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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: Vladimir Zapolskiy <[email protected]> Reviewed-by: Guenter Roeck <[email protected]> Reviewed-by: Wolfram Sang <[email protected]> Tested-by: Wolfram Sang <[email protected]> Signed-off-by: Guenter Roeck <[email protected]> Signed-off-by: Wim Van Sebroeck <[email protected]>
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Vladimir Zapolskiy
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Wim Van Sebroeck
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Oct 8, 2016
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,131 @@ | ||
| /* | ||
| * 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. | ||
| * | ||
| */ | ||
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| #include <linux/list.h> | ||
| #include <linux/slab.h> | ||
| #include <linux/spinlock.h> | ||
| #include <linux/watchdog.h> | ||
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| #include "watchdog_pretimeout.h" | ||
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| /* Default watchdog pretimeout governor */ | ||
| static struct watchdog_governor *default_gov; | ||
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| /* The spinlock protects default_gov, wdd->gov and pretimeout_list */ | ||
| static DEFINE_SPINLOCK(pretimeout_lock); | ||
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| /* List of watchdog devices, which can generate a pretimeout event */ | ||
| static LIST_HEAD(pretimeout_list); | ||
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| struct watchdog_pretimeout { | ||
| struct watchdog_device *wdd; | ||
| struct list_head entry; | ||
| }; | ||
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| int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf) | ||
| { | ||
| int count = 0; | ||
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| spin_lock_irq(&pretimeout_lock); | ||
| if (wdd->gov) | ||
| count = sprintf(buf, "%s\n", wdd->gov->name); | ||
| spin_unlock_irq(&pretimeout_lock); | ||
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| return count; | ||
| } | ||
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| void watchdog_notify_pretimeout(struct watchdog_device *wdd) | ||
| { | ||
| unsigned long flags; | ||
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| spin_lock_irqsave(&pretimeout_lock, flags); | ||
| if (!wdd->gov) { | ||
| spin_unlock_irqrestore(&pretimeout_lock, flags); | ||
| return; | ||
| } | ||
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| wdd->gov->pretimeout(wdd); | ||
| spin_unlock_irqrestore(&pretimeout_lock, flags); | ||
| } | ||
| EXPORT_SYMBOL_GPL(watchdog_notify_pretimeout); | ||
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| int watchdog_register_governor(struct watchdog_governor *gov) | ||
| { | ||
| struct watchdog_pretimeout *p; | ||
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| if (!default_gov) { | ||
| spin_lock_irq(&pretimeout_lock); | ||
| default_gov = gov; | ||
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| list_for_each_entry(p, &pretimeout_list, entry) | ||
| if (!p->wdd->gov) | ||
| p->wdd->gov = default_gov; | ||
| spin_unlock_irq(&pretimeout_lock); | ||
| } | ||
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| return 0; | ||
| } | ||
| EXPORT_SYMBOL(watchdog_register_governor); | ||
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| void watchdog_unregister_governor(struct watchdog_governor *gov) | ||
| { | ||
| struct watchdog_pretimeout *p; | ||
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| spin_lock_irq(&pretimeout_lock); | ||
| if (gov == default_gov) | ||
| default_gov = NULL; | ||
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| 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); | ||
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| int watchdog_register_pretimeout(struct watchdog_device *wdd) | ||
| { | ||
| struct watchdog_pretimeout *p; | ||
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| if (!(wdd->info->options & WDIOF_PRETIMEOUT)) | ||
| return 0; | ||
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| p = kzalloc(sizeof(*p), GFP_KERNEL); | ||
| if (!p) | ||
| return -ENOMEM; | ||
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| spin_lock_irq(&pretimeout_lock); | ||
| list_add(&p->entry, &pretimeout_list); | ||
| p->wdd = wdd; | ||
| wdd->gov = default_gov; | ||
| spin_unlock_irq(&pretimeout_lock); | ||
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| return 0; | ||
| } | ||
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| void watchdog_unregister_pretimeout(struct watchdog_device *wdd) | ||
| { | ||
| struct watchdog_pretimeout *p, *t; | ||
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| if (!(wdd->info->options & WDIOF_PRETIMEOUT)) | ||
| return; | ||
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| spin_lock_irq(&pretimeout_lock); | ||
| wdd->gov = NULL; | ||
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| list_for_each_entry_safe(p, t, &pretimeout_list, entry) { | ||
| if (p->wdd == wdd) { | ||
| list_del(&p->entry); | ||
| break; | ||
| } | ||
| } | ||
| spin_unlock_irq(&pretimeout_lock); | ||
|
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| kfree(p); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,40 @@ | ||
| #ifndef __WATCHDOG_PRETIMEOUT_H | ||
| #define __WATCHDOG_PRETIMEOUT_H | ||
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| #define WATCHDOG_GOV_NAME_MAXLEN 20 | ||
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| struct watchdog_device; | ||
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| struct watchdog_governor { | ||
| const char name[WATCHDOG_GOV_NAME_MAXLEN]; | ||
| void (*pretimeout)(struct watchdog_device *wdd); | ||
| }; | ||
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| #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); | ||
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| /* 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); | ||
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| #else | ||
| static inline int watchdog_register_pretimeout(struct watchdog_device *wdd) | ||
| { | ||
| return 0; | ||
| } | ||
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| static inline void watchdog_unregister_pretimeout(struct watchdog_device *wdd) | ||
| { | ||
| } | ||
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| static inline int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, | ||
| char *buf) | ||
| { | ||
| return -EINVAL; | ||
| } | ||
| #endif | ||
|
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| #endif |
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