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36a8947c6b
Add module parameters 'soft_reboot_cmd' and 'soft_active_on_boot' for customizing softdog configuration; config reboot command by assigning soft_reboot_cmd, and set soft_active_on_boot to start up softdog timer at module initialization stage. Signed-off-by: Woody Lin <woodylin@google.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20200708083218.3157213-1-woodylin@google.com Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
225 lines
6.2 KiB
C
225 lines
6.2 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* SoftDog: A Software Watchdog Device
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*
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* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
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* All Rights Reserved.
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*
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* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
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* warranty for any of this software. This material is provided
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* "AS-IS" and at no charge.
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*
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* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
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*
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* Software only watchdog driver. Unlike its big brother the WDT501P
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* driver this won't always recover a failed machine.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/hrtimer.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/kthread.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/reboot.h>
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#include <linux/types.h>
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#include <linux/watchdog.h>
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#include <linux/workqueue.h>
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#define TIMER_MARGIN 60 /* Default is 60 seconds */
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static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
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module_param(soft_margin, uint, 0);
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MODULE_PARM_DESC(soft_margin,
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"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
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__MODULE_STRING(TIMER_MARGIN) ")");
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout,
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"Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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static int soft_noboot;
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module_param(soft_noboot, int, 0);
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MODULE_PARM_DESC(soft_noboot,
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"Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
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static int soft_panic;
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module_param(soft_panic, int, 0);
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MODULE_PARM_DESC(soft_panic,
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"Softdog action, set to 1 to panic, 0 to reboot (default=0)");
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static char *soft_reboot_cmd;
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module_param(soft_reboot_cmd, charp, 0000);
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MODULE_PARM_DESC(soft_reboot_cmd,
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"Set reboot command. Emergency reboot takes place if unset");
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static bool soft_active_on_boot;
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module_param(soft_active_on_boot, bool, 0000);
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MODULE_PARM_DESC(soft_active_on_boot,
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"Set to true to active Softdog on boot (default=false)");
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static struct hrtimer softdog_ticktock;
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static struct hrtimer softdog_preticktock;
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static int reboot_kthread_fn(void *data)
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{
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kernel_restart(soft_reboot_cmd);
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return -EPERM; /* Should not reach here */
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}
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static void reboot_work_fn(struct work_struct *unused)
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{
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kthread_run(reboot_kthread_fn, NULL, "softdog_reboot");
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}
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static enum hrtimer_restart softdog_fire(struct hrtimer *timer)
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{
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static bool soft_reboot_fired;
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module_put(THIS_MODULE);
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if (soft_noboot) {
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pr_crit("Triggered - Reboot ignored\n");
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} else if (soft_panic) {
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pr_crit("Initiating panic\n");
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panic("Software Watchdog Timer expired");
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} else {
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pr_crit("Initiating system reboot\n");
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if (!soft_reboot_fired && soft_reboot_cmd != NULL) {
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static DECLARE_WORK(reboot_work, reboot_work_fn);
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/*
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* The 'kernel_restart' is a 'might-sleep' operation.
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* Also, executing it in system-wide workqueues blocks
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* any driver from using the same workqueue in its
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* shutdown callback function. Thus, we should execute
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* the 'kernel_restart' in a standalone kernel thread.
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* But since starting a kernel thread is also a
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* 'might-sleep' operation, so the 'reboot_work' is
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* required as a launcher of the kernel thread.
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*
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* After request the reboot, restart the timer to
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* schedule an 'emergency_restart' reboot after
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* 'TIMER_MARGIN' seconds. It's because if the softdog
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* hangs, it might be because of scheduling issues. And
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* if that is the case, both 'schedule_work' and
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* 'kernel_restart' may possibly be malfunctional at the
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* same time.
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*/
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soft_reboot_fired = true;
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schedule_work(&reboot_work);
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hrtimer_add_expires_ns(timer,
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(u64)TIMER_MARGIN * NSEC_PER_SEC);
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return HRTIMER_RESTART;
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}
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emergency_restart();
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pr_crit("Reboot didn't ?????\n");
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}
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return HRTIMER_NORESTART;
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}
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static struct watchdog_device softdog_dev;
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static enum hrtimer_restart softdog_pretimeout(struct hrtimer *timer)
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{
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watchdog_notify_pretimeout(&softdog_dev);
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return HRTIMER_NORESTART;
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}
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static int softdog_ping(struct watchdog_device *w)
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{
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if (!hrtimer_active(&softdog_ticktock))
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__module_get(THIS_MODULE);
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hrtimer_start(&softdog_ticktock, ktime_set(w->timeout, 0),
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HRTIMER_MODE_REL);
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if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) {
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if (w->pretimeout)
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hrtimer_start(&softdog_preticktock,
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ktime_set(w->timeout - w->pretimeout, 0),
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HRTIMER_MODE_REL);
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else
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hrtimer_cancel(&softdog_preticktock);
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}
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return 0;
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}
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static int softdog_stop(struct watchdog_device *w)
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{
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if (hrtimer_cancel(&softdog_ticktock))
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module_put(THIS_MODULE);
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if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT))
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hrtimer_cancel(&softdog_preticktock);
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return 0;
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}
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static struct watchdog_info softdog_info = {
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.identity = "Software Watchdog",
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.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
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};
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static const struct watchdog_ops softdog_ops = {
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.owner = THIS_MODULE,
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.start = softdog_ping,
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.stop = softdog_stop,
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};
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static struct watchdog_device softdog_dev = {
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.info = &softdog_info,
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.ops = &softdog_ops,
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.min_timeout = 1,
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.max_timeout = 65535,
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.timeout = TIMER_MARGIN,
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};
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static int __init softdog_init(void)
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{
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int ret;
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watchdog_init_timeout(&softdog_dev, soft_margin, NULL);
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watchdog_set_nowayout(&softdog_dev, nowayout);
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watchdog_stop_on_reboot(&softdog_dev);
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hrtimer_init(&softdog_ticktock, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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softdog_ticktock.function = softdog_fire;
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if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) {
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softdog_info.options |= WDIOF_PRETIMEOUT;
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hrtimer_init(&softdog_preticktock, CLOCK_MONOTONIC,
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HRTIMER_MODE_REL);
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softdog_preticktock.function = softdog_pretimeout;
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}
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if (soft_active_on_boot)
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softdog_ping(&softdog_dev);
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ret = watchdog_register_device(&softdog_dev);
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if (ret)
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return ret;
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pr_info("initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
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soft_noboot, softdog_dev.timeout, soft_panic, nowayout);
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pr_info(" soft_reboot_cmd=%s soft_active_on_boot=%d\n",
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soft_reboot_cmd ?: "<not set>", soft_active_on_boot);
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return 0;
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}
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module_init(softdog_init);
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static void __exit softdog_exit(void)
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{
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watchdog_unregister_device(&softdog_dev);
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}
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module_exit(softdog_exit);
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MODULE_AUTHOR("Alan Cox");
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MODULE_DESCRIPTION("Software Watchdog Device Driver");
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MODULE_LICENSE("GPL");
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