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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0+
 /*
  *  watchdog_dev.c
  *
  *  (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  *                      All Rights Reserved.
  *
  *  (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
  *
  *  (c) Copyright 2021 Hewlett Packard Enterprise Development LP.
  *
  *  This source code is part of the generic code that can be used
  *  by all the watchdog timer drivers.
  *
  *  This part of the generic code takes care of the following
  *  misc device: /dev/watchdog.
  *
  *  Based on source code of the following authors:
  *    Matt Domsch <Matt_Domsch@dell.com>,
  *    Rob Radez <rob@osinvestor.com>,
  *    Rusty Lynch <rusty@linux.co.intel.com>
  *    Satyam Sharma <satyam@infradead.org>
  *    Randy Dunlap <randy.dunlap@oracle.com>
  *
  *  Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
  *  admit liability nor provide warranty for any of this software.
  *  This material is provided "AS-IS" and at no charge.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/cdev.h>     /* For character device */
 #include <linux/errno.h>    /* For the -ENODEV/... values */
 #include <linux/fs.h>       /* For file operations */
 #include <linux/init.h>     /* For __init/__exit/... */
 #include <linux/hrtimer.h>  /* For hrtimers */
 #include <linux/kernel.h>   /* For printk/panic/... */
 #include <linux/kthread.h>  /* For kthread_work */
 #include <linux/miscdevice.h>   /* For handling misc devices */
 #include <linux/module.h>   /* For module stuff/... */
 #include <linux/mutex.h>    /* For mutexes */
 #include <linux/slab.h>     /* For memory functions */
 #include <linux/types.h>    /* For standard types (like size_t) */
 #include <linux/watchdog.h> /* For watchdog specific items */
 #include <linux/uaccess.h>  /* For copy_to_user/put_user/... */
 
 #include "watchdog_core.h"
 #include "watchdog_pretimeout.h"
 
 /* the dev_t structure to store the dynamically allocated watchdog devices */
 static dev_t watchdog_devt;
 /* Reference to watchdog device behind /dev/watchdog */
 static struct watchdog_core_data *old_wd_data;
 
 static struct kthread_worker *watchdog_kworker;
 
 static bool handle_boot_enabled =
     IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
 
 static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
 
 static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
 {
     return ktime_after(ktime_get(), data->open_deadline);
 }
 
 static void watchdog_set_open_deadline(struct watchdog_core_data *data)
 {
     data->open_deadline = open_timeout ?
         ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;
 }
 
 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
 {
     /* All variables in milli-seconds */
     unsigned int hm = wdd->max_hw_heartbeat_ms;
     unsigned int t = wdd->timeout * 1000;
 
     /*
      * A worker to generate heartbeat requests is needed if all of the
      * following conditions are true.
      * - Userspace activated the watchdog.
      * - The driver provided a value for the maximum hardware timeout, and
      *   thus is aware that the framework supports generating heartbeat
      *   requests.
      * - Userspace requests a longer timeout than the hardware can handle.
      *
      * Alternatively, if userspace has not opened the watchdog
      * device, we take care of feeding the watchdog if it is
      * running.
      */
     return (hm && watchdog_active(wdd) && t > hm) ||
         (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
 }
 
 static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
     unsigned int timeout_ms = wdd->timeout * 1000;
     ktime_t keepalive_interval;
     ktime_t last_heartbeat, latest_heartbeat;
     ktime_t virt_timeout;
     unsigned int hw_heartbeat_ms;
 
     if (watchdog_active(wdd))
         virt_timeout = ktime_add(wd_data->last_keepalive,
                      ms_to_ktime(timeout_ms));
     else
         virt_timeout = wd_data->open_deadline;
 
     hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
     keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
 
     /*
      * To ensure that the watchdog times out wdd->timeout seconds
      * after the most recent ping from userspace, the last
      * worker ping has to come in hw_heartbeat_ms before this timeout.
      */
     last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
     latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
     if (ktime_before(latest_heartbeat, keepalive_interval))
         return latest_heartbeat;
     return keepalive_interval;
 }
 
 static inline void watchdog_update_worker(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
 
     if (watchdog_need_worker(wdd)) {
         ktime_t t = watchdog_next_keepalive(wdd);
 
         if (t > 0)
             hrtimer_start(&wd_data->timer, t,
                       HRTIMER_MODE_REL_HARD);
     } else {
         hrtimer_cancel(&wd_data->timer);
     }
 }
 
