linux-kernel - Re: [PATCH v2 04/11] watchdog: rzg2l_wdt: Check return status of pm_runtime

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4ea02224-e9fa-4ee9-9210-bc7a7ae9e86b@roeck-us.net>
Date: Wed, 31 Jan 2024 05:16:50 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: claudiu beznea <claudiu.beznea@...on.dev>,
 Biju Das <biju.das.jz@...renesas.com>,
 "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
 "robh+dt@...nel.org" <robh+dt@...nel.org>,
 "krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>,
 "conor+dt@...nel.org" <conor+dt@...nel.org>,
 "geert+renesas@...der.be" <geert+renesas@...der.be>,
 "magnus.damm@...il.com" <magnus.damm@...il.com>,
 "mturquette@...libre.com" <mturquette@...libre.com>,
 "sboyd@...nel.org" <sboyd@...nel.org>,
 "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>
Cc: "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
 "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
 "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
 Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH v2 04/11] watchdog: rzg2l_wdt: Check return status of
 pm_runtime_put()

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@...on.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@...on.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@...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@...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