watchdog: introduce watchdog_dev_suspend/resume
The watchdog drivers often disable wdog clock during suspend and then
enable it again during resume. Nevertheless the ping worker is still
running and can issue low-level ping while the wdog clock is disabled
causing the system hang. To prevent such condition register pm notifier
in the watchdog core which will call watchdog_dev_suspend/resume and
actually cancel ping worker during suspend and restore it back, if
needed, during resume.
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210618195033.3209598-2-grzegorz.jaszczyk@linaro.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index f408967..597cf16 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -1228,6 +1228,53 @@ void __exit watchdog_dev_exit(void)
kthread_destroy_worker(watchdog_kworker);
}
+int watchdog_dev_suspend(struct watchdog_device *wdd)
+{
+ struct watchdog_core_data *wd_data = wdd->wd_data;
+ int ret = 0;
+
+ if (!wdd->wd_data)
+ return -ENODEV;
+
+ /* ping for the last time before suspend */
+ mutex_lock(&wd_data->lock);
+ if (watchdog_worker_should_ping(wd_data))
+ ret = __watchdog_ping(wd_data->wdd);
+ mutex_unlock(&wd_data->lock);
+
+ if (ret)
+ return ret;
+
+ /*
+ * make sure that watchdog worker will not kick in when the wdog is
+ * suspended
+ */
+ hrtimer_cancel(&wd_data->timer);
+ kthread_cancel_work_sync(&wd_data->work);
+
+ return 0;
+}
+
+int watchdog_dev_resume(struct watchdog_device *wdd)
+{
+ struct watchdog_core_data *wd_data = wdd->wd_data;
+ int ret = 0;
+
+ if (!wdd->wd_data)
+ return -ENODEV;
+
+ /*
+ * __watchdog_ping will also retrigger hrtimer and therefore restore the
+ * ping worker if needed.
+ */
+ mutex_lock(&wd_data->lock);
+ if (watchdog_worker_should_ping(wd_data))
+ ret = __watchdog_ping(wd_data->wdd);
+ mutex_unlock(&wd_data->lock);
+
+ return ret;
+}
+
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="