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38d7529774
When the new watchdog character device is registered, it becomes
available for opening. This creates a race where userspace may open the
device before the character device's owner is set. This results in an
imbalance in module_get calls as the cdev_get in cdev_open will not
increment the reference count on the watchdog driver module.
This causes problems when the watchdog character device is released as
the module loader's reference will also be released. This makes it
impossible to open the watchdog device later on as it now appears that
the module is being unloaded. The open will fail with -ENXIO from
chrdev_open.
The legacy watchdog device will fail with -EBUSY from the try_module_get
in watchdog_open because it's module owner is the watchdog core module
so it can still be opened but it will fail to get a refcount on the
underlying watchdog device driver.
Fixes: 72139dfa24
("watchdog: Fix the race between the release of watchdog_core_data and cdev")
Signed-off-by: Curtis Klein <curtis.klein@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20231205190522.55153-1-curtis.klein@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
1328 lines
33 KiB
C
1328 lines
33 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* watchdog_dev.c
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*
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* (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
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* All Rights Reserved.
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*
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* (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
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*
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* (c) Copyright 2021 Hewlett Packard Enterprise Development LP.
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*
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* This source code is part of the generic code that can be used
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* by all the watchdog timer drivers.
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*
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* This part of the generic code takes care of the following
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* misc device: /dev/watchdog.
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*
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* Based on source code of the following authors:
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* Matt Domsch <Matt_Domsch@dell.com>,
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* Rob Radez <rob@osinvestor.com>,
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* Rusty Lynch <rusty@linux.co.intel.com>
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* Satyam Sharma <satyam@infradead.org>
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* Randy Dunlap <randy.dunlap@oracle.com>
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*
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* Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
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* admit liability nor provide warranty for any of this software.
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* This material is provided "AS-IS" and at no charge.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/cdev.h> /* For character device */
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#include <linux/errno.h> /* For the -ENODEV/... values */
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#include <linux/fs.h> /* For file operations */
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#include <linux/init.h> /* For __init/__exit/... */
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#include <linux/hrtimer.h> /* For hrtimers */
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#include <linux/kernel.h> /* For printk/panic/... */
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#include <linux/kstrtox.h> /* For kstrto* */
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#include <linux/kthread.h> /* For kthread_work */
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#include <linux/miscdevice.h> /* For handling misc devices */
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#include <linux/module.h> /* For module stuff/... */
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#include <linux/mutex.h> /* For mutexes */
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#include <linux/slab.h> /* For memory functions */
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#include <linux/types.h> /* For standard types (like size_t) */
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#include <linux/watchdog.h> /* For watchdog specific items */
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#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
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#include "watchdog_core.h"
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#include "watchdog_pretimeout.h"
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#include <trace/events/watchdog.h>
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/* the dev_t structure to store the dynamically allocated watchdog devices */
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static dev_t watchdog_devt;
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/* Reference to watchdog device behind /dev/watchdog */
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static struct watchdog_core_data *old_wd_data;
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static struct kthread_worker *watchdog_kworker;
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static bool handle_boot_enabled =
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IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
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static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
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static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
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{
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return ktime_after(ktime_get(), data->open_deadline);
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}
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static void watchdog_set_open_deadline(struct watchdog_core_data *data)
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{
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data->open_deadline = open_timeout ?
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ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;
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}
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static inline bool watchdog_need_worker(struct watchdog_device *wdd)
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{
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/* All variables in milli-seconds */
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unsigned int hm = wdd->max_hw_heartbeat_ms;
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unsigned int t = wdd->timeout * 1000;
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/*
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* A worker to generate heartbeat requests is needed if all of the
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* following conditions are true.
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* - Userspace activated the watchdog.
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* - The driver provided a value for the maximum hardware timeout, and
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* thus is aware that the framework supports generating heartbeat
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* requests.
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* - Userspace requests a longer timeout than the hardware can handle.
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*
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* Alternatively, if userspace has not opened the watchdog
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* device, we take care of feeding the watchdog if it is
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* running.
