linux-kernel - Re: Conversion to generic boolean

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Date:	Mon, 28 Aug 2006 23:55:22 +0200
From:	Richard Knutsson <ricknu-0@...dent.ltu.se>
To:	Nicholas Miell <nmiell@...cast.net>
CC:	Jan Engelhardt <jengelh@...ux01.gwdg.de>,
	Christoph Hellwig <hch@...radead.org>,
	James.Bottomley@...elEye.com, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Conversion to generic boolean

Nicholas Miell wrote:

>On Mon, 2006-08-28 at 22:55 +0200, Richard Knutsson wrote:
>  
>
>>Nicholas Miell wrote:
>>
>>    
>>
>>>On Mon, 2006-08-28 at 14:17 +0200, Richard Knutsson wrote: 
>>>
>>>      
>>>
>>>>Jan Engelhardt wrote:
>>>>   
>>>>
>>>>        
>>>>
>>>>>>>Just would like to ask if you want patches for:
>>>>>>>        
>>>>>>>
>>>>>>>              
>>>>>>>
>>>>>>Total NACK to any of this boolean ididocy.  I very much hope you didn't
>>>>>>get the impression you actually have a chance to get this merged.
>>>>>>
>>>>>>
>>>>>>            
>>>>>>
>>>>>>>* (Most importent, may introduce bugs if left alone)
>>>>>>>Fixing boolean checking, ex:
>>>>>>>if (bool == FALSE)
>>>>>>>to
>>>>>>>if (!bool)
>>>>>>>         
>>>>>>>
>>>>>>>              
>>>>>>>
>>>>>>this one of course makes sense, but please do it without introducing
>>>>>>any boolean type.  Getting rid of all the TRUE/FALSE defines and converting
>>>>>>all scsi drivers to classic C integer as boolean semantics would be
>>>>>>very welcome janitorial work.
>>>>>>  
>>>>>>
>>>>>>            
>>>>>>
>>>>>I don't get it. You object to the 'idiocy' 
>>>>>(http://lkml.org/lkml/2006/7/27/281), but find the x==FALSE -> !x 
>>>>>a good thing?
>>>>>    
>>>>>
>>>>>          
>>>>>
>>>>That is error-prone. Not "==FALSE" but what happens if x is (for some 
>>>>reason) not 1 and then "if (x==TRUE)".
>>>>   
>>>>        
>>>>
>>>If you're using _Bool, that isn't possible. (Except at the boundaries
>>>where you have to validate untrusted data -- and the compiler makes that
>>>more difficult, because it "knows" that a _Bool can only be 0 or 1 and
>>>therefore your check to see if it's not 0 or 1 can "safely" be
>>>eliminated.)
>>> 
>>>
>>>      
>>>
>>Yes, true. But there is no _Bool's in the kernel (linus-git), only one 
>>in script/.
>>
>>    
>>
>
>Sorry, I was under the impression that the purpose of the generic
>boolean patch was to switch the kernel over to C's generic boolean.
>  
>
Oh no, my bad. Well, at least some like to do it (including me).
But you really have to bend it to make _Bool take another value then 0/1.
Regarding "== FALSE" and co., there is still no reason for them, other 
then bloater the code.

Richard Knutsson

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