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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2015-2016 Mentor Graphics
*/
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/watchdog.h>
#include "watchdog_core.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;
};
/* The mutex protects governor list and serializes external interfaces */
static DEFINE_MUTEX(governor_lock);
/* List of the registered watchdog pretimeout governors */
static LIST_HEAD(governor_list);
struct governor_priv {
struct watchdog_governor *gov;
struct list_head entry;
};
static struct governor_priv *find_governor_by_name(const char *gov_name)
{
struct governor_priv *priv;
list_for_each_entry(priv, &governor_list, entry)
if (sysfs_streq(gov_name, priv->gov->name))
return priv;
return NULL;
}
int watchdog_pretimeout_available_governors_get(char *buf)
{
struct governor_priv *priv;
int count = 0;
mutex_lock(&governor_lock);
list_for_each_entry(priv, &governor_list, entry)
count += sysfs_emit_at(buf, count, "%s\n", priv->gov->name);
mutex_unlock(&governor_lock);
return count;
}
int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf)
{
int count = 0;
spin_lock_irq(&pretimeout_lock);
if (wdd->gov)
count = sysfs_emit(buf, "%s\n", wdd->gov->name);
spin_unlock_irq(&pretimeout_lock);
return count;
}
int watchdog_pretimeout_governor_set(struct watchdog_device *wdd,
const char *buf)
{
struct governor_priv *priv;
mutex_lock(&governor_lock);
priv = find_governor_by_name(buf);
if (!priv) {
mutex_unlock(&governor_lock);
return -EINVAL;
}
spin_lock_irq(&pretimeout_lock);
wdd->gov = priv->gov;
spin_unlock_irq(&pretimeout_lock);
mutex_unlock(&governor_lock);
return 0;
}
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;
struct governor_priv *priv;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
mutex_lock(&governor_lock);
if (find_governor_by_name(gov->name)) {
mutex_unlock(&governor_lock);
kfree(priv);
return -EBUSY;
}
priv->gov = gov;
list_add(&priv->entry, &governor_list);
if (!strncmp(gov->name, WATCHDOG_PRETIMEOUT_DEFAULT_GOV,
WATCHDOG_GOV_NAME_MAXLEN)) {
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);
}
mutex_unlock(&governor_lock);
return 0;
}
EXPORT_SYMBOL(watchdog_register_governor);
void watchdog_unregister_governor(struct watchdog_governor *gov)
{
struct watchdog_pretimeout *p;
struct governor_priv *priv, *t;
mutex_lock(&governor_lock);
list_for_each_entry_safe(priv, t, &governor_list, entry) {
if (priv->gov == gov) {
list_del(&priv->entry);
kfree(priv);
break;
}
}
spin_lock_irq(&pretimeout_lock);
list_for_each_entry(p, &pretimeout_list, entry)
if (p->wdd->gov == gov)
p->wdd->gov = default_gov;
spin_unlock_irq(&pretimeout_lock);
mutex_unlock(&governor_lock);
}
EXPORT_SYMBOL(watchdog_unregister_governor);
int watchdog_register_pretimeout(struct watchdog_device *wdd)
{
struct watchdog_pretimeout *p;
if (!watchdog_have_pretimeout(wdd))
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 (!watchdog_have_pretimeout(wdd))
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);
}
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