linux-kernel - Re: [PATCH v2] vsprintf: introduce %dE for error constants

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Date:   Thu, 29 Aug 2019 19:39:45 +0200
From:   Uwe Kleine-König <uwe@...ine-koenig.org>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Juergen Gross <jgross@...e.com>, Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Jonathan Corbet <corbet@....net>,
        metux IT consult Enrico Weigelt <lkml@...ux.net>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] vsprintf: introduce %dE for error constants

On 8/29/19 11:09 AM, Rasmus Villemoes wrote:
> On 29/08/2019 10.27, Juergen Gross wrote:
>> On 29.08.19 10:12, Petr Mladek wrote:
>>> On Wed 2019-08-28 21:18:37, Uwe Kleine-König  wrote:
>>>>
>>>> I'd like to postpone the discussion about "how" until we agreed about
>>>> the "if at all".
>>>
>>> It seems that all people like this feature.
>>
>> Hmm, what about already existing format strings conatining "%dE"?
>>
>> Yes, I could find only one (drivers/staging/speakup/speakup_bns.c), but
>> nevertheless...
> 
> Indeed, Uwe still needs to respond to how he wants to handle that. I

This is indeed bad and I didn't expect that. I just took a quick look
and this string is indeed used as sprintf format string.

> still prefer making it %pE, both because it's easier to convert integers
> to ERR_PTRs than having to worry about the type of PTR_ERR() being long
> and not int, and because alphanumerics after %p have been ignored for a
> long time (10 years?) whether or not those characters have been
> recognized as a %p extension, so nobody relies on %pE putting an E after
> the %p output. It also keeps the non-standard extensions in the same
> "namespace", so to speak.
> 
> Oh, 'E' is taken, well, make it 'e' then.

I like having %pe to print error valued pointers. Then maybe we could
have both %de for ints and %pe for pointers. :-)

Best regards
Uwe





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