From da0d12ff2b829a35e9921918e925d79497b82bef Mon Sep 17 00:00:00 2001 From: Vladimir Zapolskiy Date: Fri, 7 Oct 2016 15:39:56 +0300 Subject: [PATCH] watchdog: pretimeout: add panic pretimeout governor 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 Reviewed-by: Guenter Roeck Reviewed-by: Wolfram Sang Tested-by: Wolfram Sang Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/Kconfig | 14 ++++++++++ drivers/watchdog/Makefile | 1 + drivers/watchdog/pretimeout_panic.c | 47 ++++++++++++++++++++++++++++++++++ drivers/watchdog/watchdog_pretimeout.c | 6 ++--- drivers/watchdog/watchdog_pretimeout.h | 2 ++ 5 files changed, 66 insertions(+), 4 deletions(-) create mode 100644 drivers/watchdog/pretimeout_panic.c diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index 4aeb8f9..cbd3332 100644 --- a/drivers/watchdog/Kconfig +++ b/drivers/watchdog/Kconfig @@ -1856,6 +1856,14 @@ config WATCHDOG_PRETIMEOUT_DEFAULT_GOV_NOOP governor is selected by a user, write a short message to the kernel log buffer and don't do any system changes. +config WATCHDOG_PRETIMEOUT_DEFAULT_GOV_PANIC + bool "panic" + select WATCHDOG_PRETIMEOUT_GOV_PANIC + help + Use panic watchdog pretimeout governor by default, if + a watchdog pretimeout event happens, consider that + a watchdog feeder is dead and reboot is unavoidable. + endchoice config WATCHDOG_PRETIMEOUT_GOV_NOOP @@ -1864,6 +1872,12 @@ config WATCHDOG_PRETIMEOUT_GOV_NOOP Noop watchdog pretimeout governor, only an informational message is added to kernel log buffer. +config WATCHDOG_PRETIMEOUT_GOV_PANIC + tristate "Panic watchdog pretimeout governor" + help + Panic watchdog pretimeout governor, on watchdog pretimeout + event put the kernel into panic. + endif # WATCHDOG_PRETIMEOUT_GOV endif # WATCHDOG diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index 0502a21..1a34c6a 100644 --- a/drivers/watchdog/Makefile +++ b/drivers/watchdog/Makefile @@ -10,6 +10,7 @@ watchdog-objs += watchdog_core.o watchdog_dev.o watchdog-$(CONFIG_WATCHDOG_PRETIMEOUT_GOV) += watchdog_pretimeout.o obj-$(CONFIG_WATCHDOG_PRETIMEOUT_GOV_NOOP) += pretimeout_noop.o +obj-$(CONFIG_WATCHDOG_PRETIMEOUT_GOV_PANIC) += pretimeout_panic.o # Only one watchdog can succeed. We probe the ISA/PCI/USB based # watchdog-cards first, then the architecture specific watchdog diff --git a/drivers/watchdog/pretimeout_panic.c b/drivers/watchdog/pretimeout_panic.c new file mode 100644 index 0000000..0c197a1 --- /dev/null +++ b/drivers/watchdog/pretimeout_panic.c @@ -0,0 +1,47 @@ +/* + * 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. + * + */ + +#include +#include +#include + +#include "watchdog_pretimeout.h" + +/** + * pretimeout_panic - Panic on watchdog pretimeout event + * @wdd - watchdog_device + * + * Panic, watchdog has not been fed till pretimeout event. + */ +static void pretimeout_panic(struct watchdog_device *wdd) +{ + panic("watchdog pretimeout event\n"); +} + +static struct watchdog_governor watchdog_gov_panic = { + .name = "panic", + .pretimeout = pretimeout_panic, +}; + +static int __init watchdog_gov_panic_register(void) +{ + return watchdog_register_governor(&watchdog_gov_panic); +} + +static void __exit watchdog_gov_panic_unregister(void) +{ + watchdog_unregister_governor(&watchdog_gov_panic); +} +module_init(watchdog_gov_panic_register); +module_exit(watchdog_gov_panic_unregister); + +MODULE_AUTHOR("Vladimir Zapolskiy "); +MODULE_DESCRIPTION("Panic watchdog pretimeout governor"); +MODULE_LICENSE("GPL"); diff --git a/drivers/watchdog/watchdog_pretimeout.c b/drivers/watchdog/watchdog_pretimeout.c index 7261225..098c965 100644 --- a/drivers/watchdog/watchdog_pretimeout.c +++ b/drivers/watchdog/watchdog_pretimeout.c @@ -60,7 +60,8 @@ int watchdog_register_governor(struct watchdog_governor *gov) { struct watchdog_pretimeout *p; - if (!default_gov) { + if (!strncmp(gov->name, WATCHDOG_PRETIMEOUT_DEFAULT_GOV, + WATCHDOG_GOV_NAME_MAXLEN)) { spin_lock_irq(&pretimeout_lock); default_gov = gov; @@ -79,9 +80,6 @@ void watchdog_unregister_governor(struct watchdog_governor *gov) struct watchdog_pretimeout *p; spin_lock_irq(&pretimeout_lock); - if (gov == default_gov) - default_gov = NULL; - list_for_each_entry(p, &pretimeout_list, entry) if (p->wdd->gov == gov) p->wdd->gov = default_gov; diff --git a/drivers/watchdog/watchdog_pretimeout.h b/drivers/watchdog/watchdog_pretimeout.h index c4b6f88..867492a 100644 --- a/drivers/watchdog/watchdog_pretimeout.h +++ b/drivers/watchdog/watchdog_pretimeout.h @@ -22,6 +22,8 @@ int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf); #if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_DEFAULT_GOV_NOOP) #define WATCHDOG_PRETIMEOUT_DEFAULT_GOV "noop" +#elif IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_DEFAULT_GOV_PANIC) +#define WATCHDOG_PRETIMEOUT_DEFAULT_GOV "panic" #endif #else -- 2.7.4