 static int __watchdog_ping(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
     ktime_t earliest_keepalive, now;
     int err;
 
     earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
                        ms_to_ktime(wdd->min_hw_heartbeat_ms));
     now = ktime_get();
 
     if (ktime_after(earliest_keepalive, now)) {
         hrtimer_start(&wd_data->timer,
                   ktime_sub(earliest_keepalive, now),
                   HRTIMER_MODE_REL_HARD);
         return 0;
     }
 
     wd_data->last_hw_keepalive = now;
 
     if (wdd->ops->ping)
         err = wdd->ops->ping(wdd);  /* ping the watchdog */
     else
         err = wdd->ops->start(wdd); /* restart watchdog */
 
     if (err == 0)
         watchdog_hrtimer_pretimeout_start(wdd);
 
     watchdog_update_worker(wdd);
 
     return err;
 }
 
 /*
  * watchdog_ping - ping the watchdog
  * @wdd: The watchdog device to ping
  *
  * If the watchdog has no own ping operation then it needs to be
  * restarted via the start operation. This wrapper function does
  * exactly that.
  * We only ping when the watchdog device is running.
  * The caller must hold wd_data->lock.
  *
  * Return: 0 on success, error otherwise.
  */
 static int watchdog_ping(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
 
     if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
         return 0;
 
     set_bit(_WDOG_KEEPALIVE, &wd_data->status);
 
     wd_data->last_keepalive = ktime_get();
     return __watchdog_ping(wdd);
 }
 
 static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
 {
     struct watchdog_device *wdd = wd_data->wdd;
 
     if (!wdd)
         return false;
 
     if (watchdog_active(wdd))
         return true;
 
     return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);
 }
 
 static void watchdog_ping_work(struct kthread_work *work)
 {
     struct watchdog_core_data *wd_data;
 
     wd_data = container_of(work, struct watchdog_core_data, work);
 
     mutex_lock(&wd_data->lock);
     if (watchdog_worker_should_ping(wd_data))
         __watchdog_ping(wd_data->wdd);
     mutex_unlock(&wd_data->lock);
 }
 
 static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
 {
     struct watchdog_core_data *wd_data;
 
     wd_data = container_of(timer, struct watchdog_core_data, timer);
 
     kthread_queue_work(watchdog_kworker, &wd_data->work);
     return HRTIMER_NORESTART;
 }
 
 /*
  * watchdog_start - wrapper to start the watchdog
  * @wdd: The watchdog device to start
  *
  * Start the watchdog if it is not active and mark it active.
  * The caller must hold wd_data->lock.
  *
  * Return: 0 on success or a negative errno code for failure.
  */
 static int watchdog_start(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
     ktime_t started_at;
     int err;
 
     if (watchdog_active(wdd))
         return 0;
 
     set_bit(_WDOG_KEEPALIVE, &wd_data->status);
 
     started_at = ktime_get();
     if (watchdog_hw_running(wdd) && wdd->ops->ping) {
         err = __watchdog_ping(wdd);
         if (err == 0) {
             set_bit(WDOG_ACTIVE, &wdd->status);
             watchdog_hrtimer_pretimeout_start(wdd);
         }
     } else {
         err = wdd->ops->start(wdd);
         if (err == 0) {
             set_bit(WDOG_ACTIVE, &wdd->status);
             wd_data->last_keepalive = started_at;
             wd_data->last_hw_keepalive = started_at;
             watchdog_update_worker(wdd);
             watchdog_hrtimer_pretimeout_start(wdd);
         }
     }
 
     return err;
 }
 
 /*
  * watchdog_stop - wrapper to stop the watchdog
  * @wdd: The watchdog device to stop
  *
  * Stop the watchdog if it is still active and unmark it active.
  * If the 'nowayout' feature was set, the watchdog cannot be stopped.
  * The caller must hold wd_data->lock.
  *
  * Return: 0 on success or a negative errno code for failure.
  */
 static int watchdog_stop(struct watchdog_device *wdd)
 {
     int err = 0;
 
     if (!watchdog_active(wdd))
         return 0;
 
     if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
         pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
             wdd->id);
         return -EBUSY;
     }
 
     if (wdd->ops->stop) {
         clear_bit(WDOG_HW_RUNNING, &wdd->status);
         err = wdd->ops->stop(wdd);
     } else {
         set_bit(WDOG_HW_RUNNING, &wdd->status);
     }
 
