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watchdog: core: add reboot notifier support

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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>
This commit is contained in:
Damien Riegel
2015-11-20 16:54:51 -05:00
committed by Wim Van Sebroeck
parent 0ebad1e5e5
commit e131319669
3 changed files with 54 additions and 0 deletions
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8
Documentation/watchdog/watchdog-kernel-api.txt
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@@ -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 timeout value in the watchdog_device and
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: