Re: [RFC] An idea for general kernel post-processing automation in FreeBSD

On 5/25/23 13:42, Hans Petter Selasky wrote:
> On 5/25/23 12:57, Mark Millard wrote:
>> The pre-existing code expresses explicitly that no other
>> routine is allowed to have its own use of the mutex, a
>> design choice enforced by the compiler as things are
>> written. (The purpose of the limitation to block scope.)
>>
>> Your proposed change removes the compiler enforcement of
>> that design, allowing use of the mutex by other code in
>> mlx4_main.c without any notification by the compiler.
>>
>> Your proposal has a direction of being more fragile for
>> bad changes without having to be explicit in code updates
>> about the change of status.
> 
> Hi Mark,
> 
> Looking only at the mutex part alone, you are right, but not when also 
> considering the SYSINIT() part, as implemented in LinuxKPI currently.

To be more precise:

The static mutex can only be accessed from within the routine itself, 
when it is part of a block scope. That is expected.

However the static sysinit, which is also inside the block scope of the 
function, is accessed from _outside_ the function.
This might be viewed as a violation of the block scope limitation.

Therefore the DEFINE_MUTEX() should be outside the block scope, due to 
how it is implemented in the LinuxKPI currently.

--HPS

> 
> --HPS