     if (err == 0) {
         clear_bit(WDOG_ACTIVE, &wdd->status);
         watchdog_update_worker(wdd);
         watchdog_hrtimer_pretimeout_stop(wdd);
     }
 
     return err;
 }
 
 /*
  * watchdog_get_status - wrapper to get the watchdog status
  * @wdd: The watchdog device to get the status from
  *
  * Get the watchdog's status flags.
  * The caller must hold wd_data->lock.
  *
  * Return: watchdog's status flags.
  */
 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
     unsigned int status;
 
     if (wdd->ops->status)
         status = wdd->ops->status(wdd);
     else
         status = wdd->bootstatus & (WDIOF_CARDRESET |
                         WDIOF_OVERHEAT |
                         WDIOF_FANFAULT |
                         WDIOF_EXTERN1 |
                         WDIOF_EXTERN2 |
                         WDIOF_POWERUNDER |
                         WDIOF_POWEROVER);
 
     if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
         status |= WDIOF_MAGICCLOSE;
 
     if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
         status |= WDIOF_KEEPALIVEPING;
 
     if (IS_ENABLED(CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT))
         status |= WDIOF_PRETIMEOUT;
 
     return status;
 }
 
 /*
  * watchdog_set_timeout - set the watchdog timer timeout
  * @wdd:    The watchdog device to set the timeout for
  * @timeout:    Timeout to set in seconds
  *
  * The caller must hold wd_data->lock.
  *
  * Return: 0 if successful, error otherwise.
  */
 static int watchdog_set_timeout(struct watchdog_device *wdd,
                             unsigned int timeout)
 {
     int err = 0;
 
     if (!(wdd->info->options & WDIOF_SETTIMEOUT))
         return -EOPNOTSUPP;
 
     if (watchdog_timeout_invalid(wdd, timeout))
         return -EINVAL;
 
     if (wdd->ops->set_timeout) {
         err = wdd->ops->set_timeout(wdd, timeout);
     } else {
         wdd->timeout = timeout;
         /* Disable pretimeout if it doesn't fit the new timeout */
         if (wdd->pretimeout >= wdd->timeout)
             wdd->pretimeout = 0;
     }
 
     watchdog_update_worker(wdd);
 
     return err;
 }
 
 /*
  * watchdog_set_pretimeout - set the watchdog timer pretimeout
  * @wdd:    The watchdog device to set the timeout for
  * @timeout:    pretimeout to set in seconds
  *
  * Return: 0 if successful, error otherwise.
  */
 static int watchdog_set_pretimeout(struct watchdog_device *wdd,
                    unsigned int timeout)
 {
     int err = 0;
 
     if (!watchdog_have_pretimeout(wdd))
         return -EOPNOTSUPP;
 
     if (watchdog_pretimeout_invalid(wdd, timeout))
         return -EINVAL;
 
     if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
         err = wdd->ops->set_pretimeout(wdd, timeout);
     else
         wdd->pretimeout = timeout;
 
     return err;
 }
 
 /*
  * watchdog_get_timeleft - wrapper to get the time left before a reboot
  * @wdd:    The watchdog device to get the remaining time from
  * @timeleft:   The time that's left
  *
  * Get the time before a watchdog will reboot (if not pinged).
  * The caller must hold wd_data->lock.
  *
  * Return: 0 if successful, error otherwise.
  */
 static int watchdog_get_timeleft(struct watchdog_device *wdd,
                             unsigned int *timeleft)
 {
     *timeleft = 0;
 
     if (!wdd->ops->get_timeleft)
         return -EOPNOTSUPP;
 
     *timeleft = wdd->ops->get_timeleft(wdd);
 
     return 0;
 }
 
 #ifdef CONFIG_WATCHDOG_SYSFS
 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT,
                           &wdd->status));
 }
 
 static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,
                 const char *buf, size_t len)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
     unsigned int value;
     int ret;
 
     ret = kstrtouint(buf, 0, &value);
     if (ret)
         return ret;
     if (value > 1)
         return -EINVAL;
     /* nowayout cannot be disabled once set */
     if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)
         return -EPERM;
     watchdog_set_nowayout(wdd, value);
     return len;
 }
 static DEVICE_ATTR_RW(nowayout);
 
 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
     struct watchdog_core_data *wd_data = wdd->wd_data;
     unsigned int status;
 
     mutex_lock(&wd_data->lock);
     status = watchdog_get_status(wdd);
     mutex_unlock(&wd_data->lock);
 
     return sysfs_emit(buf, "0x%x\n", status);
 }
 static DEVICE_ATTR_RO(status);
 
 static ssize_t bootstatus_show(struct device *dev,
                 struct device_attribute *attr, char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%u\n", wdd->bootstatus);
 }
 static DEVICE_ATTR_RO(bootstatus);
 
