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224 lines
6.2 KiB
224 lines
6.2 KiB
// 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 <[email protected]>, |
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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 <[email protected]> |
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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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