mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-05 18:14:07 +08:00
9232c80659
Many watchdog drivers use watchdog_stop_on_reboot() helper in order to stop the watchdog on system reboot. Unfortunately, this logic is coded in driver's probe function and doesn't allows user to decide what to do during shutdown/reboot. On the other side, Xen and Qemu watchdog drivers (xen_wdt and i6300esb) may be configured to either send NMI or turn off/reboot VM as the watchdog action. As the kernel may stuck at any state, sending NMIs can't reliably reboot the VM. At Arista, we benefited from the following set-up: the emulated watchdogs trigger VM reset and softdog is set to catch less severe conditions to generate vmcore. Just before reboot watchdog's timeout is increased to some good-enough value (3 mins). That keeps watchdog always running and guarantees that VM doesn't stuck. Provide new stop_on_reboot module parameter to let user control watchdog's reboot policy. Cc: Guenter Roeck <linux@roeck-us.net> Cc: Wim Van Sebroeck <wim@linux-watchdog.org> Cc: linux-watchdog@vger.kernel.org Signed-off-by: Dmitry Safonov <dima@arista.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20200223114939.194754-1-dima@arista.com Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
441 lines
12 KiB
C
441 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0+
|
|
/*
|
|
* watchdog_core.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.
|
|
*
|
|
* 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/module.h> /* For EXPORT_SYMBOL/module stuff/... */
|
|
#include <linux/types.h> /* For standard types */
|
|
#include <linux/errno.h> /* For the -ENODEV/... values */
|
|
#include <linux/kernel.h> /* For printk/panic/... */
|
|
#include <linux/reboot.h> /* For restart handler */
|
|
#include <linux/watchdog.h> /* For watchdog specific items */
|
|
#include <linux/init.h> /* For __init/__exit/... */
|
|
#include <linux/idr.h> /* For ida_* macros */
|
|
#include <linux/err.h> /* For IS_ERR macros */
|
|
#include <linux/of.h> /* For of_get_timeout_sec */
|
|
|
|
#include "watchdog_core.h" /* For watchdog_dev_register/... */
|
|
|
|
static DEFINE_IDA(watchdog_ida);
|
|
|
|
static int stop_on_reboot = -1;
|
|
module_param(stop_on_reboot, int, 0444);
|
|
MODULE_PARM_DESC(stop_on_reboot, "Stop watchdogs on reboot (0=keep watching, 1=stop)");
|
|
|
|
/*
|
|
* Deferred Registration infrastructure.
|
|
*
|
|
* Sometimes watchdog drivers needs to be loaded as soon as possible,
|
|
* for example when it's impossible to disable it. To do so,
|
|
* raising the initcall level of the watchdog driver is a solution.
|
|
* But in such case, the miscdev is maybe not ready (subsys_initcall), and
|
|
* watchdog_core need miscdev to register the watchdog as a char device.
|
|
*
|
|
* The deferred registration infrastructure offer a way for the watchdog
|
|
* subsystem to register a watchdog properly, even before miscdev is ready.
|
|
*/
|
|
|
|
static DEFINE_MUTEX(wtd_deferred_reg_mutex);
|
|
static LIST_HEAD(wtd_deferred_reg_list);
|
|
static bool wtd_deferred_reg_done;
|
|
|
|
static void watchdog_deferred_registration_add(struct watchdog_device *wdd)
|
|
{
|
|
list_add_tail(&wdd->deferred,
|
|
&wtd_deferred_reg_list);
|
|
}
|
|
|
|
static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
|
|
{
|
|
struct list_head *p, *n;
|
|
struct watchdog_device *wdd_tmp;
|
|
|
|
list_for_each_safe(p, n, &wtd_deferred_reg_list) {
|
|
wdd_tmp = list_entry(p, struct watchdog_device,
|
|
deferred);
|
|
if (wdd_tmp == wdd) {
|
|
list_del(&wdd_tmp->deferred);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
|
|
{
|
|
/*
|
|
* Check that we have valid min and max timeout values, if
|
|
* not reset them both to 0 (=not used or unknown)
|
|
*/
|
|
if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {
|
|
pr_info("Invalid min and max timeout values, resetting to 0!\n");
|
|
wdd->min_timeout = 0;
|
|
wdd->max_timeout = 0;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* watchdog_init_timeout() - initialize the timeout field
|
|
* @wdd: watchdog device
|
|
* @timeout_parm: timeout module parameter
|
|
* @dev: Device that stores the timeout-sec property
|
|
*
|
|
* Initialize the timeout field of the watchdog_device struct with either the
|
|
* timeout module parameter (if it is valid value) or the timeout-sec property
|
|
* (only if it is a valid value and the timeout_parm is out of bounds).
