[PATCH v2 4/8] watchdog: core: Stop pretimeout hrtimer on suspend

[Guenter Roeck <linux@roeck-us.net>]

During system suspend, watchdog_dev_suspend() pings the watchdog (which
restarts the software pretimeout hrtimer) and stops the keepalive ping
worker, but fails to stop the pretimeout hrtimer. Because
CLOCK_MONOTONIC continues ticking until the system fully suspends, a
suspend process taking longer than the configured pretimeout will
trigger a spurious pretimeout event.

Stop the pretimeout hrtimer in watchdog_dev_suspend(), prevent
watchdog_hrtimer_pretimeout_start() from starting it while the watchdog
is suspended, and restart it in watchdog_dev_resume() if the hardware
watchdog is running.

Fixes: 60bcd91aafd2 ("watchdog: introduce watchdog_dev_suspend/resume")
Assisted-by: LLM
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: Added Reviewed-by: tag

 drivers/watchdog/watchdog_dev.c                | 3 +++
 drivers/watchdog/watchdog_hrtimer_pretimeout.c | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index e38f1ef8e683..af756ee228b2 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -1334,6 +1334,7 @@ int watchdog_dev_suspend(struct watchdog_device *wdd)
 	 * suspended
 	 */
 	hrtimer_cancel(&wd_data->timer);
+	watchdog_hrtimer_pretimeout_stop(wdd);
 	kthread_cancel_work_sync(&wd_data->work);
 
 	return 0;
@@ -1355,6 +1356,8 @@ int watchdog_dev_resume(struct watchdog_device *wdd)
 	clear_bit(_WDOG_SUSPENDED, &wd_data->status);
 	if (watchdog_worker_should_ping(wd_data))
 		ret = __watchdog_ping(wd_data->wdd);
+	if (watchdog_hw_running(wdd) && !ret)
+		watchdog_hrtimer_pretimeout_start(wdd);
 	mutex_unlock(&wd_data->lock);
 
 	return ret;
diff --git a/drivers/watchdog/watchdog_hrtimer_pretimeout.c b/drivers/watchdog/watchdog_hrtimer_pretimeout.c
index 49a05ea60c97..5c88e6467994 100644
--- a/drivers/watchdog/watchdog_hrtimer_pretimeout.c
+++ b/drivers/watchdog/watchdog_hrtimer_pretimeout.c
@@ -31,7 +31,8 @@ void watchdog_hrtimer_pretimeout_start(struct watchdog_device *wdd)
 {
 	if (!(wdd->info->options & WDIOF_PRETIMEOUT) &&
 	    wdd->pretimeout &&
-	    !watchdog_pretimeout_invalid(wdd, wdd->pretimeout))
+	    !watchdog_pretimeout_invalid(wdd, wdd->pretimeout) &&
+	    !test_bit(_WDOG_SUSPENDED, &wdd->wd_data->status))
 		hrtimer_start(&wdd->wd_data->pretimeout_timer,
 			      ktime_set(wdd->timeout - wdd->pretimeout, 0),
 			      HRTIMER_MODE_REL);
-- 
2.45.2