From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Joe Perches" <joe@perches.com>, "Petr Mladek" <pmladek@suse.com>,
"Sergey Senozhatsky" <sergey.senozhatsky.work@gmail.com>,
"Jani Nikula" <jani.nikula@linux.intel.com>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Uwe Kleine-König" <uwe@kleine-koenig.org>,
"Linux Documentation List" <linux-doc@vger.kernel.org>
Subject: Re: [PATCH v2] printf: add support for printing symbolic error codes
Date: Tue, 10 Sep 2019 18:26:32 +0300 [thread overview]
Message-ID: <CAHp75Vdpd5uMCM-n+4vAZLwUpN=-cHnHs1uxoV2MDd5fk+CQig@mail.gmail.com> (raw)
In-Reply-To: <20190909203826.22263-1-linux@rasmusvillemoes.dk>
On Mon, Sep 9, 2019 at 11:39 PM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> It has been suggested several times to extend vsnprintf() to be able
> to convert the numeric value of ENOSPC to print "ENOSPC". This is yet
> another attempt. Rather than adding another %p extension, simply teach
> plain %p to convert ERR_PTRs. While the primary use case is
>
> if (IS_ERR(foo)) {
> pr_err("Sorry, can't do that: %p\n", foo);
> return PTR_ERR(foo);
> }
>
> it is also more helpful to get a symbolic error code (or, worst case,
> a decimal number) in case an ERR_PTR is accidentally passed to some
> %p<something>, rather than the (efault) that check_pointer() would
> result in.
>
> With my embedded hat on, I've made it possible to remove this.
>
> I've tested that the #ifdeffery in errcode.c is sufficient to make
> this compile on arm, arm64, mips, powerpc, s390, x86 - I'm sure the
> 0day bot will tell me which ones I've missed.
>
> The symbols to include have been found by massaging the output of
>
> find arch include -iname 'errno*.h' | xargs grep -E 'define\s*E'
>
> In the cases where some common aliasing exists
> (e.g. EAGAIN=EWOULDBLOCK on all platforms, EDEADLOCK=EDEADLK on most),
> I've moved the more popular one (in terms of 'git grep -w Efoo | wc)
> to the bottom so that one takes precedence.
> +#define E(err) [err + BUILD_BUG_ON_ZERO(err <= 0 || err > 300)] = #err
> +#define E(err) [err - 512 + BUILD_BUG_ON_ZERO(err < 512 || err > 550)] = #err
From long term prospective 300 and 550 hard coded here may be forgotten.
> +const char *errcode(int err)
We got long, why not to use long type for it?
> +{
> + /* Might as well accept both -EIO and EIO. */
> + if (err < 0)
> + err = -err;
> + if (err <= 0) /* INT_MIN or 0 */
> + return NULL;
> + if (err < ARRAY_SIZE(codes_0))
> + return codes_0[err];
It won't work if one of the #ifdef:s in the array fails.
Would it?
> + if (err >= 512 && err - 512 < ARRAY_SIZE(codes_512))
> + return codes_512[err - 512];
> + /* But why? */
> + if (IS_ENABLED(CONFIG_MIPS) && err == EDQUOT) /* 1133 */
> + return "EDQUOT";
> + return NULL;
> +}
> + long err = PTR_ERR(ptr);
> + const char *sym = errcode(-err);
Do we need additional sign change if we already have such check inside
errcode()?
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2019-09-10 15:26 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-30 21:46 [PATCH] printf: add support for printing symbolic error codes Rasmus Villemoes
2019-08-30 21:53 ` Joe Perches
2019-08-30 22:03 ` Rasmus Villemoes
2019-08-30 22:21 ` Joe Perches
2019-08-30 22:50 ` Rasmus Villemoes
2019-09-02 9:07 ` David Laight
2019-08-31 9:38 ` kbuild test robot
2019-09-02 15:29 ` Uwe Kleine-König
2019-09-04 9:13 ` Rasmus Villemoes
2019-09-04 9:21 ` Uwe Kleine-König
2019-09-04 16:19 ` Andy Shevchenko
2019-09-04 16:28 ` Uwe Kleine-König
2019-09-05 11:40 ` Rasmus Villemoes
2019-09-09 20:38 ` [PATCH v2] " Rasmus Villemoes
2019-09-10 15:26 ` Andy Shevchenko [this message]
2019-09-11 0:15 ` Joe Perches
2019-09-11 6:43 ` Rasmus Villemoes
2019-09-11 9:37 ` Uwe Kleine-König
2019-09-11 10:14 ` Rasmus Villemoes
2019-09-15 9:43 ` Pavel Machek
2019-09-16 12:23 ` Uwe Kleine-König
2019-09-16 13:23 ` Rasmus Villemoes
2019-09-16 13:36 ` Uwe Kleine-König
2019-09-17 6:59 ` [PATCH v3] " Rasmus Villemoes
2019-09-25 14:36 ` Petr Mladek
2019-09-29 20:09 ` Rasmus Villemoes
2019-10-02 8:34 ` Petr Mladek
2019-10-05 21:48 ` Andrew Morton
2019-10-11 13:36 ` [PATCH v4 0/1] printf: add support for printing symbolic error names Rasmus Villemoes
2019-10-11 13:36 ` [PATCH v4 1/1] " Rasmus Villemoes
2019-10-14 5:51 ` Uwe Kleine-König
2019-10-14 13:02 ` Petr Mladek
2019-10-14 13:10 ` Andy Shevchenko
2019-10-15 12:17 ` Rasmus Villemoes
2019-10-15 13:44 ` David Laight
2019-10-15 19:07 ` [PATCH v5] " Rasmus Villemoes
2019-10-16 13:49 ` Andy Shevchenko
2019-10-16 14:52 ` Petr Mladek
2019-10-16 16:31 ` Andy Shevchenko
2019-10-17 15:02 ` Petr Mladek
2019-11-26 14:04 ` [PATCH v4 0/1] " Geert Uytterhoeven
2019-11-27 8:54 ` Petr Mladek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAHp75Vdpd5uMCM-n+4vAZLwUpN=-cHnHs1uxoV2MDd5fk+CQig@mail.gmail.com' \
--to=andy.shevchenko@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=corbet@lwn.net \
--cc=jani.nikula@linux.intel.com \
--cc=joe@perches.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@rasmusvillemoes.dk \
--cc=pmladek@suse.com \
--cc=sergey.senozhatsky.work@gmail.com \
--cc=uwe@kleine-koenig.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).