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*/
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return (hm && watchdog_active(wdd) && t > hm) ||
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(t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
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}
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static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
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{
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struct watchdog_core_data *wd_data = wdd->wd_data;
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unsigned int timeout_ms = wdd->timeout * 1000;
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ktime_t keepalive_interval;
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ktime_t last_heartbeat, latest_heartbeat;
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ktime_t virt_timeout;
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unsigned int hw_heartbeat_ms;
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if (watchdog_active(wdd))
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virt_timeout = ktime_add(wd_data->last_keepalive,
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ms_to_ktime(timeout_ms));
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else
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virt_timeout = wd_data->open_deadline;
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hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
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keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
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/*
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* To ensure that the watchdog times out wdd->timeout seconds
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* after the most recent ping from userspace, the last
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* worker ping has to come in hw_heartbeat_ms before this timeout.
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*/
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last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
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latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
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if (ktime_before(latest_heartbeat, keepalive_interval))
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return latest_heartbeat;
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return keepalive_interval;
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}
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static inline void watchdog_update_worker(struct watchdog_device *wdd)
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{
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struct watchdog_core_data *wd_data = wdd->wd_data;
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if (watchdog_need_worker(wdd)) {
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ktime_t t = watchdog_next_keepalive(wdd);
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if (t > 0)
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hrtimer_start(&wd_data->timer, t,
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HRTIMER_MODE_REL_HARD);
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} else {
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hrtimer_cancel(&wd_data->timer);
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}
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}
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static int __watchdog_ping(struct watchdog_device *wdd)
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{
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struct watchdog_core_data *wd_data = wdd->wd_data;
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ktime_t earliest_keepalive, now;
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int err;
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earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
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ms_to_ktime(wdd->min_hw_heartbeat_ms));
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now = ktime_get();
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if (ktime_after(earliest_keepalive, now)) {
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hrtimer_start(&wd_data->timer,
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ktime_sub(earliest_keepalive, now),
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HRTIMER_MODE_REL_HARD);
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return 0;
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}
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wd_data->last_hw_keepalive = now;
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if (wdd->ops->ping) {
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err = wdd->ops->ping(wdd); /* ping the watchdog */
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trace_watchdog_ping(wdd, err);
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} else {
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err = wdd->ops->start(wdd); /* restart watchdog */
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trace_watchdog_start(wdd, err);
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}
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if (err == 0)
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watchdog_hrtimer_pretimeout_start(wdd);
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watchdog_update_worker(wdd);
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return err;
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}
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/*
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* watchdog_ping - ping the watchdog
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* @wdd: The watchdog device to ping
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*
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* If the watchdog has no own ping operation then it needs to be
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* restarted via the start operation. This wrapper function does
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* exactly that.
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* We only ping when the watchdog device is running.
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* The caller must hold wd_data->lock.
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*
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* Return: 0 on success, error otherwise.
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*/
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static int watchdog_ping(struct watchdog_device *wdd)
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{
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struct watchdog_core_data *wd_data = wdd->wd_data;
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if (!watchdog_hw_running(wdd))
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return 0;
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set_bit(_WDOG_KEEPALIVE, &wd_data->status);
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wd_data->last_keepalive = ktime_get();
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return __watchdog_ping(wdd);
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}
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static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
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{
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struct watchdog_device *wdd = wd_data->wdd;
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if (!wdd)
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return false;
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if (watchdog_active(wdd))
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return true;
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return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);
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}
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static void watchdog_ping_work(struct kthread_work *work)
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{
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struct watchdog_core_data *wd_data;
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wd_data = container_of(work, struct watchdog_core_data, work);
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mutex_lock(&wd_data->lock);
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if (watchdog_worker_should_ping(wd_data))
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__watchdog_ping(wd_data->wdd);
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mutex_unlock(&wd_data->lock);
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}
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static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
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{
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struct watchdog_core_data *wd_data;
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wd_data = container_of(timer, struct watchdog_core_data, timer);
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kthread_queue_work(watchdog_kworker, &wd_data->work);
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return HRTIMER_NORESTART;
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}
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/*
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* watchdog_start - wrapper to start the watchdog
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* @wdd: The watchdog device to start
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*
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* Start the watchdog if it is not active and mark it active.
