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From e131319669e0ef5e6fcd75174daeffa40492135c Mon Sep 17 00:00:00 2001
From: Damien Riegel <damien.riegel@savoirfairelinux.com>
Date: Fri, 20 Nov 2015 16:54:51 -0500
Subject: watchdog: core: add reboot notifier support
Many watchdog drivers register a reboot notifier in order to stop the
watchdog on system reboot. Thus we can factorize this code in the
watchdog core.
For that purpose, a new notifier block is added in watchdog_device for
internal use only, as well as a new watchdog_stop_on_reboot helper
function.
If this helper is called, watchdog core registers the related notifier
block and will stop the watchdog when SYS_HALT or SYS_DOWN is received.
Since this operation can be critical on some platforms, abort the device
registration if the reboot notifier registration fails.
Suggested-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
---
Documentation/watchdog/watchdog-kernel-api.txt | 8 ++++++
drivers/watchdog/watchdog_core.c | 37 ++++++++++++++++++++++++++
include/linux/watchdog.h | 9 +++++++
3 files changed, 54 insertions(+)
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -53,6 +53,7 @@ struct watchdog_device {
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ struct notifier_block reboot_nb;
struct notifier_block restart_nb;
void *driver_data;
struct mutex lock;
@@ -76,6 +77,9 @@ It contains following fields:
* timeout: the watchdog timer's timeout value (in seconds).
* min_timeout: the watchdog timer's minimum timeout value (in seconds).
* max_timeout: the watchdog timer's maximum timeout value (in seconds).
+* reboot_nb: notifier block that is registered for reboot notifications, for
+ internal use only. If the driver calls watchdog_stop_on_reboot, watchdog core
+ will stop the watchdog on such notifications.
* restart_nb: notifier block that is registered for machine restart, for
internal use only. If a watchdog is capable of restarting the machine, it
should define ops->restart. Priority can be changed through
@@ -240,6 +244,10 @@ to set the default timeout value as time
then use this function to set the user "preferred" timeout value.
This routine returns zero on success and a negative errno code for failure.
+To disable the watchdog on reboot, the user must call the following helper:
+
+static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd);
+
To change the priority of the restart handler the following helper should be
used:
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -138,6 +138,25 @@ int watchdog_init_timeout(struct watchdo
}
EXPORT_SYMBOL_GPL(watchdog_init_timeout);
+static int watchdog_reboot_notifier(struct notifier_block *nb,
+ unsigned long code, void *data)
+{
+ struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
+ reboot_nb);
+
+ if (code == SYS_DOWN || code == SYS_HALT) {
+ if (watchdog_active(wdd)) {
+ int ret;
+
+ ret = wdd->ops->stop(wdd);
+ if (ret)
+ return NOTIFY_BAD;
+ }
+ }
+
+ return NOTIFY_DONE;
+}
+
static int watchdog_restart_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
@@ -238,6 +257,21 @@ static int __watchdog_register_device(st
return ret;
}
+ if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
+ wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
+
+ ret = register_reboot_notifier(&wdd->reboot_nb);
+ if (ret) {
+ dev_err(wdd->dev, "Cannot register reboot notifier (%d)\n",
+ ret);
+ watchdog_dev_unregister(wdd);
+ device_destroy(watchdog_class, devno);
+ ida_simple_remove(&watchdog_ida, wdd->id);
+ wdd->dev = NULL;
+ return ret;
+ }
+ }
+
if (wdd->ops->restart) {
wdd->restart_nb.notifier_call = watchdog_restart_notifier;
@@ -286,6 +320,9 @@ static void __watchdog_unregister_device
if (wdd->ops->restart)
unregister_restart_handler(&wdd->restart_nb);
+ if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
+ unregister_reboot_notifier(&wdd->reboot_nb);
+
devno = wdd->cdev.dev;
ret = watchdog_dev_unregister(wdd);
if (ret)
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -65,6 +65,7 @@ struct watchdog_ops {
* @timeout: The watchdog devices timeout value (in seconds).
* @min_timeout:The watchdog devices minimum timeout value (in seconds).
* @max_timeout:The watchdog devices maximum timeout value (in seconds).
+ * @reboot_nb: The notifier block to stop watchdog on reboot.
* @restart_nb: The notifier block to register a restart function.
* @driver-data:Pointer to the drivers private data.
* @lock: Lock for watchdog core internal use only.
@@ -92,6 +93,7 @@ struct watchdog_device {
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ struct notifier_block reboot_nb;
struct notifier_block restart_nb;
void *driver_data;
struct mutex lock;
@@ -102,6 +104,7 @@ struct watchdog_device {
#define WDOG_ALLOW_RELEASE 2 /* Did we receive the magic char ? */
#define WDOG_NO_WAY_OUT 3 /* Is 'nowayout' feature set ? */
#define WDOG_UNREGISTERED 4 /* Has the device been unregistered */
+#define WDOG_STOP_ON_REBOOT 5 /* Should be stopped on reboot */
struct list_head deferred;
};
@@ -121,6 +124,12 @@ static inline void watchdog_set_nowayout
set_bit(WDOG_NO_WAY_OUT, &wdd->status);
}
+/* Use the following function to stop the watchdog on reboot */
+static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
+{
+ set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
+}
+
/* Use the following function to check if a timeout value is invalid */
static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
{
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