linux-kernel - Re: [PATCH v2] watchdog: Start watchdog in watchdog_set_last_hw

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Message-ID: <7228af51-5390-23e8-1383-b196e44a669a@roeck-us.net>
Date:   Sun, 1 Aug 2021 10:37:53 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Jan Kiszka <jan.kiszka@....de>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-watchdog@...r.kernel.org
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] watchdog: Start watchdog in
 watchdog_set_last_hw_keepalive only if appropriate

On 8/1/21 12:56 AM, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@...mens.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@...mens.com>

Reviewed-by: Guenter Roeck <linux@...ck-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
>