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From:   Jani Nikula <jani.nikula@linux.intel.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Uwe =?utf-8?Q?Kleine-K?= =?utf-8?Q?=C3=B6nig?= 
        <uwe@kleine-koenig.org>
Cc:     Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
        Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v1 1/2] vsprintf: introduce %dE for error constants
In-Reply-To: <87o90c9rkc.fsf@intel.com>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
References: <20190824233724.1775-1-uwe@kleine-koenig.org> <20190824165829.7d330367992c62dab87f6652@linux-foundation.org> <87o90c9rkc.fsf@intel.com>
Date:   Mon, 26 Aug 2019 13:04:24 +0300
Message-ID: <87lfvg9r9z.fsf@intel.com>
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On Mon, 26 Aug 2019, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> On Sat, 24 Aug 2019, Andrew Morton <akpm@linux-foundation.org> wrote:
>>> --- a/lib/vsprintf.c
>>> +++ b/lib/vsprintf.c
>>> @@ -533,6 +533,192 @@ char *number(char *buf, char *end, unsigned long long num,
>>>  	return buf;
>>>  }
>>>  
>>> +#define ERRORCODE(x) { .str = #x, .err = x }
>>> +
>>> +static const struct {
>>> +	const char *str;
>>> +	int err;
>>> +} errorcodes[] = {
>>
>> It's a bit of a hack, but an array of char*'s and a separate array of
>> ushorts would save a bit of space.
>
> Or just
>
> #define ERRORCODE(x) [x] = #x
>
> static const char * const errorcodes[] = {
> 	ERRORCODE(EPERM),
>         ERRORCODE(ENOENT),
>         ...
> };
>
> Saves space, faster lookup, discovers at build time why EWOULDBLOCK
> would always show up as EAGAIN in the logs. We don't have holes to speak
> of in the error codes.

Meh, failed to notice the range ERESTARTSYS..ERECALLCONFLICT. Other than
that, it's nicer. ;)

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center