From: George Spelvin <lkml@sdf.org>
To: 13@sdf.org, andriy.shevchenko@linux.intel.com, lkml@sdf.org,
st5pub@yandex.ru
Cc: akpm@linux-foundation.org, daniel.wagner@siemens.com,
dchinner@redhat.com, don.mullis@gmail.com, geert@linux-m68k.org,
linux-kernel@vger.kernel.org, linux@rasmusvillemoes.dk
Subject: Re: [PATCH 1/5] lib/sort: Make swap functions more generic
Date: Thu, 14 Mar 2019 10:09:52 GMT [thread overview]
Message-ID: <201903141009.x2EA9q1Z025888@sdf.org> (raw)
In-Reply-To: <20190314092958.GV9224@smile.fi.intel.com>
On Sat, 09 Mar 2019 at 23:19:49 +0300, Andrey Abramov wrote:
>> Although I'm thinking of:
>>
>> static bool __attribute_const__
>> is_aligned(const void *base, size_t size, unsigned char align)
>> {
>> unsigned char lsbits = (unsigned char)size;
>>
>> (void)base;
>> #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
>> lsbits |= (unsigned char)(uintptr_t)base;
>> #endif
>> return (lsbits & (align - 1)) == 0;
>> }
>>
>> Any preference?
> I think it would be better.
>> I find "u32s" confusing; I keep reading the "s" as "signed" rather
>> than a plural.
>>
>> How about one of:
>> swap_bytes / swap_ints / swap_longs
>> swap_1 / swap_4 / swap_8
>
> In my opinion "swap_bytes / swap_ints / swap_longs" are the most readable.
On Thu, 14 Mar 2019 at 11:29:58 +0200, Andy Shevchenko wrote:
> On Sat, Mar 09, 2019 at 03:53:41PM +0000, lkml@sdf.org wrote:
>> static bool __attribute_const__
>> is_aligned(const void *base, size_t size, unsigned char align)
>> {
>> unsigned char lsbits = (unsigned char)size;
>> #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
>> (void)base;
>> #else
>> lsbits |= (unsigned char)(uintptr_t)base;
>> #endif
>> return (lsbits & (align - 1)) == 0;
>> }
>
>> Any preference?
>
> This one looks better in a sense we don't suppress the warnings when it's
> not needed.
>>> For such primitives that operates on top of an arrays we usually
>>> append 's' to the name. Currently the name is misleading.
>>>
>>> Perhaps u32s_swap().
>>
>> I don't worry much about the naming of static helper functions.
>> If they were exported, it would be a whole lot more important!
>>
>> I find "u32s" confusing; I keep reading the "s" as "signed" rather
>> than a plural.
>
> For signedness we use prefixes; for plural, suffixes. I don't see the point of
> confusion. And this is in use in kernel a lot.
>
>> How about one of:
>> swap_bytes / swap_ints / swap_longs
>> swap_1 / swap_4 / swap_8
>
> longs are ambiguous, so I would prefer bit-sized types.
I already implemented Andrey's suggestions, which were the exact
opposite of yours.
Pistols at dawn?
>>>> +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
>>>
>>> Why #ifdef is better than if (IS_ENABLED()) ?
>>
>> Because CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is bool and not
>> tristate. IS_ENABLED tests for 'y' or 'm' but we don't need it
>> for something that's only on or off.
>
> There is IS_BUILTIN(), though it's a common practice to use IS_ENABLED()
> even for boolean options (I think because of naming of the macro).
Well, as I said earlier, #ifdef is the most common form in the kernel.
It's also the shortest to write, and I like the fact that it slightly
simpler. (Admittedly, "IS_ENABLED" does not take a lot of brain power
to interpret, but it *is* one more macro that might be hiding magic.)
So I'm not inclined to change it without a substantial reason.
next prev parent reply other threads:[~2019-03-14 10:14 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-09 2:17 [PATCH 0/5] lib/sort & lib/list_sort: faster and smaller George Spelvin
2019-02-21 6:30 ` [PATCH 1/5] lib/sort: Make swap functions more generic George Spelvin
[not found] ` <20190309140653.GO9224@smile.fi.intel.com>
2019-03-09 15:53 ` lkml
2019-03-09 20:19 ` Andrey Abramov
2019-03-14 9:29 ` Andy Shevchenko
2019-03-14 10:09 ` George Spelvin [this message]
2019-03-14 10:41 ` Geert Uytterhoeven
2019-03-14 11:53 ` George Spelvin
2019-03-14 12:18 ` Andy Shevchenko
2019-03-14 19:59 ` Andrey Abramov
2019-03-15 3:35 ` George Spelvin
2019-03-15 8:27 ` Geert Uytterhoeven
2019-03-14 10:11 ` George Spelvin
2019-03-09 21:02 ` George Spelvin
2019-03-13 21:23 ` Rasmus Villemoes
2019-03-13 22:02 ` Geert Uytterhoeven
2019-03-13 23:15 ` George Spelvin
2019-02-21 8:21 ` [PATCH 2/5] lib/sort: Use more efficient bottom-up heapsort variant George Spelvin
2019-03-13 22:29 ` Rasmus Villemoes
2019-03-14 0:03 ` George Spelvin
2019-03-14 0:15 ` Rasmus Villemoes
2019-02-21 8:21 ` [PATCH 3/5] lib/sort: Avoid indirect calls to built-in swap George Spelvin
2019-03-05 3:06 ` [PATCH 4/5] lib/list_sort: Simplify and remove MAX_LIST_LENGTH_BITS George Spelvin
2019-03-10 21:54 ` Rasmus Villemoes
2019-03-10 22:29 ` George Spelvin
2019-03-14 9:10 ` Andy Shevchenko
2019-03-14 9:41 ` George Spelvin
2019-03-15 4:33 ` George Spelvin
2019-03-15 8:20 ` Geert Uytterhoeven
2019-03-15 10:23 ` George Spelvin
2019-03-15 12:57 ` Geert Uytterhoeven
2019-03-15 16:59 ` George Spelvin
2019-03-15 17:47 ` Geert Uytterhoeven
2019-03-15 18:53 ` Andrey Abramov
2019-03-15 19:06 ` Andy Shevchenko
2019-03-15 19:23 ` Andrey Abramov
2019-03-15 19:56 ` Andy Shevchenko
2019-03-16 3:49 ` George Spelvin
2019-03-05 5:58 ` [PATCH 5/5] lib/list_sort: Optimize number of calls to comparison function George Spelvin
2019-03-13 23:28 ` Rasmus Villemoes
2019-03-14 1:58 ` George Spelvin
2019-06-21 23:12 ` Rasmus Villemoes
2019-12-08 8:01 ` George Spelvin
2019-03-15 19:54 ` [PATCH 0/5] lib/sort & lib/list_sort: faster and smaller Andrey Abramov
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=201903141009.x2EA9q1Z025888@sdf.org \
--to=lkml@sdf.org \
--cc=13@sdf.org \
--cc=akpm@linux-foundation.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=daniel.wagner@siemens.com \
--cc=dchinner@redhat.com \
--cc=don.mullis@gmail.com \
--cc=geert@linux-m68k.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@rasmusvillemoes.dk \
--cc=st5pub@yandex.ru \
/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).