unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ unsigned int max_hw_heartbeat_ms;
struct notifier_block reboot_nb;
struct notifier_block restart_nb;
void *driver_data;
additional information about the watchdog timer itself. (Like it's unique name)
* ops: a pointer to the list of watchdog operations that the watchdog supports.
* timeout: the watchdog timer's timeout value (in seconds).
+ This is the time after which the system will reboot if user space does
+ not send a heartbeat request if WDOG_ACTIVE is set.
* min_timeout: the watchdog timer's minimum timeout value (in seconds).
-* max_timeout: the watchdog timer's maximum timeout value (in seconds).
+ If set, the minimum configurable value for 'timeout'.
+* max_timeout: the watchdog timer's maximum timeout value (in seconds),
+ as seen from userspace. If set, the maximum configurable value for
+ 'timeout'. Not used if max_hw_heartbeat_ms is non-zero.
+* max_hw_heartbeat_ms: Maximum hardware heartbeat, in milli-seconds.
+ If set, the infrastructure will send heartbeats to the watchdog driver
+ if 'timeout' is larger than max_hw_heartbeat_ms, unless WDOG_ACTIVE
+ is set and userspace failed to send a heartbeat for at least 'timeout'
+ seconds.
* reboot_nb: notifier block that is registered for reboot notifications, for
internal use only. If the driver calls watchdog_stop_on_reboot, watchdog core
will stop the watchdog on such notifications.
and -EIO for "could not write value to the watchdog". On success this
routine should set the timeout value of the watchdog_device to the
achieved timeout value (which may be different from the requested one
- because the watchdog does not necessarily has a 1 second resolution).
+ because the watchdog does not necessarily have a 1 second resolution).
+ Drivers implementing max_hw_heartbeat_ms set the hardware watchdog heartbeat
+ to the minimum of timeout and max_hw_heartbeat_ms. Those drivers set the
+ timeout value of the watchdog_device either to the requested timeout value
+ (if it is larger than max_hw_heartbeat_ms), or to the achieved timeout value.
(Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
watchdog's info structure).
If the watchdog driver does not have to perform any action but setting the
#include <linux/errno.h> /* For the -ENODEV/... values */
#include <linux/fs.h> /* For file operations */
#include <linux/init.h> /* For __init/__exit/... */
+#include <linux/jiffies.h> /* For timeout functions */
#include <linux/kernel.h> /* For printk/panic/... */
#include <linux/kref.h> /* For data references */
#include <linux/miscdevice.h> /* For handling misc devices */
#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/workqueue.h> /* For workqueue */
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
#include "watchdog_core.h"
struct cdev cdev;
struct watchdog_device *wdd;
struct mutex lock;
+ unsigned long last_keepalive;
+ struct delayed_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 ? */
/* Reference to watchdog device behind /dev/watchdog */
static struct watchdog_core_data *old_wd_data;
+static struct workqueue_struct *watchdog_wq;
+
+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.
+ */
+ return watchdog_active(wdd) && hm && t > hm;
+}
+
+static long watchdog_next_keepalive(struct watchdog_device *wdd)
+{
+ struct watchdog_core_data *wd_data = wdd->wd_data;
+ unsigned int timeout_ms = wdd->timeout * 1000;
+ unsigned long keepalive_interval;
+ unsigned long last_heartbeat;
+ unsigned long virt_timeout;
+ unsigned int hw_heartbeat_ms;
+
+ virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
+ hw_heartbeat_ms = min(timeout_ms, wdd->max_hw_heartbeat_ms);
+ keepalive_interval = msecs_to_jiffies(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 = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
+ return min_t(long, last_heartbeat - jiffies, 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)) {
+ long t = watchdog_next_keepalive(wdd);
+
+ if (t > 0)
+ mod_delayed_work(watchdog_wq, &wd_data->work, t);
+ } else {
+ cancel_delayed_work(&wd_data->work);
+ }
+}
+
+static int __watchdog_ping(struct watchdog_device *wdd)
+{
+ int err;
+
+ 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
static int watchdog_ping(struct watchdog_device *wdd)
{
- int err;
+ struct watchdog_core_data *wd_data = wdd->wd_data;
if (!watchdog_active(wdd))
return 0;
- if (wdd->ops->ping)
- err = wdd->ops->ping(wdd); /* ping the watchdog */
- else
- err = wdd->ops->start(wdd); /* restart watchdog */
