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![Guenter Roeck](/assets/img/avatar_default.png)
The use of WDOG_HW_RUNNING is currently inconsistent: If set by the driver, it will remain set until the watchdog device is opened and then closed. If set by the watchdog core, it is only set if the watchdog can not be stopped when closed. Subsequenty it is always only set while the watchdog is closed and the hardware watchdog is running. This is both misleading and inconsistent: The API states that watchdog_hw_running() indicates that the hardware watchdog is running. This is currently not always the case. Set WDOG_HW_RUNNING whenever a watchdog is successfully started for consistent behavior and to accurately report its status. This means that we no longer have to check for both watchdog_active() and watchdog_hw_running() to check if the watchdog is running because watchdog_hw_running() now implies watchdog_active(). Simplify the code accordingly where warranted. Cc: Wang Wensheng <wangwensheng4@huawei.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20230304161607.1418952-1-linux@roeck-us.net Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
485 lines
13 KiB
C
485 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* watchdog_core.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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* 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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* 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/module.h> /* For EXPORT_SYMBOL/module stuff/... */
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#include <linux/types.h> /* For standard types */
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#include <linux/errno.h> /* For the -ENODEV/... values */
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#include <linux/kernel.h> /* For printk/panic/... */
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#include <linux/reboot.h> /* For restart handler */
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#include <linux/watchdog.h> /* For watchdog specific items */
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#include <linux/init.h> /* For __init/__exit/... */
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#include <linux/idr.h> /* For ida_* macros */
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#include <linux/err.h> /* For IS_ERR macros */
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#include <linux/of.h> /* For of_get_timeout_sec */
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#include <linux/suspend.h>
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#include "watchdog_core.h" /* For watchdog_dev_register/... */
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#define CREATE_TRACE_POINTS
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#include <trace/events/watchdog.h>
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static DEFINE_IDA(watchdog_ida);
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static int stop_on_reboot = -1;
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module_param(stop_on_reboot, int, 0444);
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MODULE_PARM_DESC(stop_on_reboot, "Stop watchdogs on reboot (0=keep watching, 1=stop)");
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/*
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* Deferred Registration infrastructure.
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*
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* Sometimes watchdog drivers needs to be loaded as soon as possible,
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* for example when it's impossible to disable it. To do so,
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* raising the initcall level of the watchdog driver is a solution.
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* But in such case, the miscdev is maybe not ready (subsys_initcall), and
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* watchdog_core need miscdev to register the watchdog as a char device.
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*
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* The deferred registration infrastructure offer a way for the watchdog
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* subsystem to register a watchdog properly, even before miscdev is ready.
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*/
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static DEFINE_MUTEX(wtd_deferred_reg_mutex);
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static LIST_HEAD(wtd_deferred_reg_list);
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static bool wtd_deferred_reg_done;
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static void watchdog_deferred_registration_add(struct watchdog_device *wdd)
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{
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list_add_tail(&wdd->deferred,
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&wtd_deferred_reg_list);
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}
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static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
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{
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struct list_head *p, *n;
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struct watchdog_device *wdd_tmp;
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list_for_each_safe(p, n, &wtd_deferred_reg_list) {
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wdd_tmp = list_entry(p, struct watchdog_device,
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deferred);
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if (wdd_tmp == wdd) {
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list_del(&wdd_tmp->deferred);
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break;
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}
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}
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}
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static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
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{
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/*
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* Check that we have valid min and max timeout values, if
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* not reset them both to 0 (=not used or unknown)
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*/
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if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {
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pr_info("Invalid min and max timeout values, resetting to 0!\n");
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wdd->min_timeout = 0;
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wdd->max_timeout = 0;
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}
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}
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/**
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* watchdog_init_timeout() - initialize the timeout field
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* @wdd: watchdog device
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* @timeout_parm: timeout module parameter
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* @dev: Device that stores the timeout-sec property
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*
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* Initialize the timeout field of the watchdog_device struct with either the
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* timeout module parameter (if it is valid value) or the timeout-sec property
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* (only if it is a valid value and the timeout_parm is out of bounds).
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* If none of them are valid then we keep the old value (which should normally
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* be the default timeout value). Note that for the module parameter, '0' means
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* 'use default' while it is an invalid value for the timeout-sec property.
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* It should simply be dropped if you want to use the default value then.
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*
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* A zero is returned on success or -EINVAL if all provided values are out of
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* bounds.
