Re: [PATCH v7 3/3] check-module-params: Introduce check-module-params.sh

[John Moon]

On 12/11/2023 11:41 PM, Christoph Hellwig wrote:
> On Mon, Dec 11, 2023 at 06:02:59PM -0800, John Moon wrote:
> > One part of maintaining backwards compatibility with older
> > userspace programs is avoiding changes to module parameters.
>
> Really?  I don't think module parameters are a UAPI in the traditional
> sense.  

Agreed, they're not UAPI in the traditional sense. But, we're trying to 
establish tooling to help the community stabilize all interfaces that 
cross the kernel <-> userspace boundary and module params do fall into 
that bucket.

> Now if you break a heavily used one you got to fix it, but
> applying strict stability guarantees on module options which are not
> availble to normal users or even normal programs doesn't make a whole
> lot of sense.

True, but unfortunately we don't have any heuristic to determine if a 
param is "heavily used". However, in this rev, we added the ability to 
parse the permissions of a module param, so we could add a filter which 
does not flag change/removal of params with 0{0,4,6}000 permissions.

It's also obviously fine if the community has no interest in the script. 
We just wanted to share it as we find it to be a useful supplement to 
our code reviews and thought maintainers may find it useful as well.

Cheers,
John