Re: [PATCH v13 2/6] rust: introduce module_param module

[Andreas Hindborg <a.hindborg@kernel.org>]

"Benno Lossin" <lossin@kernel.org> writes:

> On Tue Jul 1, 2025 at 6:27 PM CEST, Miguel Ojeda wrote:
>> On Tue, Jul 1, 2025 at 5:43 PM Benno Lossin <lossin@kernel.org> wrote:
>>>
>>> Ultimately this is something for Miguel to decide.
>>
>> Only if you all cannot get to an agreement ;)
>
> :)
>
>> If Andreas wants to have it already added, then I would say just mark
>> it `unsafe` as Benno recommends (possibly with an overbearing
>> precondition), given it has proven subtle/forgettable enough and that,
>> if I understand correctly, it would actually become unsafe if someone
>> "just" added "reasonably-looking code" elsewhere.
>
> Yeah, if we added code that ran at the same time as the parameter
> parsing (such as custom parameter parsing or a way to start a "thread"
> before the parsing is completed) it would be a problem.

Guys, we are not going to accidentally add this. I do not think this is
a valid concern.

>
>> That way we have an incentive to make it safe later on and, more
>> importantly, to think again about it when such a patch lands,
>> justifying it properly. And it could plausibly protect out-of-tree
>> users, too.
>>
>> This is all assuming that we will not have many users of this added
>> right away (in a cycle or two), i.e. assuming it will be easy to
>> change callers later on (if only to remove the `unsafe {}`).
>
> Yeah we would add internal synchronization and could keep the API the
> same (except removing unsafe of course).

That is true. But I am not going to add an unsafe block to a driver just
to read module parameters. If we cannot reach agreement on merging this
with the `copy` access method, I would rather wait on a locking version.


Best regards,
Andreas Hindborg