Re: [PATCH] x86/mm: declare static variable inside a function instead of global

[Andy Lutomirski]

On 6/18/22 03:11, Fanjun Kong wrote:
> Global variables are global capacity variables, unless they are
> shadowed, they are available to the entire program.

This is true in general, but:

> -static unsigned long memory_block_size_probed;

   ^^^^^^

So this isn't actually the case.

>   unsigned long memory_block_size_bytes(void)
>   {
> +	static unsigned long memory_block_size_probed;
> +
>   	if (!memory_block_size_probed)
>   		memory_block_size_probed = probe_memory_block_size();
>   

I'm sort of okay with the patch, but it's worth noting that, in C++, 
initialized function-scope static variables have quite surprising 
semantics, so this type of change isn't a pure win in my book.  (Yes, 
the kernel is C, not C++.  But C++ programmers may be nervous anyway.)