linux-kernel - Re: [PATCH trivial] include/linux/memblock.h: Clean up code for several trivial details

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Message-ID: <574CBB3F.8020301@emindsoft.com.cn>
Date:	Tue, 31 May 2016 06:14:23 +0800
From:	Chen Gang <chengang@...ndsoft.com.cn>
To:	Joe Perches <joe@...ches.com>, akpm@...ux-foundation.org,
	trivial@...nel.org
CC:	kuleshovmail@...il.com, tony.luck@...el.com,
	tangchen@...fujitsu.com, will.deacon@....com, holt@....com,
	ard.biesheuvel@...aro.org, kirill.shutemov@...ux.intel.com,
	linux-kernel@...r.kernel.org, Chen Gang <gang.chen.5i5j@...il.com>
Subject: Re: [PATCH trivial] include/linux/memblock.h: Clean up code for several
 trivial details

On 5/30/16 22:33, Joe Perches wrote:
> On Mon, 2016-05-30 at 22:21 +0800, Chen Gang wrote:
>> On 5/29/16 23:08, Joe Perches wrote:
>>> These !! uses are't necessary.
>>> The compiler makes the bool return 0 or 1.
>> No, they are not necessary. But for me, it will be more clearer, since
>> in our kernel (at least in include/linux/), almost all Boolean functions
>> use Boolean value or expression for return (and "!!" are often used).
> 
> Opinions vary.
>

OK, thanks. I shall send patch v2 for it within this week.
 
> There seem to be fewer than 20 !! uses in bool return
> functions in include/linux/
> 

[root@...alhost linux]# pwd
/upstream/linux-next/include/linux
[root@...alhost linux]# grep -rn '!!' * | grep return | wc -l
32
[root@...alhost linux]# 

except 11 files which use int instead of bool as return value:

  ide.h:854
  mlx4/driver.h:76
  mlx5/device.h:744
  mmzone.h:793
  mtd/mtd.h:412
  nilfs2_fs.h:568
  nilfs2_fs.h:602
  nilfs2_fs.h:667
  nilfs2_fs.h:771
  page-flags.h:711
  pagemap.h:54
  
> Finding the quantity of bool conversions in include/linux
> from something other than 0, 1, true, or false to 0 or 1
> is not trivial, but it is non-zero and seems rather more
> than 20.
> 

[root@...alhost linux]# grep -rn "\<return\>" * | grep ' & ' | grep -v "==" | grep -v '||' | grep -v 'struct' | grep -v '!=' | grep -v ',' | grep -v '?' | grep -v '!' | grep -v '&&' | wc -l
259

After give a glance, more than 60% are not for bool functions (so I
guess about 100 area hint).


Thanks
-- 
Chen Gang (陈刚)

Managing Natural Environments is the Duty of Human Beings.