4.15-stable review patch. If anyone has any objections, please let me know.
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From: Rasmus Villemoes rasmus.villemoes@prevas.dk
commit bc137dfdbec27c0ec5731a89002daded4a4aa1ea upstream.
The first patch above (https://patchwork.kernel.org/patch/9970181/) makes the oops go away, but it just papers over the problem. The real problem is that the watchdog core clears WDOG_HW_RUNNING in watchdog_stop, and the gpio driver fails to set it in its stop function when it doesn't actually stop it. This means that the core doesn't know that it now has responsibility for petting the device, in turn causing the device to reset the system (I hadn't noticed this because the board I'm working on has that reset logic disabled).
How about this (other drivers may of course have the same problem, I haven't checked). One might say that ->stop should return an error when the device can't be stopped, but OTOH this brings parity between a device without a ->stop method and a GPIO wd that has always-running set. IOW, I think ->stop should only return an error when an actual attempt to stop the hardware failed.
From: Rasmus Villemoes rasmus.villemoes@prevas.dk
The watchdog framework clears WDOG_HW_RUNNING before calling ->stop. If the driver is unable to stop the device, it is supposed to set that bit again so that the watchdog core takes care of sending heart-beats while the device is not open from user-space. Update the gpio_wdt driver to honour that contract (and get rid of the redundant clearing of WDOG_HW_RUNNING).
Fixes: 3c10bbde10 ("watchdog: core: Clear WDOG_HW_RUNNING before calling the stop function") Signed-off-by: Rasmus Villemoes rasmus.villemoes@prevas.dk Reviewed-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Wim Van Sebroeck wim@iguana.be Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/watchdog/gpio_wdt.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/watchdog/gpio_wdt.c +++ b/drivers/watchdog/gpio_wdt.c @@ -80,7 +80,8 @@ static int gpio_wdt_stop(struct watchdog
if (!priv->always_running) { gpio_wdt_disable(priv); - clear_bit(WDOG_HW_RUNNING, &wdd->status); + } else { + set_bit(WDOG_HW_RUNNING, &wdd->status); }
return 0;