[PATCH -v7 04/11] Move shutdown/reboot related functions to kernel/reboot.c

Robin Holt
2013-05-01T17:09:04Z

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>
To: Andrew Morton <akpm@linux-foundation.org>
To: H. Peter Anvin <hpa@zytor.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: Arm Mailing List <linux-arm-kernel@lists.infradead.org>

---

Changes since -v6:
- Add include of linux/uaccess.h to allow building on arm.
---
kernel/Makefile | 2 +-
kernel/reboot.c | 347 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/sys.c | 331 -----------------------------------------------------
3 files changed, 348 insertions(+), 332 deletions(-)
create mode 100644 kernel/reboot.c

diff --git a/kernel/Makefile b/kernel/Makefile
index d1574d4..e7e9f54 100644
--- a/kernel/Makefile
+++ b/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
diff --git a/kernel/reboot.c b/kernel/reboot.c
new file mode 100644
index 0000000..169f0b6
--- /dev/null
+++ b/kernel/reboot.c
@@ -0,0 +1,347 @@
+/*
+ * 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 reboot_cpu = 0;
+
+ cpu_hotplug_disable();
+
+ /* Make certain the cpu I'm about to reboot on is online */
+ if (!cpu_online(reboot_cpu))
+ reboot_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(reboot_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);
diff --git a/kernel/sys.c b/kernel/sys.c
index 79b5f61..202ec9d 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -116,20 +116,6 @@ EXPORT_SYMBOL(fs_overflowuid);
EXPORT_SYMBOL(fs_overflowgid);

/*
- * 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);
-
-/*
* Returns true if current's euid is same as p's uid or euid,
* or has CAP_SYS_NICE to p's user_ns.
*
@@ -308,261 +294,6 @@ out_unlock:
return retval;
}

-/**
- * 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 reboot_cpu = 0;
-
- cpu_hotplug_disable();
-
- /* Make certain the cpu I'm about to reboot on is online */
- if (!cpu_online(reboot_cpu))
- reboot_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(reboot_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);
-}
-
/*
* Unprivileged users may change the real gid to the effective gid
* or vice versa. (BSD-style)
@@ -2262,68 +1993,6 @@ SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
return err ? -EFAULT : 0;
}

-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);
-
/**
* do_sysinfo - fill in sysinfo struct
* @info: pointer to buffer to fill
--
1.8.2.1