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* The caller must hold wd_data->lock.
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*
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* Return: 0 on success or a negative errno code for failure.
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*/
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static int watchdog_start(struct watchdog_device *wdd)
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{
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struct watchdog_core_data *wd_data = wdd->wd_data;
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ktime_t started_at;
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int err;
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if (watchdog_active(wdd))
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return 0;
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set_bit(_WDOG_KEEPALIVE, &wd_data->status);
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started_at = ktime_get();
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if (watchdog_hw_running(wdd) && wdd->ops->ping) {
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err = __watchdog_ping(wdd);
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if (err == 0) {
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set_bit(WDOG_ACTIVE, &wdd->status);
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watchdog_hrtimer_pretimeout_start(wdd);
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}
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} else {
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err = wdd->ops->start(wdd);
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trace_watchdog_start(wdd, err);
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if (err == 0) {
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set_bit(WDOG_ACTIVE, &wdd->status);
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set_bit(WDOG_HW_RUNNING, &wdd->status);
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wd_data->last_keepalive = started_at;
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wd_data->last_hw_keepalive = started_at;
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watchdog_update_worker(wdd);
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watchdog_hrtimer_pretimeout_start(wdd);
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}
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}
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return err;
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}
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/*
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* watchdog_stop - wrapper to stop the watchdog
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* @wdd: The watchdog device to stop
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*
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* Stop the watchdog if it is still active and unmark it active.
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* If the 'nowayout' feature was set, the watchdog cannot be stopped.
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* The caller must hold wd_data->lock.
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*
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* Return: 0 on success or a negative errno code for failure.
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*/
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static int watchdog_stop(struct watchdog_device *wdd)
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{
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int err = 0;
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if (!watchdog_active(wdd))
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return 0;
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if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
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pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
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wdd->id);
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return -EBUSY;
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}
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if (wdd->ops->stop) {
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clear_bit(WDOG_HW_RUNNING, &wdd->status);
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err = wdd->ops->stop(wdd);
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trace_watchdog_stop(wdd, err);
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} else {
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set_bit(WDOG_HW_RUNNING, &wdd->status);
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}
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if (err == 0) {
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clear_bit(WDOG_ACTIVE, &wdd->status);
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watchdog_update_worker(wdd);
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watchdog_hrtimer_pretimeout_stop(wdd);
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}
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return err;
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}
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/*
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* watchdog_get_status - wrapper to get the watchdog status
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* @wdd: The watchdog device to get the status from
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*
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* Get the watchdog's status flags.
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* The caller must hold wd_data->lock.
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*
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* Return: watchdog's status flags.
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*/
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static unsigned int watchdog_get_status(struct watchdog_device *wdd)
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{
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struct watchdog_core_data *wd_data = wdd->wd_data;
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unsigned int status;
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if (wdd->ops->status)
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status = wdd->ops->status(wdd);
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else
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status = wdd->bootstatus & (WDIOF_CARDRESET |
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WDIOF_OVERHEAT |
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WDIOF_FANFAULT |
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WDIOF_EXTERN1 |
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WDIOF_EXTERN2 |
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WDIOF_POWERUNDER |
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WDIOF_POWEROVER);
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if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
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status |= WDIOF_MAGICCLOSE;
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if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
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status |= WDIOF_KEEPALIVEPING;
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if (IS_ENABLED(CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT))
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status |= WDIOF_PRETIMEOUT;
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return status;
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}
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/*
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* watchdog_set_timeout - set the watchdog timer timeout
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* @wdd: The watchdog device to set the timeout for
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* @timeout: Timeout to set in seconds
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*
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* The caller must hold wd_data->lock.
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*
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* Return: 0 if successful, error otherwise.
