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

[Rasmus Villemoes]

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