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Subject: Re: [PATCH v2] vsprintf: introduce %dE for error constants
To:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Jani Nikula <jani.nikula@linux.intel.com>
Cc:     Petr Mladek <pmladek@suse.com>,
        =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= <uwe@kleine-koenig.org>,
        Steven Rostedt <rostedt@goodmis.org>, Enrico@kleine-koenig.org,
        Weigelt@kleine-koenig.org,
        Andrew Morton <akpm@linux-foundation.org>,
        metux IT consult <lkml@metux.net>,
        Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20190827211244.7210-1-uwe@kleine-koenig.org>
 <20190828113216.p2yiha4xyupkbcbs@pathway.suse.cz> <87o9097bff.fsf@intel.com>
 <20190828120246.GA31416@jagdpanzerIV>
From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
Message-ID: <087e8e18-8044-27ef-b0bd-8a1093f53b32@rasmusvillemoes.dk>
Date:   Wed, 28 Aug 2019 14:49:15 +0200
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On 28/08/2019 14.02, Sergey Senozhatsky wrote:
> On (08/28/19 14:54), Jani Nikula wrote:
> [..]
>>> I personally think that this feature is not worth the code, data,
>>> and bikeshedding.
>>
>> The obvious alternative, I think already mentioned, is to just add
>> strerror() or similar as a function. I doubt there'd be much opposition
>> to that. Folks could use %s and strerr(ret). And a follow-up could add
>> the special format specifier if needed.
> 
> Yeah, I'd say that strerror() would be a better alternative
> to vsprintf() specifier. (if we decide to add such functionality).

Please no. The .text footprint of the changes at the call sites to do
pr_err("...%s...", errcode(err)) instead of the current
pr_err("...%d...", err) would very soon dwarf whatever is necessary to
implement %pE or %dE. Also that would prevent any kind of graceful
fallback in case err doesn't have a known value - errcode() would have
to return some fixed "huh, unknown error number" string, so we'd lose
the actual number.

Rasmus