 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
     struct watchdog_core_data *wd_data = wdd->wd_data;
     ssize_t status;
     unsigned int val;
 
     mutex_lock(&wd_data->lock);
     status = watchdog_get_timeleft(wdd, &val);
     mutex_unlock(&wd_data->lock);
     if (!status)
         status = sysfs_emit(buf, "%u\n", val);
 
     return status;
 }
 static DEVICE_ATTR_RO(timeleft);
 
 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%u\n", wdd->timeout);
 }
 static DEVICE_ATTR_RO(timeout);
 
 static ssize_t min_timeout_show(struct device *dev,
                 struct device_attribute *attr, char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%u\n", wdd->min_timeout);
 }
 static DEVICE_ATTR_RO(min_timeout);
 
 static ssize_t max_timeout_show(struct device *dev,
                 struct device_attribute *attr, char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%u\n", wdd->max_timeout);
 }
 static DEVICE_ATTR_RO(max_timeout);
 
 static ssize_t pretimeout_show(struct device *dev,
                    struct device_attribute *attr, char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%u\n", wdd->pretimeout);
 }
 static DEVICE_ATTR_RO(pretimeout);
 
 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%s\n", wdd->info->identity);
 }
 static DEVICE_ATTR_RO(identity);
 
 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     if (watchdog_active(wdd))
         return sysfs_emit(buf, "active\n");
 
     return sysfs_emit(buf, "inactive\n");
 }
 static DEVICE_ATTR_RO(state);
 
 static ssize_t pretimeout_available_governors_show(struct device *dev,
                    struct device_attribute *attr, char *buf)
 {
     return watchdog_pretimeout_available_governors_get(buf);
 }
 static DEVICE_ATTR_RO(pretimeout_available_governors);
 
 static ssize_t pretimeout_governor_show(struct device *dev,
                     struct device_attribute *attr,
                     char *buf)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
 
     return watchdog_pretimeout_governor_get(wdd, buf);
 }
 
 static ssize_t pretimeout_governor_store(struct device *dev,
                      struct device_attribute *attr,
                      const char *buf, size_t count)
 {
     struct watchdog_device *wdd = dev_get_drvdata(dev);
     int ret = watchdog_pretimeout_governor_set(wdd, buf);
 
     if (!ret)
         ret = count;
 
     return ret;
 }
 static DEVICE_ATTR_RW(pretimeout_governor);
 
 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
                 int n)
 {
     struct device *dev = kobj_to_dev(kobj);
     struct watchdog_device *wdd = dev_get_drvdata(dev);
     umode_t mode = attr->mode;
 
     if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
         mode = 0;
     else if (attr == &dev_attr_pretimeout.attr && !watchdog_have_pretimeout(wdd))
         mode = 0;
     else if ((attr == &dev_attr_pretimeout_governor.attr ||
           attr == &dev_attr_pretimeout_available_governors.attr) &&
          (!watchdog_have_pretimeout(wdd) || !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
         mode = 0;
 
     return mode;
 }
 static struct attribute *wdt_attrs[] = {
     &dev_attr_state.attr,
     &dev_attr_identity.attr,
     &dev_attr_timeout.attr,
     &dev_attr_min_timeout.attr,
     &dev_attr_max_timeout.attr,
     &dev_attr_pretimeout.attr,
     &dev_attr_timeleft.attr,
     &dev_attr_bootstatus.attr,
     &dev_attr_status.attr,
     &dev_attr_nowayout.attr,
     &dev_attr_pretimeout_governor.attr,
     &dev_attr_pretimeout_available_governors.attr,
     NULL,
 };
 
 static const struct attribute_group wdt_group = {
     .attrs = wdt_attrs,
     .is_visible = wdt_is_visible,
 };
 __ATTRIBUTE_GROUPS(wdt);
 #else
 #define wdt_groups  NULL
 #endif
 
