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rust: platform: fix unrestricted &mut platform::Device

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As by now, platform::Device is implemented as:

	#[derive(Clone)]
	pub struct Device(ARef<device::Device>);

This may be convenient, but has the implication that drivers can call
device methods that require a mutable reference concurrently at any
point of time.

Instead define platform::Device as

	pub struct Device<Ctx: DeviceContext = Normal>(
		Opaque<bindings::platform_dev>,
		PhantomData<Ctx>,
	);

and manually implement the AlwaysRefCounted trait.

With this we can implement methods that should only be called from
bus callbacks (such as probe()) for platform::Device<Core>. Consequently,
we make this type accessible in bus callbacks only.

Arbitrary references taken by the driver are still of type
ARef<platform::Device> and hence don't provide access to methods that are
reserved for bus callbacks.

Fixes: 683a63befc ("rust: platform: add basic platform device / driver abstractions")
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250314160932.100165-5-dakr@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Danilo Krummrich
2025-03-14 17:09:07 +01:00
committed by Greg Kroah-Hartman
parent 7b948a2af6
commit 4d320e30ee
2 changed files with 72 additions and 34 deletions
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11
samples/rust/rust_driver_platform.rs
View File

@@ -2,10 +2,10 @@
//! Rust Platform driver sample.
use kernel::{c_str, of, platform, prelude::*};
use kernel::{c_str, device::Core, of, platform, prelude::*, types::ARef};
struct SampleDriver {
pdev: platform::Device,
pdev: ARef<platform::Device>,
}
struct Info(u32);
@@ -21,14 +21,17 @@ impl platform::Driver for SampleDriver {
type IdInfo = Info;
const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
fn probe(pdev: &mut platform::Device, info: Option<&Self::IdInfo>) -> Result<Pin<KBox<Self>>> {
fn probe(
pdev: &platform::Device<Core>,
info: Option<&Self::IdInfo>,
) -> Result<Pin<KBox<Self>>> {
dev_dbg!(pdev.as_ref(), "Probe Rust Platform driver sample.\n");
if let Some(info) = info {
dev_info!(pdev.as_ref(), "Probed with info: '{}'.\n", info.0);
}
let drvdata = KBox::new(Self { pdev: pdev.clone() }, GFP_KERNEL)?;
let drvdata = KBox::new(Self { pdev: pdev.into() }, GFP_KERNEL)?;
Ok(drvdata.into())
}