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>

1 files changed, 346 insertions, 0 deletions

diff --git a/kernel/reboot.c b/kernel/reboot.c
new file mode 100644
index 000000000000..37d2636a65c2
--- /dev/null
+++ b/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);