From: Robert Abel <rabel@robertabel.eu>
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Willy Tarreau <w@1wt.eu>,
Geert Uytterhoeven <geert@linux-m68k.org>,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
eldad@fogrefinery.com, me@tobin.cc, corbet@lwn.net,
pantelis.antoniou@konsulko.com
Subject: Re: [PATCH 3/4] auxdisplay: charlcd: fix x/y address commands
Date: Tue, 27 Feb 2018 00:00:42 +0100 [thread overview]
Message-ID: <1b66ecb1-5951-35f3-3dd2-4448628d3fbc@robertabel.eu> (raw)
In-Reply-To: <CANiq72k-bztnMoDR6D_n-ZnK2mFmpUOvNn1ttpPFq=suxrYPig@mail.gmail.com>
Hi @ll,
this is a discussion stemming from drivers/auxdisplay about the usage
and possible deprecation of simple_strto* set of functions found in
lib/vsprintf.
I cc'ed everybody who signed off and also everybody who
signed/authored/added/removed more than 20% of lib/vsprintf.
This has come up, because some auxdisplay functionality was broken by a
well-intentioned patch to switch from simple_strtoul to kstrtoul in
129957069e6af42a6e021d90679c56662c95f7e1
(https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=129957069e6af42a6e021d90679c56662c95f7e1)
and now there is discussion about whether the simple_strto* functions
are really obsolete.
On 26 Feb 2018 18:26, Miguel Ojeda wrote:
> On Mon, Feb 26, 2018 at 6:09 PM, Andy Shevchenko wrote:
>> On Mon, Feb 26, 2018 at 6:54 PM, Miguel Ojeda wrote:
>>> On Mon, Feb 26, 2018 at 12:44 PM, Andy Shevchenko wrote:
>>>> Perhaps instead of dancing around kstrtox() better to switch to
>>>> simple_strtoul() ?
>>>
>>> It seems deprecated:
>>>
>>> /* Obsolete, do not use. Use kstrto<foo> instead */
>>> extern unsigned long simple_strtoul(const char *,char **,unsigned int);
>>
>> It has been discussed several times. The comment is simple wrong.
>>
>> Because of the requirement of kstrtox() to have a \0 or \n followed by
>> \0 as "end of field".
>> simple_strto*() is suitable to be run in place.
>
> I agree that in-place versions of these kind of string functions are
> very useful, don't get me wrong! But unless someone changes the
> "official" comment, we shouldn't add new code relying on them.
So can we get clarity in form of a patch here, or not?
I'm hesitant to move back to simple_kstroul, because to me it seems that
general consensus (at least when the comment was put there) was to
remove it:
> commit 462e471107624fe9bd8b6353ac13e06305c3f3fd
> Author: Eldad Zack <>
> Date: Mon Dec 17 16:03:05 2012 -0800
>
> simple_strto*: annotate function as obsolete
>
> Update the documentation for simple_strto* to reflect that it has been
> obsoleted and advise the usage of kstrto*.
>
> Signed-off-by: Eldad Zack <>
> Cc: J. Bruce Fields <>
> Cc: Joe Perches <>
> Cc: Randy Dunlap <>
> Cc: Alexey Dobriyan <>
> Cc: Rob Landley <>
> Signed-off-by: Andrew Morton <>
> Signed-off-by: Linus Torvalds <>
One big advantage simple_kstro* functions have over their kstrto*
cousins is that strings don't need to be null-terminated. Instead, they
will be parsed as far as they can be and a pointer to the end of the
respective number will be returned.
