Re: [PATCH v2 04/11] watchdog: rzg2l_wdt: Check return status of pm_runtime_put()

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

On 1/31/24 03:00, claudiu beznea wrote:
> 
> 
> On 31.01.2024 12:41, Biju Das wrote:
>> Hi Claudiu,
>>
>>> -----Original Message-----
>>> From: claudiu beznea <claudiu.beznea@tuxon.dev>
>>> Sent: Wednesday, January 31, 2024 10:36 AM
>>> Subject: Re: [PATCH v2 04/11] watchdog: rzg2l_wdt: Check return status of
>>> pm_runtime_put()
>>>
>>> Hi, Biju,
>>>
>>> On 31.01.2024 12:32, Biju Das wrote:
>>>> Hi Claudiu,
>>>>
>>>> Thanks for the feedback.
>>>>
>>>>> -----Original Message-----
>>>>> From: Claudiu <claudiu.beznea@tuxon.dev>
>>>>> Sent: Wednesday, January 31, 2024 10:20 AM
>>>>> Subject: [PATCH v2 04/11] watchdog: rzg2l_wdt: Check return status of
>>>>> pm_runtime_put()
>>>>>
>>>>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>>
>>>>> pm_runtime_put() may return an error code. Check its return status.
>>>>>
>>>>> Along with it the rzg2l_wdt_set_timeout() function was updated to
>>>>> propagate the result of rzg2l_wdt_stop() to its caller.
>>>>>
>>>>> Fixes: 2cbc5cd0b55f ("watchdog: Add Watchdog Timer driver for
>>>>> RZ/G2L")
>>>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>> ---
>>>>>
>>>>> Changes in v2:
>>>>> - propagate the return code of rzg2l_wdt_stop() to it's callers
>>>>>
>>>>>   drivers/watchdog/rzg2l_wdt.c | 11 +++++++++--
>>>>>   1 file changed, 9 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/watchdog/rzg2l_wdt.c
>>>>> b/drivers/watchdog/rzg2l_wdt.c index d87d4f50180c..7bce093316c4
>>>>> 100644
>>>>> --- a/drivers/watchdog/rzg2l_wdt.c
>>>>> +++ b/drivers/watchdog/rzg2l_wdt.c
>>>>> @@ -144,9 +144,13 @@ static int rzg2l_wdt_start(struct
>>>>> watchdog_device
>>>>> *wdev)  static int rzg2l_wdt_stop(struct watchdog_device *wdev)  {
>>>>>   	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
>>>>> +	int ret;
>>>>>
>>>>>   	rzg2l_wdt_reset(priv);
>>>>> -	pm_runtime_put(wdev->parent);
>>>>> +
>>>>> +	ret = pm_runtime_put(wdev->parent);
>>>>> +	if (ret < 0)
>>>>> +		return ret;
>>>>
>>>> Do we need to check the return code? So far we didn't hit this
>>> condition.
>>>> If you are planning to do it, then just
>>>>
>>>> return pm_runtime_put(wdev->parent);
>>>
>>> pm_runtime_put() may return 1 if the device is suspended (which is not
>>> considered error) as explained here:
>>
>> Oops, I missed that discussion. Out of curiosity,
>> What watchdog framework/consumer is going to do with a
>> Non-error return value of 1?
> 
> Looking at this:
> https://elixir.bootlin.com/linux/latest/source/drivers/watchdog/watchdog_dev.c#L809
> 
> it seems that the positive values are not considered errors thus, indeed,
> we may return directly:
> 
> return pm_runtime_put();
> 
> Guenter,
> 
> With this (and previous discussion from [1]), are you OK to change it like:
> 
> return pm_runtime_put();
> 

Instead of looking at the source, I would kindly ask you to look at the API.

Guenter