Re: [PATCH v3 05/12] arm64, acpi, numa: NUMA support based on SRAT and SLIT

[Matthias Brugger]

On 01/02/16 19:09, Robert Richter wrote:
> On 23.01.16 17:39:20, Hanjun Guo wrote:
>
> > @@ -385,10 +386,8 @@ void __init arm64_numa_init(void)
> >   {
> >   	int ret = -ENODEV;
> >
> > -#ifdef CONFIG_OF_NUMA
> >   	if (!numa_off)
> > -		ret = numa_init(arm64_of_numa_init);
> > -#endif
> > +		ret = numa_init(acpi_disabled ? arm64_of_numa_init : arm64_acpi_numa_init);
> >
> >   	if (ret)
> >   		numa_init(dummy_numa_init);
>
> Ok, this style is mostly flavor, some people want #ifdefs (my
> preference), some not. In any case it must build with or without the
> config option set. But first some words why I like #ifdefs:
>
>   * Code is easier to understand as you don't need to look at any other
>     location whether it is enabled or not.
>
>   * You can't break the build if the options are not set. Thus, you
>     also don't need to check if the function is implemented for the
>     unset case (valid for the coder and also the reviewer). This makes
>     things a lot easier.
>
>   * Total number of lines of code that needs to be implement is
>     smaller.
>
> However, if we don't ifdef the code, we need empty functions stubs in
> the header file for them.
>
> Also, the conditional assignment does not reduce the complexity of the
> paths. It just concentrates everything in a single line.
>
> How about the following (similar to x86)?
>
> ----
> 	if (!numa_off) {
> #ifdef CONFIG_ACPI_NUMA
> 		if (!numa_init(acpi_numa_init))
> 			return 0;
> #endif
> #ifdef CONFIG_OF_NUMA
> 		if (!numa_init(of_numa_init))
> 			return 0;
> #endif
> 	}
>
> 	return numa_init(dummy_numa_init);
> ----
>
> Pretty straight and nice.

And it solves a compilation error if CONFIG_ACPI is not set and 
therefore asm/acpi.h is not included in linux/acpi.h

Regards,
Matthias