Re: [PATCH 1/1] workqueue: use type int instead of bool to index array

Re: [PATCH 1/1] workqueue: use type int instead of bool to index array

[zijun_hu]

On 2017/9/6 22:33, Tejun Heo wrote:
> Hello,
> 
> On Wed, Sep 06, 2017 at 11:34:14AM +0800, zijun_hu wrote:
>> From: zijun_hu <zijun_hu@htc.com>
>>
>> type bool is used to index three arrays in alloc_and_link_pwqs()
>> it doesn't look like conventional.
>>
>> it is fixed by using type int to index the relevant arrays.
> 
> bool is a uint type which can be either 0 or 1.  I don't see what the
> benefit of this patch is.q
> 
bool is NOT a uint type now, it is a new type introduced by gcc, it is
rather different with "typedef int bool" historically
see following code segments for more info about type bool
	bool v = 0x10;
	printf("v = %d\n", v);
the output is v = 1.

it maybe cause a invalid array index if bool is represented as uint
bool highpri = wq->flags & WQ_HIGHPRI; WQ_HIGHPRI = 1 << 4,
@highpri maybe 16, but the number of array elements is 2.

bool is a logic value, the valid value is true or false. 
indexing array by type bool is not a good program custom

it is more extendable to use type int, type bool maybe is improper if the number of
array elements is extended to more than 2 in future

besides, the relevant array is indexed by type int in many other places of the
same source file. this patch can keep consistency
> 


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Re: [PATCH 1/1] workqueue: use type int instead of bool to index array

[Tejun Heo]

On Thu, Sep 07, 2017 at 12:04:59AM +0800, zijun_hu wrote:
> On 2017/9/6 22:33, Tejun Heo wrote:
> > Hello,
> > 
> > On Wed, Sep 06, 2017 at 11:34:14AM +0800, zijun_hu wrote:
> >> From: zijun_hu <zijun_hu@htc.com>
> >>
> >> type bool is used to index three arrays in alloc_and_link_pwqs()
> >> it doesn't look like conventional.
> >>
> >> it is fixed by using type int to index the relevant arrays.
> > 
> > bool is a uint type which can be either 0 or 1.  I don't see what the
> > benefit of this patch is.q
> > 
> bool is NOT a uint type now, it is a new type introduced by gcc, it is
> rather different with "typedef int bool" historically

http://www.open-std.org/jtc1/sc22/wg14/www/docs/n815.htm

  Because C has existed for so long without a Boolean type, however, the
  new standard must coexist with the old remedies. Therefore, the type
  name is taken from the reserved identifier space. To maintain
  orthogonal promotion rules, the Boolean type is defined as an unsigned
  integer type capable of representing the values 0 and 1. The more
  conventional names for the type and its values are then made available
  only with the inclusion of the <stdbool.h> header. In addition, the
  header defines a feature test macro to aid in integrating new code
  with old code that defines its own Boolean type.

-- 
tejun

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Re: [PATCH 1/1] workqueue: use type int instead of bool to index array

[zijun_hu]

On 2017/9/7 0:40, Tejun Heo wrote:
> On Thu, Sep 07, 2017 at 12:04:59AM +0800, zijun_hu wrote:
>> On 2017/9/6 22:33, Tejun Heo wrote:
>>> Hello,
>>>
>>> On Wed, Sep 06, 2017 at 11:34:14AM +0800, zijun_hu wrote:
>>>> From: zijun_hu <zijun_hu@htc.com>
>>>>
>>>> type bool is used to index three arrays in alloc_and_link_pwqs()
>>>> it doesn't look like conventional.
>>>>
>>>> it is fixed by using type int to index the relevant arrays.
>>>
>>> bool is a uint type which can be either 0 or 1.  I don't see what the
>>> benefit of this patch is.q
>>>
>> bool is NOT a uint type now, it is a new type introduced by gcc, it is
>> rather different with "typedef int bool" historically
> 
> http://www.open-std.org/jtc1/sc22/wg14/www/docs/n815.htm
> 
>   Because C has existed for so long without a Boolean type, however, the
>   new standard must coexist with the old remedies. Therefore, the type
>   name is taken from the reserved identifier space. To maintain
>   orthogonal promotion rules, the Boolean type is defined as an unsigned
>   integer type capable of representing the values 0 and 1. The more
>   conventional names for the type and its values are then made available
>   only with the inclusion of the <stdbool.h> header. In addition, the
>   header defines a feature test macro to aid in integrating new code
>   with old code that defines its own Boolean type.
> 
in this case, i think type int is more suitable than bool in aspects of
extendibility, program custom and consistency.

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Re: [PATCH 1/1] workqueue: use type int instead of bool to index array

[Tejun Heo]

On Thu, Sep 07, 2017 at 01:07:23AM +0800, zijun_hu wrote:
> in this case, i think type int is more suitable than bool in aspects of
> extendibility, program custom and consistency.

Please stop.

-- 
tejun

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