linux-kernel - Re: [PATCH v2] iio: adc: ad4170-4: Use ERR_PTR() with %pe to improve error logging

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: <c8189da5-f660-4500-b3b3-246913453ad5@baylibre.com>
Date: Thu, 7 Aug 2025 16:14:11 -0500
From: David Lechner <dlechner@...libre.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Salah Triki <salah.triki@...il.com>, Lars-Peter Clausen
 <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>,
 Marcelo Schmitt <marcelo.schmitt@...log.com>,
 Jonathan Cameron <jic23@...nel.org>, Nuno Sá
 <nuno.sa@...log.com>, Andy Shevchenko <andy@...nel.org>,
 linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: adc: ad4170-4: Use ERR_PTR() with %pe to improve
 error logging

On 8/7/25 4:02 PM, Andy Shevchenko wrote:
> On Thu, Aug 7, 2025 at 11:01 PM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
>> On Thu, Aug 7, 2025 at 6:03 PM David Lechner <dlechner@...libre.com> wrote:
>>> On 8/7/25 3:05 AM, Salah Triki wrote:
> 
> ...
> 
>>>>       ret = __ad4170_read_sample(indio_dev, chan, val);
>>>>       if (ret) {
>>>> -             dev_err(dev, "failed to read sample: %d\n", ret);
>>>> +             dev_err(dev, "failed to read sample: %pe\n", ERR_PTR(ret));
>>>>
>>>>               ret2 = ad4170_set_channel_enable(st, chan->address, false);
>>>>               if (ret2)
>>>> -                     dev_err(dev, "failed to disable channel: %d\n", ret2);
>>>> +                     dev_err(dev, "failed to disable channel: %pe\n", ERR_PTR(ret2));
>>>>
>>>>               return ret;
>>>>       }
>>>
>>> Interesting, I didn't know we had this format specifier. But I think
>>> this is something we would want to do kernel-wide or not at all to stay
>>> consistent.
>>
>> I'm sorry but I didn't follow. This is a kernel-wide format specifier.

I meant that it would be strange to make this change just in one
driver and not do the same everywhere else.

>>
>>> And if we are doing this in more places, it would make sense to have a new
>>> format specifier for integer error values instead of casting them to
>>> pointers.
>>
>> Will _very unlikely_ to happen. This has to be a C standard for that,
>> otherwise you are suggesting to always have a kernel warning for each
>> of these cases. The only way we can customize specifiers w/o
>> introducing a compiler warnings is to continue (and still carefully)
>> using %p extensions.

OK, makes sense.

> 
> And to be clear: I am not in favour of this change exactly due to a
> bit weird (for the reader) castings just for the sake of use of %pe.
> 
>