diff options
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 19 | ||||
| -rw-r--r-- | drivers/watchdog/watchdog_dev.c | 129 | ||||
| -rw-r--r-- | include/linux/watchdog.h | 28 |
3 files changed, 158 insertions, 18 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index dd8f912c0576..15a02595ade1 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -52,6 +52,7 @@ struct watchdog_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; @@ -73,8 +74,18 @@ It contains following fields: 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. @@ -153,7 +164,11 @@ they are supported. These optional routines/operations are: 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 diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index b5e700186ae0..e668a9e8b648 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -36,6 +36,7 @@ #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 */ @@ -44,6 +45,7 @@ #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" @@ -61,6 +63,8 @@ struct watchdog_core_data { 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 ? */ @@ -71,6 +75,76 @@ static dev_t watchdog_devt; /* 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 @@ -85,17 +159,28 @@ static struct watchdog_core_data *old_wd_data; 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); } /* @@ -111,14 +196,20 @@ static int watchdog_ping(struct watchdog_device *wdd) 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; } @@ -137,6 +228,7 @@ static int watchdog_start(struct watchdog_device *wdd) static int watchdog_stop(struct watchdog_device *wdd) { + struct watchdog_core_data *wd_data = wdd->wd_data; int err; if (!watchdog_active(wdd)) @@ -149,8 +241,10 @@ static int watchdog_stop(struct watchdog_device *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; } @@ -196,6 +290,8 @@ static int watchdog_set_timeout(struct watchdog_device *wdd, else wdd->timeout = timeout; + watchdog_update_worker(wdd); + return err; } @@ -616,6 +712,8 @@ static int watchdog_release(struct inode *inode, struct file *file) 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); @@ -665,6 +763,11 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno) 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; @@ -722,6 +825,8 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd) 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); } @@ -787,6 +892,13 @@ int __init watchdog_dev_init(void) { 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"); @@ -813,4 +925,5 @@ void __exit watchdog_dev_exit(void) { unregister_chrdev_region(watchdog_devt, MAX_DOGS); class_unregister(&watchdog_class); + destroy_workqueue(watchdog_wq); } diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h index 0b565f2ad242..8e82daecb7d3 100644 --- a/include/linux/watchdog.h +++ b/include/linux/watchdog.h @@ -10,8 +10,9 @@ #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> @@ -61,14 +62,19 @@ struct watchdog_ops { * @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. @@ -89,6 +95,7 @@ struct watchdog_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; @@ -128,13 +135,18 @@ static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigne { /* * 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 */ |