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*/
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int watchdog_init_timeout(struct watchdog_device *wdd,
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unsigned int timeout_parm, struct device *dev)
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{
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const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
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(const char *)wdd->info->identity;
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unsigned int t = 0;
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int ret = 0;
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watchdog_check_min_max_timeout(wdd);
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/* check the driver supplied value (likely a module parameter) first */
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if (timeout_parm) {
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if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
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wdd->timeout = timeout_parm;
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return 0;
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}
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pr_err("%s: driver supplied timeout (%u) out of range\n",
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dev_str, timeout_parm);
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ret = -EINVAL;
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}
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/* try to get the timeout_sec property */
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if (dev && dev->of_node &&
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of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) {
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if (t && !watchdog_timeout_invalid(wdd, t)) {
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wdd->timeout = t;
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return 0;
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}
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pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t);
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ret = -EINVAL;
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}
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if (ret < 0 && wdd->timeout)
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pr_warn("%s: falling back to default timeout (%u)\n", dev_str,
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wdd->timeout);
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return ret;
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}
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EXPORT_SYMBOL_GPL(watchdog_init_timeout);
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static int watchdog_reboot_notifier(struct notifier_block *nb,
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unsigned long code, void *data)
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{
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struct watchdog_device *wdd;
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wdd = container_of(nb, struct watchdog_device, reboot_nb);
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if (code == SYS_DOWN || code == SYS_HALT) {
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if (watchdog_hw_running(wdd)) {
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int ret;
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ret = wdd->ops->stop(wdd);
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trace_watchdog_stop(wdd, ret);
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if (ret)
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return NOTIFY_BAD;
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}
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}
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return NOTIFY_DONE;
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}
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static int watchdog_restart_notifier(struct notifier_block *nb,
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unsigned long action, void *data)
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{
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struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
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restart_nb);
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int ret;
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ret = wdd->ops->restart(wdd, action, data);
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if (ret)
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return NOTIFY_BAD;
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return NOTIFY_DONE;
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}
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static int watchdog_pm_notifier(struct notifier_block *nb, unsigned long mode,
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void *data)
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{
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struct watchdog_device *wdd;
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int ret = 0;
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wdd = container_of(nb, struct watchdog_device, pm_nb);
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switch (mode) {
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case PM_HIBERNATION_PREPARE:
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case PM_RESTORE_PREPARE:
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case PM_SUSPEND_PREPARE:
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ret = watchdog_dev_suspend(wdd);
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break;
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case PM_POST_HIBERNATION:
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case PM_POST_RESTORE:
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case PM_POST_SUSPEND:
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ret = watchdog_dev_resume(wdd);
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break;
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}
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if (ret)
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return NOTIFY_BAD;
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return NOTIFY_DONE;
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}
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/**
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* watchdog_set_restart_priority - Change priority of restart handler
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* @wdd: watchdog device
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* @priority: priority of the restart handler, should follow these guidelines:
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* 0: use watchdog's restart function as last resort, has limited restart
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* capabilies
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* 128: default restart handler, use if no other handler is expected to be
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* available and/or if restart is sufficient to restart the entire system
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* 255: preempt all other handlers
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*
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* If a wdd->ops->restart function is provided when watchdog_register_device is
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* called, it will be registered as a restart handler with the priority given
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* here.
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*/
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void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
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{
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wdd->restart_nb.priority = priority;
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}
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EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
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static int __watchdog_register_device(struct watchdog_device *wdd)
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{
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int ret, id = -1;
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if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
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return -EINVAL;
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/* Mandatory operations need to be supported */
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if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
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return -EINVAL;
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watchdog_check_min_max_timeout(wdd);
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/*
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* Note: now that all watchdog_device data has been verified, we
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* will not check this anymore in other functions. If data gets
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* corrupted in a later stage then we expect a kernel panic!
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*/
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/* Use alias for watchdog id if possible */
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if (wdd->parent) {
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ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
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if (ret >= 0)
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id = ida_simple_get(&watchdog_ida, ret,
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ret + 1, GFP_KERNEL);
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}
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if (id < 0)
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id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
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if (id < 0)
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return id;
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wdd->id = id;
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ret = watchdog_dev_register(wdd);
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if (ret) {
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ida_simple_remove(&watchdog_ida, id);
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if (!(id == 0 && ret == -EBUSY))
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return ret;
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/* Retry in case a legacy watchdog module exists */
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id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
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if (id < 0)
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return id;
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wdd->id = id;
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ret = watchdog_dev_register(wdd);
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if (ret) {
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ida_simple_remove(&watchdog_ida, id);
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return ret;
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}
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}
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/* Module parameter to force watchdog policy on reboot. */
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if (stop_on_reboot != -1) {
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if (stop_on_reboot)
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set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
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else
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clear_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
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}
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if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
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if (!wdd->ops->stop)
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pr_warn("watchdog%d: stop_on_reboot not supported\n", wdd->id);
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else {
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wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
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ret = register_reboot_notifier(&wdd->reboot_nb);
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if (ret) {
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pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
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wdd->id, ret);
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watchdog_dev_unregister(wdd);
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ida_simple_remove(&watchdog_ida, id);
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return ret;
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}
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}
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}
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if (wdd->ops->restart) {
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wdd->restart_nb.notifier_call = watchdog_restart_notifier;
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ret = register_restart_handler(&wdd->restart_nb);
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if (ret)
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pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
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wdd->id, ret);
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}
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if (test_bit(WDOG_NO_PING_ON_SUSPEND, &wdd->status)) {
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wdd->pm_nb.notifier_call = watchdog_pm_notifier;
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ret = register_pm_notifier(&wdd->pm_nb);
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if (ret)
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pr_warn("watchdog%d: Cannot register pm handler (%d)\n",
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wdd->id, ret);
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}
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return 0;
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}
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/**
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* watchdog_register_device() - register a watchdog device
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* @wdd: watchdog device
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*
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* Register a watchdog device with the kernel so that the
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* watchdog timer can be accessed from userspace.
