linux-kernel - Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno strings

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Message-ID: <3a8df2e2-114c-9f2c-325a-49f234726b08@infradead.org>
Date:   Sun, 25 Jun 2017 15:47:45 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     "Enrico Weigelt, metux IT consult" <enrico.weigelt@...3.net>,
        Joe Perches <joe@...ches.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib: vsprintf: add printf format conversion %M for errno
 strings

On 06/25/2017 02:18 PM, Enrico Weigelt, metux IT consult wrote:
> On 25.06.2017 22:10, Joe Perches wrote:
> 
>>> Yeah, that's still an open problem. Actually, I still haven't found out,
>>> how it's done w/ all the other kernel-internal conversions.
>>
>> Everything else uses "%p<foo>", <object reference>
> 
> hmm, but errno's aren't pointers. Isn't %p checked for pointer values ?
>>> Already was about to do so. Shall I call it strerror() ?
>>
>> I presume kstrerror
>>
>> So use something like
>> 	"%d: (%s)", errno, kstrerror(errno)
> 
> Okay, sounds good.

but why not just do that in userspace. Sure, you can keep that as your
internal kernel patch, but there's not really much need for it to be in the
mainline kernel.  So when your driver prints "blah: foo bar error 49",
just run a little program that converts 49 to <whatever>.

-- 
~Randy