	220
	221	cpu_hotplug_disable();
	222
	223	/* Make certain the cpu I'm about to reboot on is online */
	224	if (!cpu_online(cpu))
	225	cpu = cpumask_first(cpu_online_mask);
	226
	227	/* Prevent races with other tasks migrating this task */
	228	current->flags \|= PF_NO_SETAFFINITY;
	229
	230	/* Make certain I only run on the appropriate processor */
	231	set_cpus_allowed_ptr(current, cpumask_of(cpu));
	232	}
	233
	234	/**
	235	* kernel_restart - reboot the system
	236	* @cmd: pointer to buffer containing command to execute for restart
	237	* or %NULL
	238	*
	239	* Shutdown everything and perform a clean reboot.
	240	* This is not safe to call in interrupt context.
	241	*/
	242	void kernel_restart(char *cmd)
	243	{
	244	kernel_restart_prepare(cmd);
	245	migrate_to_reboot_cpu();
	246	syscore_shutdown();
	247	if (!cmd)
972ee83d	248	pr_emerg("Restarting system\n");
15d94b82	249	else
972ee83d	250	pr_emerg("Restarting system with command '%s'\n", cmd);
15d94b82 RH	251	kmsg_dump(KMSG_DUMP_RESTART);
	252	machine_restart(cmd);
	253	}
	254	EXPORT_SYMBOL_GPL(kernel_restart);
	255
	256	static void kernel_shutdown_prepare(enum system_states state)
	257	{
	258	blocking_notifier_call_chain(&reboot_notifier_list,
972ee83d	259	(state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
15d94b82 RH	260	system_state = state;
	261	usermodehelper_disable();
	262	device_shutdown();
	263	}
	264	/**
	265	* kernel_halt - halt the system
	266	*
	267	* Shutdown everything and perform a clean system halt.
	268	*/
	269	void kernel_halt(void)
	270	{
	271	kernel_shutdown_prepare(SYSTEM_HALT);
	272	migrate_to_reboot_cpu();
	273	syscore_shutdown();
972ee83d	274	pr_emerg("System halted\n");
15d94b82 RH	275	kmsg_dump(KMSG_DUMP_HALT);
	276	machine_halt();
	277	}
15d94b82 RH	278	EXPORT_SYMBOL_GPL(kernel_halt);
	279
	280	/**
	281	* kernel_power_off - power_off the system
	282	*
	283	* Shutdown everything and perform a clean system power_off.
	284	*/
	285	void kernel_power_off(void)
	286	{
	287	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
	288	if (pm_power_off_prepare)
	289	pm_power_off_prepare();
	290	migrate_to_reboot_cpu();
	291	syscore_shutdown();
972ee83d	292	pr_emerg("Power down\n");
15d94b82 RH	293	kmsg_dump(KMSG_DUMP_POWEROFF);
	294	machine_power_off();
	295	}
	296	EXPORT_SYMBOL_GPL(kernel_power_off);
	297
55f2503c	298	DEFINE_MUTEX(system_transition_mutex);
15d94b82 RH	299
	300	/*
	301	* Reboot system call: for obvious reasons only root may call it,
	302	* and even root needs to set up some magic numbers in the registers
	303	* so that some mistake won't make this reboot the whole machine.
	304	* You can also set the meaning of the ctrl-alt-del-key here.
	305	*
	306	* reboot doesn't sync: do that yourself before calling this.
	307	*/
	308	SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
	309	void __user *, arg)
	310	{
	311	struct pid_namespace *pid_ns = task_active_pid_ns(current);
	312	char buffer[256];
	313	int ret = 0;
	314
	315	/* We only trust the superuser with rebooting the system. */
	316	if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
	317	return -EPERM;
	318
	319	/* For safety, we require "magic" arguments. */
	320	if (magic1 != LINUX_REBOOT_MAGIC1 \|\|
972ee83d RH	321	(magic2 != LINUX_REBOOT_MAGIC2 &&
972ee83d RH	322	magic2 != LINUX_REBOOT_MAGIC2A &&
15d94b82	323	magic2 != LINUX_REBOOT_MAGIC2B &&
972ee83d	324	magic2 != LINUX_REBOOT_MAGIC2C))
15d94b82 RH	325	return -EINVAL;
	326
	327	/*
	328	* If pid namespaces are enabled and the current task is in a child
	329	* pid_namespace, the command is handled by reboot_pid_ns() which will
	330	* call do_exit().
