Re: [PATCH 06/20] x86/msr: Standardize on 'u32' MSR indices in <asm/msr.h>

[Xin Li <xin@zytor.com>]

On Apr 9, 2025, at 11:41 PM, Ingo Molnar <mingo@kernel.org> wrote:
>> 
>> not worth it at all?
> 
> No:
> 
> - Using 'const' for input parameter pointers makes sense because it's
>   easy to have a bug like this in a utility function:
> 
>    obj_ptr->val = foo;
> 
>   this has a side effect on the calling context, spreading the local
>   rot, so to speak, corrupting the object not owned by this function.
> 
> - Using 'const' for non-pointer input parameters makes little sense,
>   because the worst a function can do is to corrupt it locally:
> 
>    val_high = foo;
> 
>   ... but this bug won't be able to spread via corrupting objects
>   through a pointer, any bug will be limited to that function.
> 
> So neither the kernel, nor any of the major libraries such as glibc
> will typically use const for non-pointer function parameters, outside
> of very specific exceptions that strengthen the rule.

Thanks for the explanation!