[PATCH v2] watchdog: Start watchdog in watchdog_set_last_hw_keepalive only if appropriate

[PATCH v2] watchdog: Start watchdog in watchdog_set_last_hw_keepalive only if appropriate

[Jan Kiszka]

From: Jan Kiszka <jan.kiszka@siemens.com>

We must not pet a running watchdog when handle_boot_enabled is off
because this will kick off automatic triggering before userland is
running, defeating the purpose of the handle_boot_enabled control.
Furthermore, don't ping in case watchdog_set_last_hw_keepalive was
called incorrectly when the hardware watchdog is actually not running.

Fixed: cef9572e9af3 ("watchdog: add support for adjusting last known HW keepalive time")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

Changes to v1 ("watchdog: Respect handle_boot_enabled when setting last last_hw_keepalive"):
 - add watchdog_hw_running test
 - improve commit log

 drivers/watchdog/watchdog_dev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 3bab32485273..6c73160386b9 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -1172,7 +1172,10 @@ int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,

 	wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));

-	return __watchdog_ping(wdd);
+	if (watchdog_hw_running(wdd) && handle_boot_enabled)
+		return __watchdog_ping(wdd);
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);

--
2.31.1

Re: [PATCH v2] watchdog: Start watchdog in watchdog_set_last_hw_keepalive only if appropriate

[Guenter Roeck]

On 8/1/21 12:56 AM, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> We must not pet a running watchdog when handle_boot_enabled is off
> because this will kick off automatic triggering before userland is
> running, defeating the purpose of the handle_boot_enabled control.
> Furthermore, don't ping in case watchdog_set_last_hw_keepalive was
> called incorrectly when the hardware watchdog is actually not running.
> 
> Fixed: cef9572e9af3 ("watchdog: add support for adjusting last known HW keepalive time")
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> 
> Changes to v1 ("watchdog: Respect handle_boot_enabled when setting last last_hw_keepalive"):
>   - add watchdog_hw_running test
>   - improve commit log
> 
>   drivers/watchdog/watchdog_dev.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 3bab32485273..6c73160386b9 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -1172,7 +1172,10 @@ int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
> 
>   	wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
> 
> -	return __watchdog_ping(wdd);
> +	if (watchdog_hw_running(wdd) && handle_boot_enabled)
> +		return __watchdog_ping(wdd);
> +
> +	return 0;
>   }
>   EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
> 
> --
> 2.31.1
>