Regards,
Robert
next prev parent reply other threads:[~2018-02-26 23:00 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-09 23:50 [PATCH 0/3] auxdisplay: charlcd: miscellaneous patches Robert Abel
2018-02-09 23:50 ` [PATCH 1/3] auxdisplay: charlcd: fix hex literal ranges for graphics command Robert Abel
2018-02-09 23:50 ` [PATCH 2/3] auxdisplay: charlcd: use null character instead of zero literal to terminate strings Robert Abel
2018-02-09 23:50 ` [PATCH 3/3] auxdisplay: charlcd: replace octal literal with form-feed escape sequence Robert Abel
2018-02-10 9:43 ` Miguel Ojeda
2018-02-10 9:29 ` [PATCH 2/3] auxdisplay: charlcd: use null character instead of zero literal to terminate strings Miguel Ojeda
2018-02-10 8:58 ` [PATCH 1/3] auxdisplay: charlcd: fix hex literal ranges for graphics command Miguel Ojeda
2018-02-10 9:20 ` Willy Tarreau
2018-02-10 9:41 ` Miguel Ojeda
2018-02-12 13:56 ` Miguel Ojeda
2018-02-13 13:36 ` Andy Shevchenko
2018-02-13 19:15 ` Willy Tarreau
2018-02-14 23:17 ` Robert Abel
2018-02-15 10:57 ` Andy Shevchenko
2018-02-25 23:34 ` Robert Abel
2018-02-25 23:52 ` Robert Abel
2018-02-25 23:54 ` Robert Abel
2018-02-25 23:54 ` [PATCH 1/4] auxdisplay: charlcd: fix two-line command ^[[LN not marked as processed Robert Abel
2018-02-25 23:54 ` [PATCH 2/4] auxdisplay: charlcd: name x/y address struct Robert Abel
2018-02-25 23:54 ` [PATCH 3/4] auxdisplay: charlcd: fix x/y address commands Robert Abel
2018-02-25 23:54 ` [PATCH 4/4] auxdisplay: charlcd: make home command unshift display Robert Abel
2018-02-26 17:16 ` Miguel Ojeda
2018-02-26 8:46 ` [PATCH 3/4] auxdisplay: charlcd: fix x/y address commands Geert Uytterhoeven
2018-02-26 22:29 ` Robert Abel
2018-02-26 11:44 ` Andy Shevchenko
2018-02-26 16:54 ` Miguel Ojeda
2018-02-26 17:09 ` Andy Shevchenko
2018-02-26 17:26 ` Miguel Ojeda
2018-02-26 17:56 ` Andy Shevchenko
2018-02-26 23:00 ` Robert Abel [this message]
2018-02-26 22:38 ` Robert Abel
2018-02-26 23:06 ` Miguel Ojeda
2018-02-26 16:49 ` Miguel Ojeda
2018-02-26 16:57 ` Miguel Ojeda
2018-02-26 22:43 ` Robert Abel
2018-02-27 5:19 ` Willy Tarreau
2018-02-27 19:31 ` Miguel Ojeda
2018-02-27 23:29 ` Robert Abel
2018-02-28 0:05 ` [PATCH RFC 0/2] auxdisplay: charlcd: fix movement and home commands Robert Abel
2018-02-28 0:05 ` [PATCH 1/2] auxdisplay: charlcd: fix x/y address commands Robert Abel
2018-02-28 0:05 ` [PATCH 2/2] auxdisplay: charlcd: make home command unshift display Robert Abel
2018-02-28 4:21 ` [PATCH 3/4] auxdisplay: charlcd: fix x/y address commands Willy Tarreau
2018-02-26 23:05 ` Robert Abel
2018-02-27 5:20 ` Willy Tarreau
2018-02-26 8:35 ` [PATCH 2/4] auxdisplay: charlcd: name x/y address struct Geert Uytterhoeven
2018-02-26 15:59 ` Miguel Ojeda
2018-02-26 8:34 ` [PATCH 1/4] auxdisplay: charlcd: fix two-line command ^[[LN not marked as processed Geert Uytterhoeven
2018-02-26 15:53 ` Miguel Ojeda
2018-02-26 23:08 ` [PATCH 1/3] auxdisplay: charlcd: fix hex literal ranges for graphics command Robert Abel
2018-02-10 18:31 ` Geert Uytterhoeven
2018-02-10 18:58 ` Willy Tarreau
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