 /*
  * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
  * @wdd: The watchdog device to do the ioctl on
  * @cmd: Watchdog command
  * @arg: Argument pointer
  *
  * The caller must hold wd_data->lock.
  *
  * Return: 0 if successful, error otherwise.
  */
 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
                             unsigned long arg)
 {
     if (!wdd->ops->ioctl)
         return -ENOIOCTLCMD;
 
     return wdd->ops->ioctl(wdd, cmd, arg);
 }
 
 /*
  * watchdog_write - writes to the watchdog
  * @file:   File from VFS
  * @data:   User address of data
  * @len:    Length of data
  * @ppos:   Pointer to the file offset
  *
  * A write to a watchdog device is defined as a keepalive ping.
  * Writing the magic 'V' sequence allows the next close to turn
  * off the watchdog (if 'nowayout' is not set).
  *
  * Return: @len if successful, error otherwise.
  */
 static ssize_t watchdog_write(struct file *file, const char __user *data,
                         size_t len, loff_t *ppos)
 {
     struct watchdog_core_data *wd_data = file->private_data;
     struct watchdog_device *wdd;
     int err;
     size_t i;
     char c;
 
     if (len == 0)
         return 0;
 
     /*
      * Note: just in case someone wrote the magic character
      * five months ago...
      */
     clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
 
     /* scan to see whether or not we got the magic character */
     for (i = 0; i != len; i++) {
         if (get_user(c, data + i))
             return -EFAULT;
         if (c == 'V')
             set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
     }
 
     /* someone wrote to us, so we send the watchdog a keepalive ping */
 
     err = -ENODEV;
     mutex_lock(&wd_data->lock);
     wdd = wd_data->wdd;
     if (wdd)
         err = watchdog_ping(wdd);
     mutex_unlock(&wd_data->lock);
 
     if (err < 0)
         return err;
 
     return len;
 }
 
 /*
  * watchdog_ioctl - handle the different ioctl's for the watchdog device
  * @file:   File handle to the device
  * @cmd:    Watchdog command
  * @arg:    Argument pointer
  *
  * The watchdog API defines a common set of functions for all watchdogs
  * according to their available features.
  *
  * Return: 0 if successful, error otherwise.
  */
 
 static long watchdog_ioctl(struct file *file, unsigned int cmd,
                             unsigned long arg)
 {
     struct watchdog_core_data *wd_data = file->private_data;
     void __user *argp = (void __user *)arg;
     struct watchdog_device *wdd;
     int __user *p = argp;
     unsigned int val;
     int err;
 
     mutex_lock(&wd_data->lock);
 
     wdd = wd_data->wdd;
     if (!wdd) {
         err = -ENODEV;
         goto out_ioctl;
     }
 
     err = watchdog_ioctl_op(wdd, cmd, arg);
     if (err != -ENOIOCTLCMD)
         goto out_ioctl;
 
     switch (cmd) {
     case WDIOC_GETSUPPORT:
         err = copy_to_user(argp, wdd->info,
             sizeof(struct watchdog_info)) ? -EFAULT : 0;
         break;
     case WDIOC_GETSTATUS:
         val = watchdog_get_status(wdd);
         err = put_user(val, p);
         break;
     case WDIOC_GETBOOTSTATUS:
         err = put_user(wdd->bootstatus, p);
         break;
     case WDIOC_SETOPTIONS:
         if (get_user(val, p)) {
             err = -EFAULT;
             break;
         }
         if (val & WDIOS_DISABLECARD) {
             err = watchdog_stop(wdd);
             if (err < 0)
                 break;
         }
         if (val & WDIOS_ENABLECARD)
             err = watchdog_start(wdd);
         break;
     case WDIOC_KEEPALIVE:
         if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
             err = -EOPNOTSUPP;
             break;
         }
         err = watchdog_ping(wdd);
         break;
     case WDIOC_SETTIMEOUT:
         if (get_user(val, p)) {
             err = -EFAULT;
             break;
         }
         err = watchdog_set_timeout(wdd, val);
         if (err < 0)
             break;
         /* If the watchdog is active then we send a keepalive ping
          * to make sure that the watchdog keep's running (and if
          * possible that it takes the new timeout) */
         err = watchdog_ping(wdd);
         if (err < 0)
             break;
         fallthrough;
     case WDIOC_GETTIMEOUT:
         /* timeout == 0 means that we don't know the timeout */
         if (wdd->timeout == 0) {
             err = -EOPNOTSUPP;
             break;
         }
         err = put_user(wdd->timeout, p);
         break;
     case WDIOC_GETTIMELEFT:
         err = watchdog_get_timeleft(wdd, &val);
         if (err < 0)
             break;
         err = put_user(val, p);
         break;
     case WDIOC_SETPRETIMEOUT:
         if (get_user(val, p)) {
             err = -EFAULT;
             break;
         }
         err = watchdog_set_pretimeout(wdd, val);
         break;
     case WDIOC_GETPRETIMEOUT:
         err = put_user(wdd->pretimeout, p);
         break;
     default:
         err = -ENOTTY;
         break;
     }
 
