Re: [RFC PATCH 00/11] Rust null block driver

From: Jens Axboe <axboe@kernel.dk>
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: "Keith Busch" <kbusch@kernel.org>,
	"Bart Van Assche" <bvanassche@acm.org>,
	"Andreas Hindborg" <nmi@metaspace.dk>,
	"Christoph Hellwig" <hch@lst.de>,
	"Damien Le Moal" <Damien.LeMoal@wdc.com>,
	"Hannes Reinecke" <hare@suse.de>,
	lsf-pc@lists.linux-foundation.org,
	rust-for-linux@vger.kernel.org, linux-block@vger.kernel.org,
	"Matthew Wilcox" <willy@infradead.org>,
	"Miguel Ojeda" <ojeda@kernel.org>,
	"Alex Gaynor" <alex.gaynor@gmail.com>,
	"Wedson Almeida Filho" <wedsonaf@gmail.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Benno Lossin" <benno.lossin@proton.me>,
	"open list" <linux-kernel@vger.kernel.org>,
	gost.dev@samsung.com, "Daniel Vetter" <daniel@ffwll.ch>
Subject: Re: [RFC PATCH 00/11] Rust null block driver
Date: Thu, 4 May 2023 14:22:55 -0600	[thread overview]
Message-ID: <80ed2c0e-54db-777a-175b-1aa3ff776724@kernel.dk> (raw)
In-Reply-To: <CANiq72nAMH1SfGmPTEjGHfevbb9tMLN4W7gJ3nBpJcvkCEsZ4g@mail.gmail.com>

On 5/4/23 2:11?PM, Miguel Ojeda wrote:
> On Thu, May 4, 2023 at 9:02?PM Jens Axboe <axboe@kernel.dk> wrote:
>>
>> But back to the real question... This is obviously extra burden on
>> maintainers, and that needs to be sorted out first. Block drivers in
> 
> Regarding maintenance, something we have suggested in similar cases to
> other subsystems is that the author gets involved as a maintainer of,
> at least, the Rust abstractions/driver (possibly with a different
> `MAINTAINERS` entry).

Right, but that doesn't really solve the problem when the rust bindings
get in the way of changes that you are currently making. Or if you break
them inadvertently. I do see benefits to that approach, but it's no
panacea.

> Of course, that is still work for the existing maintainer(s), i.e.
> you, since coordination takes time. However, it can also be a nice way
> to learn Rust on the side, meanwhile things are getting upstreamed and
> discussed (I think Daniel, in Cc, is taking that approach).

This seems to assume that time is plentiful and we can just add more to
our plate, which isn't always true. While I'd love to do more rust and
get more familiar with it, the time still has to be there for that. I'm
actually typing this on a laptop with a rust gpu driver :-)

And this isn't just on me, there are other regular contributors and
reviewers that would need to be onboard with this.

> And it may also be a way for you to get an extra
> maintainer/reviewer/... later on for the C parts, too, even if Rust
> does not succeed.

That is certainly a win!

>> general are not super security sensitive, as it's mostly privileged code
>> and there's not a whole lot of user visibile API. And the stuff we do
>> have is reasonably basic. So what's the long term win of having rust
>> bindings? This is a legitimate question. I can see a lot of other more
>> user exposed subsystems being of higher interest here.
> 
> From the experience of other kernel maintainers/developers that are
> making the move, the advantages seem to be well worth it, even
> disregarding the security aspect, i.e. on the language side alone.

Each case is different though, different people and different schedules
and priorities. So while the above is promising, it's also just
annecdotal and doesn't necessarily apply to our case.

-- 
Jens Axboe