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watchdog: core: add option to avoid early handling of watchdog

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On some systems its desirable to have watchdog reboot the system
when it does not come up fast enough. This adds a kernel parameter
to disable the auto-update of watchdog before userspace takes over
and a kernel option to set the default. The info messages were
added to shorten error searching on misconfigured systems.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Sebastian Reichel 2017-05-12 14:05:32 +02:00 committed by Wim Van Sebroeck
parent 166fbcf88f
commit 2501b01531
2 changed files with 27 additions and 3 deletions
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11
drivers/watchdog/Kconfig
View File

@ -46,6 +46,17 @@ config WATCHDOG_NOWAYOUT
get killed. If you say Y here, the watchdog cannot be stopped once
it has been started.
config WATCHDOG_HANDLE_BOOT_ENABLED
bool "Update boot-enabled watchdog until userspace takes over"
default y
help
The default watchdog behaviour (which you get if you say Y here) is
to ping watchdog devices that were enabled before the driver has
been loaded until control is taken over from userspace using the
/dev/watchdog file. If you say N here, the kernel will not update
the watchdog on its own. Thus if your userspace does not start fast
enough your device will reboot.
config WATCHDOG_SYSFS
bool "Read different watchdog information through sysfs"
help

13
drivers/watchdog/watchdog_dev.c
View File

@ -80,6 +80,9 @@ static struct watchdog_core_data *old_wd_data;
static struct workqueue_struct *watchdog_wq;
static bool handle_boot_enabled =
IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
static inline bool watchdog_need_worker(struct watchdog_device *wdd)
{
/* All variables in milli-seconds */
@ -956,9 +959,14 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
* and schedule an immediate ping.
*/
if (watchdog_hw_running(wdd)) {
if (handle_boot_enabled) {
__module_get(wdd->ops->owner);
kref_get(&wd_data->kref);
queue_delayed_work(watchdog_wq, &wd_data->work, 0);
} else {
pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
wdd->id);
}
}
return 0;
@ -1106,3 +1114,8 @@ void __exit watchdog_dev_exit(void)
class_unregister(&watchdog_class);
destroy_workqueue(watchdog_wq);
}
module_param(handle_boot_enabled, bool, 0444);
MODULE_PARM_DESC(handle_boot_enabled,
"Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
__MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");