From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: "Sergey Senozhatsky" <sergey.senozhatsky.work@gmail.com>,
"Uwe Kleine-König" <uwe@kleine-koenig.org>,
"Petr Mladek" <pmladek@suse.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Jani Nikula" <jani.nikula@linux.intel.com>,
"Joe Perches" <joe@perches.com>,
"Juergen Gross" <jgross@suse.com>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] printf: add support for printing symbolic error codes
Date: Wed, 4 Sep 2019 19:19:25 +0300 [thread overview]
Message-ID: <CAHp75VcAEK0KioX-mvHeRqpX+c8Y7_A5X8RqmtHUT-MU-dXy6A@mail.gmail.com> (raw)
In-Reply-To: <20190830214655.6625-1-linux@rasmusvillemoes.dk>
On Sat, Aug 31, 2019 at 12:48 AM 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.
> +/*
> + * Ensure these tables to not accidentally become gigantic if some
> + * huge errno makes it in. On most architectures, the first table will
> + * only have about 140 entries, but mips and parisc have more sparsely
> + * allocated errnos (with EHWPOISON = 257 on parisc, and EDQUOT = 1133
> + * on mips), so this wastes a bit of space on those - though we
> + * special case the EDQUOT case.
> + */
> +#define E(err) [err + BUILD_BUG_ON_ZERO(err <= 0 || err > 300)] = #err
Hmm... Perhaps better to define the upper boundary with something like
#define __E_POSIX_UPPER_BOUNDARY 300 // name sucks, I know
> +#define E(err) [err - 512 + BUILD_BUG_ON_ZERO(err < 512 || err > 550)] = #err
Similar to 550?
> +const char *errcode(int err)
> +{
> + /* 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];
> + 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";
Another possibility is to initialize the errors at run time with radix tree.
> + return NULL;
> +}
> @@ -2111,6 +2112,31 @@ static noinline_for_stack
> char *pointer(const char *fmt, char *buf, char *end, void *ptr,
> struct printf_spec spec)
> {
> + /* %px means the user explicitly wanted the pointer formatted as a hex value. */
> + if (*fmt == 'x')
> + return pointer_string(buf, end, ptr, spec);
But instead of breaking switch case apart can we use...
> +
> + /* If it's an ERR_PTR, try to print its symbolic representation. */
> + if (IS_ERR(ptr)) {
... if (IS_ERR() && *fmt != 'x') {
here?
> + long err = PTR_ERR(ptr);
> + const char *sym = errcode(-err);
> + if (sym)
> + return string_nocheck(buf, end, sym, spec);
> + /*
> + * Funky, somebody passed ERR_PTR(-1234) or some other
> + * non-existing Efoo - or more likely
> + * CONFIG_SYMBOLIC_ERRCODE=n. None of the
> + * %p<something> extensions can make any sense of an
> + * ERR_PTR(), and if this was just a plain %p, the
> + * user is still better off getting the decimal
> + * representation rather than the hash value that
> + * ptr_to_id() would generate.
> + */
> + spec.flags |= SIGN;
> + spec.base = 10;
> + return number(buf, end, err, spec);
> + }
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2019-09-04 16:19 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 [this message]
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
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=CAHp75VcAEK0KioX-mvHeRqpX+c8Y7_A5X8RqmtHUT-MU-dXy6A@mail.gmail.com \
--to=andy.shevchenko@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=jani.nikula@linux.intel.com \
--cc=jgross@suse.com \
--cc=joe@perches.com \
--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).