+ wd_data->last_keepalive = jiffies;
+ return __watchdog_ping(wdd);
+}
- return err;
+static void watchdog_ping_work(struct work_struct *work)
+{
+ struct watchdog_core_data *wd_data;
+ struct watchdog_device *wdd;
+
+ wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
+ work);
+
+ mutex_lock(&wd_data->lock);
+ wdd = wd_data->wdd;
+ if (wdd && watchdog_active(wdd))
+ __watchdog_ping(wdd);
+ mutex_unlock(&wd_data->lock);
}
/*
static int watchdog_start(struct watchdog_device *wdd)
{
+ struct watchdog_core_data *wd_data = wdd->wd_data;
+ unsigned long started_at;
int err;
if (watchdog_active(wdd))
return 0;
+ started_at = jiffies;
err = wdd->ops->start(wdd);
- if (err == 0)
+ if (err == 0) {
set_bit(WDOG_ACTIVE, &wdd->status);
+ wd_data->last_keepalive = started_at;
+ watchdog_update_worker(wdd);
+ }
return err;
}
static int watchdog_stop(struct watchdog_device *wdd)
{
+ struct watchdog_core_data *wd_data = wdd->wd_data;
int err;
if (!watchdog_active(wdd))
}
err = wdd->ops->stop(wdd);
- if (err == 0)
+ if (err == 0) {
clear_bit(WDOG_ACTIVE, &wdd->status);
+ cancel_delayed_work(&wd_data->work);
+ }
return err;
}
else
wdd->timeout = timeout;
+ watchdog_update_worker(wdd);
+
return err;
}
watchdog_ping(wdd);
}
+ cancel_delayed_work_sync(&wd_data->work);
+
/* make sure that /dev/watchdog can be re-opened */
clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
wd_data->wdd = wdd;
wdd->wd_data = wd_data;
+ if (!watchdog_wq)
+ return -ENODEV;
+
+ INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
+
if (wdd->id == 0) {
old_wd_data = wd_data;
watchdog_miscdev.parent = wdd->parent;
wdd->wd_data = NULL;
mutex_unlock(&wd_data->lock);
+ cancel_delayed_work_sync(&wd_data->work);
+
kref_put(&wd_data->kref, watchdog_core_data_release);
}
{
int err;
+ watchdog_wq = alloc_workqueue("watchdogd",
+ WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
+ if (!watchdog_wq) {
+ pr_err("Failed to create watchdog workqueue\n");
+ return -ENOMEM;
+ }
+
err = class_register(&watchdog_class);
if (err < 0) {
pr_err("couldn't register class\n");
{
unregister_chrdev_region(watchdog_devt, MAX_DOGS);
class_unregister(&watchdog_class);
+ destroy_workqueue(watchdog_wq);
}
#include <linux/bitops.h>
-#include <linux/device.h>
#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
#include <linux/notifier.h>
#include <uapi/linux/watchdog.h>
* @bootstatus: Status of the watchdog device at boot.
* @timeout: The watchdog devices timeout value (in seconds).
* @min_timeout:The watchdog devices minimum timeout value (in seconds).
- * @max_timeout:The watchdog devices maximum timeout value (in seconds).
+ * @max_timeout:The watchdog devices maximum timeout value (in seconds)
+ * as configurable from user space. Only relevant if
+ * max_hw_heartbeat_ms is not provided.
+ * @max_hw_heartbeat_ms:
+ * Hardware limit for maximum timeout, in milli-seconds.
+ * Replaces max_timeout if specified.
* @reboot_nb: The notifier block to stop watchdog on reboot.
* @restart_nb: The notifier block to register a restart function.
* @driver_data:Pointer to the drivers private data.
* @wd_data: Pointer to watchdog core internal data.
* @status: Field that contains the devices internal status bits.
- * @deferred: entry in wtd_deferred_reg_list which is used to
- * register early initialized watchdogs.
+ * @deferred: Entry in wtd_deferred_reg_list which is used to
+ * register early initialized watchdogs.
*
* The watchdog_device structure contains all information about a
* watchdog timer device.
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ unsigned int max_hw_heartbeat_ms;
struct notifier_block reboot_nb;
struct notifier_block restart_nb;
void *driver_data;
{
/*
* The timeout is invalid if
+ * - the requested value is larger than UINT_MAX / 1000
+ * (since internal calculations are done in milli-seconds),
+ * or
* - the requested value is smaller than the configured minimum timeout,
* or
- * - a maximum timeout is configured, and the requested value is larger
- * than the maximum timeout.
+ * - a maximum hardware timeout is not configured, a maximum timeout
+ * is configured, and the requested value is larger than the
+ * configured maximum timeout.
*/
- return t < wdd->min_timeout ||
- (wdd->max_timeout && t > wdd->max_timeout);
+ return t > UINT_MAX / 1000 || t < wdd->min_timeout ||
+ (!wdd->max_hw_heartbeat_ms && wdd->max_timeout &&
+ t > wdd->max_timeout);
}
/* Use the following functions to manipulate watchdog driver specific data */
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