 out_ioctl:
     mutex_unlock(&wd_data->lock);
     return err;
 }
 
 /*
  * watchdog_open - open the /dev/watchdog* devices
  * @inode:  Inode of device
  * @file:   File handle to device
  *
  * When the /dev/watchdog* device gets opened, we start the watchdog.
  * Watch out: the /dev/watchdog device is single open, so we make sure
  * it can only be opened once.
  *
  * Return: 0 if successful, error otherwise.
  */
 static int watchdog_open(struct inode *inode, struct file *file)
 {
     struct watchdog_core_data *wd_data;
     struct watchdog_device *wdd;
     bool hw_running;
     int err;
 
     /* Get the corresponding watchdog device */
     if (imajor(inode) == MISC_MAJOR)
         wd_data = old_wd_data;
     else
         wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
                        cdev);
 
     /* the watchdog is single open! */
     if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
         return -EBUSY;
 
     wdd = wd_data->wdd;
 
     /*
      * If the /dev/watchdog device is open, we don't want the module
      * to be unloaded.
      */
     hw_running = watchdog_hw_running(wdd);
     if (!hw_running && !try_module_get(wdd->ops->owner)) {
         err = -EBUSY;
         goto out_clear;
     }
 
     err = watchdog_start(wdd);
     if (err < 0)
         goto out_mod;
 
     file->private_data = wd_data;
 
     if (!hw_running)
         get_device(&wd_data->dev);
 
     /*
      * open_timeout only applies for the first open from
      * userspace. Set open_deadline to infinity so that the kernel
      * will take care of an always-running hardware watchdog in
      * case the device gets magic-closed or WDIOS_DISABLECARD is
      * applied.
      */
     wd_data->open_deadline = KTIME_MAX;
 
     /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
     return stream_open(inode, file);
 
 out_mod:
     module_put(wd_data->wdd->ops->owner);
 out_clear:
     clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
     return err;
 }
 
 static void watchdog_core_data_release(struct device *dev)
 {
     struct watchdog_core_data *wd_data;
 
     wd_data = container_of(dev, struct watchdog_core_data, dev);
 
     kfree(wd_data);
 }
 
 /*
  * watchdog_release - release the watchdog device
  * @inode:  Inode of device
  * @file:   File handle to device
  *
  * This is the code for when /dev/watchdog gets closed. We will only
  * stop the watchdog when we have received the magic char (and nowayout
  * was not set), else the watchdog will keep running.
  *
  * Always returns 0.
  */
 static int watchdog_release(struct inode *inode, struct file *file)
 {
     struct watchdog_core_data *wd_data = file->private_data;
     struct watchdog_device *wdd;
     int err = -EBUSY;
     bool running;
 
     mutex_lock(&wd_data->lock);
 
     wdd = wd_data->wdd;
     if (!wdd)
         goto done;
 
     /*
      * We only stop the watchdog if we received the magic character
      * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
      * watchdog_stop will fail.
      */
     if (!watchdog_active(wdd))
         err = 0;
     else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
          !(wdd->info->options & WDIOF_MAGICCLOSE))
         err = watchdog_stop(wdd);
 
     /* If the watchdog was not stopped, send a keepalive ping */
     if (err < 0) {
         pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
         watchdog_ping(wdd);
     }
 
     watchdog_update_worker(wdd);
 
     /* make sure that /dev/watchdog can be re-opened */
     clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 
 done:
     running = wdd && watchdog_hw_running(wdd);
     mutex_unlock(&wd_data->lock);
     /*
      * Allow the owner module to be unloaded again unless the watchdog
      * is still running. If the watchdog is still running, it can not
      * be stopped, and its driver must not be unloaded.
      */
     if (!running) {
         module_put(wd_data->cdev.owner);
         put_device(&wd_data->dev);
     }
     return 0;
 }
 
 static const struct file_operations watchdog_fops = {
     .owner      = THIS_MODULE,
     .write      = watchdog_write,
     .unlocked_ioctl = watchdog_ioctl,
     .compat_ioctl   = compat_ptr_ioctl,
     .open       = watchdog_open,
     .release    = watchdog_release,
 };
 
 static struct miscdevice watchdog_miscdev = {
     .minor      = WATCHDOG_MINOR,
     .name       = "watchdog",
     .fops       = &watchdog_fops,
 };
 
 static struct class watchdog_class = {
     .name =     "watchdog",
     .owner =    THIS_MODULE,
     .dev_groups =   wdt_groups,
 };
 