|
|
* If none of them are valid then we keep the old value (which should normally
|
|
* be the default timeout value). Note that for the module parameter, '0' means
|
|
* 'use default' while it is an invalid value for the timeout-sec property.
|
|
* It should simply be dropped if you want to use the default value then.
|
|
*
|
|
* A zero is returned on success or -EINVAL if all provided values are out of
|
|
* bounds.
|
|
*/
|
|
int watchdog_init_timeout(struct watchdog_device *wdd,
|
|
unsigned int timeout_parm, struct device *dev)
|
|
{
|
|
const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
|
|
(const char *)wdd->info->identity;
|
|
unsigned int t = 0;
|
|
int ret = 0;
|
|
|
|
watchdog_check_min_max_timeout(wdd);
|
|
|
|
/* check the driver supplied value (likely a module parameter) first */
|
|
if (timeout_parm) {
|
|
if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
|
|
wdd->timeout = timeout_parm;
|
|
return 0;
|
|
}
|
|
pr_err("%s: driver supplied timeout (%u) out of range\n",
|
|
dev_str, timeout_parm);
|
|
ret = -EINVAL;
|
|
}
|
|
|
|
/* try to get the timeout_sec property */
|
|
if (dev && dev->of_node &&
|
|
of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) {
|
|
if (t && !watchdog_timeout_invalid(wdd, t)) {
|
|
wdd->timeout = t;
|
|
return 0;
|
|
}
|
|
pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t);
|
|
ret = -EINVAL;
|
|
}
|
|
|
|
if (ret < 0 && wdd->timeout)
|
|
pr_warn("%s: falling back to default timeout (%u)\n", dev_str,
|
|
wdd->timeout);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(watchdog_init_timeout);
|
|
|
|
static int watchdog_reboot_notifier(struct notifier_block *nb,
|
|
unsigned long code, void *data)
|
|
{
|
|
struct watchdog_device *wdd;
|
|
|
|
wdd = container_of(nb, struct watchdog_device, reboot_nb);
|
|
if (code == SYS_DOWN || code == SYS_HALT) {
|
|
if (watchdog_active(wdd)) {
|
|
int ret;
|
|
|
|
ret = wdd->ops->stop(wdd);
|
|
if (ret)
|
|
return NOTIFY_BAD;
|
|
}
|
|
}
|
|
|
|
return NOTIFY_DONE;
|
|
}
|
|
|
|
static int watchdog_restart_notifier(struct notifier_block *nb,
|
|
unsigned long action, void *data)
|
|
{
|
|
struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
|
|
restart_nb);
|
|
|
|
int ret;
|
|
|
|
ret = wdd->ops->restart(wdd, action, data);
|
|
if (ret)
|
|
return NOTIFY_BAD;
|
|
|
|
return NOTIFY_DONE;
|
|
}
|
|
|
|
/**
|
|
* watchdog_set_restart_priority - Change priority of restart handler
|
|
* @wdd: watchdog device
|
|
* @priority: priority of the restart handler, should follow these guidelines:
|
|
* 0: use watchdog's restart function as last resort, has limited restart
|
|
* capabilies
|
|
* 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: preempt all other handlers
|
|
*
|
|
* If a wdd->ops->restart function is provided when watchdog_register_device is
|
|
* called, it will be registered as a restart handler with the priority given
|
|
* here.
