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Date: Fri, 24 Jan 2025 12:02:38 +0100
From: Danilo Krummrich <dakr@kernel.org>
To: Lyude Paul <lyude@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
	=?iso-8859-1?Q?Ma=EDra?= Canal <mairacanal@riseup.net>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Miguel Ojeda <ojeda@kernel.org>,
	Alex Gaynor <alex.gaynor@gmail.com>,
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
	Benno Lossin <benno.lossin@proton.me>,
	Andreas Hindborg <a.hindborg@kernel.org>,
	Alice Ryhl <aliceryhl@google.com>, Trevor Gross <tmgross@umich.edu>
Subject: Re: [PATCH 2/2] rust/kernel: Add platform::ModuleDevice
Message-ID: <Z5NzTsm7Hw-OD4n5@pollux>
References: <20250122235340.2145383-1-lyude@redhat.com>
 <20250122235340.2145383-3-lyude@redhat.com>
 <2025012329-candied-walk-f57d@gregkh>
 <0bb7270e879ae3a40d4e5500f9a7992563a68d9f.camel@redhat.com>
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In-Reply-To: <0bb7270e879ae3a40d4e5500f9a7992563a68d9f.camel@redhat.com>

On Thu, Jan 23, 2025 at 07:33:28PM -0500, Lyude Paul wrote:
> On Thu, 2025-01-23 at 07:23 +0100, Greg Kroah-Hartman wrote:
> > On Wed, Jan 22, 2025 at 06:49:22PM -0500, Lyude Paul wrote:
> > 
> > And modules are code, not data.  Let's not start to even attempt to tie
> > lifetimes of device structures to module code, that way lies madness and
> > rolls back the work we did decades ago to split the two apart :)
> 
> To make sure I'm understanding you properly, by "are code not data" you're
> suggesting that resources (devices, driver registrations, etc.) should have
> their lifetime entirely managed by the kernel and not as part of the module
> data structure correct?

I think that's two different things.

Driver registrations are bound to the module lifetime and in Rust, where we have
a structure that represents the module lifetime, driver registrations are part
of the module structure. That's fine.

Device are more of a concern here, since they ideally orginate from real
hardware and hence shouldn't be bound to a module lifetime.

I think a virtual device would need to be an exception though. What else, if not
the module should define its lifetime?