Commit ff84136c authored by Vladimir Zapolskiy's avatar Vladimir Zapolskiy Committed by Wim Van Sebroeck

watchdog: add watchdog pretimeout governor framework

The change adds a simple watchdog pretimeout framework infrastructure,
its purpose is to allow users to select a desired handling of watchdog
pretimeout events, which may be generated by some watchdog devices.

A user selects a default watchdog pretimeout governor during
compilation stage.

Watchdogs with WDIOF_PRETIMEOUT capability now have one more device
attribute in sysfs, pretimeout_governor attribute is intended to display
the selected watchdog pretimeout governor.

The framework has no impact at runtime on watchdog devices with no
WDIOF_PRETIMEOUT capability set.
Signed-off-by: default avatarVladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Reviewed-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWim Van Sebroeck <wim@iguana.be>
parent fc113d54
......@@ -48,6 +48,7 @@ struct watchdog_device {
const struct attribute_group **groups;
const struct watchdog_info *info;
const struct watchdog_ops *ops;
const struct watchdog_governor *gov;
unsigned int bootstatus;
unsigned int timeout;
unsigned int pretimeout;
......@@ -75,6 +76,7 @@ It contains following fields:
* info: a pointer to a watchdog_info structure. This structure gives some
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.
* gov: a pointer to the assigned watchdog device pretimeout governor or NULL.
* 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.
......@@ -288,3 +290,14 @@ User should follow the following guidelines for setting the priority:
* 128: default restart handler, use if no other handler is expected to be
available, and/or if restart is sufficient to restart the entire system
* 255: highest priority, will preempt all other restart handlers
To raise a pretimeout notification, the following function should be used:
void watchdog_notify_pretimeout(struct watchdog_device *wdd)
The function can be called in the interrupt context. If watchdog pretimeout
governor framework (kbuild CONFIG_WATCHDOG_PRETIMEOUT_GOV symbol) is enabled,
an action is taken by a preconfigured pretimeout governor preassigned to
the watchdog device. If watchdog pretimeout governor framework is not
enabled, watchdog_notify_pretimeout() prints a notification message to
the kernel log buffer.
......@@ -1831,4 +1831,11 @@ config USBPCWATCHDOG
Most people will say N.
comment "Watchdog Pretimeout Governors"
config WATCHDOG_PRETIMEOUT_GOV
bool "Enable watchdog pretimeout governors"
help
The option allows to select watchdog pretimeout governors.
endif # WATCHDOG
......@@ -3,9 +3,12 @@
#
# The WatchDog Timer Driver Core.
watchdog-objs += watchdog_core.o watchdog_dev.o
obj-$(CONFIG_WATCHDOG_CORE) += watchdog.o
watchdog-objs += watchdog_core.o watchdog_dev.o
watchdog-$(CONFIG_WATCHDOG_PRETIMEOUT_GOV) += watchdog_pretimeout.o
# Only one watchdog can succeed. We probe the ISA/PCI/USB based
# watchdog-cards first, then the architecture specific watchdog
# drivers and then the architecture independent "softdog" driver.
......
......@@ -49,6 +49,7 @@
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
#include "watchdog_core.h"
#include "watchdog_pretimeout.h"
/*
* struct watchdog_core_data - watchdog core internal data
......@@ -488,6 +489,16 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_RO(state);
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 DEVICE_ATTR_RO(pretimeout_governor);
static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
int n)
{
......@@ -500,6 +511,10 @@ static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
else if (attr == &dev_attr_pretimeout.attr &&
!(wdd->info->options & WDIOF_PRETIMEOUT))
mode = 0;
else if (attr == &dev_attr_pretimeout_governor.attr &&
(!(wdd->info->options & WDIOF_PRETIMEOUT) ||
!IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
mode = 0;
return mode;
}
......@@ -512,6 +527,7 @@ static struct attribute *wdt_attrs[] = {
&dev_attr_bootstatus.attr,
&dev_attr_status.attr,
&dev_attr_nowayout.attr,
&dev_attr_pretimeout_governor.attr,
NULL,
};
......@@ -989,6 +1005,12 @@ int watchdog_dev_register(struct watchdog_device *wdd)
return PTR_ERR(dev);
}
ret = watchdog_register_pretimeout(wdd);
if (ret) {
device_destroy(&watchdog_class, devno);
watchdog_cdev_unregister(wdd);
}
return ret;
}
......@@ -1002,6 +1024,7 @@ int watchdog_dev_register(struct watchdog_device *wdd)
void watchdog_dev_unregister(struct watchdog_device *wdd)
{
watchdog_unregister_pretimeout(wdd);
device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
watchdog_cdev_unregister(wdd);
}
......
/*
* Copyright (C) 2015-2016 Mentor Graphics
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/watchdog.h>
#include "watchdog_pretimeout.h"
/* Default watchdog pretimeout governor */
