linux-kernel - Re: [PATCH v2 4/8] watchdog: JZ4740: Drop module remove function

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Date:   Sat, 20 Jan 2018 21:29:43 +0530
From:   PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Paul Cercueil <paul@...pouillou.net>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Wim Van Sebroeck <wim@...ana.be>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux-MIPS <linux-mips@...ux-mips.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH v2 4/8] watchdog: JZ4740: Drop module remove function

Hi Guenter,

On 20 January 2018 at 21:20, Guenter Roeck <linux@...ck-us.net> wrote:
> On 01/19/2018 11:41 PM, PrasannaKumar Muralidharan wrote:
>>
>> Hi Paul,
>>
>> On 30 December 2017 at 19:21, Paul Cercueil <paul@...pouillou.net> wrote:
>>>
>>> When the watchdog was configured for nowayout, and after the
>>> userspace watchdog daemon closed the dev node without sending the
>>> magic character, unloading this module stopped the watchdog
>>> hardware, which was clearly a problem.
>>>
>>> Besides, unloading the module is not possible when the userspace
>>> watchdog daemon is running, so it's safe to assume that we don't
>>> need to stop the watchdog hardware in the jz4740_wdt_remove()
>>> function.
>>>
>>> For this reason, the jz4740_wdt_remove() function can then be
>>> dropped alltogether.
>>>
>>> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>> ---
>>>   drivers/watchdog/jz4740_wdt.c | 8 --------
>>>   1 file changed, 8 deletions(-)
>>>
>>>   v2: New patch in this series
>>>
>>> diff --git a/drivers/watchdog/jz4740_wdt.c
>>> b/drivers/watchdog/jz4740_wdt.c
>>> index fa7f49a3212c..02b9b8e946a2 100644
>>> --- a/drivers/watchdog/jz4740_wdt.c
>>> +++ b/drivers/watchdog/jz4740_wdt.c
>>> @@ -205,16 +205,8 @@ static int jz4740_wdt_probe(struct platform_device
>>> *pdev)
>>>          return 0;
>>>   }
>>>
>>> -static int jz4740_wdt_remove(struct platform_device *pdev)
>>> -{
>>> -       struct jz4740_wdt_drvdata *drvdata = platform_get_drvdata(pdev);
>>> -
>>> -       return jz4740_wdt_stop(&drvdata->wdt);
>>> -}
>>> -
>>>   static struct platform_driver jz4740_wdt_driver = {
>>>          .probe = jz4740_wdt_probe,
>>> -       .remove = jz4740_wdt_remove,
>>>          .driver = {
>>>                  .name = "jz4740-wdt",
>>>                  .of_match_table = of_match_ptr(jz4740_wdt_of_matches),
>>> --
>>> 2.11.0
>>>
>>>
>>
>> As ".remove" is removed and wdt is required for restarting the system
>> I am thinking that stop callback is also not required. If so does it
>> makes sense to remove the stop callback? I can submit a patch for the
>> same once this patch series goes in.
>>
> The remove function was removed because it would otherwise be an empty
> function. Since it is optional, it can and should be removed if it does not
> do anything. If the stop function is removed, it is no longer possible
> to stop the watchdog. Why would this make sense, and why would it make sense
> to drop the stop function if there is no remove function ?
>
> Guenter
>

I missed the fact that stopping is watchdog is possible. Sorry for the noise.

Thanks,
PrasannaKumar