The change adds noop watchdog pretimeout governor, only an
informational message is printed to the kernel log buffer when a
watchdog triggers a pretimeout event.
While introducing the first pretimeout governor the selected design
assumes that the default pretimeout governor is selected by its name
and it is always built-in, thus the default pretimeout governor can
not be unregistered and the correspondent check can be removed from
the watchdog_unregister_governor() function.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Reviewed-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Tested-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---
Changes from v5 to v6:
* per Wim's change request for v6 series the default pretimeout governor
is set to be noop,
* added commit tags given by Guenter and Wolfram for v5.
Changes from v4 to v5:
* fixed in source tree compilation issue, thanks to Wolfram
Changes from v3 to v4:
* returned tristate option back, it is safe to have it, because
the single governor is the default one, thus it is built-in, but with
the introduction of another governor it should be tristate
* removed "panic panic" duplication in a user's message (Wolfram)
* added minor changes to watchdog_pretimeout.c to support built time
selectable default governor
Changes from v2 to v3:
* temporarily removed tristate option, the governor can be built-in only
Changes from v1 to v2:
* removed #ifdef CONFIG_WATCHDOG_PRETIMEOUT_DEFAULT_GOV_PANIC,
now this selection is done in a centralized manner,
* added module owner reference to count users of the governor,
* slightly improved description of the governors in Kconfig.
drivers/watchdog/Kconfig | 28 ++++++++++++++++++++
drivers/watchdog/Makefile | 2 ++
drivers/watchdog/pretimeout_noop.c | 47 ++++++++++++++++++++++++++++++++++
drivers/watchdog/watchdog_pretimeout.h | 4 +++
4 files changed, 81 insertions(+)
create mode 100644 drivers/watchdog/pretimeout_noop.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 04d535ae497d..4aeb8f95beb4 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1838,4 +1838,32 @@ config WATCHDOG_PRETIMEOUT_GOV
help
The option allows to select watchdog pretimeout governors.
+if WATCHDOG_PRETIMEOUT_GOV
+
+choice
+ prompt "Default Watchdog Pretimeout Governor"
+ default WATCHDOG_PRETIMEOUT_DEFAULT_GOV_PANIC
+ help
+ This option selects a default watchdog pretimeout governor.
+ The governor takes its action, if a watchdog is capable
+ to report a pretimeout event.
+
+config WATCHDOG_PRETIMEOUT_DEFAULT_GOV_NOOP
+ bool "noop"
+ select WATCHDOG_PRETIMEOUT_GOV_NOOP
+ help
+ Use noop watchdog pretimeout governor by default. If noop
+ governor is selected by a user, write a short message to
+ the kernel log buffer and don't do any system changes.
+
+endchoice
+
+config WATCHDOG_PRETIMEOUT_GOV_NOOP
+ tristate "Noop watchdog pretimeout governor"
+ help
+ Noop watchdog pretimeout governor, only an informational
+ message is added to kernel log buffer.
+
+endif # WATCHDOG_PRETIMEOUT_GOV
+
endif # WATCHDOG
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 990c36ed4716..0502a21db1db 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -9,6 +9,8 @@ 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
+
# Only one watchdog can succeed. We probe the ISA/PCI/USB based
# watchdog-cards first, then the architecture specific watchdog
# drivers and then the architecture independent "softdog" driver.
diff --git a/drivers/watchdog/pretimeout_noop.c b/drivers/watchdog/pretimeout_noop.c
new file mode 100644
index 000000000000..85f5299d197c
--- /dev/null
+++ b/drivers/watchdog/pretimeout_noop.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 <linux/module.h>
+#include <linux/printk.h>
+#include <linux/watchdog.h>
+
+#include "watchdog_pretimeout.h"
+
+/**
+ * pretimeout_noop - No operation on watchdog pretimeout event
+ * @wdd - watchdog_device
+ *
+ * This function prints a message about pretimeout to kernel log.
+ */
+static void pretimeout_noop(struct watchdog_device *wdd)
+{
+ pr_alert("watchdog%d: pretimeout event\n", wdd->id);
+}
+
+static struct watchdog_governor watchdog_gov_noop = {
+ .name = "noop",
+ .pretimeout = pretimeout_noop,
+};
+
+static int __init watchdog_gov_noop_register(void)
+{
+ return watchdog_register_governor(&watchdog_gov_noop);
+}
+
+static void __exit watchdog_gov_noop_unregister(void)
+{
+ watchdog_unregister_governor(&watchdog_gov_noop);
+}
+module_init(watchdog_gov_noop_register);
+module_exit(watchdog_gov_noop_unregister);
+
+MODULE_AUTHOR("Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Panic watchdog pretimeout governor");
+MODULE_LICENSE("GPL");
diff --git a/drivers/watchdog/watchdog_pretimeout.h b/drivers/watchdog/watchdog_pretimeout.h
index c6cd9f80adb2..c4b6f88dc9c9 100644
--- a/drivers/watchdog/watchdog_pretimeout.h
+++ b/drivers/watchdog/watchdog_pretimeout.h
@@ -20,6 +20,10 @@ 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);
+#if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_DEFAULT_GOV_NOOP)
+#define WATCHDOG_PRETIMEOUT_DEFAULT_GOV "noop"
+#endif
+
#else
static inline int watchdog_register_pretimeout(struct watchdog_device *wdd)
{
--
2.8.1
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