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- // 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>.
- *
- *
- * 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 <uapi/linux/sched/types.h> /* For struct sched_param */
- #include "watchdog_core.h"
- #include "watchdog_pretimeout.h"
- /*
- * struct watchdog_core_data - watchdog core internal data
- * @dev: The watchdog's internal device
- * @cdev: The watchdog's Character device.
- * @wdd: Pointer to watchdog device.
- * @lock: Lock for watchdog core.
- * @status: Watchdog core internal status bits.
- */
- struct watchdog_core_data {
- struct device dev;
- struct cdev cdev;
- struct watchdog_device *wdd;
- struct mutex lock;
- ktime_t last_keepalive;
- ktime_t last_hw_keepalive;
- ktime_t open_deadline;
- struct hrtimer timer;
- struct kthread_work work;
- unsigned long status; /* Internal status bits */
- #define _WDOG_DEV_OPEN 0 /* Opened ? */
- #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
- #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
- };
- /* 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 */
- watchdog_update_worker(wdd);
- return err;
- }
- /*
- * watchdog_ping: ping the watchdog.
- * @wdd: the watchdog device to ping
- *
- * The caller must hold wd_data->lock.
- *
- * 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.
- */
- 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
- *
- * The caller must hold wd_data->lock.
- *
- * Start the watchdog if it is not active and mark it active.
- * This function returns zero 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 = wdd->ops->ping(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);
- }
- return err;
- }
- /*
- * watchdog_stop: wrapper to stop the watchdog.
- * @wdd: the watchdog device to stop
- *
- * The caller must hold wd_data->lock.
- *
- * Stop the watchdog if it is still active and unmark it active.
- * This function returns zero on success or a negative errno code for
- * failure.
- * If the 'nowayout' feature was set, the watchdog cannot be stopped.
- */
- 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);
- }
- return err;
- }
- /*
- * watchdog_get_status: wrapper to get the watchdog status
- * @wdd: the watchdog device to get the status from
- *
- * The caller must hold wd_data->lock.
- *
- * Get the 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;
- 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.
- */
- 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
- */
- static int watchdog_set_pretimeout(struct watchdog_device *wdd,
- unsigned int timeout)
- {
- int err = 0;
- if (!(wdd->info->options & WDIOF_PRETIMEOUT))
- return -EOPNOTSUPP;
- if (watchdog_pretimeout_invalid(wdd, timeout))
- return -EINVAL;
- if (wdd->ops->set_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
- *
- * The caller must hold wd_data->lock.
- *
- * Get the time before a watchdog will reboot (if not pinged).
- */
- 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 sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
- }
- static DEVICE_ATTR_RO(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 sprintf(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 sprintf(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 = sprintf(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 sprintf(buf, "%u\n", wdd->timeout);
- }
- static DEVICE_ATTR_RO(timeout);
- static ssize_t pretimeout_show(struct device *dev,
- struct device_attribute *attr, char *buf)
- {
- struct watchdog_device *wdd = dev_get_drvdata(dev);
- return sprintf(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 sprintf(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 sprintf(buf, "active\n");
- return sprintf(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 = container_of(kobj, struct device, 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 &&
- !(wdd->info->options & WDIOF_PRETIMEOUT))
- mode = 0;
- else if ((attr == &dev_attr_pretimeout_governor.attr ||
- attr == &dev_attr_pretimeout_available_governors.attr) &&
- (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
- !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_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.
- */
- 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).
- */
- 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.
- */
- 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;
- /* fall through */
- 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.
- */
- 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.
- */
- 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 (!test_bit(WDOG_ACTIVE, &wdd->status))
- 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,
- .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.
- */
- 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;
- 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
- * @watchdog: 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);
- }
- 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.
- */
- 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
- * @watchdog: 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_dev_init: init dev part of watchdog core
- *
- * Allocate a range of chardev nodes to use for watchdog devices
- */
- int __init watchdog_dev_init(void)
- {
- int err;
- struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,};
- 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_setscheduler(watchdog_kworker->task, SCHED_FIFO, ¶m);
- 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);
- }
- 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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