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*
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* A zero is returned on success and a negative errno code for
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* failure.
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*/
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int watchdog_register_device(struct watchdog_device *wdd)
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{
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const char *dev_str;
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int ret = 0;
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mutex_lock(&wtd_deferred_reg_mutex);
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if (wtd_deferred_reg_done)
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ret = __watchdog_register_device(wdd);
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else
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watchdog_deferred_registration_add(wdd);
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mutex_unlock(&wtd_deferred_reg_mutex);
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if (ret) {
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dev_str = wdd->parent ? dev_name(wdd->parent) :
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(const char *)wdd->info->identity;
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pr_err("%s: failed to register watchdog device (err = %d)\n",
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dev_str, ret);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(watchdog_register_device);
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static void __watchdog_unregister_device(struct watchdog_device *wdd)
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{
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if (wdd == NULL)
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return;
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if (wdd->ops->restart)
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unregister_restart_handler(&wdd->restart_nb);
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if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
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unregister_reboot_notifier(&wdd->reboot_nb);
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watchdog_dev_unregister(wdd);
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ida_simple_remove(&watchdog_ida, wdd->id);
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}
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/**
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* watchdog_unregister_device() - unregister a watchdog device
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* @wdd: watchdog device to unregister
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*
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* Unregister a watchdog device that was previously successfully
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* registered with watchdog_register_device().
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*/
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void watchdog_unregister_device(struct watchdog_device *wdd)
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{
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mutex_lock(&wtd_deferred_reg_mutex);
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if (wtd_deferred_reg_done)
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__watchdog_unregister_device(wdd);
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else
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watchdog_deferred_registration_del(wdd);
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mutex_unlock(&wtd_deferred_reg_mutex);
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}
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EXPORT_SYMBOL_GPL(watchdog_unregister_device);
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static void devm_watchdog_unregister_device(struct device *dev, void *res)
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{
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watchdog_unregister_device(*(struct watchdog_device **)res);
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}
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/**
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* devm_watchdog_register_device() - resource managed watchdog_register_device()
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* @dev: device that is registering this watchdog device
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* @wdd: watchdog device
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*
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* Managed watchdog_register_device(). For watchdog device registered by this
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* function, watchdog_unregister_device() is automatically called on driver
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* detach. See watchdog_register_device() for more information.
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*/
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int devm_watchdog_register_device(struct device *dev,
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struct watchdog_device *wdd)
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{
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struct watchdog_device **rcwdd;
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int ret;
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rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
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GFP_KERNEL);
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if (!rcwdd)
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return -ENOMEM;
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ret = watchdog_register_device(wdd);
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if (!ret) {
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*rcwdd = wdd;
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devres_add(dev, rcwdd);
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} else {
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devres_free(rcwdd);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
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static int __init watchdog_deferred_registration(void)
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{
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mutex_lock(&wtd_deferred_reg_mutex);
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wtd_deferred_reg_done = true;
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while (!list_empty(&wtd_deferred_reg_list)) {
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struct watchdog_device *wdd;
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wdd = list_first_entry(&wtd_deferred_reg_list,
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struct watchdog_device, deferred);
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list_del(&wdd->deferred);
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__watchdog_register_device(wdd);
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}
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mutex_unlock(&wtd_deferred_reg_mutex);
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return 0;
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}
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static int __init watchdog_init(void)
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{
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int err;
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err = watchdog_dev_init();
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if (err < 0)
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return err;
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watchdog_deferred_registration();
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return 0;
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}
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static void __exit watchdog_exit(void)
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{
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watchdog_dev_exit();
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ida_destroy(&watchdog_ida);
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}
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subsys_initcall_sync(watchdog_init);
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module_exit(watchdog_exit);
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MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
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MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
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MODULE_DESCRIPTION("WatchDog Timer Driver Core");
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MODULE_LICENSE("GPL");
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