Re: [PATCH 0/6] Initial Rust V4L2 support

Willy Tarreau
2023-04-11T16:53:01Z

On Tue, Apr 11, 2023 at 04:13:36PM +0200, Miguel Ojeda wrote:
> On Tue, Apr 11, 2023 at 2:49 PM Willy Tarreau <w@1wt.eu> wrote:
> >
> > This might sound strange, but I suspect that having a TAINT_RUST flag
> > could possibly help maintainers that are already lacking time, because
> > it may quickly allow some of them to ask "please try again without the
> > Rust code to see if the problem is still there", just like happens with
> > out-of-tree code for which the knowledge is limited to null. This could
> > allow to route issue reports to one maintainer when an issue is confirmed
> > in both cases or to another one when it only happens in a single case.
> >
> > Of course it will not help with code reviews but we know that a great
> > part of maintainers' time it spent trying to analyse problem reports
> > that happen under vague conditions. All the time not spent debugging
> > something not well understood is more time available for reviews.
>
> You can already ask to disable `CONFIG_RUST`.
>
> In fact, we asked that a few times, when people reported a problem
> that looked unrelated to Rust, to confirm that was the case and thus
> redirect the report.
>
> So it is definitely a good idea to ask for that when you get a report
> with `RUST=y` and you suspect it may be related to that, especially in
> the beginning where `RUST=y` should not be common.

But if that code is only under a module, there's no need to turn all
that code off if it's sufficient to be certain the module was no loaded.
Plus it's more friendly to the user who doesn't have to rebuild a kernel,
just blacklist a module and check that the kernel doesn't get tainted
again.

> However, I think Rust in-tree code is different to out-of-tree code,
> since you do have the code, and thus (in general) you should be able
> to reproduce the build, and you can ask for help to the given
> maintainers to understand it.

It could depend on the layer where it plugs and the level of intimacy
with the core. Sometimes you need a deep understanding of all interactions
between elements to imagine possible scenarios.

Cheers,
Willy