	331	*/
	332	ret = reboot_pid_ns(pid_ns, cmd);
	333	if (ret)
	334	return ret;
	335
	336	/* Instead of trying to make the power_off code look like
	337	* halt when pm_power_off is not set do it the easy way.
	338	*/
	339	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
	340	cmd = LINUX_REBOOT_CMD_HALT;
	341
55f2503c	342	mutex_lock(&system_transition_mutex);
15d94b82 RH	343	switch (cmd) {
	344	case LINUX_REBOOT_CMD_RESTART:
	345	kernel_restart(NULL);
	346	break;
	347
	348	case LINUX_REBOOT_CMD_CAD_ON:
	349	C_A_D = 1;
	350	break;
	351
	352	case LINUX_REBOOT_CMD_CAD_OFF:
	353	C_A_D = 0;
	354	break;
	355
	356	case LINUX_REBOOT_CMD_HALT:
	357	kernel_halt();
	358	do_exit(0);
	359	panic("cannot halt");
	360
	361	case LINUX_REBOOT_CMD_POWER_OFF:
	362	kernel_power_off();
	363	do_exit(0);
	364	break;
	365
	366	case LINUX_REBOOT_CMD_RESTART2:
972ee83d RH	367	ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
972ee83d RH	368	if (ret < 0) {
15d94b82 RH	369	ret = -EFAULT;
	370	break;
	371	}
	372	buffer[sizeof(buffer) - 1] = '\0';
	373
	374	kernel_restart(buffer);
	375	break;
	376
2965faa5	377	#ifdef CONFIG_KEXEC_CORE
15d94b82 RH	378	case LINUX_REBOOT_CMD_KEXEC:
	379	ret = kernel_kexec();
	380	break;
	381	#endif
	382
	383	#ifdef CONFIG_HIBERNATION
	384	case LINUX_REBOOT_CMD_SW_SUSPEND:
	385	ret = hibernate();
	386	break;
	387	#endif
	388
	389	default:
	390	ret = -EINVAL;
	391	break;
	392	}
55f2503c	393	mutex_unlock(&system_transition_mutex);
15d94b82 RH	394	return ret;
	395	}
	396
	397	static void deferred_cad(struct work_struct *dummy)
	398	{
	399	kernel_restart(NULL);
	400	}
	401
	402	/*
	403	* This function gets called by ctrl-alt-del - ie the keyboard interrupt.
	404	* As it's called within an interrupt, it may NOT sync: the only choice
	405	* is whether to reboot at once, or just ignore the ctrl-alt-del.
	406	*/
	407	void ctrl_alt_del(void)
	408	{
	409	static DECLARE_WORK(cad_work, deferred_cad);
	410
	411	if (C_A_D)
	412	schedule_work(&cad_work);
	413	else
	414	kill_cad_pid(SIGINT, 1);
	415	}
	416
	417	char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
7a54f46b	418	static const char reboot_cmd[] = "/sbin/reboot";
15d94b82	419
7a54f46b	420	static int run_cmd(const char *cmd)
15d94b82 RH	421	{
	422	char **argv;
	423	static char *envp[] = {
	424	"HOME=/",
	425	"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
	426	NULL
	427	};
	428	int ret;
7a54f46b	429	argv = argv_split(GFP_KERNEL, cmd, NULL);
15d94b82 RH	430	if (argv) {
	431	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
	432	argv_free(argv);
	433	} else {
15d94b82 RH	434	ret = -ENOMEM;
	435	}
	436
7a54f46b JS	437	return ret;
	438	}
	439
	440	static int __orderly_reboot(void)
	441	{
	442	int ret;
	443
	444	ret = run_cmd(reboot_cmd);
	445
	446	if (ret) {
	447	pr_warn("Failed to start orderly reboot: forcing the issue\n");
	448	emergency_sync();
	449	kernel_restart(NULL);
	450	}
	451
	452	return ret;
	453	}
	454
	455	static int __orderly_poweroff(bool force)
	456	{
	457	int ret;
	458
	459	ret = run_cmd(poweroff_cmd);
	460
15d94b82	461	if (ret && force) {
972ee83d	462	pr_warn("Failed to start orderly shutdown: forcing the issue\n");
7a54f46b	463
15d94b82 RH	464	/*
	465	* I guess this should try to kick off some daemon to sync and
	466	* poweroff asap. Or not even bother syncing if we're doing an
	467	* emergency shutdown?
