Re: [XEN PATCH v3 05/16] xen/x86: address violations of MISRA C:2012 Directive 4.10

[Jan Beulich <jbeulich@xxxxxxxx>]

On 26.06.2024 11:20, Nicola Vetrini wrote:
> On 2024-06-26 11:06, Jan Beulich wrote:
>> On 25.06.2024 21:31, Nicola Vetrini wrote:
>>> On 2024-03-12 09:16, Jan Beulich wrote:
>>>> On 11.03.2024 09:59, Simone Ballarin wrote:
>>>>> --- a/xen/arch/x86/Makefile
>>>>> +++ b/xen/arch/x86/Makefile
>>>>> @@ -258,18 +258,20 @@ $(obj)/asm-macros.i: CFLAGS-y += -P
>>>>>  $(objtree)/arch/x86/include/asm/asm-macros.h: $(obj)/asm-macros.i
>>>>> $(src)/Makefile
>>>>>   $(call filechk,asm-macros.h)
>>>>>
>>>>> +ARCHDIR = $(shell echo $(SRCARCH) | tr a-z A-Z)
>>>>
>>>> This wants to use :=, I think - there's no reason to invoke the shell
>>>> ...
>>>
>>> I agree on this
>>>
>>>>
>>>>>  define filechk_asm-macros.h
>>>>> +    echo '#ifndef ASM_$(ARCHDIR)_ASM_MACROS_H'; \
>>>>> +    echo '#define ASM_$(ARCHDIR)_ASM_MACROS_H'; \
>>>>>      echo '#if 0'; \
>>>>>      echo '.if 0'; \
>>>>>      echo '#endif'; \
>>>>> -    echo '#ifndef __ASM_MACROS_H__'; \
>>>>> -    echo '#define __ASM_MACROS_H__'; \
>>>>>      echo 'asm ( ".include \"$@\"" );'; \
>>>>> -    echo '#endif /* __ASM_MACROS_H__ */'; \
>>>>>      echo '#if 0'; \
>>>>>      echo '.endif'; \
>>>>>      cat $<; \
>>>>> -    echo '#endif'
>>>>> +    echo '#endif'; \
>>>>> +    echo '#endif /* ASM_$(ARCHDIR)_ASM_MACROS_H */'
>>>>>  endef
>>>>
>>>> ... three times while expanding this macro. Alternatively (to avoid
>>>> an unnecessary shell invocation when this macro is never expanded at
>>>> all) a shell variable inside the "define" above would want 
>>>> introducing.
>>>> Whether this 2nd approach is better depends on whether we anticipate
>>>> further uses of ARCHDIR.
>>>
>>> However here I'm not entirely sure about the meaning of this latter
>>> proposal.
>>> My proposal is the following:
>>>
>>> ARCHDIR := $(shell echo $(SRCARCH) | tr a-z A-Z)
>>>
>>> in a suitably generic place (such as Kbuild.include or maybe
>>> xen/Makefile) as you suggested in subsequent patches that reused this
>>> pattern.
>>
>> If $(ARCHDIR) is going to be used elsewhere, then what you suggest is 
>> fine.
>> My "whether" in the earlier reply specifically left open for 
>> clarification
>> what the intentions with the variable are. The alternative I had 
>> described
>> makes sense only when $(ARCHDIR) would only ever be used inside the
>> filechk_asm-macros.h macro.
> 
> Yes, the intention is to reuse $(ARCHDIR) in the formation of other 
> places, as you can tell from the fact that subsequent patches replicate 
> the same pattern. This is going to save some duplication.
> The only matter left then is whether xen/Makefile (around line 250, just 
> after setting SRCARCH) would be better, or Kbuild.include. To me the 
> former place seems more natural, but I'm not totally sure.

Depends on where all the intended uses are. If they're all in xen/Makefile,
then having the macro just there is of course sufficient. Whereas when it's
needed elsewhere, instead of exporting putting it in Kbuild.include would
seem more natural / desirable to me.

Jan