|
|
*/
|
|
void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
|
|
{
|
|
wdd->restart_nb.priority = priority;
|
|
}
|
|
EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
|
|
|
|
static int __watchdog_register_device(struct watchdog_device *wdd)
|
|
{
|
|
int ret, id = -1;
|
|
|
|
if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
|
|
return -EINVAL;
|
|
|
|
/* Mandatory operations need to be supported */
|
|
if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
|
|
return -EINVAL;
|
|
|
|
watchdog_check_min_max_timeout(wdd);
|
|
|
|
/*
|
|
* Note: now that all watchdog_device data has been verified, we
|
|
* will not check this anymore in other functions. If data gets
|
|
* corrupted in a later stage then we expect a kernel panic!
|
|
*/
|
|
|
|
/* Use alias for watchdog id if possible */
|
|
if (wdd->parent) {
|
|
ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
|
|
if (ret >= 0)
|
|
id = ida_simple_get(&watchdog_ida, ret,
|
|
ret + 1, GFP_KERNEL);
|
|
}
|
|
|
|
if (id < 0)
|
|
id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
|
|
|
|
if (id < 0)
|
|
return id;
|
|
wdd->id = id;
|
|
|
|
ret = watchdog_dev_register(wdd);
|
|
if (ret) {
|
|
ida_simple_remove(&watchdog_ida, id);
|
|
if (!(id == 0 && ret == -EBUSY))
|
|
return ret;
|
|
|
|
/* Retry in case a legacy watchdog module exists */
|
|
id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
|
|
if (id < 0)
|
|
return id;
|
|
wdd->id = id;
|
|
|
|
ret = watchdog_dev_register(wdd);
|
|
if (ret) {
|
|
ida_simple_remove(&watchdog_ida, id);
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
/* Module parameter to force watchdog policy on reboot. */
|
|
if (stop_on_reboot != -1) {
|
|
if (stop_on_reboot)
|
|
set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
|
|
else
|
|
clear_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
|
|
}
|
|
|
|
if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
|
|
wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
|
|
|
|
ret = register_reboot_notifier(&wdd->reboot_nb);
|
|
if (ret) {
|
|
pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
|
|
wdd->id, ret);
|
|
watchdog_dev_unregister(wdd);
|
|
ida_simple_remove(&watchdog_ida, id);
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
if (wdd->ops->restart) {
|
|
wdd->restart_nb.notifier_call = watchdog_restart_notifier;
|
|
|
|
ret = register_restart_handler(&wdd->restart_nb);
|
|
if (ret)
|
|
pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
|
|
wdd->id, ret);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* watchdog_register_device() - register a watchdog device
|
|
* @wdd: watchdog device
|
|
*
|
|
* Register a watchdog device with the kernel so that the
|
|
* watchdog timer can be accessed from userspace.
|
|
*
|
|
* A zero is returned on success and a negative errno code for
|
|
* failure.