	468	*/
	469	emergency_sync();
	470	kernel_power_off();
	471	}
	472
	473	return ret;
	474	}
	475
	476	static bool poweroff_force;
	477
	478	static void poweroff_work_func(struct work_struct *work)
	479	{
	480	__orderly_poweroff(poweroff_force);
	481	}
	482
	483	static DECLARE_WORK(poweroff_work, poweroff_work_func);
	484
	485	/**
	486	* orderly_poweroff - Trigger an orderly system poweroff
	487	* @force: force poweroff if command execution fails
	488	*
	489	* This may be called from any context to trigger a system shutdown.
	490	* If the orderly shutdown fails, it will force an immediate shutdown.
	491	*/
7a54f46b	492	void orderly_poweroff(bool force)
15d94b82 RH	493	{
	494	if (force) /* do not override the pending "true" */
	495	poweroff_force = true;
	496	schedule_work(&poweroff_work);
15d94b82 RH	497	}
15d94b82 RH	498	EXPORT_SYMBOL_GPL(orderly_poweroff);
1b3a5d02	499
7a54f46b JS	500	static void reboot_work_func(struct work_struct *work)
	501	{
	502	__orderly_reboot();
	503	}
	504
	505	static DECLARE_WORK(reboot_work, reboot_work_func);
	506
	507	/**
	508	* orderly_reboot - Trigger an orderly system reboot
	509	*
	510	* This may be called from any context to trigger a system reboot.
	511	* If the orderly reboot fails, it will force an immediate reboot.
	512	*/
	513	void orderly_reboot(void)
	514	{
	515	schedule_work(&reboot_work);
	516	}
	517	EXPORT_SYMBOL_GPL(orderly_reboot);
	518
1b3a5d02 RH	519	static int __init reboot_setup(char *str)
	520	{
	521	for (;;) {
	522	/*
	523	* Having anything passed on the command line via
	524	* reboot= will cause us to disable DMI checking
	525	* below.
	526	*/
	527	reboot_default = 0;
	528
	529	switch (*str) {
	530	case 'w':
	531	reboot_mode = REBOOT_WARM;
	532	break;
	533
	534	case 'c':
	535	reboot_mode = REBOOT_COLD;
	536	break;
	537
	538	case 'h':
	539	reboot_mode = REBOOT_HARD;
	540	break;
	541
	542	case 's':
616feab7 FF	543	{
	544	int rc;
	545
	546	if (isdigit(*(str+1))) {
	547	rc = kstrtoint(str+1, 0, &reboot_cpu);
	548	if (rc)
	549	return rc;
	550	} else if (str[1] == 'm' && str[2] == 'p' &&
	551	isdigit(*(str+3))) {
	552	rc = kstrtoint(str+3, 0, &reboot_cpu);
	553	if (rc)
	554	return rc;
	555	} else
1b3a5d02 RH	556	reboot_mode = REBOOT_SOFT;
1b3a5d02 RH	557	break;
616feab7	558	}
1b3a5d02 RH	559	case 'g':
	560	reboot_mode = REBOOT_GPIO;
	561	break;
	562
	563	case 'b':
	564	case 'a':
	565	case 'k':
	566	case 't':
	567	case 'e':
	568	case 'p':
	569	reboot_type = *str;
	570	break;
	571
	572	case 'f':
	573	reboot_force = 1;
	574	break;
	575	}
	576
	577	str = strchr(str, ',');
	578	if (str)
	579	str++;
	580	else
	581	break;
	582	}
	583	return 1;
	584	}
	585	__setup("reboot=", reboot_setup);