svn commit: r362781 - head/sys/compat/linuxkpi/common/include/linux

[Hans Petter Selasky]

On 2020-06-29 22:32, Ian Lepore wrote:
> On Mon, 2020-06-29 at 14:26 -0600, Warner Losh wrote:
>> On Mon, Jun 29, 2020, 2:15 PM Ravi Pokala <rpokala at freebsd.org>
>> wrote:
>>
>>> -----Original Message-----
>>> From: <owner-src-committers at freebsd.org> on behalf of Hans Petter
>>> Selasky
>>> <hselasky at FreeBSD.org>
>>> Date: 2020-06-29, Monday at 06:08
>>> To: <src-committers at freebsd.org>, <svn-src-all at freebsd.org>, <
>>> svn-src-head at freebsd.org>
>>> Subject: svn commit: r362781 -
>>> head/sys/compat/linuxkpi/common/include/linux
>>>
>>>      Author: hselasky
>>>      Date: Mon Jun 29 13:08:40 2020
>>>      New Revision: 362781
>>>      URL: https://svnweb.freebsd.org/changeset/base/362781
>>>
>>>      Log:
>>>        Implement is_signed(), type_max() and type_min() function
>>> macros in
>>> the
>>>        LinuxKPI.
>>>
>>>        MFC after:        1 week
>>>        Sponsored by:     Mellanox Technologies
>>>
>>>      Modified:
>>>        head/sys/compat/linuxkpi/common/include/linux/kernel.h
>>>
>>>      Modified:
>>> head/sys/compat/linuxkpi/common/include/linux/kernel.h
>>>
>>> ===================================================================
>>> ===========
>>>      --- head/sys/compat/linuxkpi/common/include/linux/kernel.h  Mon
>>> Jun 29
>>> 12:59:09 2020        (r362780)
>>>      +++ head/sys/compat/linuxkpi/common/include/linux/kernel.h  Mon
>>> Jun 29
>>> 13:08:40 2020        (r362781)
>>>      @@ -564,4 +564,20 @@ linux_ratelimited(linux_ratelimit_t *rl)
>>>       #define    __is_constexpr(x) \
>>>          __builtin_constant_p(x)
>>>
>>> Hi Hans,
>>>
>>>      +#define            is_signed(x) (((x)-1 / (x)2) == (x)0)
>>>
>>> It took me several reads to understand this, until I figured out
>>> that 'x'
>>> is not a variable, it's the name of a *type*.
>>>
>>> If 'x' is a variable, then '(x)-1' is subtraction, but '(x)2' and
>>> '(x)0'
>>> are nonsensical.
>>>
>>> If 'x' is a *type*, then '(x)-1' is typecasting '-1', and similarly
>>> for
>>> '(x)2' and '(x)0'.
>>>
>>> So, perhaps a comment, or a better name for 'x'?
>>>
>>
>> I had similar thoughts. Maybe 't' instead?
>>
> 
> Or maybe since there's no one-character restriction on macro variable
> names, something actually descriptive like 'datatype'.
> 
> -- Ian
> 
>> Warner
>>
>> Thanks,
>>>
>>> Ravi (rpokala@)
>>>

Thanks for the feedback. I'll have a look at using a more descriptive 
name there for the macro argument.

--HPS