static struct watchdog_governor *default_gov;
/* The spinlock protects default_gov, wdd->gov and pretimeout_list */
static DEFINE_SPINLOCK(pretimeout_lock);
/* List of watchdog devices, which can generate a pretimeout event */
static LIST_HEAD(pretimeout_list);
struct watchdog_pretimeout {
struct watchdog_device *wdd;
struct list_head entry;
};
int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf)
{
int count = 0;
spin_lock_irq(&pretimeout_lock);
if (wdd->gov)
count = sprintf(buf, "%s\n", wdd->gov->name);
spin_unlock_irq(&pretimeout_lock);
return count;
}
void watchdog_notify_pretimeout(struct watchdog_device *wdd)
{
unsigned long flags;
spin_lock_irqsave(&pretimeout_lock, flags);
if (!wdd->gov) {
spin_unlock_irqrestore(&pretimeout_lock, flags);
return;
}
wdd->gov->pretimeout(wdd);
spin_unlock_irqrestore(&pretimeout_lock, flags);
}
EXPORT_SYMBOL_GPL(watchdog_notify_pretimeout);
int watchdog_register_governor(struct watchdog_governor *gov)
{
struct watchdog_pretimeout *p;
if (!default_gov) {
spin_lock_irq(&pretimeout_lock);
default_gov = gov;
list_for_each_entry(p, &pretimeout_list, entry)
if (!p->wdd->gov)
p->wdd->gov = default_gov;
spin_unlock_irq(&pretimeout_lock);
}
return 0;
}
EXPORT_SYMBOL(watchdog_register_governor);
void watchdog_unregister_governor(struct watchdog_governor *gov)
{
struct watchdog_pretimeout *p;
spin_lock_irq(&pretimeout_lock);
if (gov == default_gov)
default_gov = NULL;
list_for_each_entry(p, &pretimeout_list, entry)
if (p->wdd->gov == gov)
p->wdd->gov = default_gov;
spin_unlock_irq(&pretimeout_lock);
}
EXPORT_SYMBOL(watchdog_unregister_governor);
int watchdog_register_pretimeout(struct watchdog_device *wdd)
{
struct watchdog_pretimeout *p;
if (!(wdd->info->options & WDIOF_PRETIMEOUT))
return 0;
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p)
return -ENOMEM;
spin_lock_irq(&pretimeout_lock);
list_add(&p->entry, &pretimeout_list);
p->wdd = wdd;
wdd->gov = default_gov;
spin_unlock_irq(&pretimeout_lock);
return 0;
}
void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
{
struct watchdog_pretimeout *p, *t;
if (!(wdd->info->options & WDIOF_PRETIMEOUT))
return;
spin_lock_irq(&pretimeout_lock);
wdd->gov = NULL;
list_for_each_entry_safe(p, t, &pretimeout_list, entry) {
if (p->wdd == wdd) {
list_del(&p->entry);
break;
}
}
spin_unlock_irq(&pretimeout_lock);
kfree(p);
}
#ifndef __WATCHDOG_PRETIMEOUT_H
#define __WATCHDOG_PRETIMEOUT_H
#define WATCHDOG_GOV_NAME_MAXLEN 20
struct watchdog_device;
struct watchdog_governor {
const char name[WATCHDOG_GOV_NAME_MAXLEN];
void (*pretimeout)(struct watchdog_device *wdd);
};
#if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)
/* Interfaces to watchdog pretimeout governors */
int watchdog_register_governor(struct watchdog_governor *gov);
void watchdog_unregister_governor(struct watchdog_governor *gov);
/* Interfaces to watchdog_dev.c */
int watchdog_register_pretimeout(struct watchdog_device *wdd);
void watchdog_unregister_pretimeout(struct watchdog_device *wdd);
int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf);
#else
static inline int watchdog_register_pretimeout(struct watchdog_device *wdd)
{
return 0;
}
static inline void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
{
}
static inline int watchdog_pretimeout_governor_get(struct watchdog_device *wdd,
char *buf)
{
return -EINVAL;
}
#endif
#endif
......@@ -19,6 +19,7 @@
struct watchdog_ops;
struct watchdog_device;
struct watchdog_core_data;
struct watchdog_governor;
/** struct watchdog_ops - The watchdog-devices operations
*
......@@ -61,6 +62,7 @@ struct watchdog_ops {
* watchdog device.
* @info: Pointer to a watchdog_info structure.
* @ops: Pointer to the list of watchdog operations.
* @gov: Pointer to watchdog pretimeout governor.
* @bootstatus: Status of the watchdog device at boot.
* @timeout: The watchdog devices timeout value (in seconds).
* @pretimeout: The watchdog devices pre_timeout value.
......@@ -97,6 +99,7 @@ struct watchdog_device {
const struct attribute_group **groups;
const struct watchdog_info *info;
const struct watchdog_ops *ops;
const struct watchdog_governor *gov;
unsigned int bootstatus;
unsigned int timeout;
unsigned int pretimeout;
......@@ -185,6 +188,16 @@ static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
return wdd->driver_data;
}
/* Use the following functions to report watchdog pretimeout event */
#if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)
void watchdog_notify_pretimeout(struct watchdog_device *wdd);
#else
static inline void watchdog_notify_pretimeout(struct watchdog_device *wdd)
{
pr_alert("watchdog%d: pretimeout event\n", wdd->id);
}
#endif
/* drivers/watchdog/watchdog_core.c */
void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
extern int watchdog_init_timeout(struct watchdog_device *wdd,
......
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