 /*
  * watchdog_cdev_register - register watchdog character device
  * @wdd: Watchdog device
  *
  * Register a watchdog character device including handling the legacy
  * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
  * thus we set it up like that.
  *
  * Return: 0 if successful, error otherwise.
  */
 static int watchdog_cdev_register(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data;
     int err;
 
     wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
     if (!wd_data)
         return -ENOMEM;
     mutex_init(&wd_data->lock);
 
     wd_data->wdd = wdd;
     wdd->wd_data = wd_data;
 
     if (IS_ERR_OR_NULL(watchdog_kworker)) {
         kfree(wd_data);
         return -ENODEV;
     }
 
     device_initialize(&wd_data->dev);
     wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
     wd_data->dev.class = &watchdog_class;
     wd_data->dev.parent = wdd->parent;
     wd_data->dev.groups = wdd->groups;
     wd_data->dev.release = watchdog_core_data_release;
     dev_set_drvdata(&wd_data->dev, wdd);
     dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
 
     kthread_init_work(&wd_data->work, watchdog_ping_work);
     hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
     wd_data->timer.function = watchdog_timer_expired;
     watchdog_hrtimer_pretimeout_init(wdd);
 
     if (wdd->id == 0) {
         old_wd_data = wd_data;
         watchdog_miscdev.parent = wdd->parent;
         err = misc_register(&watchdog_miscdev);
         if (err != 0) {
             pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
                 wdd->info->identity, WATCHDOG_MINOR, err);
             if (err == -EBUSY)
                 pr_err("%s: a legacy watchdog module is probably present.\n",
                     wdd->info->identity);
             old_wd_data = NULL;
             put_device(&wd_data->dev);
             return err;
         }
     }
 
     /* Fill in the data structures */
     cdev_init(&wd_data->cdev, &watchdog_fops);
 
     /* Add the device */
     err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
     if (err) {
         pr_err("watchdog%d unable to add device %d:%d\n",
             wdd->id,  MAJOR(watchdog_devt), wdd->id);
         if (wdd->id == 0) {
             misc_deregister(&watchdog_miscdev);
             old_wd_data = NULL;
             put_device(&wd_data->dev);
         }
         return err;
     }
 
     wd_data->cdev.owner = wdd->ops->owner;
 
     /* Record time of most recent heartbeat as 'just before now'. */
     wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
     watchdog_set_open_deadline(wd_data);
 
     /*
      * If the watchdog is running, prevent its driver from being unloaded,
      * and schedule an immediate ping.
      */
     if (watchdog_hw_running(wdd)) {
         __module_get(wdd->ops->owner);
         get_device(&wd_data->dev);
         if (handle_boot_enabled)
             hrtimer_start(&wd_data->timer, 0,
                       HRTIMER_MODE_REL_HARD);
         else
             pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
                 wdd->id);
     }
 
     return 0;
 }
 
 /*
  * watchdog_cdev_unregister - unregister watchdog character device
  * @wdd: Watchdog device
  *
  * Unregister watchdog character device and if needed the legacy
  * /dev/watchdog device.
  */
 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
 
     cdev_device_del(&wd_data->cdev, &wd_data->dev);
     if (wdd->id == 0) {
         misc_deregister(&watchdog_miscdev);
         old_wd_data = NULL;
     }
 
     if (watchdog_active(wdd) &&
         test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
         watchdog_stop(wdd);
     }
 
     watchdog_hrtimer_pretimeout_stop(wdd);
 
     mutex_lock(&wd_data->lock);
     wd_data->wdd = NULL;
     wdd->wd_data = NULL;
     mutex_unlock(&wd_data->lock);
 
     hrtimer_cancel(&wd_data->timer);
     kthread_cancel_work_sync(&wd_data->work);
 
     put_device(&wd_data->dev);
 }
 
 /**
  * watchdog_dev_register - register a watchdog device
  * @wdd: Watchdog device
  *
  * Register a watchdog device including handling the legacy
  * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
  * thus we set it up like that.
  *
  * Return: 0 if successful, error otherwise.
  */
 int watchdog_dev_register(struct watchdog_device *wdd)
 {
     int ret;
 
     ret = watchdog_cdev_register(wdd);
     if (ret)
         return ret;
 
     ret = watchdog_register_pretimeout(wdd);
     if (ret)
         watchdog_cdev_unregister(wdd);
 
     return ret;
 }
 
 /**
  * watchdog_dev_unregister - unregister a watchdog device
  * @wdd: watchdog device
  *
  * Unregister watchdog device and if needed the legacy
  * /dev/watchdog device.
  */
 void watchdog_dev_unregister(struct watchdog_device *wdd)
 {
     watchdog_unregister_pretimeout(wdd);
     watchdog_cdev_unregister(wdd);
 }
 