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*/
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static int watchdog_set_timeout(struct watchdog_device *wdd,
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unsigned int timeout)
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{
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int err = 0;
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if (!(wdd->info->options & WDIOF_SETTIMEOUT))
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return -EOPNOTSUPP;
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if (watchdog_timeout_invalid(wdd, timeout))
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return -EINVAL;
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if (wdd->ops->set_timeout) {
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err = wdd->ops->set_timeout(wdd, timeout);
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trace_watchdog_set_timeout(wdd, timeout, err);
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} else {
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wdd->timeout = timeout;
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/* Disable pretimeout if it doesn't fit the new timeout */
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if (wdd->pretimeout >= wdd->timeout)
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wdd->pretimeout = 0;
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}
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watchdog_update_worker(wdd);
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return err;
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}
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/*
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* watchdog_set_pretimeout - set the watchdog timer pretimeout
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* @wdd: The watchdog device to set the timeout for
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* @timeout: pretimeout to set in seconds
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*
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* Return: 0 if successful, error otherwise.
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*/
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static int watchdog_set_pretimeout(struct watchdog_device *wdd,
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unsigned int timeout)
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{
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int err = 0;
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if (!watchdog_have_pretimeout(wdd))
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return -EOPNOTSUPP;
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if (watchdog_pretimeout_invalid(wdd, timeout))
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return -EINVAL;
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if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
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err = wdd->ops->set_pretimeout(wdd, timeout);
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else
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wdd->pretimeout = timeout;
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return err;
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}
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/*
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* watchdog_get_timeleft - wrapper to get the time left before a reboot
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* @wdd: The watchdog device to get the remaining time from
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* @timeleft: The time that's left
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*
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* Get the time before a watchdog will reboot (if not pinged).
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* The caller must hold wd_data->lock.
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*
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* Return: 0 if successful, error otherwise.
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*/
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static int watchdog_get_timeleft(struct watchdog_device *wdd,
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unsigned int *timeleft)
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{
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*timeleft = 0;
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if (!wdd->ops->get_timeleft)
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return -EOPNOTSUPP;
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*timeleft = wdd->ops->get_timeleft(wdd);
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return 0;
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}
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#ifdef CONFIG_WATCHDOG_SYSFS
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static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct watchdog_device *wdd = dev_get_drvdata(dev);
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return sysfs_emit(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT,
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&wdd->status));
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}
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static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t len)
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{
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struct watchdog_device *wdd = dev_get_drvdata(dev);
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unsigned int value;
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int ret;
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ret = kstrtouint(buf, 0, &value);
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if (ret)
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return ret;
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if (value > 1)
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return -EINVAL;
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/* nowayout cannot be disabled once set */
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if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)
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return -EPERM;
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watchdog_set_nowayout(wdd, value);
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return len;
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}
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static DEVICE_ATTR_RW(nowayout);
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static ssize_t status_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct watchdog_device *wdd = dev_get_drvdata(dev);
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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 options_show(struct device *dev, struct device_attribute *attr,
|
|
char *buf)
|
|
{
|
|
struct watchdog_device *wdd = dev_get_drvdata(dev);
|
|
|
|
return sysfs_emit(buf, "0x%x\n", wdd->info->options);
|
|
}
|
|
static DEVICE_ATTR_RO(options);
|
|
|
|
static ssize_t fw_version_show(struct device *dev, struct device_attribute *attr,
|
|
char *buf)
|
|
{
|
|
struct watchdog_device *wdd = dev_get_drvdata(dev);
|
|
|
|
return sysfs_emit(buf, "%d\n", wdd->info->firmware_version);
|
|
}
|
|
static DEVICE_ATTR_RO(fw_version);
|
|
|
|
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_options.attr,
|
|
&dev_attr_fw_version.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",
|
|
.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);
|
|
err = dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
|
|
if (err) {
|
|
put_device(&wd_data->dev);
|
|
return err;
|
|
}
|
|
|
|
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);
|
|
wd_data->cdev.owner = wdd->ops->owner;
|
|
|
|
/* 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;
|
|
}
|
|
|
|
/* 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) ")");
|