Re: [PATCH] watchdog: iTCO_wdt: Set NO_REBOOT if the watchdog is not already running

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On 10/27/22 23:27, Mika Westerberg wrote:
> Daniel reported that the commit 1ae3e78c0820 ("watchdog: iTCO_wdt: No
> need to stop the timer in probe") makes QEMU implementation of the iTCO
> watchdog not to trigger reboot anymore when NO_REBOOT flag is initially
> cleared using this option (in QEMU command line):
>
>    -global ICH9-LPC.noreboot=false
>
> The problem with the commit is that it left the unconditional setting of
> NO_REBOOT that is not cleared anymore when the kernel keeps pinging the
> watchdog (as opposed to the previous code that called iTCO_wdt_stop()
> that cleared it).
>
> Fix this so that we only set NO_REBOOT if the watchdog was not initially
> running.
>
> Fixes: 1ae3e78c0820 ("watchdog: iTCO_wdt: No need to stop the timer in probe")
> Reported-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

> ---
> Hi,
>
> I tested this with the command line Daniel provided:
>
>        -watchdog-action poweroff \
>        -global ICH9-LPC.noreboot=false
>
> With the patch QEMU shuts down after ~60s and without it keeps running.
>
>   drivers/watchdog/iTCO_wdt.c | 21 ++++++++++++++-------
>   1 file changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index 34693f11385f..e937b4dd28be 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -423,14 +423,18 @@ static unsigned int iTCO_wdt_get_timeleft(struct watchdog_device *wd_dev)
>   	return time_left;
>   }
>   
> -static void iTCO_wdt_set_running(struct iTCO_wdt_private *p)
> +/* Returns true if the watchdog was running */
> +static bool iTCO_wdt_set_running(struct iTCO_wdt_private *p)
>   {
>   	u16 val;
>   
> -	/* Bit 11: TCO Timer Halt -> 0 = The TCO timer is * enabled */
> +	/* Bit 11: TCO Timer Halt -> 0 = The TCO timer is enabled */
>   	val = inw(TCO1_CNT(p));
> -	if (!(val & BIT(11)))
> +	if (!(val & BIT(11))) {
>   		set_bit(WDOG_HW_RUNNING, &p->wddev.status);
> +		return true;
> +	}
> +	return false;
>   }
>   
>   /*
> @@ -518,9 +522,6 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>   		return -ENODEV;	/* Cannot reset NO_REBOOT bit */
>   	}
>   
> -	/* Set the NO_REBOOT bit to prevent later reboots, just for sure */
> -	p->update_no_reboot_bit(p->no_reboot_priv, true);
> -
>   	if (turn_SMI_watchdog_clear_off >= p->iTCO_version) {
>   		/*
>   		 * Bit 13: TCO_EN -> 0
> @@ -572,7 +573,13 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>   	watchdog_set_drvdata(&p->wddev, p);
>   	platform_set_drvdata(pdev, p);
>   
> -	iTCO_wdt_set_running(p);
> +	if (!iTCO_wdt_set_running(p)) {
> +		/*
> +		 * If the watchdog was not running set NO_REBOOT now to
> +		 * prevent later reboots.
> +		 */
> +		p->update_no_reboot_bit(p->no_reboot_priv, true);
> +	}
>   
>   	/* Check that the heartbeat value is within it's range;
>   	   if not reset to the default */