 /**
  * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
  * @wdd:        Watchdog device
  * @last_ping_ms:   Time since last HW heartbeat
  *
  * Adjusts the last known HW keepalive time for a watchdog timer.
  * This is needed if the watchdog is already running when the probe
  * function is called, and it can't be pinged immediately. This
  * function must be called immediately after watchdog registration,
  * and min_hw_heartbeat_ms must be set for this to be useful.
  *
  * Return: 0 if successful, error otherwise.
  */
 int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
                    unsigned int last_ping_ms)
 {
     struct watchdog_core_data *wd_data;
     ktime_t now;
 
     if (!wdd)
         return -EINVAL;
 
     wd_data = wdd->wd_data;
 
     now = ktime_get();
 
     wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
 
     if (watchdog_hw_running(wdd) && handle_boot_enabled)
         return __watchdog_ping(wdd);
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
 
 /**
  * watchdog_dev_init - init dev part of watchdog core
  *
  * Allocate a range of chardev nodes to use for watchdog devices.
  *
  * Return: 0 if successful, error otherwise.
  */
 int __init watchdog_dev_init(void)
 {
     int err;
 
     watchdog_kworker = kthread_create_worker(0, "watchdogd");
     if (IS_ERR(watchdog_kworker)) {
         pr_err("Failed to create watchdog kworker\n");
         return PTR_ERR(watchdog_kworker);
     }
     sched_set_fifo(watchdog_kworker->task);
 
     err = class_register(&watchdog_class);
     if (err < 0) {
         pr_err("couldn't register class\n");
         goto err_register;
     }
 
     err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
     if (err < 0) {
         pr_err("watchdog: unable to allocate char dev region\n");
         goto err_alloc;
     }
 
     return 0;
 
 err_alloc:
     class_unregister(&watchdog_class);
 err_register:
     kthread_destroy_worker(watchdog_kworker);
     return err;
 }
 
 /**
  * watchdog_dev_exit - exit dev part of watchdog core
  *
  * Release the range of chardev nodes used for watchdog devices.
  */
 void __exit watchdog_dev_exit(void)
 {
     unregister_chrdev_region(watchdog_devt, MAX_DOGS);
     class_unregister(&watchdog_class);
     kthread_destroy_worker(watchdog_kworker);
 }
 
 int watchdog_dev_suspend(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
     int ret = 0;
 
     if (!wdd->wd_data)
         return -ENODEV;
 
     /* ping for the last time before suspend */
     mutex_lock(&wd_data->lock);
     if (watchdog_worker_should_ping(wd_data))
         ret = __watchdog_ping(wd_data->wdd);
     mutex_unlock(&wd_data->lock);
 
     if (ret)
         return ret;
 
     /*
      * make sure that watchdog worker will not kick in when the wdog is
      * suspended
      */
     hrtimer_cancel(&wd_data->timer);
     kthread_cancel_work_sync(&wd_data->work);
 
     return 0;
 }
 
 int watchdog_dev_resume(struct watchdog_device *wdd)
 {
     struct watchdog_core_data *wd_data = wdd->wd_data;
     int ret = 0;
 
     if (!wdd->wd_data)
         return -ENODEV;
 
     /*
      * __watchdog_ping will also retrigger hrtimer and therefore restore the
      * ping worker if needed.
      */
     mutex_lock(&wd_data->lock);
     if (watchdog_worker_should_ping(wd_data))
         ret = __watchdog_ping(wd_data->wdd);
     mutex_unlock(&wd_data->lock);
 
     return ret;
 }
 
 module_param(handle_boot_enabled, bool, 0444);
 MODULE_PARM_DESC(handle_boot_enabled,
     "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
     __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");
 
 module_param(open_timeout, uint, 0644);
 MODULE_PARM_DESC(open_timeout,
     "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
     __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");

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