Re: [PATCH] gpio: Revert regression in sysfs-gpio (gpiolib.c)

[Thorsten Leemhuis <regressions@leemhuis.info>]

On 07.03.22 10:58, Bartosz Golaszewski wrote:
> On Fri, Mar 4, 2022 at 8:13 AM Thorsten Leemhuis
> <regressions@leemhuis.info> wrote:
>> On 16.02.22 15:40, Bartosz Golaszewski wrote:
>>> On Tue, Feb 15, 2022 at 10:56 PM Linus Walleij <linus.walleij@linaro.org> wrote:
>>>>
>>>> On Mon, Feb 14, 2022 at 12:24 AM Marcelo Roberto Jimenez
>>>> <marcelo.jimenez@gmail.com> wrote:
>>>>> On Sat, Feb 12, 2022 at 1:55 PM Linus Walleij <linus.walleij@linaro.org> wrote:
>>>>
>>>>>> I am curious about the usecases and how deeply you have built
>>>>>> yourselves into this.
>>>>>
>>>>> I don't know if I understand what you mean, sorry.
>>>>
>>>> Why does the user need the sysfs ABI? What is it used for?
>>>>
>>>> I.e what is the actual use case?
>>>>
>>>>>>> In any case, the upstream file should be enough to test the issue reported here.
>>>>>>
>>>>>> The thing is that upstream isn't super happy that you have been
>>>>>> making yourselves dependent on features that we are actively
>>>>>> discouraging and then demanding that we support these features.
>>>>>
>>>>> Hum, demanding seems to be a strong word for what I am doing here.
>>>>>
>>>>> Deprecated should not mean broken. My point is: the API seems to be
>>>>> currently broken. User space apps got broken, that's a fact. I even
>>>>> took the time to bisect the kernel and show you which commit broke it.
>>>>> So, no, I am not demanding. More like reporting and providing a
>>>>> temporary solution to those with a similar problem.
>>>>>
>>>>> Maybe it is time to remove the API, but this is up to "upstream".
>>>>> Leaving the API broken seems pointless and unproductive.
>>>>>
>>>>> Sorry for the "not super happiness of upstream", but maybe upstream
>>>>> got me wrong.
>>>>>
>>>>> We are not "making ourselves dependent on features ...". The API was
>>>>> there. We used it. Now it is deprecated, ok, we should move on. I got
>>>>> the message.
>>>>
>>>> Ouch I deserved some slamming for this.
>>>>
>>>> I'm sorry if I came across as harsh :(
>>>>
>>>> I just don't know how to properly push for this.
>>>>
>>>> I have even pushed the option of the deprecated sysfs ABI
>>>> behind the CONFIG_EXPERT option, which should mean that
>>>> the kernel config has been made by someone who has checked
>>>> the option "yes I am an expert I know what I am doing"
>>>> yet failed to observe that this ABI is obsoleted since 5 years
>>>> and hence failed to be an expert.
>>>>
>>>> Of course the ABI (not API really) needs to be fixed if we can find the
>>>> problem. It's frustrating that fixing it seems to fix broken other
>>>> features which are not deprecated, hence the annoyance on my
>>>> part.
>>>>
>>>
>>> I'm afraid we'll earn ourselves a good old LinusRant if we keep
>>> pushing the character device as a solution to the problem here.
>>> Marcelo is right after all: he used an existing user interface, the
>>> interface broke, it must be fixed.
>>>
>>> I would prefer to find a solution that fixes Marcelo's issue while
>>> keeping the offending patches in tree but it seems like the issue is
>>> more complicated and will require some rework of the sysfs interface.
>>>
>>> In which case unless there are objections I lean towards reverting the
>>> relevant commits.
>>
>> Sounds good to me, but that was two weeks ago and afaics nothing
>> happened since then. Or did the discussion continue somewhere else?
> 
> Now queued for fixes, thanks for the reminder.

thx, and yw, that's what I'm here for ;-)

Sadly that commit didn't use 'Link:' tags pointing to the report (the
start of this thread) using lore.kernel.org/r/, as explained in
'Documentation/process/submitting-patches.rst' and
'Documentation/process/5.Posting.rst'. I'd say that would have been
really wise here if someone sooner or later needs to look into the
backstory of the fix. And is also means that I have to tell my
regression tracking bot about this issue manually now. :-/

#regzbot fixed-by: 86528d306d1826cfe59481001d63761ba793317a

But whatever, thx for taking care of this!

Have a nice week everyone!

Ciao, Thorsten

>>>>> And I will also tell the dev team that they must use the GPIO char dev
>>>>> and libgpiod from now on and must port everything to it. And we will
>>>>> likely have another group of people who are not super happy, but
>>>>> that's life... :)
>>>>
>>>> I'm happy to hear this!
>>
>> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
>>
>> P.S.: As the Linux kernel's regression tracker I'm getting a lot of
>> reports on my table. I can only look briefly into most of them and lack
>> knowledge about most of the areas they concern. I thus unfortunately
>> will sometimes get things wrong or miss something important. I hope
>> that's not the case here; if you think it is, don't hesitate to tell me
>> in a public reply, it's in everyone's interest to set the public record
>> straight.
>>
>> #regzbot poke
>