|
|
*/
|
|
|
|
int watchdog_register_device(struct watchdog_device *wdd)
|
|
{
|
|
const char *dev_str;
|
|
int ret = 0;
|
|
|
|
mutex_lock(&wtd_deferred_reg_mutex);
|
|
if (wtd_deferred_reg_done)
|
|
ret = __watchdog_register_device(wdd);
|
|
else
|
|
watchdog_deferred_registration_add(wdd);
|
|
mutex_unlock(&wtd_deferred_reg_mutex);
|
|
|
|
if (ret) {
|
|
dev_str = wdd->parent ? dev_name(wdd->parent) :
|
|
(const char *)wdd->info->identity;
|
|
pr_err("%s: failed to register watchdog device (err = %d)\n",
|
|
dev_str, ret);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(watchdog_register_device);
|
|
|
|
static void __watchdog_unregister_device(struct watchdog_device *wdd)
|
|
{
|
|
if (wdd == NULL)
|
|
return;
|
|
|
|
if (wdd->ops->restart)
|
|
unregister_restart_handler(&wdd->restart_nb);
|
|
|
|
if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
|
|
unregister_reboot_notifier(&wdd->reboot_nb);
|
|
|
|
watchdog_dev_unregister(wdd);
|
|
ida_simple_remove(&watchdog_ida, wdd->id);
|
|
}
|
|
|
|
/**
|
|
* watchdog_unregister_device() - unregister a watchdog device
|
|
* @wdd: watchdog device to unregister
|
|
*
|
|
* Unregister a watchdog device that was previously successfully
|
|
* registered with watchdog_register_device().
|
|
*/
|
|
|
|
void watchdog_unregister_device(struct watchdog_device *wdd)
|
|
{
|
|
mutex_lock(&wtd_deferred_reg_mutex);
|
|
if (wtd_deferred_reg_done)
|
|
__watchdog_unregister_device(wdd);
|
|
else
|
|
watchdog_deferred_registration_del(wdd);
|
|
mutex_unlock(&wtd_deferred_reg_mutex);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(watchdog_unregister_device);
|
|
|
|
static void devm_watchdog_unregister_device(struct device *dev, void *res)
|
|
{
|
|
watchdog_unregister_device(*(struct watchdog_device **)res);
|
|
}
|
|
|
|
/**
|
|
* devm_watchdog_register_device() - resource managed watchdog_register_device()
|
|
* @dev: device that is registering this watchdog device
|
|
* @wdd: watchdog device
|
|
*
|
|
* Managed watchdog_register_device(). For watchdog device registered by this
|
|
* function, watchdog_unregister_device() is automatically called on driver
|
|
* detach. See watchdog_register_device() for more information.
|
|
*/
|
|
int devm_watchdog_register_device(struct device *dev,
|
|
struct watchdog_device *wdd)
|
|
{
|
|
struct watchdog_device **rcwdd;
|
|
int ret;
|
|
|
|
rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
|
|
GFP_KERNEL);
|
|
if (!rcwdd)
|
|
return -ENOMEM;
|
|
|
|
ret = watchdog_register_device(wdd);
|
|
if (!ret) {
|
|
*rcwdd = wdd;
|
|
devres_add(dev, rcwdd);
|
|
} else {
|
|
devres_free(rcwdd);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
|
|
|
|
static int __init watchdog_deferred_registration(void)
|
|
{
|
|
mutex_lock(&wtd_deferred_reg_mutex);
|
|
wtd_deferred_reg_done = true;
|
|
while (!list_empty(&wtd_deferred_reg_list)) {
|
|
struct watchdog_device *wdd;
|
|
|
|
wdd = list_first_entry(&wtd_deferred_reg_list,
|
|
struct watchdog_device, deferred);
|
|
list_del(&wdd->deferred);
|
|
__watchdog_register_device(wdd);
|
|
}
|
|
mutex_unlock(&wtd_deferred_reg_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int __init watchdog_init(void)
|
|
{
|
|
int err;
|
|
|
|
err = watchdog_dev_init();
|
|
if (err < 0)
|
|
return err;
|
|
|
|
watchdog_deferred_registration();
|
|
return 0;
|
|
}
|
|
|
|
static void __exit watchdog_exit(void)
|
|
{
|
|
watchdog_dev_exit();
|
|
ida_destroy(&watchdog_ida);
|
|
}
|
|
|
|
subsys_initcall_sync(watchdog_init);
|
|
module_exit(watchdog_exit);
|
|
|
|
MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
|
|
MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
|
|
MODULE_DESCRIPTION("WatchDog Timer Driver Core");
|
|
MODULE_LICENSE("GPL");
|