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The change adds panic watchdog pretimeout governor, on watchdog pretimeout event the kernel shall panic. In general watchdog pretimeout event means that something essentially bad is going on the system, for example a process scheduler stalls or watchdog feeder is killed due to OOM, so printing out information attendant to panic and before likely unavoidable reboot caused by a watchdog may help to determine a root cause of the issue. Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
130 lines
2.9 KiB
C
130 lines
2.9 KiB
C
/*
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* Copyright (C) 2015-2016 Mentor Graphics
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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*/
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#include <linux/list.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/watchdog.h>
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#include "watchdog_pretimeout.h"
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/* Default watchdog pretimeout governor */
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static struct watchdog_governor *default_gov;
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/* The spinlock protects default_gov, wdd->gov and pretimeout_list */
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static DEFINE_SPINLOCK(pretimeout_lock);
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/* List of watchdog devices, which can generate a pretimeout event */
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static LIST_HEAD(pretimeout_list);
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struct watchdog_pretimeout {
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struct watchdog_device *wdd;
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struct list_head entry;
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};
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int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf)
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{
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int count = 0;
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spin_lock_irq(&pretimeout_lock);
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if (wdd->gov)
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count = sprintf(buf, "%s\n", wdd->gov->name);
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spin_unlock_irq(&pretimeout_lock);
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return count;
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}
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void watchdog_notify_pretimeout(struct watchdog_device *wdd)
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{
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unsigned long flags;
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spin_lock_irqsave(&pretimeout_lock, flags);
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if (!wdd->gov) {
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spin_unlock_irqrestore(&pretimeout_lock, flags);
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return;
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}
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wdd->gov->pretimeout(wdd);
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spin_unlock_irqrestore(&pretimeout_lock, flags);
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}
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EXPORT_SYMBOL_GPL(watchdog_notify_pretimeout);
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int watchdog_register_governor(struct watchdog_governor *gov)
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{
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struct watchdog_pretimeout *p;
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if (!strncmp(gov->name, WATCHDOG_PRETIMEOUT_DEFAULT_GOV,
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WATCHDOG_GOV_NAME_MAXLEN)) {
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spin_lock_irq(&pretimeout_lock);
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default_gov = gov;
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list_for_each_entry(p, &pretimeout_list, entry)
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if (!p->wdd->gov)
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p->wdd->gov = default_gov;
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spin_unlock_irq(&pretimeout_lock);
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}
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return 0;
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}
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EXPORT_SYMBOL(watchdog_register_governor);
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void watchdog_unregister_governor(struct watchdog_governor *gov)
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{
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struct watchdog_pretimeout *p;
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spin_lock_irq(&pretimeout_lock);
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list_for_each_entry(p, &pretimeout_list, entry)
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if (p->wdd->gov == gov)
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p->wdd->gov = default_gov;
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spin_unlock_irq(&pretimeout_lock);
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}
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EXPORT_SYMBOL(watchdog_unregister_governor);
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int watchdog_register_pretimeout(struct watchdog_device *wdd)
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{
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struct watchdog_pretimeout *p;
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if (!(wdd->info->options & WDIOF_PRETIMEOUT))
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return 0;
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p = kzalloc(sizeof(*p), GFP_KERNEL);
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if (!p)
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return -ENOMEM;
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spin_lock_irq(&pretimeout_lock);
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list_add(&p->entry, &pretimeout_list);
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p->wdd = wdd;
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wdd->gov = default_gov;
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spin_unlock_irq(&pretimeout_lock);
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return 0;
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}
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void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
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{
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struct watchdog_pretimeout *p, *t;
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if (!(wdd->info->options & WDIOF_PRETIMEOUT))
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return;
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spin_lock_irq(&pretimeout_lock);
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wdd->gov = NULL;
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list_for_each_entry_safe(p, t, &pretimeout_list, entry) {
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if (p->wdd == wdd) {
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list_del(&p->entry);
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break;
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}
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}
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spin_unlock_irq(&pretimeout_lock);
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kfree(p);
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}
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